逆さの池の作り方

# MIT License
#
# Copyright (c) 2026 Pyxel 100 contributors
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
# The bundled Noto-derived bitmap glyphs are separately licensed under SIL OFL.
# See assets/NOTO-LICENSE.txt.

"""逆さの池・教材 1/5：固定刻みで歩いて跳ぶ。Python 3.11+ / Pyxel 2.9.9。"""
from dataclasses import dataclass, replace, asdict
from math import hypot, isfinite
import hashlib, json
DT = 1 / 120
GRAVITY = 80.0
JUMP = 76.0
MAX_VX = 36.0
MAX_VY = 70.0
HX, HY = 3.0, 4.0
WATER = 64.0
EPS = 0.001

@dataclass(frozen=True)
class Level:
    name: str
    portals: tuple
    start: tuple

@dataclass(frozen=True)
class Input:
    move: int = 0
    jump: bool = False

@dataclass(frozen=True)
class State:
    x: float
    y: float
    vx: float = 0.
    vy: float = 0.
    gravity: int = 1
    grounded: bool = True
    time: float = 0.
    status: str = 'playing'

LEVELS = (Level('Practice bank', (), (42., 60.)),)
FLOOR = 60.

def initial(level):
    return State(*level.start)

def move_practice(x, y, vx, vy, dt):
    """Teaching-only endpoint clamp; no shelves and no swept collision."""
    x += vx * dt
    y += vy * dt
    normals = []
    if x < 7: x, vx = 7., 0.; normals.append((1, 0))
    if x > 185: x, vx = 185., 0.; normals.append((-1, 0))
    if y < 12: y, vy = 12., 0.; normals.append((0, 1))
    if y > FLOOR: y, vy = FLOOR, 0.; normals.append((0, -1))
    return x, y, vx, vy, tuple(normals)

def step(level, s, control=Input(), dt=DT):
    if s.status != 'playing': return s, ()
    if not (0 < dt <= 1/30): raise ValueError('Use a bounded fixed step')
    if not all(isfinite(v) for v in (s.x, s.y, s.vx, s.vy)):
        raise ValueError('Nonfinite state')
    move = max(-1, min(1, control.move))
    vx, vy, ground = s.vx, s.vy, s.grounded
    if move:
        vx = max(-MAX_VX, min(MAX_VX, vx + move * 100 * dt))
    else:
        drag = (120 if ground else 12) * dt
        vx = max(0, vx-drag) if vx > 0 else min(0, vx+drag)
    if control.jump and ground:
        vy = -s.gravity * JUMP
        ground = False
    vy += s.gravity * GRAVITY * dt
    if vy * s.gravity > MAX_VY: vy = s.gravity * MAX_VY
    x, y, vx, vy, normals = move_practice(s.x, s.y, vx, vy, dt)
    ground = any(ny == -s.gravity for _, ny in normals)
    return replace(s, x=x, y=y, vx=vx, vy=vy, grounded=ground, time=s.time+dt), ()

def frame(level, s, control=Input()):
    events = []
    for i in range(4):
        s, event = step(level, s, Input(control.move, control.jump and i == 0))
        events.extend(event)
    return s, tuple(events)

def state_hash(s):
    return hashlib.sha256(json.dumps(asdict(s), sort_keys=True, separators=(',', ':'), ensure_ascii=False).encode('utf-8')).hexdigest()


# The renderer and controls are shared scaffolding; the model above grows by stage.
STAGE = 1
DEMO_FRAMES = 90
KEYS = ('LEFT', 'RIGHT', 'SPACE', 'P', 'R', 'Z', 'N', '1', '2', '3')
DEMO_PLAN = ((14, 0, True), (82, 1, False), (20, 0, False))

class App:
    def __init__(self):
        self.level = 0
        self.state = initial(LEVELS[self.level])
        self.pause = False
        self.gate = 0
        self.undo_state = None
        self.trail = []
        self.demo_tick = 0

    def reset(self):
        self.state = initial(LEVELS[self.level])
        self.pause = False
        self.undo_state = None
        self.trail = []
        self.gate = 2

    def advance(self, control):
        before = self.state
        self.state, events = frame(LEVELS[self.level], self.state, control)
        for event in events: self.undo_state = event.before
        self.trail.append((self.state.x, self.state.y))
        self.trail = self.trail[-40:]
        if before.status != 'success' and self.state.status == 'success': self.gate = 2

    def control(self, pressed=(), held=()):
        # Two completely released updates prevent held keys leaking after a switch.
        if self.gate:
            self.gate = 2 if set(held).intersection(KEYS) else self.gate-1
            return
        if 'R' in pressed: self.reset(); return
        if STAGE == 5:
            for index in range(3):
                if str(index+1) in pressed:
                    self.level = index; self.reset(); return
        if 'P' in pressed:
            self.pause = not self.pause; self.gate = 2; return
        if self.pause: return
        if STAGE >= 4 and 'Z' in pressed:
            if self.undo_state is not None:
                self.state = self.undo_state; self.undo_state = None; self.trail = []
            self.gate = 2
            return
        if self.state.status == 'success':
            if STAGE == 5 and 'N' in pressed:
                self.level = (self.level+1) % len(LEVELS); self.reset()
            return
        self.advance(Input(int('RIGHT' in held)-int('LEFT' in held), 'SPACE' in pressed))

    def demo_update(self):
        tick = self.demo_tick
        self.demo_tick += 1
        if STAGE == 1:
            control = Input(1 if tick < 30 else 0, tick == 0)
        elif STAGE == 2:
            control = Input(1 if tick < 30 else 0)
        elif STAGE == 3:
            control = Input()
        else:
            control = Input()
            for count, move, jump in DEMO_PLAN:
                if tick < count:
                    control = Input(move, bool(jump and tick == 0)); break
                tick -= count
        held = ('RIGHT',) if control.move > 0 else ('LEFT',) if control.move < 0 else ()
        self.control(('SPACE',) if control.jump else (), held)

    def draw(self, p):
        s, level = self.state, LEVELS[self.level]
        p.cls(1)
        p.text(12, 10, '018 INVERTED POND / STAGE '+str(STAGE), 10)
        p.text(12, 24, ('PAUSED' if self.pause else s.status.upper())+'   TIME '+format(s.time, '.3f')+' s', 11)
        p.text(12, 38, 'X '+format(s.x, '.3f')+'  Y '+format(s.y, '.3f')+'  VX '+format(s.vx, '.2f')+'  VY '+format(s.vy, '.2f'), 7)
        p.text(12, 52, 'GRAVITY '+('DOWN' if s.gravity == 1 else 'UP')+'  CROSSES '+str(getattr(s, 'crossings', 0))+'  GROUNDED '+str(s.grounded), 10)
        if STAGE >= 3:
            p.text(12, 66, 'ARMED '+str(s.armed)+'  FLOATING '+str(s.floating), 6)
        ox, oy = 32, 82
        def xy(x, y): return ox+2*x, oy+2*y
        p.rect(ox, oy, 384, 256, 2)
        p.rect(ox, oy+128, 384, 128, 1)
        for x in range(4, 188, 12):
            p.line(*xy(x, 56), *xy(x+5, 56), 5)
            p.line(*xy(x, 72), *xy(x+5, 72), 5)
        p.text(ox+10, oy+20, 'WORLD 192 x 128 / +Y DOWN', 6)
        for x in range(4, 188):
            opened = STAGE >= 2 and any(a <= x < b for a, b in level.portals)
            if not opened: p.line(*xy(x, 63), *xy(x, 65), 6)
            elif x % 3 == 0: p.line(*xy(x, 64), *xy(x+1, 64), 12)
        p.rect(ox, oy, 8, 256, 5); p.rect(ox+376, oy, 8, 256, 5)
        p.rect(ox, oy, 384, 16, 5); p.rect(ox, oy+240, 384, 16, 5)
        if STAGE >= 4:
            for rock in level.rocks:
                x, y = xy(rock.x1, rock.y1)
                p.rect(x, y, (rock.x2-rock.x1)*2, (rock.y2-rock.y1)*2, 13)
                p.rectb(x, y, (rock.x2-rock.x1)*2, (rock.y2-rock.y1)*2, 7)
            hx, hy = xy(*level.start)
            p.rect(hx-9, hy-22, 18, 22, 4)
            p.tri(hx-13, hy-22, hx, hy-34, hx+13, hy-22, 9)
            if STAGE == 5:
                for name, ix, iy in level.items:
                    x, y = xy(ix, iy)
                    if name in s.collected: p.circb(x, y, 7, 5)
                    elif name == 'moon':
                        p.circ(x, y, 7, 10); p.circ(x+3, y-3, 6, 1)
                    else: p.tri(x-7, y+2, x+6, y-7, x+4, y+5, 11)
        for x, y in self.trail[::3]: p.pset(*xy(x, y), 6)
        x, y = xy(s.x, s.y); g = s.gravity
        p.rect(x-5, y-7, 11, 15, 7)
        p.rect(x-4, y-6*g-1, 9, 4, 12)
        p.pset(x-2, y-4*g, 1); p.pset(x+2, y-4*g, 1)
        p.line(x+14, y-7*g, x+14, y+8*g, 10)
        p.line(x+10, y+4*g, x+14, y+8*g, 10)
        p.line(x+18, y+4*g, x+14, y+8*g, 10)
        if getattr(s, 'floating', False): p.ellib(x-9, y-3, 19, 7, 12)
        messages = {1: 'ACCELERATION -> VELOCITY -> POSITION / FLAT BANK',
                    2: 'CROSS THE LINE: SAME POSITION, NEW GRAVITY',
                    3: 'DASHES = 8 px / FLOAT? SPACE TO JUMP OUT',
                    4: 'SWEPT BANKS + SHELF / Z UNDO LAST CROSS',
                    5: 'ROOM '+str(self.level+1)+' / ITEMS '+str(len(getattr(s, 'collected', ())))+'/'+str(len(getattr(level, 'items', ())))}
        p.text(12, 350, messages[STAGE], 10)
        p.text(12, 364, 'LEFT/RIGHT MOVE  SPACE JUMP  P PAUSE  R RESET', 7)
        p.text(12, 378, '1/2/3 ROOM  Z UNDO  N NEXT  ESC QUIT' if STAGE == 5 else 'MODEL 120 Hz / VIEW 30 FPS / ESC QUIT', 6)
        if s.status == 'success':
            p.rect(108, 176, 232, 38, 1); p.rectb(108, 176, 232, 38, 11)
            p.text(144, 193, 'SUCCESS / N NEXT ROOM', 11)
        elif self.pause:
            p.rect(144, 182, 160, 26, 1); p.text(160, 193, 'PAUSED / P RESUME', 10)


def parse_args(argv=None):
    """All QA arguments are bounded and validated before Pyxel is imported."""
    import argparse
    from pathlib import Path
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--headless-smoke', action='store_true')
    parser.add_argument('--demo-checkpoint', action='store_true')
    parser.add_argument('--frames', type=int)
    parser.add_argument('--screenshot')
    parser.add_argument('--state-output')
    args = parser.parse_args(argv)
    if not args.headless_smoke and (args.demo_checkpoint or args.frames is not None or args.screenshot or args.state_output):
        parser.error('QA options require --headless-smoke')
    minimum = DEMO_FRAMES if args.demo_checkpoint else 4
    if args.frames is None: args.frames = minimum
    if not minimum <= args.frames <= 600:
        parser.error('--frames must be between '+str(minimum)+' and 600')
    for name, suffix in (('screenshot', '.png'), ('state_output', '.json')):
        value = getattr(args, name)
        if value is not None and (not value.strip() or Path(value).suffix.lower() != suffix):
            parser.error('--'+name.replace('_', '-')+' requires a '+suffix+' file path')
    return args


def main(argv=None):
    args = parse_args(argv)
    from pathlib import Path
    import pyxel as p
    app = App()
    p.init(448, 400, title='018 Inverted Pond', fps=30, display_scale=2, headless=args.headless_smoke)
    keys = {name: getattr(p, 'KEY_'+name) for name in KEYS}
    finished = False
    def update():
        if args.headless_smoke:
            if args.demo_checkpoint and p.frame_count < DEMO_FRAMES: app.demo_update()
        else:
            app.control({name for name, key in keys.items() if p.btnp(key)},
                        {name for name, key in keys.items() if p.btn(key)})
    def draw():
        nonlocal finished
        app.draw(p)
        if args.headless_smoke and p.frame_count >= args.frames-1 and not finished:
            finished = True
            for name in ('screenshot', 'state_output'):
                value = getattr(args, name)
                if value:
                    path = Path(value).resolve(); path.parent.mkdir(parents=True, exist_ok=True)
                    if name == 'screenshot': p.screenshot(str(path), scale=2)
                    else: path.write_text(json.dumps(asdict(app.state), ensure_ascii=False, indent=2)+'\n', encoding='utf-8')
            p.quit()
    p.run(update, draw)

if __name__ == '__main__':
    main()

# MIT License
#
# Copyright (c) 2026 Pyxel 100 contributors
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
# The bundled Noto-derived bitmap glyphs are separately licensed under SIL OFL.
# See assets/NOTO-LICENSE.txt.

"""逆さの池・教材 2/5：位置を変換せず重力を反転。Python 3.11+ / Pyxel 2.9.9。"""
from dataclasses import dataclass, replace, asdict
from math import hypot, isfinite
import hashlib, json
DT = 1 / 120
GRAVITY = 80.0
JUMP = 76.0
MAX_VX = 36.0
MAX_VY = 70.0
HX, HY = 3.0, 4.0
WATER = 64.0
EPS = 0.001

@dataclass(frozen=True)
class Level:
    name: str
    portals: tuple
    start: tuple

@dataclass(frozen=True)
class Input:
    move: int = 0
    jump: bool = False

@dataclass(frozen=True)
class State:
    x: float
    y: float
    vx: float = 0.
    vy: float = 0.
    gravity: int = 1
    grounded: bool = True
    time: float = 0.
    status: str = 'playing'
    crossings: int = 0

@dataclass(frozen=True)
class Event:
    kind: str
    before: State
    x: float
    y: float

LEVELS = (Level('Open practice pond', ((4, 188),), (90., 40.)),)
FLOOR = 116.

def initial(level):
    return State(*level.start, grounded=False)

def move_practice(x, y, vx, vy, dt):
    """Teaching-only endpoint clamp; no shelves and no swept collision."""
    x += vx * dt
    y += vy * dt
    normals = []
    if x < 7: x, vx = 7., 0.; normals.append((1, 0))
    if x > 185: x, vx = 185., 0.; normals.append((-1, 0))
    if y < 12: y, vy = 12., 0.; normals.append((0, 1))
    if y > FLOOR: y, vy = FLOOR, 0.; normals.append((0, -1))
    return x, y, vx, vy, tuple(normals)

def step(level, s, control=Input(), dt=DT):
    if s.status != 'playing': return s, ()
    if not (0 < dt <= 1/30): raise ValueError('Use a bounded fixed step')
    if not all(isfinite(v) for v in (s.x, s.y, s.vx, s.vy)):
        raise ValueError('Nonfinite state')
    move = max(-1, min(1, control.move))
    vx, vy, ground = s.vx, s.vy, s.grounded
    if move:
        vx = max(-MAX_VX, min(MAX_VX, vx + move * 100 * dt))
    else:
        drag = (120 if ground else 12) * dt
        vx = max(0, vx-drag) if vx > 0 else min(0, vx+drag)
    if control.jump and ground:
        vy = -s.gravity * JUMP
        ground = False
    vy += s.gravity * GRAVITY * dt
    if vy * s.gravity > MAX_VY: vy = s.gravity * MAX_VY
    x, y, vx, vy, normals = move_practice(s.x, s.y, vx, vy, dt)
    gravity, crossings, events = s.gravity, s.crossings, []
    crosses = (s.y < WATER <= y and s.gravity == 1) or (s.y > WATER >= y and s.gravity == -1)
    if crosses:
        t = (WATER-s.y) / (y-s.y)
        cx = s.x + (x-s.x) * t
        gravity = -s.gravity
        crossings += 1
        events.append(Event('cross', s, cx, WATER))
        rem = dt * (1-t)
        vy += 2 * gravity * GRAVITY * rem
        x, y, vx, vy, after = move_practice(cx, WATER, vx, vy, rem)
        normals += after
    ground = any(ny == -gravity for _, ny in normals)
    return replace(s, x=x, y=y, vx=vx, vy=vy, gravity=gravity, grounded=ground,
                   crossings=crossings, time=s.time+dt), tuple(events)

def frame(level, s, control=Input()):
    events = []
    for i in range(4):
        s, event = step(level, s, Input(control.move, control.jump and i == 0))
        events.extend(event)
    return s, tuple(events)

def state_hash(s):
    return hashlib.sha256(json.dumps(asdict(s), sort_keys=True, separators=(',', ':'), ensure_ascii=False).encode('utf-8')).hexdigest()


# The renderer and controls are shared scaffolding; the model above grows by stage.
STAGE = 2
DEMO_FRAMES = 90
KEYS = ('LEFT', 'RIGHT', 'SPACE', 'P', 'R', 'Z', 'N', '1', '2', '3')
DEMO_PLAN = ((14, 0, True), (82, 1, False), (20, 0, False))

class App:
    def __init__(self):
        self.level = 0
        self.state = initial(LEVELS[self.level])
        self.pause = False
        self.gate = 0
        self.undo_state = None
        self.trail = []
        self.demo_tick = 0

    def reset(self):
        self.state = initial(LEVELS[self.level])
        self.pause = False
        self.undo_state = None
        self.trail = []
        self.gate = 2

    def advance(self, control):
        before = self.state
        self.state, events = frame(LEVELS[self.level], self.state, control)
        for event in events: self.undo_state = event.before
        self.trail.append((self.state.x, self.state.y))
        self.trail = self.trail[-40:]
        if before.status != 'success' and self.state.status == 'success': self.gate = 2

    def control(self, pressed=(), held=()):
        # Two completely released updates prevent held keys leaking after a switch.
        if self.gate:
            self.gate = 2 if set(held).intersection(KEYS) else self.gate-1
            return
        if 'R' in pressed: self.reset(); return
        if STAGE == 5:
            for index in range(3):
                if str(index+1) in pressed:
                    self.level = index; self.reset(); return
        if 'P' in pressed:
            self.pause = not self.pause; self.gate = 2; return
        if self.pause: return
        if STAGE >= 4 and 'Z' in pressed:
            if self.undo_state is not None:
                self.state = self.undo_state; self.undo_state = None; self.trail = []
            self.gate = 2
            return
        if self.state.status == 'success':
            if STAGE == 5 and 'N' in pressed:
                self.level = (self.level+1) % len(LEVELS); self.reset()
            return
        self.advance(Input(int('RIGHT' in held)-int('LEFT' in held), 'SPACE' in pressed))

    def demo_update(self):
        tick = self.demo_tick
        self.demo_tick += 1
        if STAGE == 1:
            control = Input(1 if tick < 30 else 0, tick == 0)
        elif STAGE == 2:
            control = Input(1 if tick < 30 else 0)
        elif STAGE == 3:
            control = Input()
        else:
            control = Input()
            for count, move, jump in DEMO_PLAN:
                if tick < count:
                    control = Input(move, bool(jump and tick == 0)); break
                tick -= count
        held = ('RIGHT',) if control.move > 0 else ('LEFT',) if control.move < 0 else ()
        self.control(('SPACE',) if control.jump else (), held)

    def draw(self, p):
        s, level = self.state, LEVELS[self.level]
        p.cls(1)
        p.text(12, 10, '018 INVERTED POND / STAGE '+str(STAGE), 10)
        p.text(12, 24, ('PAUSED' if self.pause else s.status.upper())+'   TIME '+format(s.time, '.3f')+' s', 11)
        p.text(12, 38, 'X '+format(s.x, '.3f')+'  Y '+format(s.y, '.3f')+'  VX '+format(s.vx, '.2f')+'  VY '+format(s.vy, '.2f'), 7)
        p.text(12, 52, 'GRAVITY '+('DOWN' if s.gravity == 1 else 'UP')+'  CROSSES '+str(getattr(s, 'crossings', 0))+'  GROUNDED '+str(s.grounded), 10)
        if STAGE >= 3:
            p.text(12, 66, 'ARMED '+str(s.armed)+'  FLOATING '+str(s.floating), 6)
        ox, oy = 32, 82
        def xy(x, y): return ox+2*x, oy+2*y
        p.rect(ox, oy, 384, 256, 2)
        p.rect(ox, oy+128, 384, 128, 1)
        for x in range(4, 188, 12):
            p.line(*xy(x, 56), *xy(x+5, 56), 5)
            p.line(*xy(x, 72), *xy(x+5, 72), 5)
        p.text(ox+10, oy+20, 'WORLD 192 x 128 / +Y DOWN', 6)
        for x in range(4, 188):
            opened = STAGE >= 2 and any(a <= x < b for a, b in level.portals)
            if not opened: p.line(*xy(x, 63), *xy(x, 65), 6)
            elif x % 3 == 0: p.line(*xy(x, 64), *xy(x+1, 64), 12)
        p.rect(ox, oy, 8, 256, 5); p.rect(ox+376, oy, 8, 256, 5)
        p.rect(ox, oy, 384, 16, 5); p.rect(ox, oy+240, 384, 16, 5)
        if STAGE >= 4:
            for rock in level.rocks:
                x, y = xy(rock.x1, rock.y1)
                p.rect(x, y, (rock.x2-rock.x1)*2, (rock.y2-rock.y1)*2, 13)
                p.rectb(x, y, (rock.x2-rock.x1)*2, (rock.y2-rock.y1)*2, 7)
            hx, hy = xy(*level.start)
            p.rect(hx-9, hy-22, 18, 22, 4)
            p.tri(hx-13, hy-22, hx, hy-34, hx+13, hy-22, 9)
            if STAGE == 5:
                for name, ix, iy in level.items:
                    x, y = xy(ix, iy)
                    if name in s.collected: p.circb(x, y, 7, 5)
                    elif name == 'moon':
                        p.circ(x, y, 7, 10); p.circ(x+3, y-3, 6, 1)
                    else: p.tri(x-7, y+2, x+6, y-7, x+4, y+5, 11)
        for x, y in self.trail[::3]: p.pset(*xy(x, y), 6)
        x, y = xy(s.x, s.y); g = s.gravity
        p.rect(x-5, y-7, 11, 15, 7)
        p.rect(x-4, y-6*g-1, 9, 4, 12)
        p.pset(x-2, y-4*g, 1); p.pset(x+2, y-4*g, 1)
        p.line(x+14, y-7*g, x+14, y+8*g, 10)
        p.line(x+10, y+4*g, x+14, y+8*g, 10)
        p.line(x+18, y+4*g, x+14, y+8*g, 10)
        if getattr(s, 'floating', False): p.ellib(x-9, y-3, 19, 7, 12)
        messages = {1: 'ACCELERATION -> VELOCITY -> POSITION / FLAT BANK',
                    2: 'CROSS THE LINE: SAME POSITION, NEW GRAVITY',
                    3: 'DASHES = 8 px / FLOAT? SPACE TO JUMP OUT',
                    4: 'SWEPT BANKS + SHELF / Z UNDO LAST CROSS',
                    5: 'ROOM '+str(self.level+1)+' / ITEMS '+str(len(getattr(s, 'collected', ())))+'/'+str(len(getattr(level, 'items', ())))}
        p.text(12, 350, messages[STAGE], 10)
        p.text(12, 364, 'LEFT/RIGHT MOVE  SPACE JUMP  P PAUSE  R RESET', 7)
        p.text(12, 378, '1/2/3 ROOM  Z UNDO  N NEXT  ESC QUIT' if STAGE == 5 else 'MODEL 120 Hz / VIEW 30 FPS / ESC QUIT', 6)
        if s.status == 'success':
            p.rect(108, 176, 232, 38, 1); p.rectb(108, 176, 232, 38, 11)
            p.text(144, 193, 'SUCCESS / N NEXT ROOM', 11)
        elif self.pause:
            p.rect(144, 182, 160, 26, 1); p.text(160, 193, 'PAUSED / P RESUME', 10)


def parse_args(argv=None):
    """All QA arguments are bounded and validated before Pyxel is imported."""
    import argparse
    from pathlib import Path
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--headless-smoke', action='store_true')
    parser.add_argument('--demo-checkpoint', action='store_true')
    parser.add_argument('--frames', type=int)
    parser.add_argument('--screenshot')
    parser.add_argument('--state-output')
    args = parser.parse_args(argv)
    if not args.headless_smoke and (args.demo_checkpoint or args.frames is not None or args.screenshot or args.state_output):
        parser.error('QA options require --headless-smoke')
    minimum = DEMO_FRAMES if args.demo_checkpoint else 4
    if args.frames is None: args.frames = minimum
    if not minimum <= args.frames <= 600:
        parser.error('--frames must be between '+str(minimum)+' and 600')
    for name, suffix in (('screenshot', '.png'), ('state_output', '.json')):
        value = getattr(args, name)
        if value is not None and (not value.strip() or Path(value).suffix.lower() != suffix):
            parser.error('--'+name.replace('_', '-')+' requires a '+suffix+' file path')
    return args


def main(argv=None):
    args = parse_args(argv)
    from pathlib import Path
    import pyxel as p
    app = App()
    p.init(448, 400, title='018 Inverted Pond', fps=30, display_scale=2, headless=args.headless_smoke)
    keys = {name: getattr(p, 'KEY_'+name) for name in KEYS}
    finished = False
    def update():
        if args.headless_smoke:
            if args.demo_checkpoint and p.frame_count < DEMO_FRAMES: app.demo_update()
        else:
            app.control({name for name, key in keys.items() if p.btnp(key)},
                        {name for name, key in keys.items() if p.btn(key)})
    def draw():
        nonlocal finished
        app.draw(p)
        if args.headless_smoke and p.frame_count >= args.frames-1 and not finished:
            finished = True
            for name in ('screenshot', 'state_output'):
                value = getattr(args, name)
                if value:
                    path = Path(value).resolve(); path.parent.mkdir(parents=True, exist_ok=True)
                    if name == 'screenshot': p.screenshot(str(path), scale=2)
                    else: path.write_text(json.dumps(asdict(app.state), ensure_ascii=False, indent=2)+'\n', encoding='utf-8')
            p.quit()
    p.run(update, draw)

if __name__ == '__main__':
    main()

# MIT License
#
# Copyright (c) 2026 Pyxel 100 contributors
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
# The bundled Noto-derived bitmap glyphs are separately licensed under SIL OFL.
# See assets/NOTO-LICENSE.txt.

"""逆さの池・教材 3/5：再装填と浅い水面の静止。Python 3.11+ / Pyxel 2.9.9。"""
from dataclasses import dataclass, replace, asdict
from math import hypot, isfinite
import hashlib, json
DT = 1 / 120
GRAVITY = 80.0
JUMP = 76.0
MAX_VX = 36.0
MAX_VY = 70.0
HX, HY = 3.0, 4.0
WATER = 64.0
EPS = 0.001

@dataclass(frozen=True)
class Level:
    name: str
    portals: tuple
    start: tuple

@dataclass(frozen=True)
class Input:
    move: int = 0
    jump: bool = False

@dataclass(frozen=True)
class State:
    x: float
    y: float
    vx: float = 0.
    vy: float = 0.
    gravity: int = 1
    grounded: bool = True
    time: float = 0.
    status: str = 'playing'
    crossings: int = 0
    armed: bool = True
    floating: bool = False

@dataclass(frozen=True)
class Event:
    kind: str
    before: State
    x: float
    y: float

LEVELS = (Level('Open practice pond', ((4, 188),), (90., 60.)),)
FLOOR = 116.

def initial(level):
    return State(*level.start, grounded=False)

def move_practice(x, y, vx, vy, dt):
    """Teaching-only endpoint clamp; no shelves and no swept collision."""
    x += vx * dt
    y += vy * dt
    normals = []
    if x < 7: x, vx = 7., 0.; normals.append((1, 0))
    if x > 185: x, vx = 185., 0.; normals.append((-1, 0))
    if y < 12: y, vy = 12., 0.; normals.append((0, 1))
    if y > FLOOR: y, vy = FLOOR, 0.; normals.append((0, -1))
    return x, y, vx, vy, tuple(normals)

def step(level, s, control=Input(), dt=DT):
    if s.status != 'playing': return s, ()
    if not (0 < dt <= 1/30): raise ValueError('Use a bounded fixed step')
    if not all(isfinite(v) for v in (s.x, s.y, s.vx, s.vy)):
        raise ValueError('Nonfinite state')
    move = max(-1, min(1, control.move))
    vx, vy, ground = s.vx, s.vy, s.grounded
    if move:
        vx = max(-MAX_VX, min(MAX_VX, vx + move * 100 * dt))
    else:
        drag = (120 if ground else 12) * dt
        vx = max(0, vx-drag) if vx > 0 else min(0, vx+drag)
    floating = s.floating
    if control.jump and ground:
        vy = -s.gravity * JUMP
        ground = False
        floating = False
    elif floating:
        x, y, vx, _, _ = move_practice(s.x, s.y, vx, 0, dt)
        return replace(s, x=x, vx=vx, vy=0, time=s.time+dt), ()
    vy += s.gravity * GRAVITY * dt
    if vy * s.gravity > MAX_VY: vy = s.gravity * MAX_VY
    x, y, vx, vy, normals = move_practice(s.x, s.y, vx, vy, dt)
    gravity, armed, crossings, events = s.gravity, s.armed, s.crossings, []
    if abs(s.y-WATER) >= 8-EPS: armed = True
    crosses = (s.y < WATER <= y and s.gravity == 1) or (s.y > WATER >= y and s.gravity == -1)
    if crosses:
        t = (WATER-s.y) / (y-s.y)
        cx = s.x + (x-s.x) * t
        if armed:
            gravity = -s.gravity
            crossings += 1
            armed = False
            events.append(Event('cross', s, cx, WATER))
            if vy * vy / (2 * GRAVITY) < 8:
                x, y, vy = cx, WATER, 0
                floating, ground = True, True
            else:
                rem = dt * (1-t)
                vy += 2 * gravity * GRAVITY * rem
                x, y, vx, vy, after = move_practice(cx, WATER, vx, vy, rem)
                normals += after
        else:
            x, y, vy = cx, WATER, 0
            floating, ground = True, True
    elif not armed and ((s.gravity == -1 and s.y >= WATER and y < WATER) or (s.gravity == 1 and s.y <= WATER and y > WATER)):
        t = (WATER-s.y) / (y-s.y) if y != s.y else 0
        x, y, vy = s.x+(x-s.x)*t, WATER, 0
        floating, ground = True, True
    if not floating: ground = any(ny == -gravity for _, ny in normals)
    return replace(s, x=x, y=y, vx=vx, vy=vy, gravity=gravity, grounded=ground,
                   crossings=crossings, armed=armed, floating=floating,
                   time=s.time+dt), tuple(events)

def frame(level, s, control=Input()):
    events = []
    for i in range(4):
        s, event = step(level, s, Input(control.move, control.jump and i == 0))
        events.extend(event)
    return s, tuple(events)

def state_hash(s):
    return hashlib.sha256(json.dumps(asdict(s), sort_keys=True, separators=(',', ':'), ensure_ascii=False).encode('utf-8')).hexdigest()


# The renderer and controls are shared scaffolding; the model above grows by stage.
STAGE = 3
DEMO_FRAMES = 90
KEYS = ('LEFT', 'RIGHT', 'SPACE', 'P', 'R', 'Z', 'N', '1', '2', '3')
DEMO_PLAN = ((14, 0, True), (82, 1, False), (20, 0, False))

class App:
    def __init__(self):
        self.level = 0
        self.state = initial(LEVELS[self.level])
        self.pause = False
        self.gate = 0
        self.undo_state = None
        self.trail = []
        self.demo_tick = 0

    def reset(self):
        self.state = initial(LEVELS[self.level])
        self.pause = False
        self.undo_state = None
        self.trail = []
        self.gate = 2

    def advance(self, control):
        before = self.state
        self.state, events = frame(LEVELS[self.level], self.state, control)
        for event in events: self.undo_state = event.before
        self.trail.append((self.state.x, self.state.y))
        self.trail = self.trail[-40:]
        if before.status != 'success' and self.state.status == 'success': self.gate = 2

    def control(self, pressed=(), held=()):
        # Two completely released updates prevent held keys leaking after a switch.
        if self.gate:
            self.gate = 2 if set(held).intersection(KEYS) else self.gate-1
            return
        if 'R' in pressed: self.reset(); return
        if STAGE == 5:
            for index in range(3):
                if str(index+1) in pressed:
                    self.level = index; self.reset(); return
        if 'P' in pressed:
            self.pause = not self.pause; self.gate = 2; return
        if self.pause: return
        if STAGE >= 4 and 'Z' in pressed:
            if self.undo_state is not None:
                self.state = self.undo_state; self.undo_state = None; self.trail = []
            self.gate = 2
            return
        if self.state.status == 'success':
            if STAGE == 5 and 'N' in pressed:
                self.level = (self.level+1) % len(LEVELS); self.reset()
            return
        self.advance(Input(int('RIGHT' in held)-int('LEFT' in held), 'SPACE' in pressed))

    def demo_update(self):
        tick = self.demo_tick
        self.demo_tick += 1
        if STAGE == 1:
            control = Input(1 if tick < 30 else 0, tick == 0)
        elif STAGE == 2:
            control = Input(1 if tick < 30 else 0)
        elif STAGE == 3:
            control = Input()
        else:
            control = Input()
            for count, move, jump in DEMO_PLAN:
                if tick < count:
                    control = Input(move, bool(jump and tick == 0)); break
                tick -= count
        held = ('RIGHT',) if control.move > 0 else ('LEFT',) if control.move < 0 else ()
        self.control(('SPACE',) if control.jump else (), held)

    def draw(self, p):
        s, level = self.state, LEVELS[self.level]
        p.cls(1)
        p.text(12, 10, '018 INVERTED POND / STAGE '+str(STAGE), 10)
        p.text(12, 24, ('PAUSED' if self.pause else s.status.upper())+'   TIME '+format(s.time, '.3f')+' s', 11)
        p.text(12, 38, 'X '+format(s.x, '.3f')+'  Y '+format(s.y, '.3f')+'  VX '+format(s.vx, '.2f')+'  VY '+format(s.vy, '.2f'), 7)
        p.text(12, 52, 'GRAVITY '+('DOWN' if s.gravity == 1 else 'UP')+'  CROSSES '+str(getattr(s, 'crossings', 0))+'  GROUNDED '+str(s.grounded), 10)
        if STAGE >= 3:
            p.text(12, 66, 'ARMED '+str(s.armed)+'  FLOATING '+str(s.floating), 6)
        ox, oy = 32, 82
        def xy(x, y): return ox+2*x, oy+2*y
        p.rect(ox, oy, 384, 256, 2)
        p.rect(ox, oy+128, 384, 128, 1)
        for x in range(4, 188, 12):
            p.line(*xy(x, 56), *xy(x+5, 56), 5)
            p.line(*xy(x, 72), *xy(x+5, 72), 5)
        p.text(ox+10, oy+20, 'WORLD 192 x 128 / +Y DOWN', 6)
        for x in range(4, 188):
            opened = STAGE >= 2 and any(a <= x < b for a, b in level.portals)
            if not opened: p.line(*xy(x, 63), *xy(x, 65), 6)
            elif x % 3 == 0: p.line(*xy(x, 64), *xy(x+1, 64), 12)
        p.rect(ox, oy, 8, 256, 5); p.rect(ox+376, oy, 8, 256, 5)
        p.rect(ox, oy, 384, 16, 5); p.rect(ox, oy+240, 384, 16, 5)
        if STAGE >= 4:
            for rock in level.rocks:
                x, y = xy(rock.x1, rock.y1)
                p.rect(x, y, (rock.x2-rock.x1)*2, (rock.y2-rock.y1)*2, 13)
                p.rectb(x, y, (rock.x2-rock.x1)*2, (rock.y2-rock.y1)*2, 7)
            hx, hy = xy(*level.start)
            p.rect(hx-9, hy-22, 18, 22, 4)
            p.tri(hx-13, hy-22, hx, hy-34, hx+13, hy-22, 9)
            if STAGE == 5:
                for name, ix, iy in level.items:
                    x, y = xy(ix, iy)
                    if name in s.collected: p.circb(x, y, 7, 5)
                    elif name == 'moon':
                        p.circ(x, y, 7, 10); p.circ(x+3, y-3, 6, 1)
                    else: p.tri(x-7, y+2, x+6, y-7, x+4, y+5, 11)
        for x, y in self.trail[::3]: p.pset(*xy(x, y), 6)
        x, y = xy(s.x, s.y); g = s.gravity
        p.rect(x-5, y-7, 11, 15, 7)
        p.rect(x-4, y-6*g-1, 9, 4, 12)
        p.pset(x-2, y-4*g, 1); p.pset(x+2, y-4*g, 1)
        p.line(x+14, y-7*g, x+14, y+8*g, 10)
        p.line(x+10, y+4*g, x+14, y+8*g, 10)
        p.line(x+18, y+4*g, x+14, y+8*g, 10)
        if getattr(s, 'floating', False): p.ellib(x-9, y-3, 19, 7, 12)
        messages = {1: 'ACCELERATION -> VELOCITY -> POSITION / FLAT BANK',
                    2: 'CROSS THE LINE: SAME POSITION, NEW GRAVITY',
                    3: 'DASHES = 8 px / FLOAT? SPACE TO JUMP OUT',
                    4: 'SWEPT BANKS + SHELF / Z UNDO LAST CROSS',
                    5: 'ROOM '+str(self.level+1)+' / ITEMS '+str(len(getattr(s, 'collected', ())))+'/'+str(len(getattr(level, 'items', ())))}
        p.text(12, 350, messages[STAGE], 10)
        p.text(12, 364, 'LEFT/RIGHT MOVE  SPACE JUMP  P PAUSE  R RESET', 7)
        p.text(12, 378, '1/2/3 ROOM  Z UNDO  N NEXT  ESC QUIT' if STAGE == 5 else 'MODEL 120 Hz / VIEW 30 FPS / ESC QUIT', 6)
        if s.status == 'success':
            p.rect(108, 176, 232, 38, 1); p.rectb(108, 176, 232, 38, 11)
            p.text(144, 193, 'SUCCESS / N NEXT ROOM', 11)
        elif self.pause:
            p.rect(144, 182, 160, 26, 1); p.text(160, 193, 'PAUSED / P RESUME', 10)


def parse_args(argv=None):
    """All QA arguments are bounded and validated before Pyxel is imported."""
    import argparse
    from pathlib import Path
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--headless-smoke', action='store_true')
    parser.add_argument('--demo-checkpoint', action='store_true')
    parser.add_argument('--frames', type=int)
    parser.add_argument('--screenshot')
    parser.add_argument('--state-output')
    args = parser.parse_args(argv)
    if not args.headless_smoke and (args.demo_checkpoint or args.frames is not None or args.screenshot or args.state_output):
        parser.error('QA options require --headless-smoke')
    minimum = DEMO_FRAMES if args.demo_checkpoint else 4
    if args.frames is None: args.frames = minimum
    if not minimum <= args.frames <= 600:
        parser.error('--frames must be between '+str(minimum)+' and 600')
    for name, suffix in (('screenshot', '.png'), ('state_output', '.json')):
        value = getattr(args, name)
        if value is not None and (not value.strip() or Path(value).suffix.lower() != suffix):
            parser.error('--'+name.replace('_', '-')+' requires a '+suffix+' file path')
    return args


def main(argv=None):
    args = parse_args(argv)
    from pathlib import Path
    import pyxel as p
    app = App()
    p.init(448, 400, title='018 Inverted Pond', fps=30, display_scale=2, headless=args.headless_smoke)
    keys = {name: getattr(p, 'KEY_'+name) for name in KEYS}
    finished = False
    def update():
        if args.headless_smoke:
            if args.demo_checkpoint and p.frame_count < DEMO_FRAMES: app.demo_update()
        else:
            app.control({name for name, key in keys.items() if p.btnp(key)},
                        {name for name, key in keys.items() if p.btn(key)})
    def draw():
        nonlocal finished
        app.draw(p)
        if args.headless_smoke and p.frame_count >= args.frames-1 and not finished:
            finished = True
            for name in ('screenshot', 'state_output'):
                value = getattr(args, name)
                if value:
                    path = Path(value).resolve(); path.parent.mkdir(parents=True, exist_ok=True)
                    if name == 'screenshot': p.screenshot(str(path), scale=2)
                    else: path.write_text(json.dumps(asdict(app.state), ensure_ascii=False, indent=2)+'\n', encoding='utf-8')
            p.quit()
    p.run(update, draw)

if __name__ == '__main__':
    main()

# MIT License
#
# Copyright (c) 2026 Pyxel 100 contributors
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
# The bundled Noto-derived bitmap glyphs are separately licensed under SIL OFL.
# See assets/NOTO-LICENSE.txt.

"""逆さの池・教材 4/5：岸と棚の最初の衝突。Python 3.11+ / Pyxel 2.9.9。"""
"""Continuous position, fixed-step inversion platformer; standard library only.
Units: pixels and seconds. The water changes gravity, never world coordinates.
"""
from dataclasses import dataclass, replace, asdict
from math import inf, hypot, isfinite
import hashlib, json
DT=1/120
GRAVITY=80.0
JUMP=76.0
MAX_VX=36.0
MAX_VY=70.0
HX,HY=3.0,4.0
WATER=64.0
EPS=0.001

@dataclass(frozen=True)
class Rect:
    x1: float; y1: float; x2: float; y2: float
    name: str='rock'
@dataclass(frozen=True)
class Level:
    name: str
    portals: tuple
    rocks: tuple
    start: tuple
    items: tuple
    return_home: bool=True
    home_gravity: int=1

LEVELS=(Level('裏側の月',((72,112),),(Rect(116,84,148,88),),(42,60),(),False),)

@dataclass(frozen=True)
class State:
    x: float; y: float
    vx: float=0.; vy: float=0.
    gravity: int=1
    grounded: bool=True
    armed: bool=True
    floating: bool=False
    collected: tuple=()
    crossings: int=0
    distance: float=0.
    time: float=0.
    status: str='playing'
    checkpoint: tuple=(42.,60.,1)
    falls: int=0
    message: str=''

@dataclass(frozen=True)
class Input:
    move: int=0
    jump: bool=False

@dataclass(frozen=True)
class Event:
    kind: str
    before: State
    x: float
    y: float


def initial(level):
    return State(*level.start,gravity=level.home_gravity,checkpoint=(*level.start,level.home_gravity))

def solid_rects(level):
    banks=[];last=4
    for a,b in level.portals:
        if a>last:banks.append(Rect(last,64,last+(a-last),64,'bank'))
        last=b
    if last<188:banks.append(Rect(last,64,188,64,'bank'))
    # Top and bottom are visible safety stone, not offscreen landing surfaces.
    return tuple(banks)+level.rocks+(Rect(0,0,4,128,'edge'),Rect(188,0,192,128,'edge'),Rect(4,0,188,8,'edge'),Rect(4,120,188,128,'edge'))

def portal_at(level,x):
    return any(a+HX+EPS<x<b-HX-EPS for a,b in level.portals)

def sweep(x,y,dx,dy,rect):
    """Ray vs Minkowski-expanded rectangle. Tangential contacts do not block."""
    lo=(rect.x1-HX,rect.y1-HY);hi=(rect.x2+HX,rect.y2+HY)
    p=(x,y);d=(dx,dy);near=[-inf,-inf];far=[inf,inf];norm=[0,0]
    for axis in (0,1):
        if abs(d[axis])<1e-12:
            if p[axis]<=lo[axis]+1e-8 or p[axis]>=hi[axis]-1e-8:return None
        else:
            t1=(lo[axis]-p[axis])/d[axis];t2=(hi[axis]-p[axis])/d[axis]
            near[axis]=min(t1,t2);far[axis]=max(t1,t2);norm[axis]=-1 if d[axis]>0 else 1
    enter=max(near);leave=min(far)
    if enter>leave+1e-9 or leave<0 or enter<-1e-7 or enter>1+1e-9:return None
    axis=0 if near[0]>=near[1]-1e-9 else 1
    return max(0.,enter),(norm[axis],0) if axis==0 else (0,norm[axis])

def move_swept(level,x,y,vx,vy,dt):
    """Solve earliest static impacts, consume remaining time, at most four contacts."""
    remaining=dt;normals=[]
    for _ in range(4):
        dx,dy=vx*remaining,vy*remaining
        hits=[]
        for i,r in enumerate(solid_rects(level)):
            hit=sweep(x,y,dx,dy,r)
            if hit:hits.append((hit[0],i,hit[1]))
        if not hits:x+=dx;y+=dy;break
        t,_,(nx,ny)=min(hits,key=lambda h:(round(h[0],10),h[1]))
        x+=dx*t+nx*EPS;y+=dy*t+ny*EPS
        remaining*=1-t
        if nx:vx=0.
        if ny:vy=0.
        normals.append((nx,ny))
        if remaining<1e-9 or (vx==0 and vy==0):break
    return x,y,vx,vy,tuple(normals)

def segment_near(a,b,p,r):
    dx,dy=b[0]-a[0],b[1]-a[1];den=dx*dx+dy*dy
    t=max(0,min(1,((p[0]-a[0])*dx+(p[1]-a[1])*dy)/den)) if den else 0
    return hypot(a[0]+dx*t-p[0],a[1]+dy*t-p[1])<=r

def step(level,s,control=Input(),dt=DT,preserve_momentum=True):
    """Input, old-state forces, velocity, earliest swept collision/water, progress.
    Tiny water oscillations settle visibly at the plane. SPACE always escapes.
    """
    if s.status!='playing':return s,()
    if not (0<dt<=1/30):raise ValueError('Use a bounded fixed step')
    if not all(isfinite(v) for v in (s.x,s.y,s.vx,s.vy)):raise ValueError('Nonfinite state')
    move=max(-1,min(1,control.move));vx=s.vx;vy=s.vy;ground=s.grounded
    if move:vx=max(-MAX_VX,min(MAX_VX,vx+move*100*dt))
    else:
        drag=(120 if ground else 12)*dt
        vx=max(0,vx-drag) if vx>0 else min(0,vx+drag)
    floating=s.floating
    if control.jump and ground:
        vy=-s.gravity*JUMP;ground=False;floating=False
    elif floating:
        # The player visibly floats half in the pond. Horizontal motion stops at
        # solid banks, and SPACE jumps into the current side, rearming at 8px.
        nx,ny,nvx,_,normals=move_swept(level,s.x,s.y,vx,0,dt)
        return replace(s,x=nx,vx=nvx,vy=0,time=s.time+dt,distance=s.distance+abs(nx-s.x)),()
    vy+=s.gravity*GRAVITY*dt
    if vy*s.gravity>MAX_VY:vy=s.gravity*MAX_VY
    # Compute candidate physical motion first so a solid bank wins ties.
    x,y,vx,vy,normals=move_swept(level,s.x,s.y,vx,vy,dt)
    gravity=s.gravity;armed=s.armed;events=[];crossings=s.crossings
    if abs(s.y-WATER)>=8-EPS:armed=True
    crosses=(s.y<WATER<=y and s.gravity==1) or (s.y>WATER>=y and s.gravity==-1)
    # At the plane, a jump into the current side is never another crossing.
    if crosses and portal_at(level,s.x+(x-s.x)*(WATER-s.y)/(y-s.y)):
        t=(WATER-s.y)/(y-s.y);cx=s.x+(x-s.x)*t
        if armed:
            gravity=-s.gravity;crossings+=1;armed=False
            events.append(Event('cross',s,cx,WATER))
            if not preserve_momentum:vx=vy=0.
            # A <=8px excursion is resolved as a stable float, no repeated sign
            # change, hidden position warp, or boost. Position stays on the plane.
            if vy*vy/(2*GRAVITY)<8:
                x,y=cx,WATER;vy=0;floating=True;ground=True
            else:
                # Split the old-force velocity update at the water event, then
                # integrate its remainder with the new sign (semi-implicit Euler).
                rem=dt*(1-t);vy+=2*gravity*GRAVITY*rem
                x,y,vx,vy,after=move_swept(level,cx,WATER,vx,vy,rem)
                normals+=after
        else:
            x,y=cx,WATER;vy=0;floating=True;ground=True
    # A shallow return from the new side must not leak through with wrong gravity.
    elif not armed and ((s.gravity==-1 and s.y>=WATER and y<WATER) or (s.gravity==1 and s.y<=WATER and y>WATER)):
        t=(WATER-s.y)/(y-s.y) if y!=s.y else 0
        x=s.x+(x-s.x)*t;y=WATER;vy=0;floating=True;ground=True
    if not floating:ground=any(ny==-gravity for _,ny in normals)
    got=[]  # Collection and completion are added in stage 5.
    checkpoint=s.checkpoint
    if ground and not floating and ((gravity==1 and y<63) or (gravity==-1 and y>65)):
        checkpoint=(x,y,gravity)
    status='playing'

    new=State(x,y,vx,vy,gravity,ground,armed,floating,tuple(got),crossings,s.distance+hypot(x-s.x,y-s.y),s.time+dt,status,checkpoint,s.falls,'float' if floating else '')
    if x<-10 or x>202 or y<-12 or y>140:
        new=replace(new,x=checkpoint[0],y=checkpoint[1],gravity=checkpoint[2],vx=0,vy=0,grounded=True,armed=True,floating=False,falls=s.falls+1,message='岸へ戻った')
    return new,tuple(events)

def frame(level,s,control=Input(),preserve_momentum=True):
    events=[]
    for i in range(4):
        s,e=step(level,s,Input(control.move,control.jump and i==0),preserve_momentum=preserve_momentum);events.extend(e)
    return s,tuple(events)

def state_hash(s):return hashlib.sha256(json.dumps(asdict(s),sort_keys=True,separators=(',',':'),ensure_ascii=False).encode('utf-8')).hexdigest()

def replay(level,actions,preserve_momentum=True):
    s=initial(level);trace=[]
    for action in actions:
        s,e=frame(level,s,Input(action.get('move',0),action.get('jump',False)),preserve_momentum)
        trace.append(s)
    return s,trace


# The renderer and controls are shared scaffolding; the model above grows by stage.
STAGE = 4
DEMO_FRAMES = 91
KEYS = ('LEFT', 'RIGHT', 'SPACE', 'P', 'R', 'Z', 'N', '1', '2', '3')
DEMO_PLAN = ((14, 0, True), (82, 1, False), (20, 0, False))

class App:
    def __init__(self):
        self.level = 0
        self.state = initial(LEVELS[self.level])
        self.pause = False
        self.gate = 0
        self.undo_state = None
        self.trail = []
        self.demo_tick = 0

    def reset(self):
        self.state = initial(LEVELS[self.level])
        self.pause = False
        self.undo_state = None
        self.trail = []
        self.gate = 2

    def advance(self, control):
        before = self.state
        self.state, events = frame(LEVELS[self.level], self.state, control)
        for event in events: self.undo_state = event.before
        self.trail.append((self.state.x, self.state.y))
        self.trail = self.trail[-40:]
        if before.status != 'success' and self.state.status == 'success': self.gate = 2

    def control(self, pressed=(), held=()):
        # Two completely released updates prevent held keys leaking after a switch.
        if self.gate:
            self.gate = 2 if set(held).intersection(KEYS) else self.gate-1
            return
        if 'R' in pressed: self.reset(); return
        if STAGE == 5:
            for index in range(3):
                if str(index+1) in pressed:
                    self.level = index; self.reset(); return
        if 'P' in pressed:
            self.pause = not self.pause; self.gate = 2; return
        if self.pause: return
        if STAGE >= 4 and 'Z' in pressed:
            if self.undo_state is not None:
                self.state = self.undo_state; self.undo_state = None; self.trail = []
            self.gate = 2
            return
        if self.state.status == 'success':
            if STAGE == 5 and 'N' in pressed:
                self.level = (self.level+1) % len(LEVELS); self.reset()
            return
        self.advance(Input(int('RIGHT' in held)-int('LEFT' in held), 'SPACE' in pressed))

    def demo_update(self):
        tick = self.demo_tick
        self.demo_tick += 1
        if STAGE == 1:
            control = Input(1 if tick < 30 else 0, tick == 0)
        elif STAGE == 2:
            control = Input(1 if tick < 30 else 0)
        elif STAGE == 3:
            control = Input()
        else:
            control = Input()
            for count, move, jump in DEMO_PLAN:
                if tick < count:
                    control = Input(move, bool(jump and tick == 0)); break
                tick -= count
        held = ('RIGHT',) if control.move > 0 else ('LEFT',) if control.move < 0 else ()
        self.control(('SPACE',) if control.jump else (), held)

    def draw(self, p):
        s, level = self.state, LEVELS[self.level]
        p.cls(1)
        p.text(12, 10, '018 INVERTED POND / STAGE '+str(STAGE), 10)
        p.text(12, 24, ('PAUSED' if self.pause else s.status.upper())+'   TIME '+format(s.time, '.3f')+' s', 11)
        p.text(12, 38, 'X '+format(s.x, '.3f')+'  Y '+format(s.y, '.3f')+'  VX '+format(s.vx, '.2f')+'  VY '+format(s.vy, '.2f'), 7)
        p.text(12, 52, 'GRAVITY '+('DOWN' if s.gravity == 1 else 'UP')+'  CROSSES '+str(getattr(s, 'crossings', 0))+'  GROUNDED '+str(s.grounded), 10)
        if STAGE >= 3:
            p.text(12, 66, 'ARMED '+str(s.armed)+'  FLOATING '+str(s.floating), 6)
        ox, oy = 32, 82
        def xy(x, y): return ox+2*x, oy+2*y
        p.rect(ox, oy, 384, 256, 2)
        p.rect(ox, oy+128, 384, 128, 1)
        for x in range(4, 188, 12):
            p.line(*xy(x, 56), *xy(x+5, 56), 5)
            p.line(*xy(x, 72), *xy(x+5, 72), 5)
        p.text(ox+10, oy+20, 'WORLD 192 x 128 / +Y DOWN', 6)
        for x in range(4, 188):
            opened = STAGE >= 2 and any(a <= x < b for a, b in level.portals)
            if not opened: p.line(*xy(x, 63), *xy(x, 65), 6)
            elif x % 3 == 0: p.line(*xy(x, 64), *xy(x+1, 64), 12)
        p.rect(ox, oy, 8, 256, 5); p.rect(ox+376, oy, 8, 256, 5)
        p.rect(ox, oy, 384, 16, 5); p.rect(ox, oy+240, 384, 16, 5)
        if STAGE >= 4:
            for rock in level.rocks:
                x, y = xy(rock.x1, rock.y1)
                p.rect(x, y, (rock.x2-rock.x1)*2, (rock.y2-rock.y1)*2, 13)
                p.rectb(x, y, (rock.x2-rock.x1)*2, (rock.y2-rock.y1)*2, 7)
            hx, hy = xy(*level.start)
            p.rect(hx-9, hy-22, 18, 22, 4)
            p.tri(hx-13, hy-22, hx, hy-34, hx+13, hy-22, 9)
            if STAGE == 5:
                for name, ix, iy in level.items:
                    x, y = xy(ix, iy)
                    if name in s.collected: p.circb(x, y, 7, 5)
                    elif name == 'moon':
                        p.circ(x, y, 7, 10); p.circ(x+3, y-3, 6, 1)
                    else: p.tri(x-7, y+2, x+6, y-7, x+4, y+5, 11)
        for x, y in self.trail[::3]: p.pset(*xy(x, y), 6)
        x, y = xy(s.x, s.y); g = s.gravity
        p.rect(x-5, y-7, 11, 15, 7)
        p.rect(x-4, y-6*g-1, 9, 4, 12)
        p.pset(x-2, y-4*g, 1); p.pset(x+2, y-4*g, 1)
        p.line(x+14, y-7*g, x+14, y+8*g, 10)
        p.line(x+10, y+4*g, x+14, y+8*g, 10)
        p.line(x+18, y+4*g, x+14, y+8*g, 10)
        if getattr(s, 'floating', False): p.ellib(x-9, y-3, 19, 7, 12)
        messages = {1: 'ACCELERATION -> VELOCITY -> POSITION / FLAT BANK',
                    2: 'CROSS THE LINE: SAME POSITION, NEW GRAVITY',
                    3: 'DASHES = 8 px / FLOAT? SPACE TO JUMP OUT',
                    4: 'SWEPT BANKS + SHELF / Z UNDO LAST CROSS',
                    5: 'ROOM '+str(self.level+1)+' / ITEMS '+str(len(getattr(s, 'collected', ())))+'/'+str(len(getattr(level, 'items', ())))}
        p.text(12, 350, messages[STAGE], 10)
        p.text(12, 364, 'LEFT/RIGHT MOVE  SPACE JUMP  P PAUSE  R RESET', 7)
        p.text(12, 378, '1/2/3 ROOM  Z UNDO  N NEXT  ESC QUIT' if STAGE == 5 else 'MODEL 120 Hz / VIEW 30 FPS / ESC QUIT', 6)
        if s.status == 'success':
            p.rect(108, 176, 232, 38, 1); p.rectb(108, 176, 232, 38, 11)
            p.text(144, 193, 'SUCCESS / N NEXT ROOM', 11)
        elif self.pause:
            p.rect(144, 182, 160, 26, 1); p.text(160, 193, 'PAUSED / P RESUME', 10)


def parse_args(argv=None):
    """All QA arguments are bounded and validated before Pyxel is imported."""
    import argparse
    from pathlib import Path
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--headless-smoke', action='store_true')
    parser.add_argument('--demo-checkpoint', action='store_true')
    parser.add_argument('--frames', type=int)
    parser.add_argument('--screenshot')
    parser.add_argument('--state-output')
    args = parser.parse_args(argv)
    if not args.headless_smoke and (args.demo_checkpoint or args.frames is not None or args.screenshot or args.state_output):
        parser.error('QA options require --headless-smoke')
    minimum = DEMO_FRAMES if args.demo_checkpoint else 4
    if args.frames is None: args.frames = minimum
    if not minimum <= args.frames <= 600:
        parser.error('--frames must be between '+str(minimum)+' and 600')
    for name, suffix in (('screenshot', '.png'), ('state_output', '.json')):
        value = getattr(args, name)
        if value is not None and (not value.strip() or Path(value).suffix.lower() != suffix):
            parser.error('--'+name.replace('_', '-')+' requires a '+suffix+' file path')
    return args


def main(argv=None):
    args = parse_args(argv)
    from pathlib import Path
    import pyxel as p
    app = App()
    p.init(448, 400, title='018 Inverted Pond', fps=30, display_scale=2, headless=args.headless_smoke)
    keys = {name: getattr(p, 'KEY_'+name) for name in KEYS}
    finished = False
    def update():
        if args.headless_smoke:
            if args.demo_checkpoint and p.frame_count < DEMO_FRAMES: app.demo_update()
        else:
            app.control({name for name, key in keys.items() if p.btnp(key)},
                        {name for name, key in keys.items() if p.btn(key)})
    def draw():
        nonlocal finished
        app.draw(p)
        if args.headless_smoke and p.frame_count >= args.frames-1 and not finished:
            finished = True
            for name in ('screenshot', 'state_output'):
                value = getattr(args, name)
                if value:
                    path = Path(value).resolve(); path.parent.mkdir(parents=True, exist_ok=True)
                    if name == 'screenshot': p.screenshot(str(path), scale=2)
                    else: path.write_text(json.dumps(asdict(app.state), ensure_ascii=False, indent=2)+'\n', encoding='utf-8')
            p.quit()
    p.run(update, draw)

if __name__ == '__main__':
    main()

# MIT License
#
# Copyright (c) 2026 Pyxel 100 contributors
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
# The bundled Noto-derived bitmap glyphs are separately licensed under SIL OFL.
# See assets/NOTO-LICENSE.txt.

"""逆さの池・教材 5/5：宝を取り、足場へ帰る。Python 3.11+ / Pyxel 2.9.9。"""
"""Continuous position, fixed-step inversion platformer; standard library only.
Units: pixels and seconds. The water changes gravity, never world coordinates.
"""
from dataclasses import dataclass, replace, asdict
from math import inf, hypot, isfinite
import hashlib, json
DT=1/120
GRAVITY=80.0
JUMP=76.0
MAX_VX=36.0
MAX_VY=70.0
HX,HY=3.0,4.0
WATER=64.0
EPS=0.001

@dataclass(frozen=True)
class Rect:
    x1: float; y1: float; x2: float; y2: float
    name: str='rock'
@dataclass(frozen=True)
class Level:
    name: str
    portals: tuple
    rocks: tuple
    start: tuple
    items: tuple
    return_home: bool=True
    home_gravity: int=1

LEVELS=(
 Level('裏側の月',((72,112),),(Rect(116,84,148,88),),(42,60),(('moon',128,95),),False),
 Level('頭の上は道',((48,80),(136,168)),(Rect(92,36,120,40),Rect(92,84,128,88)),(30,60),(('leaf',106,30),('moon',106,95))),
 Level('同じ形、違う着地',((56,104),(144,176)),(Rect(104,36,132,40),Rect(108,80,132,84),Rect(144,88,180,92)),(34,60),(('leaf',118,30),('moon',120,91))),
)

@dataclass(frozen=True)
class State:
    x: float; y: float
    vx: float=0.; vy: float=0.
    gravity: int=1
    grounded: bool=True
    armed: bool=True
    floating: bool=False
    collected: tuple=()
    crossings: int=0
    distance: float=0.
    time: float=0.
    status: str='playing'
    checkpoint: tuple=(42.,60.,1)
    falls: int=0
    message: str=''

@dataclass(frozen=True)
class Input:
    move: int=0
    jump: bool=False

@dataclass(frozen=True)
class Event:
    kind: str
    before: State
    x: float
    y: float


def initial(level):
    return State(*level.start,gravity=level.home_gravity,checkpoint=(*level.start,level.home_gravity))

def solid_rects(level):
    banks=[];last=4
    for a,b in level.portals:
        if a>last:banks.append(Rect(last,64,last+(a-last),64,'bank'))
        last=b
    if last<188:banks.append(Rect(last,64,188,64,'bank'))
    # Top and bottom are visible safety stone, not offscreen landing surfaces.
    return tuple(banks)+level.rocks+(Rect(0,0,4,128,'edge'),Rect(188,0,192,128,'edge'),Rect(4,0,188,8,'edge'),Rect(4,120,188,128,'edge'))

def portal_at(level,x):
    return any(a+HX+EPS<x<b-HX-EPS for a,b in level.portals)

def sweep(x,y,dx,dy,rect):
    """Ray vs Minkowski-expanded rectangle. Tangential contacts do not block."""
    lo=(rect.x1-HX,rect.y1-HY);hi=(rect.x2+HX,rect.y2+HY)
    p=(x,y);d=(dx,dy);near=[-inf,-inf];far=[inf,inf];norm=[0,0]
    for axis in (0,1):
        if abs(d[axis])<1e-12:
            if p[axis]<=lo[axis]+1e-8 or p[axis]>=hi[axis]-1e-8:return None
        else:
            t1=(lo[axis]-p[axis])/d[axis];t2=(hi[axis]-p[axis])/d[axis]
            near[axis]=min(t1,t2);far[axis]=max(t1,t2);norm[axis]=-1 if d[axis]>0 else 1
    enter=max(near);leave=min(far)
    if enter>leave+1e-9 or leave<0 or enter<-1e-7 or enter>1+1e-9:return None
    axis=0 if near[0]>=near[1]-1e-9 else 1
    return max(0.,enter),(norm[axis],0) if axis==0 else (0,norm[axis])

def move_swept(level,x,y,vx,vy,dt):
    """Solve earliest static impacts, consume remaining time, at most four contacts."""
    remaining=dt;normals=[]
    for _ in range(4):
        dx,dy=vx*remaining,vy*remaining
        hits=[]
        for i,r in enumerate(solid_rects(level)):
            hit=sweep(x,y,dx,dy,r)
            if hit:hits.append((hit[0],i,hit[1]))
        if not hits:x+=dx;y+=dy;break
        t,_,(nx,ny)=min(hits,key=lambda h:(round(h[0],10),h[1]))
        x+=dx*t+nx*EPS;y+=dy*t+ny*EPS
        remaining*=1-t
        if nx:vx=0.
        if ny:vy=0.
        normals.append((nx,ny))
        if remaining<1e-9 or (vx==0 and vy==0):break
    return x,y,vx,vy,tuple(normals)

def segment_near(a,b,p,r):
    dx,dy=b[0]-a[0],b[1]-a[1];den=dx*dx+dy*dy
    t=max(0,min(1,((p[0]-a[0])*dx+(p[1]-a[1])*dy)/den)) if den else 0
    return hypot(a[0]+dx*t-p[0],a[1]+dy*t-p[1])<=r

def step(level,s,control=Input(),dt=DT,preserve_momentum=True):
    """Input, old-state forces, velocity, earliest swept collision/water, progress.
    Tiny water oscillations settle visibly at the plane. SPACE always escapes.
    """
    if s.status!='playing':return s,()
    if not (0<dt<=1/30):raise ValueError('Use a bounded fixed step')
    if not all(isfinite(v) for v in (s.x,s.y,s.vx,s.vy)):raise ValueError('Nonfinite state')
    move=max(-1,min(1,control.move));vx=s.vx;vy=s.vy;ground=s.grounded
    if move:vx=max(-MAX_VX,min(MAX_VX,vx+move*100*dt))
    else:
        drag=(120 if ground else 12)*dt
        vx=max(0,vx-drag) if vx>0 else min(0,vx+drag)
    floating=s.floating
    if control.jump and ground:
        vy=-s.gravity*JUMP;ground=False;floating=False
    elif floating:
        # The player visibly floats half in the pond. Horizontal motion stops at
        # solid banks, and SPACE jumps into the current side, rearming at 8px.
        nx,ny,nvx,_,normals=move_swept(level,s.x,s.y,vx,0,dt)
        return replace(s,x=nx,vx=nvx,vy=0,time=s.time+dt,distance=s.distance+abs(nx-s.x)),()
    vy+=s.gravity*GRAVITY*dt
    if vy*s.gravity>MAX_VY:vy=s.gravity*MAX_VY
    # Compute candidate physical motion first so a solid bank wins ties.
    x,y,vx,vy,normals=move_swept(level,s.x,s.y,vx,vy,dt)
    gravity=s.gravity;armed=s.armed;events=[];crossings=s.crossings
    if abs(s.y-WATER)>=8-EPS:armed=True
    crosses=(s.y<WATER<=y and s.gravity==1) or (s.y>WATER>=y and s.gravity==-1)
    # At the plane, a jump into the current side is never another crossing.
    if crosses and portal_at(level,s.x+(x-s.x)*(WATER-s.y)/(y-s.y)):
        t=(WATER-s.y)/(y-s.y);cx=s.x+(x-s.x)*t
        if armed:
            gravity=-s.gravity;crossings+=1;armed=False
            events.append(Event('cross',s,cx,WATER))
            if not preserve_momentum:vx=vy=0.
            # A <=8px excursion is resolved as a stable float, no repeated sign
            # change, hidden position warp, or boost. Position stays on the plane.
            if vy*vy/(2*GRAVITY)<8:
                x,y=cx,WATER;vy=0;floating=True;ground=True
            else:
                # Split the old-force velocity update at the water event, then
                # integrate its remainder with the new sign (semi-implicit Euler).
                rem=dt*(1-t);vy+=2*gravity*GRAVITY*rem
                x,y,vx,vy,after=move_swept(level,cx,WATER,vx,vy,rem)
                normals+=after
        else:
            x,y=cx,WATER;vy=0;floating=True;ground=True
    # A shallow return from the new side must not leak through with wrong gravity.
    elif not armed and ((s.gravity==-1 and s.y>=WATER and y<WATER) or (s.gravity==1 and s.y<=WATER and y>WATER)):
        t=(WATER-s.y)/(y-s.y) if y!=s.y else 0
        x=s.x+(x-s.x)*t;y=WATER;vy=0;floating=True;ground=True
    if not floating:ground=any(ny==-gravity for _,ny in normals)
    got=list(s.collected)
    for name,ix,iy in level.items:
        if name not in got and segment_near((s.x,s.y),(x,y),(ix,iy),7):got.append(name)
    checkpoint=s.checkpoint
    if ground and not floating and ((gravity==1 and y<63) or (gravity==-1 and y>65)):
        checkpoint=(x,y,gravity)
    status='playing'
    if len(got)==len(level.items) and ground and (not level.return_home or (gravity==level.home_gravity and ground and abs(x-level.start[0])<11 and abs(y-level.start[1])<5)):status='success'
    new=State(x,y,vx,vy,gravity,ground,armed,floating,tuple(got),crossings,s.distance+hypot(x-s.x,y-s.y),s.time+dt,status,checkpoint,s.falls,'float' if floating else '')
    if x<-10 or x>202 or y<-12 or y>140:
        new=replace(new,x=checkpoint[0],y=checkpoint[1],gravity=checkpoint[2],vx=0,vy=0,grounded=True,armed=True,floating=False,falls=s.falls+1,message='岸へ戻った')
    return new,tuple(events)

def frame(level,s,control=Input(),preserve_momentum=True):
    events=[]
    for i in range(4):
        s,e=step(level,s,Input(control.move,control.jump and i==0),preserve_momentum=preserve_momentum);events.extend(e)
    return s,tuple(events)

def state_hash(s):return hashlib.sha256(json.dumps(asdict(s),sort_keys=True,separators=(',',':'),ensure_ascii=False).encode('utf-8')).hexdigest()

def replay(level,actions,preserve_momentum=True):
    s=initial(level);trace=[]
    for action in actions:
        s,e=frame(level,s,Input(action.get('move',0),action.get('jump',False)),preserve_momentum)
        trace.append(s)
    return s,trace


# The renderer and controls are shared scaffolding; the model above grows by stage.
STAGE = 5
DEMO_FRAMES = 91
KEYS = ('LEFT', 'RIGHT', 'SPACE', 'P', 'R', 'Z', 'N', '1', '2', '3')
DEMO_PLAN = ((14, 0, True), (82, 1, False), (20, 0, False))

class App:
    def __init__(self):
        self.level = 0
        self.state = initial(LEVELS[self.level])
        self.pause = False
        self.gate = 0
        self.undo_state = None
        self.trail = []
        self.demo_tick = 0

    def reset(self):
        self.state = initial(LEVELS[self.level])
        self.pause = False
        self.undo_state = None
        self.trail = []
        self.gate = 2

    def advance(self, control):
        before = self.state
        self.state, events = frame(LEVELS[self.level], self.state, control)
        for event in events: self.undo_state = event.before
        self.trail.append((self.state.x, self.state.y))
        self.trail = self.trail[-40:]
        if before.status != 'success' and self.state.status == 'success': self.gate = 2

    def control(self, pressed=(), held=()):
        # Two completely released updates prevent held keys leaking after a switch.
        if self.gate:
            self.gate = 2 if set(held).intersection(KEYS) else self.gate-1
            return
        if 'R' in pressed: self.reset(); return
        if STAGE == 5:
            for index in range(3):
                if str(index+1) in pressed:
                    self.level = index; self.reset(); return
        if 'P' in pressed:
            self.pause = not self.pause; self.gate = 2; return
        if self.pause: return
        if STAGE >= 4 and 'Z' in pressed:
            if self.undo_state is not None:
                self.state = self.undo_state; self.undo_state = None; self.trail = []
            self.gate = 2
            return
        if self.state.status == 'success':
            if STAGE == 5 and 'N' in pressed:
                self.level = (self.level+1) % len(LEVELS); self.reset()
            return
        self.advance(Input(int('RIGHT' in held)-int('LEFT' in held), 'SPACE' in pressed))

    def demo_update(self):
        tick = self.demo_tick
        self.demo_tick += 1
        if STAGE == 1:
            control = Input(1 if tick < 30 else 0, tick == 0)
        elif STAGE == 2:
            control = Input(1 if tick < 30 else 0)
        elif STAGE == 3:
            control = Input()
        else:
            control = Input()
            for count, move, jump in DEMO_PLAN:
                if tick < count:
                    control = Input(move, bool(jump and tick == 0)); break
                tick -= count
        held = ('RIGHT',) if control.move > 0 else ('LEFT',) if control.move < 0 else ()
        self.control(('SPACE',) if control.jump else (), held)

    def draw(self, p):
        s, level = self.state, LEVELS[self.level]
        p.cls(1)
        p.text(12, 10, '018 INVERTED POND / STAGE '+str(STAGE), 10)
        p.text(12, 24, ('PAUSED' if self.pause else s.status.upper())+'   TIME '+format(s.time, '.3f')+' s', 11)
        p.text(12, 38, 'X '+format(s.x, '.3f')+'  Y '+format(s.y, '.3f')+'  VX '+format(s.vx, '.2f')+'  VY '+format(s.vy, '.2f'), 7)
        p.text(12, 52, 'GRAVITY '+('DOWN' if s.gravity == 1 else 'UP')+'  CROSSES '+str(getattr(s, 'crossings', 0))+'  GROUNDED '+str(s.grounded), 10)
        if STAGE >= 3:
            p.text(12, 66, 'ARMED '+str(s.armed)+'  FLOATING '+str(s.floating), 6)
        ox, oy = 32, 82
        def xy(x, y): return ox+2*x, oy+2*y
        p.rect(ox, oy, 384, 256, 2)
        p.rect(ox, oy+128, 384, 128, 1)
        for x in range(4, 188, 12):
            p.line(*xy(x, 56), *xy(x+5, 56), 5)
            p.line(*xy(x, 72), *xy(x+5, 72), 5)
        p.text(ox+10, oy+20, 'WORLD 192 x 128 / +Y DOWN', 6)
        for x in range(4, 188):
            opened = STAGE >= 2 and any(a <= x < b for a, b in level.portals)
            if not opened: p.line(*xy(x, 63), *xy(x, 65), 6)
            elif x % 3 == 0: p.line(*xy(x, 64), *xy(x+1, 64), 12)
        p.rect(ox, oy, 8, 256, 5); p.rect(ox+376, oy, 8, 256, 5)
        p.rect(ox, oy, 384, 16, 5); p.rect(ox, oy+240, 384, 16, 5)
        if STAGE >= 4:
            for rock in level.rocks:
                x, y = xy(rock.x1, rock.y1)
                p.rect(x, y, (rock.x2-rock.x1)*2, (rock.y2-rock.y1)*2, 13)
                p.rectb(x, y, (rock.x2-rock.x1)*2, (rock.y2-rock.y1)*2, 7)
            hx, hy = xy(*level.start)
            p.rect(hx-9, hy-22, 18, 22, 4)
            p.tri(hx-13, hy-22, hx, hy-34, hx+13, hy-22, 9)
            if STAGE == 5:
                for name, ix, iy in level.items:
                    x, y = xy(ix, iy)
                    if name in s.collected: p.circb(x, y, 7, 5)
                    elif name == 'moon':
                        p.circ(x, y, 7, 10); p.circ(x+3, y-3, 6, 1)
                    else: p.tri(x-7, y+2, x+6, y-7, x+4, y+5, 11)
        for x, y in self.trail[::3]: p.pset(*xy(x, y), 6)
        x, y = xy(s.x, s.y); g = s.gravity
        p.rect(x-5, y-7, 11, 15, 7)
        p.rect(x-4, y-6*g-1, 9, 4, 12)
        p.pset(x-2, y-4*g, 1); p.pset(x+2, y-4*g, 1)
        p.line(x+14, y-7*g, x+14, y+8*g, 10)
        p.line(x+10, y+4*g, x+14, y+8*g, 10)
        p.line(x+18, y+4*g, x+14, y+8*g, 10)
        if getattr(s, 'floating', False): p.ellib(x-9, y-3, 19, 7, 12)
        messages = {1: 'ACCELERATION -> VELOCITY -> POSITION / FLAT BANK',
                    2: 'CROSS THE LINE: SAME POSITION, NEW GRAVITY',
                    3: 'DASHES = 8 px / FLOAT? SPACE TO JUMP OUT',
                    4: 'SWEPT BANKS + SHELF / Z UNDO LAST CROSS',
                    5: 'ROOM '+str(self.level+1)+' / ITEMS '+str(len(getattr(s, 'collected', ())))+'/'+str(len(getattr(level, 'items', ())))}
        p.text(12, 350, messages[STAGE], 10)
        p.text(12, 364, 'LEFT/RIGHT MOVE  SPACE JUMP  P PAUSE  R RESET', 7)
        p.text(12, 378, '1/2/3 ROOM  Z UNDO  N NEXT  ESC QUIT' if STAGE == 5 else 'MODEL 120 Hz / VIEW 30 FPS / ESC QUIT', 6)
        if s.status == 'success':
            p.rect(108, 176, 232, 38, 1); p.rectb(108, 176, 232, 38, 11)
            p.text(144, 193, 'SUCCESS / N NEXT ROOM', 11)
        elif self.pause:
            p.rect(144, 182, 160, 26, 1); p.text(160, 193, 'PAUSED / P RESUME', 10)


def parse_args(argv=None):
    """All QA arguments are bounded and validated before Pyxel is imported."""
    import argparse
    from pathlib import Path
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--headless-smoke', action='store_true')
    parser.add_argument('--demo-checkpoint', action='store_true')
    parser.add_argument('--frames', type=int)
    parser.add_argument('--screenshot')
    parser.add_argument('--state-output')
    args = parser.parse_args(argv)
    if not args.headless_smoke and (args.demo_checkpoint or args.frames is not None or args.screenshot or args.state_output):
        parser.error('QA options require --headless-smoke')
    minimum = DEMO_FRAMES if args.demo_checkpoint else 4
    if args.frames is None: args.frames = minimum
    if not minimum <= args.frames <= 600:
        parser.error('--frames must be between '+str(minimum)+' and 600')
    for name, suffix in (('screenshot', '.png'), ('state_output', '.json')):
        value = getattr(args, name)
        if value is not None and (not value.strip() or Path(value).suffix.lower() != suffix):
            parser.error('--'+name.replace('_', '-')+' requires a '+suffix+' file path')
    return args


def main(argv=None):
    args = parse_args(argv)
    from pathlib import Path
    import pyxel as p
    app = App()
    p.init(448, 400, title='018 Inverted Pond', fps=30, display_scale=2, headless=args.headless_smoke)
    keys = {name: getattr(p, 'KEY_'+name) for name in KEYS}
    finished = False
    def update():
        if args.headless_smoke:
            if args.demo_checkpoint and p.frame_count < DEMO_FRAMES: app.demo_update()
        else:
            app.control({name for name, key in keys.items() if p.btnp(key)},
                        {name for name, key in keys.items() if p.btn(key)})
    def draw():
        nonlocal finished
        app.draw(p)
        if args.headless_smoke and p.frame_count >= args.frames-1 and not finished:
            finished = True
            for name in ('screenshot', 'state_output'):
                value = getattr(args, name)
                if value:
                    path = Path(value).resolve(); path.parent.mkdir(parents=True, exist_ok=True)
                    if name == 'screenshot': p.screenshot(str(path), scale=2)
                    else: path.write_text(json.dumps(asdict(app.state), ensure_ascii=False, indent=2)+'\n', encoding='utf-8')
            p.quit()
    p.run(update, draw)

if __name__ == '__main__':
    main()