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# Pyxel is an external dependency under its own MIT license.

"""潮待ちポスト・教材 1/5。原作「ふたつの潮」の基本便を段階化。
実行: python 01_grid.py
Cを通常の島Iに置換。日本語の解説はLESSON.md。画面はASCIIのみ。
原作ライセンスの字形例外は上に保持。教材はNoto字形を使用しない。
"""
from dataclasses import dataclass, replace

# (列, 行) で扱う。Cの追加便は教材に含めず、同じ位置をIにする。
ROWS = ("S-a-I-B", "|...b.|", "I~I-I-I", "b.|...b", "A-I...I")
DIRECTIONS = {"L": (-1, 0), "R": (1, 0), "U": (0, -1), "D": (0, 1)}
TILE = 28
STAGE = 1


def find(char):
    return next((x, y) for y, row in enumerate(ROWS)
                for x, cell in enumerate(row) if cell == char)


START = find("S")


@dataclass(frozen=True)
class State:
    x: int = START[0]
    y: int = START[1]
    used: int = 0


def step(state, command):
    if command not in DIRECTIONS:
        return state, "invalid"
    dx, dy = DIRECTIONS[command]
    x, y = state.x + dx, state.y + dy
    if y < 0 or y >= len(ROWS) or x < 0 or x >= len(ROWS[y]) or ROWS[y][x] == ".":
        return state, "water"
    return replace(state, x=x, y=y, used=state.used + 1), "move"


class Session:
    def __init__(self):
        self.state = State()
        self.event = "ready"

    def act(self, command):
        self.state, self.event = step(self.state, command)

    def restart(self):
        self.state = State()
        self.event = "ready"


def main(headless=False, screenshot=None):
    import json
    import pyxel  # 純粋ルールのテストでは読み込まない。

    session = Session()
    draws = 0
    keys = ((pyxel.KEY_LEFT, "L"), (pyxel.KEY_RIGHT, "R"),
            (pyxel.KEY_UP, "U"), (pyxel.KEY_DOWN, "D"))

    def update():
        if headless and draws >= 12:
            if screenshot:
                pyxel.screenshot(screenshot, scale=2)
            print(json.dumps({"stage": STAGE, "rendered_frames": draws,
                              "screenshot": screenshot, "mode": "headless-smoke"}), flush=True)
            pyxel.quit()
            return
        if pyxel.btnp(pyxel.KEY_ESCAPE):
            pyxel.quit()
            return
        if pyxel.btnp(pyxel.KEY_R):
            session.restart()
            return
        for key, command in keys:
            if pyxel.btnp(key):
                session.act(command)
                break  # 一つのフレームに進めるのは一手だけ。

    def draw():
        nonlocal draws
        draws += 1
        state = session.state
        pyxel.cls(1)
        pyxel.text(12, 9, f"TIDEPOST / STEP {STAGE}", 10)
        pyxel.text(12, 22, f"MOVES {state.used}", 7)
        for y, row in enumerate(ROWS):
            for x, char in enumerate(row):
                px, py = 12 + x * TILE, 42 + y * TILE
                if char == ".":
                    pyxel.line(px + 8, py + 14, px + 15, py + 14, 5)
                    continue
                if char in "SIAB":
                    pyxel.rect(px + 1, py + 1, TILE - 2, TILE - 2, 3)
                    pyxel.rectb(px + 1, py + 1, TILE - 2, TILE - 2, 11)
                    pyxel.text(px + 4, py + 3, char, 7)
                else:
                    color = 12 if char == "a" else 9 if char == "b" else 10 if char == "~" else 4
                    active = True  # 01では橋の種類による制約をまだ入れない。
                    if y % 2 == 0:
                        box = (px, py + 9, TILE, 10)
                    else:
                        box = (px + 9, py, 10, TILE)
                    if active:
                        pyxel.rect(*box, color)
                    else:
                        pyxel.rectb(*box, color)
                    pyxel.text(px + 12, py + 11, char, 0 if active else color)
        px, py = 12 + state.x * TILE, 42 + state.y * TILE
        pyxel.circ(px + 14, py + 18, 5, 8)
        pyxel.pset(px + 15, py + 16, 7)
        pyxel.text(220, 62, "MAP PRACTICE", 6)
        pyxel.text(220, 77, "A/B: ISLANDS", 6)
        pyxel.text(220, 92, "NO PARCELS YET", 6)
        pyxel.text(220, 110, "ALL BRIDGES OPEN", 6)
        notices = {
            "ready": "READY", "move": "STEP", "water": "WATER: NO MOVE",
            "invalid": "UNKNOWN COMMAND", "tide": "TIDE CHANGED",
            "unsafe": "SWITCH TIDE ON AN ISLAND", "tide_block": "BRIDGE UNDER WATER",
            "heavy": "DELIVER B TO USE ~", "delivery": "DELIVERED!",
            "win": "CLEAR! BACK AT S", "done": "CLEAR! R: RESET", "undo": "ONE STEP BACK",
        }
        pyxel.text(12, 194, notices[session.event], 10)
        pyxel.text(12, 210, "ARROWS: STEP  R: RESET  ESC: QUIT", 7)
        pyxel.text(12, 222, "TIDE RULE STARTS IN STEP 2", 6)
        pyxel.text(12, 234, "UNDO STARTS IN STEP 5", 5)

    pyxel.init(364, 250, title=f"Tidepost - Stage {STAGE}", fps=30, headless=headless)
    pyxel.run(update, draw)


if __name__ == "__main__":
    import argparse

    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--headless-smoke", action="store_true",
                        help="Render 12 frames then quit; not a human playtest")
    parser.add_argument("--screenshot", metavar="PATH", help="PNG path for --headless-smoke")
    args = parser.parse_args()
    if args.screenshot and not args.headless_smoke:
        parser.error("--screenshot requires --headless-smoke")
    main(headless=args.headless_smoke, screenshot=args.screenshot)