"""Umrechnung zwischen gtadb-Weltkoordinaten, Kacheln und Mosaikpixeln.

Spiegelt src/world/coords.js. Beide Seiten müssen dieselben Werte liefern.
"""
TILE_PX = 256
WORLD_HALF = 16384
CHUNK_SIZE = 250
SLICE = {"x0": -1000, "x1": 2000, "y0": -500, "y1": 2500}


def tile_for_world(x: float, y: float) -> tuple[int, int]:
    return (int((WORLD_HALF - y) // TILE_PX), int((x + WORLD_HALF) // TILE_PX))


def slice_tiles() -> list[tuple[int, int]]:
    r0, c0 = tile_for_world(SLICE["x0"], SLICE["y1"])
    r1, c1 = tile_for_world(SLICE["x1"] - 1, SLICE["y0"] + 1)
    return [(r, c) for r in range(r0, r1 + 1) for c in range(c0, c1 + 1)]


def mosaic_origin_px() -> tuple[int, int]:
    """Pixelversatz der Ausschnittsecke innerhalb des ungeschnittenen Kachelrasters."""
    r0, c0 = tile_for_world(SLICE["x0"], SLICE["y1"])
    return (SLICE["x0"] + WORLD_HALF - c0 * TILE_PX, (WORLD_HALF - SLICE["y1"]) - r0 * TILE_PX)


def pixel_to_world(px: int, py: int) -> tuple[float, float]:
    return (SLICE["x0"] + px, SLICE["y1"] - py)