import math
from pathlib import Path

from .assets import load_json, load_rgb
from .settings import BOARD_DECK, DECKS_DIR, BuildConfig


def board_target_mm_for_mode(
    board_path: Path,
    board_mode: str,
    board_custom_mm: tuple[float, float] | None = None,
) -> tuple[float, float]:
    if board_custom_mm is not None:
        return board_custom_mm
    ratio = board_aspect_ratio(board_path)
    if board_mode == "a4-fit":
        max_w, max_h = 210.0, 297.0
        if ratio > max_w / max_h:
            return max_w, max_w / ratio
        return max_h * ratio, max_h
    if board_mode == "a5-fit":
        max_w, max_h = 148.0, 210.0
        if ratio > max_w / max_h:
            return max_w, max_w / ratio
        return max_h * ratio, max_h

    # Default: preserve aspect ratio while using approximately A5 area,
    # capped to fit inside A4.
    a5_area = 148.0 * 210.0
    width = math.sqrt(a5_area * ratio)
    height = math.sqrt(a5_area / ratio)
    if width > 210.0 or height > 297.0:
        scale = min(210.0 / width, 297.0 / height)
        width *= scale
        height *= scale
    return width, height


def board_aspect_ratio(board_path: Path) -> float:
    deck_json = board_path.parent / "deck.json"
    if deck_json.exists():
        meta = load_json(deck_json)
        if meta.get("cardWidth") and meta.get("cardHeight"):
            return float(meta["cardWidth"]) / float(meta["cardHeight"])
    with load_rgb(board_path) as img:
        return img.width / img.height


def board_target_mm(board_path: Path, config: BuildConfig) -> tuple[float, float]:
    return board_target_mm_for_mode(board_path, config.board_mode, config.board_custom_mm)


def board_mode_fits_paper(board_mode: str, paper_mm: tuple[float, float], margin_mm: float) -> bool:
    usable_w = paper_mm[0] - 2 * margin_mm
    usable_h = paper_mm[1] - 2 * margin_mm
    board_paths = sorted((DECKS_DIR / BOARD_DECK).glob("*-jumbo-front.png"))
    if not board_paths:
        return True
    for board_path in board_paths:
        board_w, board_h = board_target_mm_for_mode(board_path, board_mode)
        fits_upright = board_w <= usable_w and board_h <= usable_h
        fits_rotated = board_h <= usable_w and board_w <= usable_h
        if not (fits_upright or fits_rotated):
            return False
    return True