import time
import urllib.error
import urllib.request
from pathlib import Path

import numpy as np
from PIL import Image

from .coords import SLICE, TILE_PX, mosaic_origin_px, slice_tiles

COMMIT = "4093e8c874e480d47c38b37fe7a404f8b0c5275e"
BASE = f"https://raw.githubusercontent.com/rolux/gtadb.org/{COMMIT}/maps/tiles/6/yanis%2C15/5"
UA = {"User-Agent": "leonida-extract/0.1 (local hobby project)"}


def download_tiles(cache: Path) -> None:
    """Lädt alle Kacheln des Ausschnitts; vorhandene werden übersprungen."""
    cache.mkdir(parents=True, exist_ok=True)
    missing = []
    for row, col in slice_tiles():
        name = f"5,{row},{col}.jpg"
        dst = cache / name
        if dst.exists():
            continue
        for attempt in range(3):
            try:
                req = urllib.request.Request(f"{BASE}/{name}", headers=UA)
                dst.write_bytes(urllib.request.urlopen(req, timeout=30).read())
                break
            except (urllib.error.URLError, TimeoutError):
                time.sleep(2 ** attempt)
        else:
            missing.append(name)
    if missing:
        raise RuntimeError(f"{len(missing)} Kacheln fehlen: {missing[:5]} ...")


def assemble(load_tile) -> np.ndarray:
    """Setzt die Kacheln zusammen und schneidet auf den Ausschnitt zu."""
    tiles = slice_tiles()
    r0 = min(r for r, _ in tiles)
    c0 = min(c for _, c in tiles)
    rows = max(r for r, _ in tiles) - r0 + 1
    cols = max(c for _, c in tiles) - c0 + 1
    full = np.zeros((rows * TILE_PX, cols * TILE_PX, 3), dtype=np.uint8)
    for row, col in tiles:
        y, x = (row - r0) * TILE_PX, (col - c0) * TILE_PX
        full[y:y + TILE_PX, x:x + TILE_PX] = load_tile(row, col)
    ox, oy = mosaic_origin_px()
    w = SLICE["x1"] - SLICE["x0"]
    h = SLICE["y1"] - SLICE["y0"]
    return full[oy:oy + h, ox:ox + w]


def load_mosaic(cache: Path) -> np.ndarray:
    def load_tile(row: int, col: int) -> np.ndarray:
        with Image.open(cache / f"5,{row},{col}.jpg") as img:
            return np.asarray(img.convert("RGB"))
    return assemble(load_tile)