#!/usr/bin/env python3
"""
Stitch keystone.guru tile pyramid (z=4 by default) into one WebP per
dungeon-floor. Reads `data/kg/_summary.json` (produced by kg_fetch.py) for
the grid bounds.

Output: web/assets/maps/<tile_key>[_floor<n>].webp
"""
from __future__ import annotations
import argparse
import concurrent.futures
import json
import sys
from pathlib import Path
from PIL import Image

ROOT = Path(__file__).resolve().parent.parent
KG_DIR = ROOT / "data" / "kg"
WEB_MAPS = ROOT / "web" / "assets" / "maps"

TILE_W, TILE_H = 384, 256


def stitch_one(args):
    tile_key, floor_info, zoom, all_floors_count, quality = args
    floor = floor_info["index"]
    cols, rows = floor_info["cols"], floor_info["rows"]
    src_dir = KG_DIR / tile_key / f"floor{floor}" / f"z{zoom}"

    canvas = Image.new("RGBA", (cols * TILE_W, rows * TILE_H), (0, 0, 0, 255))
    missing = 0
    for x in range(cols):
        for y in range(rows):
            tile_path = src_dir / f"{x}_{y}.png"
            if not tile_path.exists():
                missing += 1
                continue
            with Image.open(tile_path) as t:
                canvas.paste(t.convert("RGBA"), (x * TILE_W, y * TILE_H))

    suffix = f"_floor{floor}" if all_floors_count > 1 else ""
    out = WEB_MAPS / f"{tile_key}{suffix}.webp"
    out.parent.mkdir(parents=True, exist_ok=True)
    canvas.convert("RGB").save(out, "WEBP", quality=quality, method=4)
    return tile_key, floor, canvas.size, missing


def main() -> int:
    ap = argparse.ArgumentParser()
    ap.add_argument("--quality", type=int, default=85)
    ap.add_argument("--workers", type=int, default=4)
    args = ap.parse_args()

    summary_path = KG_DIR / "_summary.json"
    if not summary_path.exists():
        print(f"missing {summary_path} — run kg_fetch.py first", file=sys.stderr)
        return 1
    summary = json.loads(summary_path.read_text())

    jobs = []
    for d in summary["dungeons"]:
        if not d.get("floors"):
            continue
        for floor_info in d["floors"]:
            jobs.append((d["tile_key"], floor_info, d["max_zoom"],
                         len(d["floors"]), args.quality))

    print(f"stitching {len(jobs)} dungeon-floors with {args.workers} workers...")
    with concurrent.futures.ProcessPoolExecutor(max_workers=args.workers) as pool:
        for tile_key, floor, size, missing in pool.map(stitch_one, jobs):
            note = f" ({missing} missing tiles)" if missing else ""
            print(f"  {tile_key} f{floor}: {size[0]}×{size[1]}{note}")

    print(f"done → {WEB_MAPS}")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())