#!/usr/bin/env python3
"""Unify and recompress event picture DDS files to DXT5 + 10 mip chain.

Reads every .dds under `gfx/event_pictures/`, normalizes to 512x256 with
a 10-level mip chain, and re-encodes as DXT5 (BC3). Alpha channel is
preserved for every file (DXT5 is lossless on alpha within the codec's
quantization, but at 512x256 the visual delta from full BGRA is below
perception for the kinds of content in this mod).

Existing files that already match the target (BC3 + 512x256 + 10 mips)
are skipped to avoid needless re-encoding.

Usage:
    python convert_eventpicture_dds.py                 # process all under gfx/event_pictures/
    python convert_eventpicture_dds.py <dir>           # process all .dds under <dir>
    python convert_eventpicture_dds.py <dir> --dry-run # report only, do not write
    python convert_eventpicture_dds.py <dir> -j 8      # 8 worker threads (default 4)

Requires tools/bin/texconv.exe next to this script.
"""
import argparse
import collections
import concurrent.futures
import glob
import os
import struct
import subprocess
import sys
import tempfile
import threading
import time

from PIL import Image

HERE = os.path.dirname(os.path.abspath(__file__))
TEXCONV = os.path.join(HERE, "bin", "texconv.exe")

TARGET_W, TARGET_H = 512, 256
TARGET_MIPS = 10
TARGET_FOURCC = b"DXT5"


def read_dds_header(path: str) -> dict | None:
    with open(path, "rb") as f:
        data = f.read(128)
    if len(data) < 128 or data[:4] != b"DDS ":
        return None
    h, w, _, _, mipmap_count = struct.unpack("<IIIII", data[12:32])
    _, _, fourcc, _, *_ = struct.unpack("<II4s5I", data[76:108])
    return dict(w=w, h=h, mips=mipmap_count, fourcc=fourcc)


def is_target_format(hdr: dict) -> bool:
    return (
        hdr["w"] == TARGET_W
        and hdr["h"] == TARGET_H
        and hdr["mips"] == TARGET_MIPS
        and hdr["fourcc"] == TARGET_FOURCC
    )


def decode_to_png(src_dds: str, tmpdir: str) -> str:
    """texconv decodes any DDS variant to a PNG inside tmpdir."""
    cmd = [TEXCONV, "-ft", "png", "-y", "-o", tmpdir, src_dds]
    r = subprocess.run(cmd, capture_output=True, text=True)
    if r.returncode != 0:
        raise RuntimeError(
            f"texconv decode failed for {src_dds}\nstdout: {r.stdout}\nstderr: {r.stderr}"
        )
    base = os.path.splitext(os.path.basename(src_dds))[0]
    produced = os.path.join(tmpdir, base + ".png")
    if not os.path.isfile(produced):
        raise RuntimeError(f"texconv produced no PNG for {src_dds}")
    return produced


def encode_dds(png_path: str, tmpdir: str) -> str:
    """texconv encodes a PNG as DXT5 with full mip chain."""
    cmd = [
        TEXCONV,
        "-f", "DXT5",
        "-m", "0",  # full mip chain
        "-ft", "dds",
        "-y",
        "-o", tmpdir,
        png_path,
    ]
    r = subprocess.run(cmd, capture_output=True, text=True)
    if r.returncode != 0:
        raise RuntimeError(
            f"texconv encode failed for {png_path}\nstdout: {r.stdout}\nstderr: {r.stderr}"
        )
    base = os.path.splitext(os.path.basename(png_path))[0]
    produced = os.path.join(tmpdir, base + ".dds")
    if not os.path.isfile(produced):
        raise RuntimeError(f"texconv produced no DDS for {png_path}")
    return produced


def prepare_png(src_png: str, tmpdir: str) -> str:
    """Center-crop to 2:1, resize to 512x256, return staged PNG path."""
    im = Image.open(src_png)
    if im.mode not in ("RGB", "RGBA"):
        im = im.convert("RGB")

    sw, sh = im.size
    target_ar = TARGET_W / TARGET_H  # 2.0
    src_ar = sw / sh if sh else 1.0
    if abs(src_ar - target_ar) > 0.01:
        if src_ar > target_ar:
            new_w = round(sh * target_ar)
            x0 = (sw - new_w) // 2
            im = im.crop((x0, 0, x0 + new_w, sh))
        else:
            new_h = round(sw / target_ar)
            y0 = (sh - new_h) // 2
            im = im.crop((0, y0, sw, y0 + new_h))

    im = im.resize((TARGET_W, TARGET_H), Image.LANCZOS)
    staged = os.path.join(tmpdir, "stage.png")
    im.save(staged, format="PNG")
    return staged


_print_lock = threading.Lock()


def _log(msg: str) -> None:
    with _print_lock:
        print(msg, file=sys.stderr, flush=True)


def process_one(src_dds: str, dry_run: bool) -> tuple[str, str]:
    """Return (status, reason). status is one of: skip / wrote / error."""
    hdr = read_dds_header(src_dds)
    if hdr is None:
        return ("error", "not a DDS")
    if is_target_format(hdr):
        return ("skip", f"already {TARGET_FOURCC.decode()}+{TARGET_W}x{TARGET_H}+{TARGET_MIPS}mip")
    if dry_run:
        return (
            "would-write",
            f"{hdr['w']}x{hdr['h']} mip={hdr['mips']} -> DXT5+10mip",
        )

    # Each file gets its own ASCII temp dir to keep texconv happy with
    # unicode source paths.
    with tempfile.TemporaryDirectory() as tmp:
        try:
            decoded = decode_to_png(src_dds, tmp)
        except Exception as e:
            return ("error", f"decode: {e}")
        try:
            staged = prepare_png(decoded, tmp)
        except Exception as e:
            return ("error", f"prepare: {e}")
        try:
            new_dds = encode_dds(staged, tmp)
        except Exception as e:
            return ("error", f"encode: {e}")
        os.replace(new_dds, src_dds)
    return ("wrote", "ok")


def main() -> int:
    ap = argparse.ArgumentParser(description=__doc__.split("\n", 1)[0])
    ap.add_argument(
        "root",
        nargs="?",
        default=os.path.normpath(
            os.path.join(HERE, "..", "gfx", "event_pictures")
        ),
        help="Directory to scan for .dds (default: gfx/event_pictures).",
    )
    ap.add_argument(
        "--dry-run",
        action="store_true",
        help="Report what would happen without writing anything.",
    )
    ap.add_argument(
        "-j",
        "--jobs",
        type=int,
        default=4,
        help="Number of worker threads (default: 4).",
    )
    args = ap.parse_args()

    if not os.path.isfile(TEXCONV):
        print(f"error: texconv not found at {TEXCONV}", file=sys.stderr)
        return 1
    if not os.path.isdir(args.root):
        print(f"error: directory not found: {args.root}", file=sys.stderr)
        return 1

    paths = sorted(glob.glob(os.path.join(args.root, "**", "*.dds"), recursive=True))
    print(f"scanning: {args.root}")
    print(f"found: {len(paths)} dds files")
    print(f"target: DXT5 (BC3) {TARGET_W}x{TARGET_H} + {TARGET_MIPS}-level mip chain")
    print(f"workers: {args.jobs}")
    if args.dry_run:
        print("(dry run; no files will be written)")

    counts: collections.Counter = collections.Counter()
    error_samples: list[tuple[str, str]] = []
    started = time.time()

    def work(p: str) -> tuple[str, str, str]:
        status, reason = process_one(p, args.dry_run)
        return (p, status, reason)

    completed = 0
    with concurrent.futures.ThreadPoolExecutor(max_workers=args.jobs) as ex:
        futures = {ex.submit(work, p): p for p in paths}
        for fut in concurrent.futures.as_completed(futures):
            p, status, reason = fut.result()
            counts[status] += 1
            completed += 1
            if status == "error":
                _log(f"  ERROR  {p}: {reason}")
                if len(error_samples) < 5:
                    error_samples.append((p, reason))
            if completed % 100 == 0 or completed == len(paths):
                elapsed = time.time() - started
                rate = completed / elapsed if elapsed else 0
                eta = (len(paths) - completed) / rate if rate else 0
                _log(
                    f"  ... {completed}/{len(paths)} "
                    f"({rate:.1f}/s, eta {eta/60:.1f} min)"
                )

    elapsed = time.time() - started
    print()
    print("=== summary ===")
    for k in ("skip", "would-write", "wrote", "error"):
        print(f"  {k}: {counts[k]}")
    print(f"  elapsed: {elapsed/60:.1f} min")
    if error_samples:
        print()
        print("=== first errors ===")
        for p, reason in error_samples:
            print(f"  {p}: {reason}")

    return 0 if counts["error"] == 0 else 2


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