#!/usr/bin/env python3

import os
import csv
import re
import shutil
import hashlib
from pathlib import Path

import bencodepy


BT_BACKUP_DIR = Path("BT_backup")
FIXED_TORRENTS_DIR = Path("qbit1")
OUTPUT_DIR = Path("grouped_torrents")


def decode_value(v):
    if isinstance(v, bytes):
        return v.decode("utf-8", errors="replace")
    return v


def get_field(data, key):
    return decode_value(data.get(key.encode()) or data.get(key))


def safe_rel_path(path_str):
    if not path_str:
        return Path("_unknown")

    s = path_str.strip().replace("\\", "/")

    m = re.match(r"^([A-Za-z]):/(.*)$", s)
    if m:
        s = f"{m.group(1)}/{m.group(2)}"
    else:
        s = s.lstrip("/")

    parts = []
    for part in s.split("/"):
        part = part.strip()
        if not part:
            continue
        part = re.sub(r'[<>:"|?*\x00-\x1F]', "_", part)
        parts.append(part)

    return Path(*parts) if parts else Path("_unknown")


def read_bencode(path):
    with open(path, "rb") as f:
        return bencodepy.decode(f.read())


def torrent_infohash_v1(torrent_path):
    """
    Liczy klasyczny SHA1 infohash z pola 'info' w pliku .torrent.
    To jest hash używany przez qBittorrent dla zwykłych torrentów v1.
    """
    data = read_bencode(torrent_path)
    info = data.get(b"info") or data.get("info")
    if info is None:
        raise ValueError("Brak pola 'info' w torrent")

    encoded_info = bencodepy.encode(info)
    return hashlib.sha1(encoded_info).hexdigest().upper()


def build_fixed_torrent_index():
    """
    Zwraca mapę: INFOHASH -> ścieżka do poprawionego .torrent
    """
    index = {}
    duplicates = []

    for torrent_path in sorted(FIXED_TORRENTS_DIR.glob("*.torrent")):
        try:
            infohash = torrent_infohash_v1(torrent_path)
        except Exception as e:
            print(f"[WARN] Nie moge odczytac {torrent_path}: {e}")
            continue

        if infohash in index:
            duplicates.append(infohash)
        else:
            index[infohash] = torrent_path

    if duplicates:
        print(f"[WARN] Zduplikowane infohash w qbit1: {len(duplicates)}")

    print(f"Zindeksowano poprawione torrenty: {len(index)}")
    return index


def main():
    if not BT_BACKUP_DIR.is_dir():
        raise SystemExit(f"Brak katalogu: {BT_BACKUP_DIR}")
    if not FIXED_TORRENTS_DIR.is_dir():
        raise SystemExit(f"Brak katalogu: {FIXED_TORRENTS_DIR}")

    OUTPUT_DIR.mkdir(parents=True, exist_ok=True)

    fixed_index = build_fixed_torrent_index()

    rows = []
    processed = 0
    copied = 0
    missing_fixed_torrent = 0
    broken_fastresume = 0

    for fastresume_path in sorted(BT_BACKUP_DIR.glob("*.fastresume")):
        torrent_hash = fastresume_path.stem.upper()
        processed += 1

        try:
            data = read_bencode(fastresume_path)
        except Exception as e:
            broken_fastresume += 1
            rows.append({
                "hash": torrent_hash,
                "torrent_name": "",
                "save_path": "",
                "output_dir": "",
                "status": f"broken_fastresume: {e}",
            })
            continue

        save_path = (
            get_field(data, "qBt-savePath")
            or get_field(data, "save_path")
            or ""
        )
        torrent_name = (
            get_field(data, "qBt-name")
            or get_field(data, "name")
            or ""
        )

        rel_dir = safe_rel_path(save_path)
        target_dir = OUTPUT_DIR / rel_dir
        target_dir.mkdir(parents=True, exist_ok=True)

        fixed_torrent_path = fixed_index.get(torrent_hash)

        if fixed_torrent_path and fixed_torrent_path.exists():
            out_name = fixed_torrent_path.name
            shutil.copy2(fixed_torrent_path, target_dir / out_name)
            status = "ok"
            copied += 1
        else:
            status = "missing_fixed_torrent"
            missing_fixed_torrent += 1

        rows.append({
            "hash": torrent_hash,
            "torrent_name": torrent_name,
            "save_path": save_path,
            "output_dir": str(target_dir),
            "status": status,
        })

    csv_path = OUTPUT_DIR / "mapping.csv"
    with open(csv_path, "w", newline="", encoding="utf-8") as f:
        writer = csv.DictWriter(
            f,
            fieldnames=["hash", "torrent_name", "save_path", "output_dir", "status"]
        )
        writer.writeheader()
        writer.writerows(rows)

    print(f"Przetworzono fastresume:        {processed}")
    print(f"Skopiowano poprawione torrent: {copied}")
    print(f"Brak poprawionych torrentow:   {missing_fixed_torrent}")
    print(f"Uszkodzone fastresume:         {broken_fastresume}")
    print(f"CSV: {csv_path}")


if __name__ == "__main__":
    main()