#!/usr/bin/env python3
"""
migrate_replay_ids.py

One-shot migration: renames decimal replay directories to hex and updates
the _id field inside each replay_data.json.gz to match.

Run on the server:
    python3 migrate_replay_ids.py
    python3 migrate_replay_ids.py --dry-run   # preview without touching anything

Reads STORAGE_VOL_PATH from environment or TSSBOT/.env.
"""
from __future__ import annotations

import argparse
import gzip
import json
import os
import sys
from pathlib import Path

_HERE = Path(__file__).resolve().parent

# Try loading .env if python-dotenv is available
try:
    from dotenv import load_dotenv
    load_dotenv(dotenv_path=_HERE / ".env")
except ImportError:
    pass

STORAGE_VOL_PATH = os.environ.get("STORAGE_VOL_PATH", "").strip()
if not STORAGE_VOL_PATH:
    print("ERROR: STORAGE_VOL_PATH not set", file=sys.stderr)
    sys.exit(1)

REPLAYS_DIR = Path(STORAGE_VOL_PATH) / "REPLAYS" / "TSS"


def is_decimal_id(name: str) -> bool:
    """True if the directory name looks like a plain decimal integer (not hex)."""
    try:
        int(name)
        return True
    except ValueError:
        return False


def to_hex(decimal_str: str) -> str:
    return hex(int(decimal_str))[2:].lower()


def migrate_one(src_dir: Path, *, dry_run: bool) -> tuple[str, str] | None:
    """
    Rename src_dir from decimal to hex, update _id inside replay_data.json.gz.
    Returns (old_name, new_name) on success, None if already hex or skipped.
    """
    name = src_dir.name
    if not is_decimal_id(name):
        return None

    hex_name = to_hex(name)
    dst_dir  = src_dir.parent / hex_name

    if dst_dir.exists():
        print(f"  SKIP {name} → {hex_name} (destination already exists)")
        return None

    gz_path = src_dir / "replay_data.json.gz"

    if gz_path.exists():
        try:
            with gzip.open(gz_path, "rb") as fh:
                data = json.loads(fh.read().decode("utf-8"))
        except Exception as exc:
            print(f"  ERROR reading {gz_path}: {exc}")
            return None

        data["_id"] = hex_name

        if not dry_run:
            with gzip.open(gz_path, "wb") as fh:
                fh.write(json.dumps(data, ensure_ascii=False).encode("utf-8"))

    if not dry_run:
        src_dir.rename(dst_dir)

    return name, hex_name


def main() -> None:
    parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
    parser.add_argument("--dry-run", action="store_true", help="Print what would happen without changing anything")
    args = parser.parse_args()

    if not REPLAYS_DIR.is_dir():
        print(f"ERROR: {REPLAYS_DIR} does not exist", file=sys.stderr)
        sys.exit(1)

    entries = sorted(p for p in REPLAYS_DIR.iterdir() if p.is_dir())
    candidates = [p for p in entries if is_decimal_id(p.name)]

    if not candidates:
        print("No decimal-named replay directories found. Nothing to do.")
        return

    mode = "DRY RUN — " if args.dry_run else ""
    print(f"{mode}Found {len(candidates)} decimal director(ies) to migrate in {REPLAYS_DIR}\n")

    ok = skipped = errors = 0
    for src_dir in candidates:
        result = migrate_one(src_dir, dry_run=args.dry_run)
        if result is None:
            skipped += 1
        else:
            old, new = result
            tag = "[dry-run] " if args.dry_run else ""
            print(f"  {tag}{old}  →  {new}")
            ok += 1

    print(f"\nDone. migrated={ok}  skipped={skipped}  errors={errors}")
    if args.dry_run:
        print("(dry run — nothing was changed)")


if __name__ == "__main__":
    main()