"""Formal export/import migration workflow for rebuilding to current schema.

Usage examples:

1) Export current DB + uploads to a bundle:
   uv run python tools/export_import_migration.py export --bundle-dir .migration-bundle

2) Import bundle into a fresh target DB + uploads root:
   uv run python tools/export_import_migration.py import --bundle-dir .migration-bundle
       --target-db .\\data\\transcription-new.db --target-upload-dir .\\data-new

3) One-shot rebuild flow:
   uv run python tools/export_import_migration.py migrate --bundle-dir .migration-bundle
       --target-db .\\data\\transcription-new.db --target-upload-dir .\\data-new
"""

from __future__ import annotations

import argparse
import json
from pathlib import Path
from typing import Final

from transcription.config import get_settings
from transcription.db.migration import MigrationPaths
from transcription.db.migration import default_sync_db_url
from transcription.db.migration import export_bundle
from transcription.db.migration import import_bundle
from transcription.db.migration import migrate_via_bundle
from transcription.db.migration import sqlite_url_from_path
from transcription.db.migration import verify_migration

DEFAULT_BUNDLE_DIR: Final[Path] = Path(".migration-bundle")


def _db_url(value: str | None, *, default_url: str) -> str:
    if value is None or not value.strip():
        return default_url
    candidate = value.strip()
    if "://" in candidate:
        return candidate
    return sqlite_url_from_path(Path(candidate))


def _path(value: str | None, *, default_path: Path) -> Path:
    if value is None or not value.strip():
        return default_path
    return Path(value)


def main() -> int:
    settings = get_settings()
    parser = argparse.ArgumentParser(description=__doc__)
    subparsers = parser.add_subparsers(dest="command", required=True)

    common = argparse.ArgumentParser(add_help=False)
    common.add_argument("--bundle-dir", default=str(DEFAULT_BUNDLE_DIR), help="Directory for export bundle artifacts")
    common.add_argument(
        "--source-db",
        default=None,
        help="Source database path or SQLAlchemy URL (default: current configured database)",
    )
    common.add_argument(
        "--source-upload-dir",
        default=None,
        help="Source upload directory (default: current UPLOAD_DIR setting)",
    )
    common.add_argument(
        "--target-db",
        default=None,
        help="Target database path or SQLAlchemy URL (required for import/migrate if not using current DB)",
    )
    common.add_argument(
        "--target-upload-dir",
        default=None,
        help="Target upload directory (required for import/migrate if not using current UPLOAD_DIR)",
    )

    subparsers.add_parser("export", parents=[common], help="Export DB rows and uploads into bundle")
    subparsers.add_parser("import", parents=[common], help="Import bundle into target DB and uploads")
    subparsers.add_parser("migrate", parents=[common], help="Run export then import in one command")
    subparsers.add_parser("verify", parents=[common], help="Compare source/target row counts and integrity checks")

    args = parser.parse_args()
    bundle_dir = Path(args.bundle_dir)

    source_db_url = _db_url(args.source_db, default_url=default_sync_db_url(settings))
    source_upload_dir = _path(args.source_upload_dir, default_path=settings.upload_dir)
    target_db_url = _db_url(args.target_db, default_url=default_sync_db_url(settings))
    target_upload_dir = _path(args.target_upload_dir, default_path=settings.upload_dir)

    if args.command == "export":
        export_bundle(
            source_db_url=source_db_url,
            source_upload_dir=source_upload_dir,
            bundle_dir=bundle_dir,
        )
        print(f"Export complete: {bundle_dir}")
        return 0

    if args.command == "import":
        import_bundle(
            target_db_url=target_db_url,
            target_upload_dir=target_upload_dir,
            bundle_dir=bundle_dir,
        )
        print(f"Import complete: db={target_db_url} uploads={target_upload_dir}")
        return 0

    if args.command == "verify":
        report = verify_migration(source_db_url=source_db_url, target_db_url=target_db_url)
        print(json.dumps(report.to_dict(), indent=2))
        return 0 if report.success else 1

    migrate_via_bundle(
        MigrationPaths(
            source_db_url=source_db_url,
            target_db_url=target_db_url,
            source_upload_dir=source_upload_dir,
            target_upload_dir=target_upload_dir,
            bundle_dir=bundle_dir,
        )
    )
    print(f"Migration complete: bundle={bundle_dir} target_db={target_db_url} target_upload_dir={target_upload_dir}")
    return 0


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