"""Peewee SQLite database instance and initialization."""
from peewee import SqliteDatabase

from imptune.config import DB_PATH

# Deferred init — path is set at runtime via init_db() so tests can override DB_PATH
db = SqliteDatabase(None)


def init_db() -> None:
    """Initialize the SQLite database with WAL mode and foreign keys.

    Idempotent — safe to call on every application startup.
    Creates all ORM tables if they do not already exist.

    Closes any existing connection before re-initializing so that test
    fixtures can monkeypatch DB_PATH between test runs.
    """
    from imptune.db.models import Client, Driver, Owner, Printer, Icon

    # Re-read DB_PATH each time so tests can patch imptune.config.DB_PATH
    import imptune.config as cfg

    # Close any lingering connection from a previous run (important for tests)
    if not db.is_closed():
        db.close()

    db.init(
        cfg.DB_PATH,
        pragmas={
            "journal_mode": "wal",
            "foreign_keys": 1,
        },
    )
    db.connect(reuse_if_open=True)
    db.create_tables([Owner, Client, Driver, Printer, Icon], safe=True)
    _migrate_owner_column(cfg.DATA_DIR)


def _migrate_owner_column(data_dir: str) -> None:
    """Add owner_id to printer/client if missing, backfilling pre-existing rows.

    Runs against a DB created before per-owner scoping existed. Idempotent:
    a no-op once the column exists and no rows are left with a NULL owner_id.
    """
    from pathlib import Path

    from imptune.db.models import Client, Owner, Printer
    from imptune.services.session import generate_key

    for table in ("printer", "client"):
        columns = {row[1] for row in db.execute_sql(f"PRAGMA table_info({table})")}
        if "owner_id" not in columns:
            db.execute_sql(
                f"ALTER TABLE {table} ADD COLUMN owner_id INTEGER REFERENCES owner (id)"
            )

    orphaned = Printer.select().where(Printer.owner.is_null()).count() or Client.select().where(
        Client.owner.is_null()
    ).count()
    if not orphaned:
        return

    legacy_owner = Owner.create(key=generate_key(), is_permanent=True)
    Printer.update(owner=legacy_owner.id).where(Printer.owner.is_null()).execute()
    Client.update(owner=legacy_owner.id).where(Client.owner.is_null()).execute()

    key_path = Path(data_dir) / "legacy_owner_key.txt"
    key_path.write_text(legacy_owner.key, encoding="utf-8")
    print(f"[imptune] Pre-existing printers/clients migrated to a legacy owner. "
          f"Restore key written to {key_path} — paste it into /session/restore to reclaim them.")