"""Database connection management for XER MCP Server."""

import sqlite3
from collections.abc import Generator
from contextlib import contextmanager

from xer_mcp.db.schema import get_schema


class DatabaseManager:
    """Manages SQLite database connections and schema initialization."""

    def __init__(self) -> None:
        """Initialize database manager with in-memory database."""
        self._connection: sqlite3.Connection | None = None

    def initialize(self) -> None:
        """Initialize the in-memory database with schema."""
        self._connection = sqlite3.connect(":memory:", check_same_thread=False)
        self._connection.row_factory = sqlite3.Row
        self._connection.executescript(get_schema())

    def clear(self) -> None:
        """Clear all data from the database."""
        if self._connection is None:
            return

        tables = ["relationships", "activities", "wbs", "calendars", "projects"]
        for table in tables:
            self._connection.execute(f"DELETE FROM {table}")  # noqa: S608
        self._connection.commit()

    @property
    def connection(self) -> sqlite3.Connection:
        """Get the database connection."""
        if self._connection is None:
            raise RuntimeError("Database not initialized. Call initialize() first.")
        return self._connection

    @contextmanager
    def cursor(self) -> Generator[sqlite3.Cursor]:
        """Get a cursor for executing queries."""
        cur = self.connection.cursor()
        try:
            yield cur
        finally:
            cur.close()

    def commit(self) -> None:
        """Commit the current transaction."""
        self.connection.commit()

    def close(self) -> None:
        """Close the database connection."""
        if self._connection is not None:
            self._connection.close()
            self._connection = None

    @property
    def is_initialized(self) -> bool:
        """Check if the database is initialized."""
        return self._connection is not None


# Global database manager instance
db = DatabaseManager()