package registry

import (
	"database/sql"
	"fmt"
	"os"
	"path/filepath"

	_ "github.com/mattn/go-sqlite3"
)

// DB wraps a SQLite connection for the registry.
type DB struct {
	conn *sql.DB
	path string
}

// Open opens or creates the registry database at the given path.
func Open(path string) (*DB, error) {
	dir := filepath.Dir(path)
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return nil, fmt.Errorf("creating db directory: %w", err)
	}

	conn, err := sql.Open("sqlite3", path+"?_foreign_keys=on")
	if err != nil {
		return nil, fmt.Errorf("opening database: %w", err)
	}

	// WAL mode: enables concurrent reads while writing.
	if _, err := conn.Exec("PRAGMA journal_mode=WAL"); err != nil {
		conn.Close()
		return nil, fmt.Errorf("setting WAL mode: %w", err)
	}

	if err := migrate(conn); err != nil {
		conn.Close()
		return nil, fmt.Errorf("running migrations: %w", err)
	}

	return &DB{conn: conn, path: path}, nil
}

// Close closes the database connection.
func (db *DB) Close() error {
	return db.conn.Close()
}

// WalCheckpoint flushes the WAL to the main database file so external
// readers (e.g. Metabase via bind mount) see the latest data.
func (db *DB) WalCheckpoint() {
	db.conn.Exec("PRAGMA wal_checkpoint(TRUNCATE)")
}

// Drop removes the database file. Used by `fn index` to regenerate.
func (db *DB) Drop() error {
	db.Close()
	return os.Remove(db.path)
}

// Conn returns the underlying *sql.DB for callers that need raw SQL access
// (e.g. registry_mcp for aggregations not covered by Search/Get helpers).
func (db *DB) Conn() *sql.DB {
	return db.conn
}

// Path returns the filesystem path of the database file.
func (db *DB) Path() string {
	return db.path
}