package database

import (
	"os"
	"path/filepath"
	"time"

	"log/slog"

	"github.com/jmoiron/sqlx"
	_ "github.com/mattn/go-sqlite3"
	"github.com/pkg/errors"
)

var (
	log      = slog.New(slog.NewJSONHandler(os.Stdout, nil))
	dbDriver = "sqlite3"
)

// VerifyDB checks if required tables exist
func (d *DB) VerifyDB() error {
	var exists int
	err := d.Conn.Get(&exists, `SELECT 1 FROM sqlite_master WHERE type='table' AND name='questions' LIMIT 1`)
	if err != nil {
		return errors.Wrap(err, "database verification failed")
	}
	if exists != 1 {
		return errors.New("required tables not found in database")
	}
	return nil
}

type DB struct {
	Conn *sqlx.DB
	URI  string
}

func (d *DB) CloseAll() error {
	for _, conn := range []*sqlx.DB{d.Conn} {
		if err := closeConn(conn); err != nil {
			return err
		}
	}
	return nil
}

func closeConn(conn *sqlx.DB) error {
	return conn.Close()
}

func Init(dbPath string) (*DB, error) {
	var result DB
	var err error
	
	// Default to in-memory DB if no path specified
	if dbPath == "" {
		dbPath = ":memory:"
	} else if !filepath.IsAbs(dbPath) {
		// Convert relative paths to absolute
		dbPath = filepath.Join(".", dbPath)
	}

	result.Conn, err = openDBConnection(dbPath, dbDriver)
	if err != nil {
		return nil, err
	}
	result.URI = dbPath
	if err := testConnection(result.Conn); err != nil {
		return nil, err
	}

	if err := result.VerifyDB(); err != nil {
		return nil, errors.Wrap(err, "database schema verification failed")
	}

	return &result, nil
}

func openDBConnection(dbPath, driver string) (*sqlx.DB, error) {
	// Ensure the directory exists
	if err := os.MkdirAll(filepath.Dir(dbPath), 0755); err != nil {
		return nil, errors.Wrap(err, "failed to create db directory")
	}

	conn, err := sqlx.Open(driver, dbPath)
	if err != nil {
		return nil, err
	}

	// SQLite-specific optimizations
	conn.SetMaxOpenConns(1) // SQLite only supports one writer at a time
	conn.SetConnMaxLifetime(0) // Connections don't need to be closed/reopened

	return conn, nil
}

func testConnection(conn *sqlx.DB) error {
	err := conn.Ping()
	if err != nil {
		return errors.Wrap(err, "can't ping database")
	}
	return nil
}

func (d *DB) PingRoutine(interval time.Duration) {
	ticker := time.NewTicker(interval)
	done := make(chan bool)
	for {
		select {
		case <-done:
			return
		case t := <-ticker.C:
			if err := testConnection(d.Conn); err != nil {
				log.Error("failed to ping postrges db", "error", err, "ping_at", t)
				// reconnect
				if err := closeConn(d.Conn); err != nil {
					log.Error("failed to close db connection", "error", err, "ping_at", t)
				}
				d.Conn, err = openDBConnection(d.URI, dbDriver)
				if err != nil {
					log.Error("failed to reconnect", "error", err, "ping_at", t)
				}
			}
		}
	}
}