package database

import (
	"context"
	"database/sql"
	"fmt"
	"os"

	"go.ntppool.org/common/logger"
)

// OpenDB opens a database connection with the specified configuration options
func OpenDB(ctx context.Context, options ConfigOptions) (*sql.DB, error) {
	log := logger.Setup()

	configFile, err := findConfigFile(options.ConfigFiles)
	if err != nil {
		return nil, err
	}

	dbconn := sql.OpenDB(Driver{
		CreateConnectorFunc: createConnector(configFile),
	})

	// Set connection pool parameters
	dbconn.SetConnMaxLifetime(options.ConnMaxLifetime)
	dbconn.SetMaxOpenConns(options.MaxOpenConns)
	dbconn.SetMaxIdleConns(options.MaxIdleConns)

	err = dbconn.Ping()
	if err != nil {
		log.Error("could not connect to database", "err", err)
		return nil, err
	}

	// Start optional connection pool monitoring
	if options.EnablePoolMonitoring && options.PrometheusRegisterer != nil {
		go monitorConnectionPool(ctx, dbconn, options.PrometheusRegisterer)
	}

	return dbconn, nil
}

// OpenDBWithConfigFile opens a database connection using an explicit config file path
// This is a convenience function for API package compatibility
func OpenDBWithConfigFile(ctx context.Context, configFile string) (*sql.DB, error) {
	options := DefaultConfigOptions()
	options.ConfigFiles = []string{configFile}
	return OpenDB(ctx, options)
}

// OpenDBMonitor opens a database connection with monitor-specific defaults
// This is a convenience function for Monitor package compatibility
func OpenDBMonitor() (*sql.DB, error) {
	options := MonitorConfigOptions()
	return OpenDB(context.Background(), options)
}

// findConfigFile searches for the first existing config file from the list
func findConfigFile(configFiles []string) (string, error) {
	var firstErr error

	for _, configFile := range configFiles {
		if configFile == "" {
			continue
		}
		if _, err := os.Stat(configFile); err == nil {
			return configFile, nil
		} else if firstErr == nil {
			firstErr = err
		}
	}

	if firstErr != nil {
		return "", fmt.Errorf("no config file found: %w", firstErr)
	}
	return "", fmt.Errorf("no valid config files provided")
}