package config

import (
	"database/sql"
	"fmt"

	"edge-infra.dev/pkg/lib/gcp/cloudsql"
)

// Returns an initialised connection to the database using the configuration
// defined in config. Database may be accessed through CloudSQL or via a port number
// Returns an error when config includes invalid configuration or an attempt to
// connect to the DB fails
func DB(config SQLConfig) (*sql.DB, func() error, error) {
	check := func() error {
		return fmt.Errorf("error db not initialised")
	}

	// Use cloudsql to handle connection
	var edgeDb *cloudsql.EdgePostgres

	// Initialise the correct type of connection: CLoudSQL or local host, port pair,
	// determined by the presence of the ConnectionName configuration param
	switch {
	case config.ConnectionName != "":
		edgeDb = cloudsql.GCPPostgresConnection(config.ConnectionName)
	case config.ConnectionName == "" && config.Host != "":
		if config.Port == "" {
			return nil, check, fmt.Errorf("database port is required")
		}
		edgeDb = cloudsql.PostgresConnection(config.Host, config.Port).
			Password(config.Password)
	default:
		return nil, check, fmt.Errorf("database-connection-name or database-host must be provided")
	}

	// Open the connection to the configured DB
	edgeDb = edgeDb.
		DBName(config.DatabaseName).
		Username(config.User)

	// Only set search_path when the schema is a non-empty string
	if config.Schema != "" {
		edgeDb = edgeDb.SearchPath(config.Schema)
	}

	db, err := edgeDb.NewConnection()
	if err != nil {
		return nil, check, err
	}

	// Test connection to DB before returning
	if err := db.Ping(); err != nil {
		return nil, check, err
	}
	return db, checkDB(db), nil
}

func checkDB(db *sql.DB) func() error {
	return func() error {
		if _, err := db.Exec("SELECT 1;"); err != nil {
			return fmt.Errorf("database not ready: %w", err)
		}
		return nil
	}
}