package dbx

import (
	"database/sql"
	"errors"

	"gitea.auvem.com/go-toolkit/app"
	"gitea.auvem.com/go-toolkit/dbx/internal/dbxshared"
	"github.com/go-jet/jet/v2/qrm"
)

const (
	// ModuleDBName is the name of the database module.
	ModuleDBName = "database"

	// DialectPostgres is the PostgreSQL dialect.
	DialectPostgres Dialect = "postgres"
	// DialectMySQL is the MySQL dialect.
	DialectMySQL Dialect = "mysql"
)

// Dialect is the SQL dialect used by the database connection.
type Dialect string

// String implements the Stringer interface for Dialect.
func (d Dialect) String() string {
	return string(d)
}

// dbState stores package-level state for the database connection.
type dbState struct {
	sqlDB    *sql.DB
	config   *DBConfig
	dialect  Dialect
	debugLog bool
}

var (
	// ErrNoRows is returned when a query returns no rows.
	ErrNoRows = qrm.ErrNoRows

	// ErrValueIsZero is returned when an expected value is missing.
	ErrValueIsZero = errors.New("value is zero-value for type")

	state = dbState{}
)

// SQLO returns the current SQL database handle.
func SQLO() *sql.DB {
	dbxshared.DBModule.RequireLoaded("dbx.SQLO requires database module")
	if state.sqlDB == nil {
		panic("SQL database not initialized")
	}
	return state.sqlDB
}

// ModuleDB returns the database module with the provided configuration.
// dialect specifies the SQL dialect to use (e.g., DialectPostgres, DialectMySQL).
// config specifies the database connection configuration.
// forceDebugLog forces debug logging to be enabled regardless of the config setting.
func ModuleDB(dialect Dialect, config *DBConfig, forceDebugLog bool) *app.Module {
	if dbxshared.DBModule != nil {
		panic("ModuleDB initialized multiple times")
	}
	if config == nil {
		panic("ModuleDB requires a non-nil DBConfig")
	}

	state.config = config
	state.dialect = dialect
	state.debugLog = config.DebugLog || forceDebugLog

	dbxshared.DBModule = app.NewModule(ModuleDBName, app.ModuleOpts{
		Setup:    setupDB,
		Teardown: teardownDB,
	})

	return dbxshared.DBModule
}

func setupDB(m *app.Module) error {
	if state.sqlDB != nil && state.sqlDB.Ping() == nil {
		m.Logger().Warn("Database connection already established")
		return nil
	}

	logArgs := []any{
		"user", state.config.User,
		"name", state.config.Name,
		"uri", state.config.URI,
		"dialect", state.dialect,
	}

	var err error
	state.sqlDB, err = sql.Open(string(state.dialect), state.config.ConnectionString(state.dialect))
	if err != nil {
		logArgs = append(logArgs, "err", err)
		m.Logger().Error("Couldn't open SQL database", logArgs...)
		return err
	}

	if err := state.sqlDB.Ping(); err != nil {
		logArgs = append(logArgs, "err", err)
		m.Logger().Error("Couldn't ping SQL database", logArgs...)
		return err
	}

	state.sqlDB.SetMaxOpenConns(state.config.MaxConn)

	stats := state.sqlDB.Stats()
	m.Logger().Info(
		"Connected to SQL database",
		"user", state.config.User,
		"name", state.config.Name,
		"uri", state.config.URI,
		"maxConnections", stats.MaxOpenConnections,
		"currConnections", stats.OpenConnections,
	)

	if state.debugLog {
		dbxshared.InitLogger(state.dialect)
	}

	return nil
}

func teardownDB(m *app.Module) error {
	if state.sqlDB == nil {
		return nil
	}

	if err := state.sqlDB.Close(); err != nil {
		m.Logger().Error("Couldn't close database", "err", err)
		return err
	}
	m.Logger().Info("Closed database connection")
	return nil
}