package mysqlx

import (
	"errors"
	"time"

	mysqldriver "github.com/go-sql-driver/mysql"
	"gorm.io/gorm"
	"gorm.io/gorm/logger"
	"gorm.io/gorm/schema"
)

// Option configures the SDK client.
type Option func(*config)

type config struct {
	DSN             string
	DSNConfig       *mysqldriver.Config
	DSNUser         string
	DSNPassword     string
	DSNNet          string
	DSNAddr         string
	DSNDBName       string
	DSNParams       map[string]string
	DSNParseTime    *bool
	DSNTLSConfig    string
	DSNLoc          *time.Location
	DSNCollation    string
	DSNTimeout      time.Duration
	DSNReadTimeout  time.Duration
	DSNWriteTimeout time.Duration

	Dialector                                gorm.Dialector
	Logger                                   logger.Interface
	NamingStrategy                           schema.NamingStrategy
	MaxIdleConns                             int
	MaxOpenConns                             int
	ConnMaxIdleTime                          time.Duration
	ConnMaxLifetime                          time.Duration
	DisableForeignKeyConstraintWhenMigrating bool
	SkipDefaultTransaction                   bool
	DryRun                                   bool
}

type DSN struct {
}

func defaultConfig() *config {
	return &config{
		Logger:         logger.Default,
		NamingStrategy: schema.NamingStrategy{SingularTable: true},
		MaxIdleConns:   10,
		MaxOpenConns:   100,
	}
}

func buildDSN(cfg *config) (string, error) {
	var mysqlConfig *mysqldriver.Config
	if cfg.DSN != "" {
		parsed, err := mysqldriver.ParseDSN(cfg.DSN)
		if err != nil {
			return "", err
		}
		mysqlConfig = parsed
	} else if cfg.DSNConfig != nil {
		mysqlConfig = cfg.DSNConfig.Clone()
	} else {
		mysqlConfig = mysqldriver.NewConfig()
	}

	applyMySQLConfigOverrides(mysqlConfig, cfg)

	if mysqlConfig.User == "" && mysqlConfig.Passwd == "" && mysqlConfig.Addr == "" && mysqlConfig.DBName == "" && len(mysqlConfig.Params) == 0 {
		if cfg.DSN == "" {
			return "", errors.New("mysqlx: DSN or expanded DSN configuration must be provided")
		}
	}

	return mysqlConfig.FormatDSN(), nil
}

func applyMySQLConfigOverrides(mysqlConfig *mysqldriver.Config, cfg *config) {
	if cfg.DSNConfig != nil {
		mergeMySQLConfig(mysqlConfig, cfg.DSNConfig)
	}
	if cfg.DSNUser != "" {
		mysqlConfig.User = cfg.DSNUser
	}
	if cfg.DSNPassword != "" {
		mysqlConfig.Passwd = cfg.DSNPassword
	}
	if cfg.DSNNet != "" {
		mysqlConfig.Net = cfg.DSNNet
	}
	if cfg.DSNAddr != "" {
		mysqlConfig.Addr = cfg.DSNAddr
	}
	if cfg.DSNDBName != "" {
		mysqlConfig.DBName = cfg.DSNDBName
	}
	if cfg.DSNParams != nil {
		if mysqlConfig.Params == nil {
			mysqlConfig.Params = map[string]string{}
		}
		for key, value := range cfg.DSNParams {
			mysqlConfig.Params[key] = value
		}
	}
	if cfg.DSNParseTime != nil {
		mysqlConfig.ParseTime = *cfg.DSNParseTime
	}
	if cfg.DSNTLSConfig != "" {
		mysqlConfig.TLSConfig = cfg.DSNTLSConfig
	}
	if cfg.DSNLoc != nil {
		mysqlConfig.Loc = cfg.DSNLoc
	}
	if cfg.DSNCollation != "" {
		mysqlConfig.Collation = cfg.DSNCollation
	}
	if cfg.DSNTimeout > 0 {
		mysqlConfig.Timeout = cfg.DSNTimeout
	}
	if cfg.DSNReadTimeout > 0 {
		mysqlConfig.ReadTimeout = cfg.DSNReadTimeout
	}
	if cfg.DSNWriteTimeout > 0 {
		mysqlConfig.WriteTimeout = cfg.DSNWriteTimeout
	}
}

func mergeMySQLConfig(base, override *mysqldriver.Config) {
	if override.User != "" {
		base.User = override.User
	}
	if override.Passwd != "" {
		base.Passwd = override.Passwd
	}
	if override.Net != "" {
		base.Net = override.Net
	}
	if override.Addr != "" {
		base.Addr = override.Addr
	}
	if override.DBName != "" {
		base.DBName = override.DBName
	}
	if override.Params != nil {
		if base.Params == nil {
			base.Params = map[string]string{}
		}
		for key, value := range override.Params {
			base.Params[key] = value
		}
	}
	if override.Collation != "" {
		base.Collation = override.Collation
	}
	if override.Loc != nil {
		base.Loc = override.Loc
	}
	if override.TLSConfig != "" {
		base.TLSConfig = override.TLSConfig
	}
	if override.Timeout > 0 {
		base.Timeout = override.Timeout
	}
	if override.ReadTimeout > 0 {
		base.ReadTimeout = override.ReadTimeout
	}
	if override.WriteTimeout > 0 {
		base.WriteTimeout = override.WriteTimeout
	}
	if override.ParseTime {
		base.ParseTime = override.ParseTime
	}
}

// WithDSN sets the MySQL DSN used to open the database.
func WithDSN(dsn string) Option {
	return func(cfg *config) {
		cfg.DSN = dsn
	}
}

// WithDSNConfig sets the underlying mysql.Config used to generate the DSN.
func WithDSNConfig(mysqlConfig *mysqldriver.Config) Option {
	return func(cfg *config) {
		cfg.DSNConfig = mysqlConfig
	}
}

// WithDSNUser sets the MySQL username.
func WithDSNUser(user string) Option {
	return func(cfg *config) {
		cfg.DSNUser = user
	}
}

// WithDSNPassword sets the MySQL password.
func WithDSNPassword(password string) Option {
	return func(cfg *config) {
		cfg.DSNPassword = password
	}
}

// WithDSNNet sets the network type for the DSN.
func WithDSNNet(net string) Option {
	return func(cfg *config) {
		cfg.DSNNet = net
	}
}

// WithDSNAddr sets the database address for the DSN.
func WithDSNAddr(addr string) Option {
	return func(cfg *config) {
		cfg.DSNAddr = addr
	}
}

// WithDSNDBName sets the database name for the DSN.
func WithDSNDBName(dbName string) Option {
	return func(cfg *config) {
		cfg.DSNDBName = dbName
	}
}

// WithDSNParams sets additional DSN query parameters.
func WithDSNParams(params map[string]string) Option {
	return func(cfg *config) {
		if cfg.DSNParams == nil {
			cfg.DSNParams = map[string]string{}
		}
		for key, value := range params {
			cfg.DSNParams[key] = value
		}
	}
}

// WithDSNParseTime configures parseTime for the DSN.
func WithDSNParseTime(parseTime bool) Option {
	return func(cfg *config) {
		cfg.DSNParseTime = &parseTime
	}
}

// WithDSNTLSConfig sets the TLS configuration name for the DSN.
func WithDSNTLSConfig(tlsConfig string) Option {
	return func(cfg *config) {
		cfg.DSNTLSConfig = tlsConfig
	}
}

// WithDSNLocation sets the time location for DSN parsing.
func WithDSNLocation(loc *time.Location) Option {
	return func(cfg *config) {
		cfg.DSNLoc = loc
	}
}

// WithDSNCollation sets the connection collation for the DSN.
func WithDSNCollation(collation string) Option {
	return func(cfg *config) {
		cfg.DSNCollation = collation
	}
}

// WithDSNTimeout sets the dial timeout for the DSN.
func WithDSNTimeout(timeout time.Duration) Option {
	return func(cfg *config) {
		cfg.DSNTimeout = timeout
	}
}

// WithDSNReadTimeout sets the read timeout for the DSN.
func WithDSNReadTimeout(timeout time.Duration) Option {
	return func(cfg *config) {
		cfg.DSNReadTimeout = timeout
	}
}

// WithDSNWriteTimeout sets the write timeout for the DSN.
func WithDSNWriteTimeout(timeout time.Duration) Option {
	return func(cfg *config) {
		cfg.DSNWriteTimeout = timeout
	}
}

// WithDialector sets a custom gorm Dialector.
func WithDialector(dialector gorm.Dialector) Option {
	return func(cfg *config) {
		cfg.Dialector = dialector
	}
}

// WithLogger sets the gorm logger.
func WithLogger(logger logger.Interface) Option {
	return func(cfg *config) {
		cfg.Logger = logger
	}
}

// WithNamingStrategy sets the naming strategy for gorm models.
func WithNamingStrategy(strategy schema.NamingStrategy) Option {
	return func(cfg *config) {
		cfg.NamingStrategy = strategy
	}
}

// WithSingularTable enables or disables singular table names for gorm models.
func WithSingularTable(singular bool) Option {
	return func(cfg *config) {
		cfg.NamingStrategy.SingularTable = singular
	}
}

// WithConnectionPool configures database connection pooling.
func WithConnectionPool(maxIdleConns, maxOpenConns int, maxIdleTime, maxLifetime time.Duration) Option {
	return func(cfg *config) {
		cfg.MaxIdleConns = maxIdleConns
		cfg.MaxOpenConns = maxOpenConns
		cfg.ConnMaxIdleTime = maxIdleTime
		cfg.ConnMaxLifetime = maxLifetime
	}
}

// WithDisableForeignKeyConstraintWhenMigrating toggles foreign key constraint creation during migrations.
func WithDisableForeignKeyConstraintWhenMigrating(disable bool) Option {
	return func(cfg *config) {
		cfg.DisableForeignKeyConstraintWhenMigrating = disable
	}
}

// WithSkipDefaultTransaction toggles default transactions in gorm.
func WithSkipDefaultTransaction(skip bool) Option {
	return func(cfg *config) {
		cfg.SkipDefaultTransaction = skip
	}
}

// WithDryRun toggles gorm dry run mode.
func WithDryRun(dryRun bool) Option {
	return func(cfg *config) {
		cfg.DryRun = dryRun
	}
}