package model

import (
	"fmt"
	"sync"

	"qoobing.com/gomod/gorm"
	"qoobing.com/gomod/log"
	"qoobing.com/gomod/redis"
)

var (
	instances          = map[string]instance{}
	errNoModelFound    = errorsWrap("named model(%s) not found")
	errModeAlreadyInit = errorsWrap("named model(%s) already initilized")
	errOpenDBFailed    = errorsWrap("open database failed: %s")
	errOpenRedisFailed = errorsWrap("open redis failed: %s")
)

func errorsWrap(base string) func(...any) error {
	return func(v ...any) error {
		return fmt.Errorf(base, v...)
	}
}

const (
	tx_status_none     = 0
	tx_status_doing    = 1
	tx_status_commit   = 2
	tx_status_rollback = 3
)

type Model struct {
	mu       sync.Mutex
	dbCfg    *gorm.Config
	redisCfg *redis.Config

	db         *gorm.DB
	dbTxStatus int
	redis      redis.Conn
	redisPool  *redis.Pool
}

func (m *Model) Begin() {
	if m.DB() == nil {
		panic("unreachable code, db is uninitialized")
	} else if m.dbTxStatus != tx_status_none {
		panic("unreachable code, begin transaction towice???")
	} else {
		m.dbTxStatus = tx_status_doing
		m.db = m.db.Begin()
	}
}

func (m *Model) Commit() error {
	if m.DB() == nil {
		panic("unreachable code, db is uninitialized")
	} else if m.dbTxStatus != tx_status_doing {
		return nil
	} else if err := m.db.Commit().Error; err != nil {
		m.dbTxStatus = tx_status_rollback
		return err
	} else {
		m.dbTxStatus = tx_status_commit
		return nil
	}
}

func (m *Model) Close() {
	if m.redis != nil {
		m.redis.Close()
	}
	if m.db == nil {
		m.dbTxStatus = tx_status_none
	} else if m.dbTxStatus == tx_status_doing {
		m.db.Rollback()
		m.dbTxStatus = tx_status_rollback
	}
}

func (m *Model) DB() *gorm.DB {
	return m.db
}

func (m *Model) Redis() redis.Conn {
	return m.redis
}

func (m *Model) RedisPool() *redis.Pool {
	return m.redisPool
}

type instance struct {
	db       *gorm.DB
	dbCfg    *gorm.Config
	redis    *redis.Pool
	redisCfg *redis.Config
}

// OpenDefault open 'default' model
func OpenDefault() (*Model, error) {
	return Open("default")
}

// OpenDefault open named model, if err is nil, caller MUST call m.Close() in defer.
func Open(name string) (m *Model, err error) {
	// check initialize
	cfg, ok := instances[name]
	if !ok {
		return nil, errNoModelFound(name)
	}

	// open redis
	var rds redis.Conn
	if cfg.redisCfg == nil {
		// don't need to open redis
	} else if cfg.redis != nil {
		rds = cfg.redis.Get()
	} else if cfg.redis = redis.NewPool(*cfg.redisCfg); cfg.redis == nil {
		return nil, errOpenRedisFailed("new redis pool return nil")
	} else {
		rds = cfg.redis.Get()
	}
	defer func() {
		if m == nil && rds != nil {
			rds.Close()
		}
	}()

	// open db
	var db *gorm.DB
	if cfg.dbCfg == nil {
		// don't need to open database
	} else if cfg.db != nil {
		db = gorm.NewSession(cfg.db)
	} else if cfg.db, err = gorm.NewDB(*cfg.dbCfg); err != nil {
		return nil, errOpenDBFailed(err)
	} else {
		db = gorm.NewSession(cfg.db)
	}

	// success
	m = &Model{
		dbCfg:     cfg.dbCfg,
		redisCfg:  cfg.redisCfg,
		db:        db,
		redis:     rds,
		redisPool: cfg.redis,
	}
	return m, nil
}

// Init init default database config & redis config
func InitDefault(_defaultDb *gorm.Config, _defaultRds *redis.Config) error {
	return Init("default", _defaultDb, _defaultRds)
}

// Init init named database config & redis config
func Init(name string, dbCfg *gorm.Config, rdsCfg *redis.Config) error {
	_, ok := instances[name]
	if ok {
		return errModeAlreadyInit(name)
	}
	instances[name] = instance{
		dbCfg:    dbCfg,
		redisCfg: rdsCfg,
	}
	if dbCfg != nil && dbCfg.Debug {
		log.Infof("init model(%s) database:%s", name, gorm.GetSecDsn(dbCfg))
	}
	if rdsCfg != nil && rdsCfg.Debug {
		log.Infof("init model(%s) redis:%s", name, redis.)
	}
	log.Infof("init model(%s) done", name)
	return nil
}