package db

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

	// PostgreSQL
	_ "github.com/lib/pq"
	// MySQL
	_ "github.com/go-sql-driver/mysql"
	"github.com/jmoiron/sqlx"
)

// DB db
type DB struct {
	Driver string
	c      *sqlx.DB
	tx     *sqlx.Tx
}

type Tx struct {
	tx *sqlx.Tx
}

var (
	defaultConfig Option
	defaultDb     *DB
	db            *sqlx.DB
	once          sync.Once
)

// SetDefaultOption default connect option
func SetDefaultOption(opt Option) (err error) {
	defaultConfig = opt
	defaultDb = &DB{Driver: opt.Driver}
	defaultDb.c, err = connect()
	return
}

// ReleaseDefault release default connect
func ReleaseDefault() error {
	if defaultDb != nil {
		if defaultDb.c != nil {
			defaultDb.c.Close()
		}
	}
	return nil
}

// New new DB dynamic object
func New(opt Option) (dbx *DB, err error) {
	//dbx = &DB{}
	dbx.Driver = opt.Driver
	dbx.c, err = sqlx.Connect(opt.Driver, opt.DNS)
	if err != nil {
		return
	}

	dbx.c.SetMaxOpenConns(opt.MaxOpenConns)
	dbx.c.SetMaxIdleConns(opt.MaxIdle)
	dbx.c.SetConnMaxLifetime(opt.MaxLifetime)
	err = dbx.c.Ping()
	return
}

// Release release connect
func Release(dbx *DB) (err error) {
	if dbx.c != nil {
		err = dbx.c.Close()
	}
	return
}

func connect() (dbx *sqlx.DB, err error) {
	once.Do(func() {
		db, err = sqlx.Connect(defaultConfig.Driver, defaultConfig.DNS)
		if err == nil {
			db.DB.SetMaxOpenConns(defaultConfig.MaxOpenConns)
			db.DB.SetMaxIdleConns(defaultConfig.MaxIdle)
			db.DB.SetConnMaxLifetime(defaultConfig.MaxLifetime)
			err = db.Ping()
		}
	})

	dbx = db
	return
}

// Connect connect to database
func (d *DB) Connect() (err error) {
	if d.c != nil {
		return
	}

	d.c, err = connect()
	return
}

/*
// Close close database connect
func (d *DB) Close() error {
	// not use pool
		if d.c != nil {
			return d.c.Close()
		}
	return nil
}
// */

// Ping verifies a connection to the database is still alive, establishing a connection if necessary.
func (d *DB) Ping() error {
	return d.c.Ping()
}

// PingContext verifies a connection to the database is still alive, establishing a connection if necessary.
func (d *DB) PingContext(ctx context.Context) error {
	return d.c.PingContext(ctx)
}

// Stats returns database statistics.
func (d *DB) Stats() sql.DBStats {
	return d.c.Stats()
}

// BeginTrans begin trans
func (d *DB) BeginTrans() (err error) {
	d.c, err = connect()
	if err != nil {
		return
	}

	d.tx = d.c.MustBegin()
	return
}

// Trans begin trans
func (d *DB) Trans() (tx *Tx, err error) {
	d.c, err = connect()
	if err != nil {
		return
	}

	tx.tx = d.c.MustBegin()
	return
}

// Commit commit
func (d *DB) Commit() error {
	return d.tx.Commit()
}

// Rollback rollback
func (d *DB) Rollback() error {
	return d.tx.Rollback()
}

// TransNamedExec trans execute
func (d *DB) TransExec(query string, args ...interface{}) (LastInsertId, RowsAffected int64, err error) {
	rs, err := d.tx.Exec(query, args...)
	if err != nil {
		return
	}

	RowsAffected, _ = rs.RowsAffected()
	LastInsertId, _ = rs.LastInsertId()
	return
}

// TransNamedExec trans execute, named bindvars
func (d *DB) TransNamedExec(query string, args interface{}) (LastInsertId, RowsAffected int64, err error) {
	rs, err := d.tx.NamedExec(query, args)
	if err != nil {
		return
	}

	RowsAffected, _ = rs.RowsAffected()
	LastInsertId, _ = rs.LastInsertId()
	return
}

// TransGet trans get row
func (d *DB) TransGet(dest interface{}, query string, args ...interface{}) (err error) {
	err = d.tx.Get(dest, query, args...)
	return
}

// TransNamedGet trans get row, named bindvars
func (d *DB) TransNamedGet(dest interface{}, query string, args interface{}) (err error) {
	var nstmt *sqlx.NamedStmt
	nstmt, err = d.tx.PrepareNamed(query)
	if err != nil {
		return
	}
	defer nstmt.Close()

	err = nstmt.Get(dest, args)
	return
}

// TransSelect trans get rows
func (d *DB) TransSelect(dest interface{}, query string, args ...interface{}) (err error) {
	err = d.tx.Select(dest, query, args...)
	return
}

// Get get one
func (d *DB) Get(dest interface{}, query string, args ...interface{}) (err error) {
	err = d.Connect()
	if err != nil {
		return
	}
	//defer d.Close()

	err = d.c.Get(dest, query, args...)
	return
}

// Get get one, named bindvars
func (d *DB) NamedGet(dest interface{}, query string, args interface{}) (err error) {
	err = d.Connect()
	if err != nil {
		return
	}
	//defer d.Close()

	nstmt, err := d.c.PrepareNamed(query)
	if err != nil {
		return
	}
	defer nstmt.Close()

	err = nstmt.Get(dest, args)
	return
}

// Select select rows
func (d *DB) Select(dest interface{}, query string, args ...interface{}) error {
	err := d.Connect()
	if err != nil {
		return err
	}
	//defer d.Close()

	err = d.c.Select(dest, query, args...)
	return err
}

// NamedSelect select rows, named bindvars
func (d *DB) NamedSelect(dest interface{}, query string, args interface{}) (err error) {
	err = d.Connect()
	if err != nil {
		return err
	}
	//defer d.Close()

	nstmt, err := d.c.PrepareNamed(query)
	if err != nil {
		return err
	}
	defer nstmt.Close()

	err = nstmt.Select(dest, args)
	return err
}

// Exec exec
func (d *DB) Exec(query string, args ...interface{}) (LastInsertId, RowsAffected int64, err error) {
	err = d.Connect()
	if err != nil {
		return
	}
	//defer d.Close()

	var rs sql.Result
	rs, err = d.c.Exec(query, args...)
	if err != nil {
		return
	}

	LastInsertId, _ = rs.LastInsertId()
	RowsAffected, _ = rs.RowsAffected()
	return
}

// NamedExec exec, named bindvars
func (d *DB) NamedExec(query string, args interface{}) (LastInsertId, RowsAffected int64, err error) {
	err = d.Connect()
	if err != nil {
		return
	}
	//defer d.Close()

	var rs sql.Result
	rs, err = d.c.NamedExec(query, args)
	if err != nil {
		return
	}

	LastInsertId, _ = rs.LastInsertId()
	RowsAffected, _ = rs.RowsAffected()
	return
}

// Limit MySQL/PostgreSQL limit
func (d *DB) Limit(page, pagesize int) string {
	// MySQL limit n, size
	if d.Driver == DriverMySQL {
		return fmt.Sprintf(" LIMIT %d, %d", (page-1)*pagesize, pagesize)
	}
	// // PostgreSQL limit size offset n
	return fmt.Sprintf(" LIMIT %d OFFSET %d", pagesize, (page-1)*pagesize)
}

// Commit commit
func (t *Tx) Commit() error {
	return t.tx.Commit()
}

// Rollback rollback
func (t *Tx) Rollback() error {
	return t.tx.Rollback()
}

// TransNamedExec trans execute
func (t *Tx) TransExec(query string, args ...interface{}) (LastInsertId, RowsAffected int64, err error) {
	rs, err := t.tx.Exec(query, args...)
	if err != nil {
		return
	}

	RowsAffected, _ = rs.RowsAffected()
	LastInsertId, _ = rs.LastInsertId()
	return
}

// TransNamedExec trans execute, named bindvars
func (t *Tx) TransNamedExec(query string, args interface{}) (LastInsertId, RowsAffected int64, err error) {
	rs, err := t.tx.NamedExec(query, args)
	if err != nil {
		return
	}

	RowsAffected, _ = rs.RowsAffected()
	LastInsertId, _ = rs.LastInsertId()
	return
}

// TransGet trans get row
func (t *Tx) TransGet(dest interface{}, query string, args ...interface{}) (err error) {
	err = t.tx.Get(dest, query, args...)
	return
}

// TransNamedGet trans get row, named bindvars
func (t *Tx) TransNamedGet(dest interface{}, query string, args interface{}) (err error) {
	var nstmt *sqlx.NamedStmt
	nstmt, err = t.tx.PrepareNamed(query)
	if err != nil {
		return
	}
	defer nstmt.Close()

	err = nstmt.Get(dest, args)
	return
}

// TransSelect trans get rows
func (t *Tx) TransSelect(dest interface{}, query string, args ...interface{}) (err error) {
	err = t.tx.Select(dest, query, args...)
	return
}

// Ping verifies a connection to the database is still alive, establishing a connection if necessary.
func Ping() error {
	return defaultDb.Ping()
}

// PingContext verifies a connection to the database is still alive, establishing a connection if necessary.
func PingContext(ctx context.Context) error {
	return defaultDb.PingContext(ctx)
}

/*
// Close close database connect
func Close() error {
	return defaultDb.Close()
}
// */

// Stats returns database statistics.
func Stats() sql.DBStats {
	return defaultDb.Stats()
}

// BeginTrans begin trans
func BeginTrans() (tx *Tx, err error) {
	return defaultDb.Trans()
}

// Get get one
func Get(dest interface{}, query string, args ...interface{}) error {
	return defaultDb.Get(dest, query, args...)
}

// Get get one, named bindvars
func NamedGet(dest interface{}, query string, args interface{}) (err error) {
	return defaultDb.NamedGet(dest, query, args)
}

// Select select rows
func Select(dest interface{}, query string, args ...interface{}) error {
	return defaultDb.Select(dest, query, args...)
}

// NamedSelect select rows, named bindvars
func NamedSelect(dest interface{}, query string, args interface{}) (err error) {
	return defaultDb.NamedSelect(dest, query, args)
}

// Exec execute
func Exec(query string, args ...interface{}) (LastInsertId, RowsAffected int64, err error) {
	return defaultDb.Exec(query, args...)
}

// NamedExec exec, named bindvars
func NamedExec(query string, args interface{}) (LastInsertId, RowsAffected int64, err error) {
	return defaultDb.NamedExec(query, args)
}

// Limit MySQL/PostgreSQL limit
func Limit(page, pagesize int) string {
	return defaultDb.Limit(page, pagesize)
}