package sqlmock

import (
	"database/sql"
	"database/sql/driver"
	"fmt"
	"sync"
)

var pool *mockDriver

func init() {
	pool = &mockDriver{
		conns: make(map[string]*Sqlmock),
	}
	sql.Register("sqlmock", pool)
}

type mockDriver struct {
	sync.Mutex
	counter int
	conns   map[string]*Sqlmock
}

func (d *mockDriver) Open(dsn string) (driver.Conn, error) {
	d.Lock()
	defer d.Unlock()

	c, ok := d.conns[dsn]
	if !ok {
		return c, fmt.Errorf("expected a connection to be available, but it is not")
	}

	c.opened++
	return c, nil
}

// New creates sqlmock database connection
// and a mock to manage expectations.
// Pings db so that all expectations could be
// asserted.
func New() (db *sql.DB, mock *Sqlmock, err error) {
	pool.Lock()
	dsn := fmt.Sprintf("sqlmock_db_%d", pool.counter)
	pool.counter++

	mock = &Sqlmock{dsn: dsn, drv: pool, MatchExpectationsInOrder: true}
	pool.conns[dsn] = mock
	pool.Unlock()

	db, err = sql.Open("sqlmock", dsn)
	if err != nil {
		return
	}
	return db, mock, db.Ping()
}