package db_info

import (
	"database/sql"
	"fmt"

	"github.com/pingcap/tispector/service/task"
	"github.com/pingcap/tispector/util"
)

const defaultDBName = "information_schema"

type DBInfoTool struct {
}

var DBTool DBInfoTool

func (DBInfoTool) GetDBConn(dbName, clusterName string) (*task.DBInfo, error) {
	cluster, err := GetClusterByName(clusterName)
	if err != nil {
		return nil, fmt.Errorf("get cluster info err: %s", err.Error())
	}

	db, err := sql.Open("mysql",
		fmt.Sprintf("%s:%s@tcp(%s)/%s?charset=utf8", cluster.User, cluster.Pwd, cluster.Addr, dbName))
	if err != nil {
		return nil, fmt.Errorf("open db conn err: %s", err.Error())
	}

	defaultDB, err := sql.Open("mysql",
		fmt.Sprintf("%s:%s@tcp(%s)/%s?charset=utf8", cluster.User, cluster.Pwd, cluster.Addr, defaultDBName))
	if err != nil {
		return nil, fmt.Errorf("open db conn err: %s", err.Error())
	}

	return &task.DBInfo{DB: db, DefaultDB: defaultDB, DBName: dbName}, nil
}

// return dbs and mapping cluster
func ListAllDB() (map[string][]string, error) {
	clusters, err := ListCluster()
	if err != nil {
		return nil, err
	}

	resp := make(map[string][]string)
	for _, cluster := range clusters {
		dbs, err := ListDbByCluster(&cluster)
		if err != nil {
			return nil, err
		}

		for _, db := range dbs {
			resp[db] = append(resp[db], cluster.Name)
		}
	}

	return resp, nil
}

func ListDbByCluster(cluster *TispectorCluster) ([]string, error) {
	deCryptoData, err := util.AesDeCrypto(util.ParseStringedByte(cluster.Pwd))
	if err != nil {
		return nil, err
	}

	cluster.Pwd = fmt.Sprintf("%s", deCryptoData)
	conn, err := sql.Open("mysql",
		fmt.Sprintf("%s:%s@tcp(%s)/%s?charset=utf8", cluster.User, cluster.Pwd, cluster.Addr, defaultDBName))
	if err != nil {
		return nil, fmt.Errorf("open db_info conn err: %s", err.Error())
	}
	defer conn.Close()

	rows, err := conn.Query("show databases;")
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var dbs []string
	for rows.Next() {
		var dbName string
		if err = rows.Scan(&dbName); err != nil {
			return nil, err
		}
		dbs = append(dbs, dbName)
	}
	return dbs, nil
}