"use strict";

var Mysql = require('mysql');
var configs = require('../../conf/config.inc.js');
var AppErrors = require('./AppErrors.js');

var objPools = {};

/**
 * 基本类，提供增删改查
 * @param {string} dbKey
 */
class OujMySql {

    constructor(dbKey) {
        this.dbKey = dbKey || 'default';
    }

    getPool() {
        if (!objPools[this.dbKey]) {
            var config = configs.dbInfo[this.dbKey];
            if (config) {
                objPools[this.dbKey] = Mysql.createPool(config);
            } else {
                throw new AppErrors.DbError("数据库:" + this.dbKey + "没有配置");
            }
        }

        return objPools[this.dbKey];
    }

    query(sql, values) {
        let that = this;
        return new Promise(function(resolve, reject) {
            that.getPool().query(sql, values, function(err, result) {
                if (err) {
                    reject(err);
                    throw new AppErrors.DbError(err);
                } else {
                    resolve(result);
                }
            });
        });
    };

    /**
     * 更新数据
     * @param {string} sql
     */
    update(sql) {
        return this.query(sql, []);
    };

    /**
     * 获取一个值
     * @param {string}  sql
     * @return Promise
     */
    getOne(sql) {
        var that = this;
        return new Promise(function(resolve, reject) {
            var p1 = that.getAll(sql, 1);
            p1.then(function(rows) {
                var row = rows[0];
                var val = null;
                if (row) {
                    var keys = Object.keys(row);
                    val = keys && row[keys[0]];
                }
                resolve(val);
            }, reject);
        });
    };

    /**
     * 获取一列数据
     * @param sql
     * @param limit 行数
     */
    getCol(sql, limit) {
        let that = this;
        return new Promise(function(resolve, reject) {
            var p1 = that.getAll(sql, limit);
            p1.then(function(rows) {
                var cols = [];
                if (rows[0] && rows.length) {
                    var keys = Object.keys(rows[0]);
                    let key = keys[0];

                    for (var i = 0; i < rows.length; i++) {
                        cols.push(rows[i][key]);
                    }
                }

                resolve(cols);
            }, reject);
        });
    };

    /**
     * 获取一行数据
     * @param sql
     */
    getRow(sql) {
        let that = this;
        return new Promise(function(resolve, reject) {
            var p1 = that.getAll(sql, 1);

            p1.then(function(rows) {
                resolve(rows[0] || null);
            }, reject);
        });
    };

    /**
     * 获取所有行数据
     * @param sql
     * @param limit 行数
     */
    getAll(sql, limit) {
        if (typeof limit == 'number' && limit > 0) {
            sql += " LIMIT " + limit;
        }

        return this.query(sql, []);
    };

    /**
     * 关闭连接池
     */
    close() {
        return new Promise(function(resolve, reject) {
            this.getPool().end(function(err) {
                if (err) {
                    reject(err);
                } else {
                    resolve();
                }
            });
        });
    };

}

module.exports = OujMySql;