const mysql = require('mysql2/promise');
const config = require('./config.js');
const fs = require('fs-extra');
const path = require('path');

module.exports = {
    init() {
        if (!this.pool) {
            this.pool = mysql.createPool(config.mysql);
            this.pool.on('connection', connection => {
                connection.config.namedPlaceholders = true;
            });
        }
    },

    /**
     * Makes a query from a raw sql
     * @param {String} query - The raw SQL query
     * @param {Object} params - Parameterized values
     *
     * @return {Object} - Result promise
     */
    rawSql(query, params) {
        return this.pool.query(query, params).then(([rows]) => {
            return rows;
        });
    },

    /**
     * Makes a query from a SQL file
     * @param {String} queryName - The SQL file name
     * @param {Object} params - Parameterized values
     * @param {Object} dirname - Referenced path
     *
     * @return {Object} - Result promise
     */
    rawSqlFromDef(queryName, params, dirname = '.') {
        const sqlPath = path.join(dirname, 'sql', `${queryName}.sql`);
        const query = fs.readFileSync(sqlPath, 'utf8');

        return this.rawSql(query, params);
    },

    /**
     * Returns the first row from a given raw sql
     * @param {String} query - The raw SQL query
     * @param {Object} params - Parameterized values
     *
     * @return {Object} - Result promise
     */
    findOne(query, params) {
        return this.rawSql(query, params).then(([row]) => row);
    },

    /**
     * Returns the first row from a given SQL file
     * @param {String} queryName - The SQL file name
     * @param {Object} params - Parameterized values
     * @param {Object} dirname - Referenced path
     *
     * @return {Object} - Result promise
     */
    findOneFromDef(queryName, params, dirname) {
        return this.rawSqlFromDef(queryName, params, dirname)
            .then(([row]) => row);
    },

    /**
     * Returns the first property from a given raw sql
     * @param {String} query - The raw SQL query
     * @param {Object} params - Parameterized values
     *
     * @return {Object} - Result promise
     */
    findValue(query, params) {
        return this.findOne(query, params).then(row => {
            return Object.values(row)[0];
        });
    },

    /**
     * Returns the first property from a given SQL file
     * @param {String} queryName - The SQL file name
     * @param {Object} params - Parameterized values
     * @param {Object} dirname - Referenced path
     *
     * @return {Object} - Result promise
     */
    findValueFromDef(queryName, params, dirname) {
        return this.findOneFromDef(queryName, params, dirname).then(row => {
            return Object.values(row)[0];
        });
    },

    getCaller() {
        let originalFunc = Error.prepareStackTrace;
        let callerfile;
        try {
            const err = new Error();

            Error.prepareStackTrace = function(err, stack) {
                return stack;
            };

            const currentfile = err.stack.shift().getFileName();

            while (err.stack.length) {
                callerfile = err.stack.shift().getFileName();

                if (currentfile !== callerfile) break;
            }
        } catch (e) {}

        Error.prepareStackTrace = originalFunc;

        return path.dirname(callerfile);
    }
};