'use strict';

exports = module.exports = {
    initialize,
    uninitialize,
    query,
    transaction,

    importFromFile,
    exportToFile,

    _clear: clear
};

const assert = require('assert'),
    BoxError = require('./boxerror.js'),
    constants = require('./constants.js'),
    debug = require('debug')('box:database'),
    execSync = require('child_process').execSync,
    mysql = require('mysql2/promise'),
    safe = require('safetydance'),
    shell = require('./shell.js')('database');

let gConnectionPool = null;

const gDatabase = {
    hostname: '127.0.0.1',
    username: 'root',
    password: 'password',
    port: 3306,
    name: 'box'
};

async function initialize() {
    if (gConnectionPool !== null) return;

    if (constants.TEST) {
        // see setupTest script how the mysql-server is run
        gDatabase.hostname = execSync('docker inspect -f "{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}" mysql-server').toString().trim();
    }

    // https://github.com/mysqljs/mysql#pool-options
    gConnectionPool  = mysql.createPool({
        connectionLimit: 5,
        connectTimeout: 60000,
        host: gDatabase.hostname,
        user: gDatabase.username,
        password: gDatabase.password,
        port: gDatabase.port,
        database: gDatabase.name,
        multipleStatements: false,
        waitForConnections: true, // getConnection() will wait until a connection is avaiable
        ssl: false,
        timezone: 'Z', // mysql follows the SYSTEM timezone. on Cloudron, this is UTC
        charset: 'utf8mb4',
        jsonStrings: true, // for JSON types, JSONARRAYAGG will return string instead of JSON
    });

    // run one time setup commands on new connections. connections are reused and so we cannot use 'acquire' event of the pool
    gConnectionPool.on('connection', async function (connection) { // https://github.com/sidorares/node-mysql2/issues/565, 567
        debug('new connection');

        const conn = connection.promise(); // convert PoolConnection to PromisePoolConnection

        try {
            // await connection.query('SET NAMES utf8mb4 COLLATE utf8mb4_bin');
            await conn.query('SET SESSION sql_mode = \'strict_all_tables\''); // disable type coercion etc
            // GROUP_CONCAT has only 1024 default. we use it in the groups API which doesn't support pagination yet
            // a crypto.randomUUID is 36 in length. so the value below provides for roughly 10k users
            await conn.query('SET SESSION group_concat_max_len = 360000');
        } catch (error) {
            debug(`failed to init new db connection ${connection.threadId}:`, error); // only log. we will let the app handle the exception when it calls query()/transaction()
        }
    });
}

async function uninitialize() {
    if (!gConnectionPool) return;

    await safe(gConnectionPool.end(), { debug });
    gConnectionPool = null;
    debug('pool closed');
}

async function clear() {
    const tables = await query('SELECT table_name FROM information_schema.tables WHERE table_schema = ? AND table_name != ?', [ 'box', 'migrations' ]);
    const queries = [{ query: 'SET FOREIGN_KEY_CHECKS = 0' }];
    for (const t of tables) queries.push({ query: `TRUNCATE TABLE ${t.TABLE_NAME}` });
    queries.push({ query: 'SET FOREIGN_KEY_CHECKS = 1' }); // this is a session/connection variable, must be reset back

    await transaction(queries);
}

async function query(...args) {
    assert.notStrictEqual(gConnectionPool, null, 'Database connection is already closed');

    const [error, result] = await safe(gConnectionPool.query(...args)); // this is same as getConnection/query/release
    if (error) throw new BoxError(BoxError.DATABASE_ERROR, error, { code: error.code, sqlMessage: error.sqlMessage || null });
    return result[0]; // the promise version returns a tuple of [rows, fields]
}

async function transaction(queries) {
    assert(Array.isArray(queries));

    const [error, connection] = await safe(gConnectionPool.getConnection());
    if (error) throw new BoxError(BoxError.DATABASE_ERROR, error, { code: error.code, sqlMessage: error.sqlMessage });

    try {
        await connection.beginTransaction();
        const results = [];
        for (const query of queries) {
            const [rows /*, fields */] = await connection.query(query.query, query.args);
            results.push(rows);
        }
        await connection.commit();
        connection.release(); // no await!
        return results;
    } catch (error) {
        await safe(connection.rollback(), { debug });
        connection.release(); // no await!
        throw new BoxError(BoxError.DATABASE_ERROR, error, { code: error.code, sqlMessage: error.sqlMessage || null });
    }
}

async function importFromFile(file) {
    assert.strictEqual(typeof file, 'string');

    const cmd = `/usr/bin/mysql -h "${gDatabase.hostname}" -u ${gDatabase.username} -p${gDatabase.password} ${gDatabase.name} < ${file}`;
    await query('CREATE DATABASE IF NOT EXISTS box');
    const [error] = await safe(shell.bash(cmd, {}));
    if (error) throw new BoxError(BoxError.DATABASE_ERROR, error);
}

async function exportToFile(file) {
    assert.strictEqual(typeof file, 'string');

    // latest mysqldump enables column stats by default which is not present in 5.7 util
    const mysqlDumpHelp = await shell.spawn('/usr/bin/mysqldump', ['--help'], { encoding: 'utf8' });
    const hasColStats = mysqlDumpHelp.includes('column-statistics');
    const colStats = hasColStats ? '--column-statistics=0' : '';

    const cmd = `/usr/bin/mysqldump -h "${gDatabase.hostname}" -u root -p${gDatabase.password} ${colStats} --single-transaction --routines --triggers ${gDatabase.name} > "${file}"`;

    const [error] = await safe(shell.bash(cmd, {}));
    if (error) throw new BoxError(BoxError.DATABASE_ERROR, error);
}