const mysql = require('mysql');
const databaseConfig = require('../config/databaseConfig');
const utils = require('./utils');

const connection = mysql.createConnection({
    host: databaseConfig.database_host,
    user: databaseConfig.database_user,
    password: databaseConfig.database_password,
    database: databaseConfig.database_database
});

const nodesTable = `${databaseConfig.database_database}.nodes`;

connection.connect()

/** Get all nodes the server knows about regardless of status
 * @param {*} callback Callback function
 */
exports.getAllNodes = (callback) => {
    const sqlQuery = `SELECT * FROM ${nodesTable}`
    runSQL(sqlQuery, (rows) => {
        return callback(rows);
    })
}

/** Get all nodes that have the online status set true (are online)
 * @param callback Callback function
 */
exports.getOnlineNodes = (callback) => {
    const sqlQuery = `SELECT * FROM ${nodesTable} WHERE online = 1;`
    runSQL(sqlQuery, (rows) => {
        return callback(rows);
    })
}

/** Get info on a node based on ID
 * @param nodeId The ID of the node 
 * @param callback Callback function
 */ 
exports.getNodeInfoFromId = (nodeId, callback) => {
    const sqlQuery = `SELECT * FROM ${nodesTable} WHERE id = ${nodeId}`
    runSQL(sqlQuery, (rows) => {
        // Call back the first (and theoretically only) row
        // Specify 0 so downstream functions don't have to worry about it
        return callback(rows[0]);
    })
}

/** Add a new node to the DB
 * @param nodeObject Node information object
 * @param callback Callback function
 */
exports.addNewNode = (nodeObject, callback) => {
    if (!nodeObject.name) throw new Error("No name provided");
    const name = nodeObject.name,
        ip = nodeObject.ip,
        port = nodeObject.port,
        location = nodeObject.location,
        nearbySystems = utils.JsonToBuffer(nodeObject.nearbySystems),
        online = nodeObject.online;
    const sqlQuery  = `INSERT INTO ${nodesTable} (name, ip, port, location, nearbySystems, online) VALUES ('${name}', '${ip}', ${port}, '${location}', '${nearbySystems}', ${online})`;

    runSQL(sqlQuery, (rows) => {
        return callback(rows);
    })
}

/** Update the known info on a node
 * @param nodeObject Node information object
 * @param callback Callback function
 */
exports.updateNodeInfo = (nodeObject, callback) => {
    const name = nodeObject.name,
        ip = nodeObject.ip,
        port = nodeObject.port,
        location = nodeObject.location,
        online = nodeObject.online;
    let queryParams = [],
        nearbySystems = nodeObject.nearbySystems;

    if (name) queryParams.push(`name = '${name}'`);
    if (ip) queryParams.push(`ip = '${ip}'`);
    if (port) queryParams.push(`port = ${port}`);
    if (location) queryParams.push(`location = '${location}'`);
    if (nearbySystems) {
        nearbySystems = utils.JsonToBuffer(nearbySystems)
        queryParams.push(`nearbySystems = '${nearbySystems}'`);
    }
    if (typeof online === "boolean") {
        if (online) queryParams.push(`online = 1`);
        else queryParams.push(`online = 0`);
    }

    let sqlQuery = `UPDATE ${nodesTable} SET`
    if (!queryParams || queryParams.length === 0) return callback(undefined);
    if (queryParams.length === 1) {
        sqlQuery = `${sqlQuery} ${queryParams[0]}`
    } else {
        let i = 0;
        for (const param of queryParams) {
            if (i === queryParams.length-1) {
                sqlQuery = `${sqlQuery} ${param}`
                i += 1;
            }
            else {
                sqlQuery = `${sqlQuery} ${param},`
                i += 1;
            }
        }
    }

    sqlQuery = `${sqlQuery} WHERE id = ${nodeObject.id};`

    runSQL(sqlQuery, (rows) => {
        if (rows.affectedRows === 1) return callback(true);
        else return callback(rows);
    })
}

// Function to run and handle SQL errors
function runSQL(sqlQuery, callback, error = (err) => {
    console.log(err);
    throw err;
}) {
    connection.query(sqlQuery, (err, rows) => {
        if (err) return error(err);
        //console.log('The rows are:', rows);
        return callback(rows);
    })
}

exports.closeConnection = () => {
    connection.end()
}