// Require modules:

const fs = require( "fs" );

const JSONStream = require( "JSONStream" );

const es = require('event-stream');

const debug = require('debug')('Main');

const path = require('path');

// Require Configuration settings:

const config = require('./config.js');

// Require DB Connection:

const db = require('./dbManipulator');

let first = true;

let i;

/**

* a handler for inputing config arguments

* @param argNum the index in the process.argv

* @param atrName the attribute name inside the config file

* @returns true if got input. false, otherwise.

*/

async function getConfigAtribute(argNum, atrName){

var ans = false;

if(process.argv[argNum] && process.argv[argNum].length>0){

config[atrName] = process.argv[argNum];

ans = true;

}else if(config[atrName] && config[atrName].length>0){

ans = true;

}

return ans;

}

// validate whether we got all the input needed to run the app

async function validateInput(){

debug('validating input..');

let i=2;

const gotJSONPath = await getConfigAtribute(i++, 'jsonPath');

if (gotJSONPath){

const gotDBName = await getConfigAtribute(i++, 'dbName');

if (gotDBName){

const gotTblName = await getConfigAtribute(i++, 'tblName');

if (gotTblName){

debug('Got all config input needed.');

}else{

throw new Error('you need to specify a JSON file path in config.js{jsonPath} or using the command\n "node index.js %file_path%"');

}

}else{

throw new Error('you need to specify a DB name in config.js{dbName} or using the command\n "node index.js %file_path% %DB_name%"');

}

}else{

throw new Error('you need to specify a JSON file path in config.js{jsonPath} or using the command\n "node index.js %file_path%"');

}

}

// create a stream to read & pass JS objs from the JSON file:

var getStream = function () {

try{

var stream = fs.createReadStream(config.jsonPath, {encoding: 'utf8'});

var parser = JSONStream.parse('*');

return stream.pipe(parser);

}catch(err){

throw new Error('JSON file corrupted or is not found!');

}

};

//start Streaming to get the first JSO and build the DB Table from its image

async function getTableFromFirstObject(){

return new Promise(function(res, rej){

debug('Streaming the first JSO from the input file to build a table..');

var j=0;

var firstStream = getStream();

firstStream.on('close', async () => { debug('bye First!');})

firstStream.pipe(es.mapSync(async function(obj) {

if (first){

//close. distroy, end

debug('ending firstStream..');

firstStream.end();

first = false;

debug('firstStream ended.');

var tableCreated = await db.buildTable(obj);

if (tableCreated) res();

else rej('Error creating table');

}else{

debug((j++)+' : how did you get through the first object?!');

}

}));

});

}

//start Streaming and deal with each JSO separately

async function startStreaming(){

return new Promise(function(res, rej){

debug('Streaming all JSOs from the input file..');

var secondStream = getStream();

secondStream.on('close', async () => {await finishApp(); })

secondStream.pipe(es.mapSync(async function (obj) {

try{

await db.insertToDB(obj);

}catch(err){

console.error(err.message);

}

}));

});

}

async function finishApp(){

debug('finished streaming. queing JSOs to be added to the DB..')

await db.endConnection();

console.log('\nThe job is done. all Documents have been moved to the new location, found at: \n');

console.log(config.host+', under database named "'+config.dbName+'", inside table named "'+config.tblName+'".\n');

debug('Good bye! :)');

}

// Main function:

exports.startScript = async function(dbName, mySqlUser, mySqlPass, rootPass){

try{

config.initDbParams(dbName, mySqlUser, mySqlPass, rootPass);

console.log('JSON2MySQL started. \nworking..');

//await validateInput();

//await db.init(config.host, config.user, config.password, config.dbName, config.tblName);

await db.init(config.host, config.user, config.password, config.dbName, config.tblName);

await db.runDatabase();

// dlt next row when app's rdy:

await db.dropTable(config.tblName);

////////

await getTableFromFirstObject();

await startStreaming();

}catch(err){

console.error(err.message);

await db.endConnection();

}

}

exports.getAllAccounts = async function() {

try{

return await db.getAllRecords();

}catch(err){

console.error(err);

}

}