// Node packages for file system
var fs = require('fs');
var path = require('path')

var booksCSV = path.join(__dirname, 'books.csv');
var booksJSON = path.join(__dirname, 'books.json');
var delim = ';';

// Read CSV
var f = fs.readFileSync(booksCSV, { encoding: 'utf-8' },
    function (err) { console.log(err); });

// Split on row
f = f.split("\n");

// Get first row for column headers
var headers = f.shift().split(delim).map(s => s = s.trim());

var tmpArr = []; //temporary array
var rowCouner = 1;
f.forEach(function (dat) {
    // Loop through each row
    let tmp = {};
    let row = dat.split(delim);
    if (row.length === headers.length) {    //skip rows with wrong number of columns
        for (var i = 0; i < headers.length; i++) {
            tmp[headers[i]] = row[i].trim();
        }
        // Add object to list
        tmpArr.push(tmp);
    } else {
        console.log('Row #' + rowCouner + ' skipped because of error.');
    };
    rowCouner++;
});

let tmpjson = [];
while (tmpArr.length !== 0) { //grouping elems by author
    let authorDecription = { //object for elements on "authors" array
        author: '',
        books: []
    };

    let book = {    //object for books description
        title: '',
        description: ''
    };

    let elem = tmpArr.shift();
    book.title = elem['Title'];
    book.description = elem['Annotation'];
    let ind = tmpjson.findIndex((item) => {
        return item.author === elem['Author'];
    });
    if ((ind !== -1)> 0) {
        tmpjson[ind].books.push(book);
    } else {
        authorDecription.author = elem['Author'];
        authorDecription.books.push(book);
        tmpjson.push(authorDecription);
    };
};

let json = {}
json.authors = tmpjson;
// Convert object to string, write json to file
fs.writeFileSync(booksJSON, JSON.stringify(json, ' '),
    function (err) { console.log(err); });