/**
 * Reduces the Data Structure to the account names.
 * @param {any[]} data 
 * @returns 
 */
function getAccounts(data) {
    const resultData = [];
    for (let i = 0; i < data.length; i++) {
        resultData.push(data[i].name);
    }
    return resultData;
}

/**
 * Sums up every entry and returns it.
 * @param {any[]} entries 
 * @returns 
 */
function getSummation(entries) {
    return entries.reduce((sum, e) => sum + parseFloat(e.amount), 0);
}

/**
 * Turns the given String in dd-MM-yyyy into a Javascript Date Object
 * @param {string} s 
 * @returns 
 */
function toDateByComponents(s) {
    const parts = s.split("-");
    if (parts.length !== 3) return null;
    const day = parseInt(parts[0]);
    const month = parseInt(parts[1]) - 1;
    const year = parseInt(parts[2]);
    if (isNaN(day) || isNaN(month) || isNaN(year)) return null;
    return new Date(year, month, day).getTime();
}

/**
 * formats the given date into a dd-MM-yyyy String
 * @param {Date} d 
 * @returns 
 */
function toStringDate(d) {
    console.log(d);
    return ("" + d.getDate()).padStart(2, "0") + 
           "-" + ("" + (d.getMonth() + 1)).padStart(2, "0") + 
           "-" + d.getFullYear();
}

/**
 * Maps each entry to a line in a ListView while adhering to the visible amount of char columns
 * @param {any[]} entries 
 * @param {number} visibleCols 
 * @returns 
 */
function toListViewEntries(entries, visibleCols) {
    let cols = visibleCols;
    return entries.map(e => {
        const amount = parseFloat(e.amount);
        const subject = ("" + e.subject).substr(0, cols - 20).padEnd(cols - 20, ' ');
        const sum = ((amount >= 0 ? "+" : "") + amount.toFixed(2)).substr(0, 10).padStart(10, ' ');
        const d = new Date(e.date);
        const date = d.getDate().toString().padStart(2, '0') + "-" + (d.getMonth() + 1).toString().padStart(2, '0') + "-" + d.getFullYear();
        let s = (date.substr(0, 10)) + " " + subject + " " + sum;
        return s;
    });
}

exports.getAccounts = getAccounts;
exports.getSummation = getSummation;
exports.toDateByComponents = toDateByComponents;
exports.toListViewEntries = toListViewEntries;
exports.toStringDate = toStringDate;