/*
 * line: string, must be trimmed of whitespace beforehand
 * tableItems: int | null, result output will be padded or trimmed to it if specified
 *
 * Returns an array of strings
 */
function splitByPipe(line, tableItems = null) {
    let res = [];
    let item = "";
    let consecutiveBackslashes = 0;

    if (line.startsWith("|")) {
        line = line.substring(1);
    }

    for (let char of line) {
        if (char === "\\") {
            item += "\\";
            consecutiveBackslashes++;
        } else if (char === "|" && consecutiveBackslashes % 2 === 1) {
            item = item.substring(0, item.length - 1) + "|";
            consecutiveBackslashes = 0;
        } else if (char === "|" && consecutiveBackslashes % 2 === 0) {
            item = item.trim();
            res.push(item);

            item = "";
            consecutiveBackslashes = 0;
        } else {
            item += char;
            consecutiveBackslashes = 0;
        }
    }
    item = item.trim();
    if (item.length !== 0) {
        res.push(item);
    }

    while (tableItems !== null && res.length < tableItems) {
        res.push("");
    }
    while (tableItems !== null && res.length > tableItems) {
        res.pop();
    }
    return res;
}

/*
 * line: string, must be trimmed of whitespace beforehand
 * headerRow: array of strings
 *
 * Returns an array of objects, which has the following keys:
 * - text: string
 * - leftAligned: boolean
 * - rightAligned: boolean
 */
function parseDelimiterRow(line, headerRow) {
    let res = [];
    let delimiterRow = splitByPipe(line);

    if (delimiterRow.length !== headerRow.length) {
        throw new Error(`delimiter row is not as long as the header row (${delimiterRow.length} !== ${headerRow.length})`);
    }

    for (let i = 0; i < headerRow.length; i++) {
        let header = headerRow[i];
        let delimiter = delimiterRow[i];
        let match = delimiter.match(/^(:)?-+(:)?$/);

        if (match === null) {
            throw new Error(`invalid delimiter row (index: ${i}): ${delimiter}`);
        }
        res.push({
            text: header,
            leftAligned: match[1] === ":",
            rightAligned: match[2] === ":"
        });
    }

    return res;
}

/*
 * lines: array of strings, each item must be trimmed of whitespace beforehand
 *
 * See parseDelimiterRow() for the return type
 */
function parseHeader(lines) {
    if (lines.length < 2) {
        throw new Error(`input must be at least 2 lines long (${lines.length} < 2)`);
    }

    let headerRow = splitByPipe(lines[0]);
    if (headerRow.length === 0) {
        throw new Error("header row must have at least one item");
    }

    return parseDelimiterRow(lines[1], headerRow);
}

/*
 * input: string
 *
 * Returns an object with the following keys:
 * - columns: See parseHeader() for the first item
 * - rows: array of an array of strings
 */
function deserializeTable(input) {
    let lines = [];
    let rows = [];

    for (let line of input.trim().split("\n")) {
        lines.push(line.trim());
    }

    let columns = parseHeader(lines);
    for (let i = 2; i < lines.length; i++) {
        rows.push(splitByPipe(lines[i], columns.length));
    }

    return {columns, rows};
}



export {deserializeTable};