#! /usr/bin/env runjs

var argsjs = require('component-args.js');

var parseSize = (s) => {
    if (s == null) { return $$.num(0); }
    s = s.toLowerCase();
    if (!(/^\d+[kmg]?$/i.test(s))) {
        throw 'Size format error: ' + s;
    }
    if (s.endsWith('k')) {
        return $$.num(s.substring(0, s.length - 1)).mul(1024);
    }
    if (s.endsWith('m')) {
        return $$.num(s.substring(0, s.length - 1)).mul(1024).mul(1024);
    }
    if (s.endsWith('g')) {
        return $$.num(s.substring(0, s.length - 1)).mul(1024).mul(1024).mul(1024);
    }
    return $$.num(s);
};

var main = () => {
    var args = argsjs.parseDefARGs(['h', 'help']);
    if ((args.flg('h', 'help')) || (args.length == 0)) {
        println('split.js <file.ext>');
        println(' -h, --help         Print help');
        println(' -s, --size         File size(default 20m)');
        println(' -p, --prefix       File prefix(default filename + ".")');
        println('     --suffix       File suffix(default "")');
        return;
    }
    var file = $$.file(args[0]);
    if (!file.exists()) {
        xprintln('[ERROR] File not exists: ' + file);
        return;
    }
    var size = parseSize(args.val('s', 'size') || '20m');
    xprintln('[INFO] Split size: ' + size);

    if (size.compareTo(0) < 0) {
        xprintln('[ERROR] Split file size cannot less than 0: ' + size);
        return;
    }
    if (size.compareTo(file.length()) >= 0) {
        xprintln('[ERROR] Split file size larger or equals then origin file, ' + size + ' vs ' + file.length());
        return;
    }

    var prefix = args.val('p', 'prefix') || file.getName();
    if (!prefix.endsWith('.')) { prefix += '.'; }
    xprintln('[INFO] Split file prefix: ' + prefix);
    var suffix = args.val('suffix') || '';
    if (!suffix.startsWith('.') && ($STR(suffix) != '')) { suffix = '.' + suffix; }
    xprintln('[INFO] Split file suffix: ' + (($STR(suffix) == '') ? '(empty)' : suffix));

    var fileIndex = 0;
    var writted = $$.num(0);
    var buff = $$.byteArray(1024);

    var fnList = [];
    var fn = prefix + $$.numFormat('000').format(fileIndex) + suffix;
    if ($$.file(fn).exists()) {
        xprintln('[ERROR] File exists: ' + fn);
        return;
    }

    fnList.push(fn);
    xprintln('[INFO] Write file: ' + fn);
    var os = new java.io.BufferedOutputStream(new java.io.FileOutputStream($$.file(fn)));
    var is = $$.rFile(file).rStream().buffered().stream();
    for (var len; ((len = is.read(buff)) != -1);) {
        os.write(buff, 0, len);
        writted = writted.add(len);
        if (writted.compareTo(size.mul(fileIndex + 1)) >= 0) {
            os.close();
            fileIndex++;
            if (writted.compareTo(file.length()) < 0) {
                fn = prefix + $$.numFormat('000').format(fileIndex) + suffix;
                fnList.push(fn);
                xprintln('[INFO] Write file: ' + fn);
                os = new java.io.BufferedOutputStream(new java.io.FileOutputStream($$.file(fn)));
            } else {
                os = null;
            }
        }
    }
    if (os != null) { os.close(); }
    println();
    xprintln('[OK] Use command to join file:\ncat ' + fnList.join(' \\\n    ') + ' \\\n    > ' + file.getName());
    println();
    xprintln('[INFO] Split file done!');
};

main();