#!/usr/bin/env node

// requirements
const os = require('os');
const path = require('path');
const fs = require('fs');
const fse = require('fs-extra');
const async = require('async');
const commander = require('commander');
const recursive = require('recursive-readdir');
const metadata = require('musicmetadata');
const progress = require('progress');
const app = require('./package.json');

// general options
commander
    .version(app.version)
    .usage('[options] <command>')
    .option('-c, --concurrency <n>', 'specify concurrency level', os.cpus().length);

// conversion mode
commander
    .command('convert <input> <output>')
    .description('convert .flac to .mp3 files')
    .option('-b, --bitrate <n>', 'specify conversion bitrate', 320)
    .action(function (input, output, options) {
        console.log('--- CONVERT MODE ---');
        console.log('input: ' + input);
        console.log('output: ' + output);
        console.log('bitrate: ' + commander.options.bitrate);
        console.log('conc: ' + commander.concurrency);
    });

// sort mode
commander
    .command('sort <input> <output>')
    .description('sort audio files by tags')
    .option('-f, --format <type>', 'specify audio format (\'flac\', \'mp3\')', 'flac')
    .action(sort);

// parse command line arguments
commander.parse(process.argv);

// functions
function sort(input, output, options) {
    const start = process.hrtime();
    const concurrency = commander.concurrency;
    console.log('--- SORT MODE ---');
    console.log('concurrency: ' + concurrency);
    // get files in input directory
    recursive(input, [ignoreFilter], function (err, files) {
        if (err) {
            exit(err);
        }
        // display progressbar
        const bar = createProgressBar(files.length);
        // handle each file
        async.eachLimit(files, concurrency, function (file, eachCallback) {
            handleSource(output, file, function (err) {
                bar.tick();
                if (err) {
                    return eachCallback(err);
                }
                eachCallback();
            });
        }, function (err) {
            const diff = process.hrtime(start);
            console.log('done after ' + (diff[0] * 1000 + diff[1] / 1000000) + ' milliseconds');
            exit(err);
        });
    });

    function ignoreFilter(file, stats) {
        return !stats.isDirectory() && path.extname(file).indexOf(options.format) == -1;
    }
}

function exit(err) {
    if (err) {
        console.error(err);
        process.exit(1);
    }
    console.log('DONE');
    process.exit(0);
}

function handleSource(output, file, callback) {
    async.waterfall([
        function (asyncCallback) {
            extractMetadata(file, asyncCallback)
        },
        function (metadata, asyncCallback) {
            pathFromMetadata(output, metadata, asyncCallback);
        }
        // TODO: create output directory, append file extension and move file
    ], function (err, results) {
        if (err) {
            return callback(err);
        }
        callback(null, results);
    });
}

function extractMetadata(file, callback) {
    const stream = fs.createReadStream(file);
    metadata(stream, function (err, metadata) {
        if (err) {
            return callback(err);
        }
        stream.close();
        callback(null, metadata)
    });
}

function pathFromMetadata(output, metadata, callback) {
    // define directory
    let directory = path.normalize(path.join(output));
    if (metadata.albumartist && metadata.albumartist.length > 0) {
        let tmp;
        const artistCount = metadata.albumartist.length;
        for (let counter = 0; counter < artistCount; counter++) {
            if (counter > 0) {
                tmp += ' - ' + metadata.albumartist[counter];
            } else {
                tmp = metadata.albumartist[counter];
            }
        }
        directory = path.join(directory, tmp);
    } else {
        directory = path.join(directory, metadata.artist[0]);
    }
    if (metadata.album) {
        directory = path.join(directory, metadata.album);
    }
    // define filename
    let file = '';
    if (metadata.disk.no) {
        file += frontFill(metadata.disk.no, '0', 2);
    }
    if (metadata.track.no) {
        if (file) {
            file += '-' + frontFill(metadata.track.no, '0', 2) + ' ';
        } else {
            file += frontFill(metadata.track.no, '0', 2) + ' ';
        }
    }
    if (metadata.artist && metadata.albumartist.length > 0) {
        file += metadata.artist[0] + ' - ';
    }
    if (metadata.title) {
        file += metadata.title;
    }

    callback(null, directory, file);
}

function frontFill(string, fill, length) {
    while (string.length > length) {
        string = fill + string;
    }
    return string;
}

function createProgressBar(total) {
    return new progress(':bar | progress: :current/:total (:percent) | elapsed: :elapseds | eta: :etas', {
        total: total,
        width: 32
    });
}