const crypto = require('crypto');
const fs = require('fs');

function md5File(path) {
    return new Promise((ok, ko) => {
        const readStream = fs.createReadStream(path);
        let hash = crypto.createHash('md5');

        readStream.on('data', chunk => hash.update(chunk.toString()));
        readStream.once('end', () => {
            ok(hash.digest('hex'));
        });
        readStream.once('error', () => ok(""));
    });
}

function md5String(input) {
    return crypto.createHash('md5').update(input).digest('hex');
}

function md5Stats(path) {
    return new Promise((ok, ko) => {
        fs.stat(path, (err, st) => {
            if (err)
                ok("");
            else
                ok(md5String(JSON.stringify({
                    path: path,
                    size: st.size,
                    atimeMs: st.atimeMs,
                    mtimeMs: st.mtimeMs,
                    ctimeMs: st.ctimeMs
                })));
        });
    });
}

module.exports = {
    file: md5File,
    string: md5String,
    stats: md5Stats
}