'use strict';
const through = require('through2');
const gutil = require('gulp-util');
const col = gutil.colors;
const Tail = require('tail').Tail;

module.exports = (handler) => {
    let stream = null;
    let tail = null;

    const bufferContents = (file, enc, callback) => {
        tail = new Tail(file.path);
        tail.on("line", handler);
        callback();
    };

    const endStream = (callback) => {
        if (tail) {
            tail.unwatch();
            tail = null;
        }
        callback();
    };

    return stream = through.obj(bufferContents, endStream);
};