'use strict';
var Promise = require('pinkie-promise');
var arrayUnion = require('array-union');
var objectAssign = require('object-assign');
var glob = require('glob');
var arrify = require('arrify');
var pify = require('pify');

var globP = pify(glob, Promise).bind(glob);

function isNegative(pattern) {
	return pattern[0] === '!';
}

function generateGlobTasks(patterns, opts) {
	var globTasks = [];

	patterns = arrify(patterns);
	opts = objectAssign({ignore: []}, opts);

	patterns.forEach(function (pattern, i) {
		if (isNegative(pattern)) {
			return;
		}

		var ignore = patterns.slice(i).filter(isNegative).map(function (pattern) {
			return pattern.slice(1);
		});

		globTasks.push({
			pattern: pattern,
			opts: objectAssign({}, opts, {
				ignore: opts.ignore.concat(ignore)
			})
		});
	});

	return globTasks;
}

module.exports = function (patterns, opts) {
	var globTasks = generateGlobTasks(patterns, opts);

	return Promise.all(globTasks.map(function (task) {
		return globP(task.pattern, task.opts);
	})).then(function (paths) {
		return arrayUnion.apply(null, paths);
	});
};

module.exports.sync = function (patterns, opts) {
	var globTasks = generateGlobTasks(patterns, opts);

	return globTasks.reduce(function (matches, task) {
		return arrayUnion(matches, glob.sync(task.pattern, task.opts));
	}, []);
};

module.exports.generateGlobTasks = generateGlobTasks;