'use strict';

var async = require('async');
var db = require('./database');
var utils = require('./utils');

var DEFAULT_BATCH_SIZE = 100;

exports.processSortedSet = function (setKey, process, options, callback) {
	if (typeof options === 'function') {
		callback = options;
		options = {};
	}

	callback = typeof callback === 'function' ? callback : function () {};
	options = options || {};

	if (typeof process !== 'function') {
		return callback(new Error('[[error:process-not-a-function]]'));
	}

	// use the fast path if possible
	if (db.processSortedSet && typeof options.doneIf !== 'function' && !utils.isNumber(options.alwaysStartAt)) {
		return db.processSortedSet(setKey, process, options.batch || DEFAULT_BATCH_SIZE, callback);
	}

	// custom done condition
	options.doneIf = typeof options.doneIf === 'function' ? options.doneIf : function () {};

	var batch = options.batch || DEFAULT_BATCH_SIZE;
	var start = 0;
	var stop = batch;
	var done = false;

	async.whilst(
		function () {
			return !done;
		},
		function (next) {
			db.getSortedSetRange(setKey, start, stop, function (err, ids) {
				if (err) {
					return next(err);
				}
				if (!ids.length || options.doneIf(start, stop, ids)) {
					done = true;
					return next();
				}
				process(ids, function (err) {
					if (err) {
						return next(err);
					}
					start += utils.isNumber(options.alwaysStartAt) ? options.alwaysStartAt : batch + 1;
					stop = start + batch;
					next();
				});
			});
		},
		callback
	);
};

exports.processArray = function (array, process, options, callback) {
	if (typeof options === 'function') {
		callback = options;
		options = {};
	}

	callback = typeof callback === 'function' ? callback : function () {};
	options = options || {};

	if (!Array.isArray(array) || !array.length) {
		return callback();
	}
	if (typeof process !== 'function') {
		return callback(new Error('[[error:process-not-a-function]]'));
	}

	var batch = options.batch || DEFAULT_BATCH_SIZE;
	var start = 0;
	var done = false;

	async.whilst(
		function () {
			return !done;
		},
		function (next) {
			var currentBatch = array.slice(start, start + batch);
			if (!currentBatch.length) {
				done = true;
				return next();
			}
			process(currentBatch, function (err) {
				if (err) {
					return next(err);
				}
				start += batch;
				if (options.interval) {
					setTimeout(next, options.interval);
				} else {
					next();
				}
			});
		},
		function (err) {
			callback(err);
		}
	);
};