var Handlebars = require('handlebars');
var markdown = require('markdown').markdown;
var _ = require('underscore');
var less = require('less');
var when = require('when');
var helpers = require('./helpers.js');

module.exports = function (config, mongodataInstance) {

	var sourceHead =
		'<script src="//cdnjs.cloudflare.com/ajax/libs/modernizr/2.6.2/modernizr.min.js"></script>\n' +
			'{{#if debug}}' +
			'<link href="/content/{{collection}}/{{name}}/style.css" media="all" rel="stylesheet/less" type="text/css">\n' +
			'<script src="//cdnjs.cloudflare.com/ajax/libs/less.js/1.3.3/less.min.js"></script>\n' +
			'{{else}}' +
			'<link href="/content/{{collection}}/{{name}}/style.css" media="all" rel="stylesheet" type="text/css">\n' +
			'{{/if}}';

	var getPreviewHTML = function (content, options, callback) {
		config.debug && console.log('getPreviewHTML', content);
		var promises = replaceMarkers(content, options);

		function handler(text, result) {
			return text.replace(result.regExp, result.replacement);
		}

		helpers.handTextManipulation(content,
			promises,
			handler,
			callback
		);
	};

	var replaceMarkers = function (html, options) {

		var promises = [];

		var script_tag = 'script__([A-Za-z0-9]+)_([A-Za-z0-9]+)_([A-Za-z0-9]+)';
		var script_regexp = new RegExp(helpers.marker_prefix + script_tag + helpers.marker_postfix);
		promises.push(
			helpers.replace(html, script_tag, function (result, callback) {
				var parts = script_regexp.exec(result);
				var context = {
					collection: parts[1],
					name: parts[2],
					attribute: parts[3]
				};
				return callback(null, {
					regExp: new RegExp(result, 'gmi'),
					value: '<script src="/content/' + context.collection + '/' + context.name + '/' + context.attribute + '.js"></script>'
				});
			}));

		var style_tag = 'style__([A-Za-z0-9]+)_([A-Za-z0-9]+)_([A-Za-z0-9]+)';
		var style_regexp = new RegExp(helpers.marker_prefix + style_tag + helpers.marker_postfix);
		promises.push(
			helpers.replace(html, style_tag, function (result, callback) {
				var parts = style_regexp.exec(result);
				var context = {
					collection: parts[1],
					name: parts[2],
					attribute: parts[3]
				};
				return callback(null, {
					regExp: new RegExp(result, 'gmi'),
					value: '<link href="/content/' + context.collection + '/' + context.name + '/' + context.attribute + '.css" media="all" rel="stylesheet" type="text/css">'
				});
			}));

		var template_tag = 'template__([A-Za-z0-9]+)_([A-Za-z0-9]+)_([A-Za-z0-9]+)__context__([A-Za-z0-9]+)_([A-Za-z0-9]+)';
		var template_regexp = new RegExp(helpers.marker_prefix + template_tag + helpers.marker_postfix);
		promises.push(
			helpers.replace(html, template_tag, function (result, callback) {
				var parts = template_regexp.exec(result);
				var template = {
					collection: parts[1],
					name: parts[2],
					attribute: parts[3],
					query: { name: parts[2]}
				};
				var context = {
					collection: parts[4],
					name: parts[5],
					query: { name: parts[5]},
					req: options.req
				};
				mongodataInstance.getMongoContent(context, function (err, context_result) {
					if (err) {
						config.errors && console.log('ERR template_tag getMongoContent', context);
						return callback(err);
					}
					mongodataInstance.getMongoAttribute(template, function (err, attribute_result) {
						if (err) {
							config.errors && console.log('ERR template_tag getMongoAttribute', template, err);
							return callback(err);
						}
						var compiled_template = null;
						var keys_to_collect = {};
						// Handlebars is synchronous ouch !!
						var handlebars = Handlebars.create();
						_.forEach(_.keys(context_result), function (key) {
							handlebars.registerHelper(key, function (key_context, key_options) {
								if (context_result[key].guid) {
									if (keys_to_collect.hasOwnProperty(key)) {
										return keys_to_collect[key];
									} else {
										keys_to_collect[key] = null;
										return "";
									}
								}
								return "";
							});
						});
						try {
							compiled_template = handlebars.compile(attribute_result[template.attribute]);
						} catch (err) {
							config.errors && console.log('ERR template_tag Handlebars.compile', template, err);
							return callback(err);
						}
						try {
							var tmp_rendered = compiled_template(context_result);
						} catch (err) {
							config.errors && console.log('ERR template_tag Handlebars.render', template, context, err);
							return callback(err);
						}
						var promises = [];
						_.forEach(_.keys(keys_to_collect), function (key) {
							var deferred = when.defer();
							var promise = deferred.promise;
							promises.push(promise);
							var attribute_context = {
								collection: context.collection,
								attribute: key,
								query: { _id: context_result._id}
							};
							mongodataInstance.getMongoAttribute(attribute_context, function (err, template_attribute_result) {
								if (err) {
									config.errors && console.log('ERR handlebar.registerHelper getMongoAttribute', err);
									deferred.reject(err);
								}
								var value = template_attribute_result[key];
								keys_to_collect[key] = value;
								deferred.resolve(value);
							});
						});
						when.all(
							promises,
							function onSuccess(values) {
								var rendered = null;
								try {
									rendered = compiled_template(context_result);
								} catch (err) {
									config.errors && console.log('ERR template_tag Handlebars.render', template, context, err);
									return callback(err);
								}
								config.debug && console.log('// recurse markers on rendered template');
								context.query = {_id: context_result._id};
								getPreviewHTML(rendered, context, function (err, preview_html) {
									if (err) {
										config.errors && console.log('ERR template_tag getPreviewHTML', err);
										return callback(err);
									}
									return callback(null, {
										regExp: new RegExp(result, 'gmi'),
										value: preview_html
									});
								});
							},
							function onFailure(err) {
								config.errors && console.log('ERR template_tag resolving promises', err);
								return callback(err);
							}
						)
					});
				});
			}));

		var markdown_tag = 'markdown__([A-Za-z0-9]+)_([A-Za-z0-9]+)_([A-Za-z0-9]+)';
		var markdown_regexp = new RegExp(helpers.marker_prefix + markdown_tag + helpers.marker_postfix);
		promises.push(
			helpers.replace(html, markdown_tag, function (result, callback) {
				var parts = markdown_regexp.exec(result);
				var attribute = {
					collection: parts[1],
					name: parts[2],
					attribute: parts[3]
				};
				mongodataInstance.getMongoAttribute(attribute, function (err, attribute_result) {
					if (err) {
						return callback(err);
					}
					var html = markdown.toHTML(attribute_result[options.attribute]);
					return callback(null, {
						regExp: new RegExp(result, 'gmi'),
						value: html
					});
				});
			}));

		var remove_tag = 'remove_([\\w\\W]*?)_end_remove';
		//var remove_regexp = new RegExp(remove_tag);
		promises.push(
			helpers.replace(html, remove_tag, function (result, callback) {
				return callback(null, {
					regExp: null,
					value: ""
				});
			}, true));

		return promises;
	};


	return {
		getPreviewHTML: getPreviewHTML,
		_replaceMarkers: replaceMarkers
	};
};