/**
 * Durandal 2.1.0 Copyright (c) 2012 Blue Spire Consulting, Inc. All Rights Reserved.
 * Available via the MIT license.
 * see: http://durandaljs.com or https://github.com/BlueSpire/Durandal for details.
 */
/**
 * The viewLocator module collaborates with the viewEngine module to provide views (literally dom sub-trees) to other parts of the framework as needed. The primary consumer of the viewLocator is the composition module.
 * @module viewLocator
 * @requires system
 * @requires viewEngine
 */
define(['durandal/system', 'durandal/viewEngine'], function (system, viewEngine) {
    function findInElements(nodes, url) {
        for (var i = 0; i < nodes.length; i++) {
            var current = nodes[i];
            var existingUrl = current.getAttribute('data-view');
            if (existingUrl == url) {
                return current;
            }
        }
    }
    
    function escape(str) {
        return (str + '').replace(/([\\\.\+\*\?\[\^\]\$\(\)\{\}\=\!\<\>\|\:])/g, "\\$1");
    }

    /**
     * @class ViewLocatorModule
     * @static
     */
    return {
        /**
         * Allows you to set up a convention for mapping module folders to view folders. It is a convenience method that customizes `convertModuleIdToViewId` and `translateViewIdToArea` under the covers.
         * @method useConvention
         * @param {string} [modulesPath] A string to match in the path and replace with the viewsPath. If not specified, the match is 'viewmodels'.
         * @param {string} [viewsPath] The replacement for the modulesPath. If not specified, the replacement is 'views'.
         * @param {string} [areasPath] Partial views are mapped to the "views" folder if not specified. Use this parameter to change their location.
         */
        useConvention: function(modulesPath, viewsPath, areasPath) {
            modulesPath = modulesPath || 'viewmodels';
            viewsPath = viewsPath || 'views';
            areasPath = areasPath || viewsPath;

            var reg = new RegExp(escape(modulesPath), 'gi');

            this.convertModuleIdToViewId = function (moduleId) {
                return moduleId.replace(reg, viewsPath);
            };

            this.translateViewIdToArea = function (viewId, area) {
                if (!area || area == 'partial') {
                    return areasPath + '/' + viewId;
                }
                
                return areasPath + '/' + area + '/' + viewId;
            };
        },
        /**
         * Maps an object instance to a view instance.
         * @method locateViewForObject
         * @param {object} obj The object to locate the view for.
         * @param {string} [area] The area to translate the view to.
         * @param {DOMElement[]} [elementsToSearch] An existing set of elements to search first.
         * @return {Promise} A promise of the view.
         */
        locateViewForObject: function(obj, area, elementsToSearch) {
            var view;

            if (obj.getView) {
                view = obj.getView();
                if (view) {
                    return this.locateView(view, area, elementsToSearch);
                }
            }

            if (obj.viewUrl) {
                return this.locateView(obj.viewUrl, area, elementsToSearch);
            }

            var id = system.getModuleId(obj);
            if (id) {
                return this.locateView(this.convertModuleIdToViewId(id), area, elementsToSearch);
            }

            return this.locateView(this.determineFallbackViewId(obj), area, elementsToSearch);
        },
        /**
         * Converts a module id into a view id. By default the ids are the same.
         * @method convertModuleIdToViewId
         * @param {string} moduleId The module id.
         * @return {string} The view id.
         */
        convertModuleIdToViewId: function(moduleId) {
            return moduleId;
        },
        /**
         * If no view id can be determined, this function is called to genreate one. By default it attempts to determine the object's type and use that.
         * @method determineFallbackViewId
         * @param {object} obj The object to determine the fallback id for.
         * @return {string} The view id.
         */
        determineFallbackViewId: function (obj) {
            var funcNameRegex = /function (.{1,})\(/;
            var results = (funcNameRegex).exec((obj).constructor.toString());
            var typeName = (results && results.length > 1) ? results[1] : "";
            typeName = typeName.trim();
            return 'views/' + typeName;
        },
        /**
         * Takes a view id and translates it into a particular area. By default, no translation occurs.
         * @method translateViewIdToArea
         * @param {string} viewId The view id.
         * @param {string} area The area to translate the view to.
         * @return {string} The translated view id.
         */
        translateViewIdToArea: function (viewId, area) {
            return viewId;
        },
        /**
         * Locates the specified view.
         * @method locateView
         * @param {string|DOMElement} viewOrUrlOrId A view, view url or view id to locate.
         * @param {string} [area] The area to translate the view to.
         * @param {DOMElement[]} [elementsToSearch] An existing set of elements to search first.
         * @return {Promise} A promise of the view.
         */
        locateView: function(viewOrUrlOrId, area, elementsToSearch) {
            if (typeof viewOrUrlOrId === 'string') {
                var viewId;

                if (viewEngine.isViewUrl(viewOrUrlOrId)) {
                    viewId = viewEngine.convertViewUrlToViewId(viewOrUrlOrId);
                } else {
                    viewId = viewOrUrlOrId;
                }

                if (area) {
                    viewId = this.translateViewIdToArea(viewId, area);
                }

                if (elementsToSearch) {
                    var existing = findInElements(elementsToSearch, viewId);
                    if (existing) {
                        return system.defer(function(dfd) {
                            dfd.resolve(existing);
                        }).promise();
                    }
                }

                return viewEngine.createView(viewId);
            }

            return system.defer(function(dfd) {
                dfd.resolve(viewOrUrlOrId);
            }).promise();
        }
    };
});