source: Dev/trunk/src/client/dojox/data/GoogleSearchStore.js

define(["dojo/_base/kernel", "dojo/_base/lang", "dojo/_base/declare", "dojo/_base/query",
                "dojo/dom-construct","dojo/io/script"], 
  function(kernel, lang, declare, domQuery, domConstruct, scriptIO) {

kernel.experimental("dojox.data.GoogleSearchStore");

var SearchStore = declare("dojox.data.GoogleSearchStore",null,{
        // summary:
        //              A data store for retrieving search results from Google.
        //              This data store acts as a base class for Google searches,
        //              and has a number of child data stores that implement different
        //              searches. This store defaults to searching the web, and is functionally
        //              identical to the dojox.data.GoogleWebSearchStore object.
        //              The following attributes are supported on each item:
        //
        //              - url - The URL for the item
        //              - unescapedUrl - The URL for the item, with URL escaping. This is often more readable
        //              - visibleUrl - The URL with no protocol specified.
        //              - cacheUrl - The URL to the copy of the document cached by Google
        //              - title - The page title in HTML format.
        //              - titleNoFormatting - The page title in plain text
        //              - content - A snippet of information about the page
        //
        //              The query accepts one parameter: text - The string to search for
        constructor: function(/*Object*/args){
                // summary:
                //              Initializer for the GoogleSearchStore store.
                // description:
                //              The GoogleSearchStore is a Datastore interface to
                //              the Google search service. The constructor accepts the following arguments:
                //
                //              - label - the label attribute to use. Defaults to titleNoFormatting
                //              - key - The API key to use. This is optional
                //              - lang - The language locale to use. Defaults to the browser locale

                if(args){
                        if(args.label){
                                this.label = args.label;
                        }
                        if(args.key){
                                this._key = args.key;
                        }
                        if(args.lang){
                                this._lang = args.lang;
                        }
                        if("urlPreventCache" in args){
                                this.urlPreventCache = args.urlPreventCache?true:false;
                        }
                }
                this._id = dojox.data.GoogleSearchStore.prototype._id++;
        },

        // _id: Integer
        //              A unique identifier for this store.
        _id: 0,

        // _requestCount: Integer
        //              A counter for the number of requests made. This is used to define
        //              the callback function that GoogleSearchStore will use.
        _requestCount: 0,

        // _googleUrl: String
        //              The URL to Googles search web service.
        _googleUrl: "http://ajax.googleapis.com/ajax/services/search/",

        // _storeRef: String
        //              The internal reference added to each item pointing at the store which owns it.
        _storeRef: "_S",

        // _attributes: Array
        //              The list of attributes that this store supports
        _attributes: [  "unescapedUrl", "url", "visibleUrl", "cacheUrl", "title",
                        "titleNoFormatting", "content", "estimatedResultCount"],

        // _aggregtedAttributes: Hash
        //              Maps per-query aggregated attributes that this store supports to the result keys that they come from.
        _aggregatedAttributes: {
                estimatedResultCount: "cursor.estimatedResultCount"
        },

        // label: String
        //              The default attribute which acts as a label for each item.
        label: "titleNoFormatting",

        // type: String
        //              The type of search. Valid values are "web", "local", "video", "blogs", "news", "books", "images".
        //              This should not be set directly. Instead use one of the child classes.
        _type: "web",

        // urlPreventCache: boolean
        //              Sets whether or not to pass preventCache to dojo.io.script.
        urlPreventCache: true,


        // _queryAttrs: Hash
        //              Maps query hash keys to Google query parameters.
        _queryAttrs: {
                text: 'q'
        },

        _assertIsItem: function(/* item */ item){
                // summary:
                //              This function tests whether the item passed in is indeed an item in the store.
                // item:
                //              The item to test for being contained by the store.
                if(!this.isItem(item)){
                        throw new Error("dojox.data.GoogleSearchStore: a function was passed an item argument that was not an item");
                }
        },

        _assertIsAttribute: function(/* attribute-name-string */ attribute){
                // summary:
                //              This function tests whether the item passed in is indeed a valid 'attribute' like type for the store.
                // attribute:
                //              The attribute to test for being contained by the store.
                if(typeof attribute !== "string"){
                        throw new Error("dojox.data.GoogleSearchStore: a function was passed an attribute argument that was not an attribute name string");
                }
        },

        getFeatures: function(){
                // summary:
                //              See dojo/data/api/Read.getFeatures()
                return {
                        'dojo.data.api.Read': true
                };
        },

        getValue: function(item, attribute, defaultValue){
                // summary:
                //              See dojo/data/api/Read.getValue()
                var values = this.getValues(item, attribute);
                if(values && values.length > 0){
                        return values[0];
                }
                return defaultValue;
        },

        getAttributes: function(item){
                // summary:
                //              See dojo/data/api/Read.getAttributes()
                return this._attributes;
        },

        hasAttribute: function(item, attribute){
                // summary:
                //              See dojo/data/api/Read.hasAttributes()
                if(this.getValue(item,attribute)){
                        return true;
                }
                return false;
        },

        isItemLoaded: function(item){
                // summary:
                //              See dojo/data/api/Read.isItemLoaded()
                return this.isItem(item);
        },

        loadItem: function(keywordArgs){
                // summary:
                //              See dojo/data/api/Read.loadItem()
        },

        getLabel: function(item){
                // summary:
                //              See dojo/data/api/Read.getLabel()
                return this.getValue(item,this.label);
        },

        getLabelAttributes: function(item){
                // summary:
                //              See dojo/data/api/Read.getLabelAttributes()
                return [this.label];
        },

        containsValue: function(item, attribute, value){
                // summary:
                //              See dojo/data/api/Read.containsValue()
                var values = this.getValues(item,attribute);
                for(var i = 0; i < values.length; i++){
                        if(values[i] === value){
                                return true;
                        }
                }
                return false;
        },

        getValues: function(item, attribute){
                // summary:
                //              See dojo/data/api/Read.getValue()
                this._assertIsItem(item);
                this._assertIsAttribute(attribute);
                var val = item[attribute];
                if(lang.isArray(val)) {
                        return val;
                }else if(val !== undefined){
                        return [val];
                }else{
                        return [];
                }
        },

        isItem: function(item){
                // summary:
                //              See dojo/data/api/Read.isItem()
                if(item && item[this._storeRef] === this){
                        return true;
                }
                return false;
        },

        close: function(request){
                // summary:
                //              See dojo/data/api/Read.close()
        },

        _format: function(item, name){
                return item;//base implementation does not format any items
        },

        fetch: function(request){
                // summary:
                //              Fetch Google search items that match to a query
                // request:
                //              A request object
                // fetchHandler:
                //              A function to call for fetched items
                // errorHandler:
                //              A function to call on error
                request = request || {};

                var scope = request.scope || kernel.global;

                if(!request.query){
                        if(request.onError){
                                request.onError.call(scope, new Error(this.declaredClass +
                                        ": A query must be specified."));
                                return;
                        }
                }
                //Make a copy of the request object, in case it is
                //modified outside the store in the middle of a request
                var query = {};
                for(var attr in this._queryAttrs) {
                        query[attr] = request.query[attr];
                }
                request = {
                        query: query,
                        onComplete: request.onComplete,
                        onError: request.onError,
                        onItem: request.onItem,
                        onBegin: request.onBegin,
                        start: request.start,
                        count: request.count
                };

                //Google's web api will only return a max of 8 results per page.
                var pageSize = 8;

                //Generate a unique function to be called back
                var callbackFn = "GoogleSearchStoreCallback_" + this._id + "_" + (++this._requestCount);

                //Build up the content to send the request for.
                //rsz is the result size, "large" gives 8 results each time
                var content = this._createContent(query, callbackFn, request);

                var firstRequest;

                if(typeof(request.start) === "undefined" || request.start === null){
                        request.start = 0;
                }

                if(!request.count){
                        request.count = pageSize;
                }
                firstRequest = {start: request.start - request.start % pageSize};

                var _this = this;
                var searchUrl = this._googleUrl + this._type;

                var getArgs = {
                        url: searchUrl,
                        preventCache: this.urlPreventCache,
                        content: content
                };

                var items = [];
                var successfulReq = 0;
                var finished = false;
                var lastOnItem = request.start -1;
                var numRequests = 0;
                var scriptIds = [];

                // Performs the remote request.
                function doRequest(req){
                        //Record how many requests have been made.
                        numRequests ++;
                        getArgs.content.context = getArgs.content.start = req.start;

                        var deferred = scriptIO.get(getArgs);
                        scriptIds.push(deferred.ioArgs.id);

                        //We only set up the errback, because the callback isn't ever really used because we have
                        //to link to the jsonp callback function....
                        deferred.addErrback(function(error){
                                if(request.onError){
                                        request.onError.call(scope, error, request);
                                }
                        });
                }

                // Function to handle returned data.
                var myHandler = function(start, data){
                        if (scriptIds.length > 0) {
                                // Delete the script node that was created.
                                domQuery("#" + scriptIds.splice(0,1)).forEach(domConstruct.destroy);
                        }
                        if(finished){return;}

                        var results = _this._getItems(data);
                        var cursor = data ? data['cursor']: null;

                        if(results){
                                //Process the results, adding the store reference to them
                                for(var i = 0; i < results.length && i + start < request.count + request.start; i++) {
                                        _this._processItem(results[i], data);
                                        items[i + start] = results[i];
                                }
                                successfulReq ++;
                                if(successfulReq == 1){
                                        // After the first request, we know how many results exist.
                                        // So perform any follow up requests to retrieve more data.
                                        var pages = cursor ? cursor.pages : null;
                                        var firstStart = pages ? Number(pages[pages.length - 1].start) : 0;

                                        //Call the onBegin method if it exists
                                        if (request.onBegin){
                                                var est = cursor ? cursor.estimatedResultCount : results.length;
                                                var total =  est ? Math.min(est, firstStart + results.length) : firstStart + results.length;
                                                request.onBegin.call(scope, total, request);
                                        }

                                        // Request the next pages.
                                        var nextPage = (request.start - request.start % pageSize) + pageSize;
                                        var page = 1;
                                        while(pages){
                                                if(!pages[page] || Number(pages[page].start) >= request.start + request.count){
                                                        break;
                                                }
                                                if(Number(pages[page].start) >= nextPage) {
                                                        doRequest({start: pages[page].start});
                                                }
                                                page++;
                                        }
                                }

                                // Call the onItem function on all retrieved items.
                                if(request.onItem && items[lastOnItem + 1]){
                                        do{
                                                lastOnItem++;
                                                request.onItem.call(scope, items[lastOnItem], request);
                                        }while(items[lastOnItem + 1] && lastOnItem < request.start + request.count);
                                }

                                //If this is the last request, call final fetch handler.
                                if(successfulReq == numRequests){
                                        //Process the items...
                                        finished = true;
                                        //Clean up the function, it should never be called again
                                        kernel.global[callbackFn] = null;
                                        if(request.onItem){
                                                request.onComplete.call(scope, null, request);
                                        }else{
                                                items = items.slice(request.start, request.start + request.count);
                                                request.onComplete.call(scope, items, request);
                                        }

                                }
                        }
                };

                var callbacks = [];
                var lastCallback = firstRequest.start - 1;

                // Attach a callback function to the global namespace, where Google can call it.
                kernel.global[callbackFn] = function(start, data, responseCode, errorMsg){
                        try {
                                if(responseCode != 200){
                                        if(request.onError){
                                                request.onError.call(scope, new Error("Response from Google was: " + responseCode), request);
                                        }
                                        kernel.global[callbackFn] = function(){};//an error occurred, do not return anything else.
                                        return;
                                }
        
                                if(start == lastCallback + 1){
                                        myHandler(Number(start), data);
                                        lastCallback += pageSize;
        
                                        //make sure that the callbacks happen in the correct sequence
                                        if(callbacks.length > 0){
                                                callbacks.sort(_this._getSort());
                                                //In case the requsts do not come back in order, sort the returned results.
                                                while(callbacks.length > 0 && callbacks[0].start == lastCallback + 1){
                                                        myHandler(Number(callbacks[0].start), callbacks[0].data);
                                                        callbacks.splice(0,1);
                                                        lastCallback += pageSize;
                                                }
                                        }
                                }else{
                                        callbacks.push({start:start, data: data});
                                }
                        } catch (e) {
                                request.onError.call(scope, e, request);
                        }
                };

                // Perform the first request. When this has finished
                // we will have a list of pages, which can then be
                // gone through
                doRequest(firstRequest);
        },
        
        _getSort: function() {
                return function(a,b){
                        if(a.start < b.start){return -1;}
                        if(b.start < a.start){return 1;}
                        return 0;
                };
        },

        _processItem: function(item, data) {
                item[this._storeRef] = this;
                // Copy aggregated attributes from query results to the item.
                for(var attribute in this._aggregatedAttributes) {
                        item[attribute] = lang.getObject(this._aggregatedAttributes[attribute], false, data);
                }
        },

        _getItems: function(data){
                return data['results'] || data;
        },

        _createContent: function(query, callback, request){
                var content = {
                        v: "1.0",
                        rsz: "large",
                        callback: callback,
                        key: this._key,
                        hl: this._lang
                };
                for(var attr in this._queryAttrs) {
                        content[this._queryAttrs[attr]] = query[attr];
                }
                return content;
        }
});

var WebSearchStore = declare("dojox.data.GoogleWebSearchStore", SearchStore,{
        // summary:
        //              A data store for retrieving search results from Google.
        //              The following attributes are supported on each item:
        //
        //              - title - The page title in HTML format.
        //              - titleNoFormatting - The page title in plain text
        //              - content - A snippet of information about the page
        //              - url - The URL for the item
        //              - unescapedUrl - The URL for the item, with URL escaping. This is often more readable
        //              - visibleUrl - The URL with no protocol specified.
        //              - cacheUrl - The URL to the copy of the document cached by Google
        //              - estimatedResultCount - (aggregated per-query) estimated number of results
        //
        //              The query accepts one parameter: text - The string to search for
});

var BlogSearchStore = declare("dojox.data.GoogleBlogSearchStore", SearchStore,{
        // summary:
        //              A data store for retrieving search results from Google.
        //              The following attributes are supported on each item:
        //
        //              - title - The blog post title in HTML format.
        //              - titleNoFormatting - The  blog post title in plain text
        //              - content - A snippet of information about the blog post
        //              - blogUrl - The URL for the blog
        //              - postUrl - The URL for the a single blog post
        //              - visibleUrl - The URL with no protocol specified.
        //              - cacheUrl - The URL to the copy of the document cached by Google
        //              - author - The author of the blog post
        //              - publishedDate - The published date, in RFC-822 format
        //
        //              The query accepts one parameter: text - The string to search for
        _type: "blogs",
        _attributes: ["blogUrl", "postUrl", "title", "titleNoFormatting", "content",
                        "author", "publishedDate"],
        _aggregatedAttributes: { }
});


var LocalSearchStore = declare("dojox.data.GoogleLocalSearchStore", SearchStore,{
        // summary:
        //              A data store for retrieving search results from Google.
        //              The following attributes are supported on each item:
        //
        //              - title - The blog post title in HTML format.
        //              - titleNoFormatting - The  blog post title in plain text
        //              - content - A snippet of information about the blog post
        //              - url - The URL for the item
        //              - lat - The latitude.
        //              - lng - The longtitude.
        //              - streetAddress - The street address
        //              - city - The city
        //              - region - The region
        //              - country - The country
        //              - phoneNumbers - Phone numbers associated with this address. Can be one or more.
        //              - ddUrl - A URL that can be used to provide driving directions from the center of the search results to this search results
        //              - ddUrlToHere - A URL that can be used to provide driving directions from this search result to a user specified location
        //              - staticMapUrl - The published date, in RFC-822 format
        //              - viewport - Recommended viewport for the query results (same for all results in a query)
        //                      - center - contains lat, lng properties
        //                      - span - lat, lng properties for the viewport span
        //                      - ne, sw - lat, lng properties for the viewport corners
        //
        //              The query accepts the following parameters:
        //
        //              - text - The string to search for
        //              - centerLatLong - Comma-separated lat & long for the center of the search (e.g. "48.8565,2.3509")
        //              - searchSpan - Comma-separated lat & long degrees indicating the size of the desired search area (e.g. "0.065165,0.194149")

        _type: "local",
        _attributes: ["title", "titleNoFormatting", "url", "lat", "lng", "streetAddress",
                        "city", "region", "country", "phoneNumbers", "ddUrl", "ddUrlToHere",
                        "ddUrlFromHere", "staticMapUrl", "viewport"],
        _aggregatedAttributes: {
                viewport: "viewport"
        },
        _queryAttrs: {
                text: 'q',
                centerLatLong: 'sll',
                searchSpan: 'sspn'
        }
});

var VideoSearchStore = declare("dojox.data.GoogleVideoSearchStore", SearchStore,{
        // summary:
        //              A data store for retrieving search results from Google.
        //              The following attributes are supported on each item:
        //
        //              - title - The blog post title in HTML format.
        //              - titleNoFormatting - The  blog post title in plain text
        //              - content - A snippet of information about the blog post
        //              - url - The URL for the item
        //              - published - The published date, in RFC-822 format.
        //              - publisher - The name of the publisher.
        //              - duration - The approximate duration, in seconds, of the video.
        //              - tbWidth - The width in pixels of the video.
        //              - tbHeight - The height in pixels of the video
        //              - tbUrl - The URL to a thumbnail representation of the video.
        //              - playUrl - If present, supplies the url of the flash version of the video that can be played inline on your page. To play this video simply create and <embed> element on your page using this value as the src attribute and using application/x-shockwave-flash as the type attribute. If you want the video to play right away, make sure to append &autoPlay=true to the url..
        //
        //              The query accepts one parameter: text - The string to search for
        _type: "video",
        _attributes: ["title", "titleNoFormatting", "content", "url", "published", "publisher",
                        "duration", "tbWidth", "tbHeight", "tbUrl", "playUrl"],
        _aggregatedAttributes: { }
});

var NewsSearchStore = declare("dojox.data.GoogleNewsSearchStore", SearchStore,{
        // summary:
        //              A data store for retrieving search results from Google.
        //              The following attributes are supported on each item:
        //
        //              - title - The news story title in HTML format.
        //              - titleNoFormatting - The news story title in plain text
        //              - content - A snippet of information about the news story
        //              - url - The URL for the item
        //              - unescapedUrl - The URL for the item, with URL escaping. This is often more readable
        //              - publisher - The name of the publisher
        //              - clusterUrl - A URL pointing to a page listing related storied.
        //              - location - The location of the news story.
        //              - publishedDate - The date of publication, in RFC-822 format.
        //              - relatedStories - An optional array of objects specifying related stories.
        //                      Each object has the following subset of properties:
        //                      "title", "titleNoFormatting", "url", "unescapedUrl", "publisher", "location", "publishedDate".
        //
        //              The query accepts one parameter: text - The string to search for
        _type: "news",
        _attributes: ["title", "titleNoFormatting", "content", "url", "unescapedUrl", "publisher",
                        "clusterUrl", "location", "publishedDate", "relatedStories" ],
        _aggregatedAttributes: { }
});

var BookSearchStore = declare("dojox.data.GoogleBookSearchStore", SearchStore,{
        // summary:
        //              A data store for retrieving search results from Google.
        //              The following attributes are supported on each item:
        //
        //              - title - The book title in HTML format.
        //              - titleNoFormatting - The book title in plain text
        //              - authors - An array of authors
        //              - url - The URL for the item
        //              - unescapedUrl - The URL for the item, with URL escaping. This is often more readable
        //              - bookId - An identifier for the book, usually an ISBN.
        //              - pageCount - The number of pages in the book.
        //              - publishedYear - The year of publication.
        //
        //              The query accepts one parameter: text - The string to search for
        _type: "books",
        _attributes: ["title", "titleNoFormatting", "authors", "url", "unescapedUrl", "bookId",
                        "pageCount", "publishedYear"],
        _aggregatedAttributes: { }
});

var ImageSearchStore = declare("dojox.data.GoogleImageSearchStore", SearchStore,{
        // summary:
        //              A data store for retrieving search results from Google.
        //              The following attributes are supported on each item:
        //
        //              - title - The image title in HTML format.
        //              - titleNoFormatting - The image title in plain text
        //              - url - The URL for the image
        //              - unescapedUrl - The URL for the image, with URL escaping. This is often more readable
        //              - tbUrl - The URL for the image thumbnail
        //              - visibleUrl - A shortened version of the URL associated with the result, stripped of a protocol and path
        //              - originalContextUrl - The URL of the page containing the image.
        //              - width - The width of the image in pixels.
        //              - height - The height of the image in pixels.
        //              - tbWidth - The width of the image thumbnail in pixels.
        //              - tbHeight - The height of the image thumbnail in pixels.
        //              - content - A snippet of information about the image, in HTML format
        //              - contentNoFormatting - A snippet of information about the image, in plain text
        //
        //              The query accepts one parameter: text - The string to search for
        _type: "images",
        _attributes: ["title", "titleNoFormatting", "visibleUrl", "url", "unescapedUrl",
                        "originalContextUrl", "width", "height", "tbWidth", "tbHeight",
                        "tbUrl", "content", "contentNoFormatting"],
        _aggregatedAttributes: { }
});

return {
        Search: SearchStore,
        ImageSearch: ImageSearchStore,
        BookSearch: BookSearchStore,
        NewsSearch: NewsSearchStore,
        VideoSearch: VideoSearchStore,
        LocalSearch: LocalSearchStore,
        BlogSearch: BlogSearchStore,
        WebSearch: WebSearchStore
        }
});