dojo.provide("dojox.data.FlickrRestStore");

dojo.require("dojox.data.FlickrStore");

dojo.declare("dojox.data.FlickrRestStore",
	dojox.data.FlickrStore, {
	constructor: function(/*Object*/args){ 
		// summary:
		//	Initializer for the FlickrRestStore store.  
		// description:
		//	The FlickrRestStore is a Datastore interface to one of the basic services
		//	of the Flickr service, the public photo feed.  This does not provide
		//	access to all the services of Flickr.
		//	This store cannot do * and ? filtering as the flickr service 
		//	provides no interface for wildcards.
		if(args){
			if(args.label) {
				this.label = args.label;
			}
			if(args.apikey) {
				this._apikey = args.apikey;
			}
		}
		this._cache = [];
		this._prevRequests = {};
		this._handlers = {};
		this._prevRequestRanges = [];
		this._maxPhotosPerUser = {};
		this._id = dojox.data.FlickrRestStore.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 Flickr will use.
	_requestCount: 0,
	
	// _flickrRestUrl: String
	//	The URL to the Flickr REST services.
	_flickrRestUrl: "http://www.flickr.com/services/rest/",

	// _apikey: String
	//	The users API key to be used when accessing Flickr REST services.
	_apikey: null,
	
	// _storeRef: String
	//	A key used to mark an data store item as belonging to this store.
	_storeRef: "_S",
	
	// _cache: Array
	//	An Array of all previously downloaded picture info.
	_cache: null,
	
	// _prevRequests: Object
	//	A HashMap used to record the signature of a request to prevent duplicate 
	//	request being made.
	_prevRequests: null,
	
	// _handlers: Object
	//	A HashMap used to record the handlers registered for a single remote request.  Multiple 
	//	requests may be made for the same information before the first request has finished. 
	//	Each element of this Object is an array of handlers to call back when the request finishes.
	//	This prevents multiple requests being made for the same information.  
	_handlers: null,
	
	// _sortAttributes: Object
	// A quick lookup of valid attribute names in a sort query.
	_sortAttributes: {
		"date-posted": true,
		"date-taken": true,
		"interestingness": true
	},
			
	_fetchItems: function(	/*Object*/ request, 
							/*Function*/ fetchHandler, 
							/*Function*/ errorHandler){
		//	summary: Fetch flickr 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
		var query = {};
		if(!request.query){
			request.query = query = {};
		} else {
			dojo.mixin(query, request.query);	
		}
		
		var primaryKey = [];
		var secondaryKey = [];
		
		//Build up the content to send the request for.
		var content = {
			format: "json",
			method: "flickr.photos.search",
			api_key: this._apikey,
			extras: "owner_name,date_upload,date_taken"
		};
		var isRest = false;
		if(query.userid){
			isRest = true;
			content.user_id = request.query.userid;
			primaryKey.push("userid"+request.query.userid);
		}

		if(query.apikey){
			isRest = true;
			content.api_key = request.query.apikey;
			secondaryKey.push("api"+request.query.apikey);
		}else if(content.api_key){
			isRest = true;
			request.query.apikey = content.api_key;
			secondaryKey.push("api"+content.api_key);
		}else{
			throw Error("dojox.data.FlickrRestStore: An API key must be specified.");
		}

		request._curCount = request.count;

		if(query.page){
			content.page = request.query.page;
			secondaryKey.push("page" + content.page);
		}else if(typeof(request.start) != "undefined" && request.start != null){
			if(!request.count){
				request.count = 20;
			}
			var diff = request.start % request.count;
			var start = request.start, count = request.count;
			// If the count does not divide cleanly into the start number,
			// more work has to be done to figure out the best page to request
			if(diff != 0) {
				if(start < count / 2){
					// If the first record requested is less than half the
					// amount requested, then request from 0 to the count record
					count = start + count;
					start = 0; 
				}else{
					var divLimit = 20, div = 2;
					for(var i = divLimit; i > 0; i--){
						if(start % i == 0 && (start/i) >= count){
							div = i;
							break;
						}
					}
					count = start/div;
				}
				request._realStart = request.start;
				request._realCount = request.count;
				request._curStart = start;
				request._curCount = count;
			}else{
				request._realStart = request._realCount = null;
				request._curStart = request.start;
				request._curCount = request.count;
			}
			
			content.page = (start / count) + 1;
			secondaryKey.push("page" + content.page);
		}

		if(request._curCount){
			content.per_page = request._curCount;
			secondaryKey.push("count" + request._curCount);
		}
		
		if(query.lang){
			content.lang = request.query.lang;
			primaryKey.push("lang" + request.lang);
		}
		var url = this._flickrRestUrl;
		
		if(query.setid){
			content.method = "flickr.photosets.getPhotos";
			content.photoset_id = request.query.setid; 
			primaryKey.push("set" + request.query.setid);
		}
		
		if(query.tags){
			if(query.tags instanceof Array){
				content.tags = query.tags.join(",");
			}else{
				content.tags = query.tags;				
			}
			primaryKey.push("tags" + content.tags);
			
			if(query["tag_mode"] && (query.tag_mode.toLowerCase() == "any"
				|| query.tag_mode.toLowerCase() == "all")){
				content.tag_mode = query.tag_mode;
			}
		}
		if(query.text){
			content.text=query.text;
			primaryKey.push("text:"+query.text);
		}
		
		//The store only supports a single sort attribute, even though the
		//Read API technically allows multiple sort attributes
		if(query.sort && query.sort.length > 0){			
			//The default sort attribute is 'date-posted'
			if(!query.sort[0].attribute){
				query.sort[0].attribute = "date-posted";
			}
			
			//If the sort attribute is valid, check if it is ascending or
			//descending.
			if(this._sortAttributes[query.sort[0].attribute]) {
				if(query.sort[0].descending){
					content.sort = query.sort[0].attribute + "-desc";
				}else{
					content.sort = query.sort[0].attribute + "-asc";
				}
			}
		}else{
			//The default sort in the Dojo Data API is ascending.
			content.sort = "date-posted-asc";
		}
		primaryKey.push("sort:"+content.sort);
	
		//Generate a unique key for this request, so the store can 
		//detect duplicate requests.
		primaryKey = primaryKey.join(".");
		secondaryKey = secondaryKey.length > 0 ? "." + secondaryKey.join(".") : "";
		var requestKey = primaryKey + secondaryKey;
		
		//Make a copy of the request, in case the source object is modified
		//before the request completes
		request = {
			query: query,
			count: request._curCount,
			start: request._curStart,
			_realCount: request._realCount,
			_realStart: request._realStart,
			onBegin: request.onBegin,
			onComplete: request.onComplete,
			onItem: request.onItem
		};

		var thisHandler = {
			request: request,
	    	fetchHandler: fetchHandler,
	    	errorHandler: errorHandler
	   	};

	   	//If the request has already been made, but not yet completed,
	   	//then add the callback handler to the list of handlers
	   	//for this request, and finish.
	   	if(this._handlers[requestKey]){
	    	this._handlers[requestKey].push(thisHandler);
	    	return;
	   	}

  		this._handlers[requestKey] = [thisHandler];

  		//Linking this up to Flickr is a PAIN!
  		var handle = null;
  		var getArgs = {
			url: this._flickrRestUrl,
			preventCache: true,
			content: content,
			callbackParamName: "jsoncallback"
		};
		
  		var doHandle = dojo.hitch(this, function(processedData, data, handler){
			var onBegin = handler.request.onBegin;
			handler.request.onBegin = null;
			var maxPhotos;
			var req = handler.request;
			
			if(typeof(req._realStart) != undefined && req._realStart != null){
				req.start = req._realStart;
				req.count = req._realCount;
				req._realStart = req._realCount = null;
			}

			//If the request contains an onBegin method, the total number
			//of photos must be calculated.
			if(onBegin){
				var photos = null;
				if(data){
					photos = (data.photoset ? data.photoset : data.photos);
				}
				if(photos && typeof(photos.perpage) != "undefined" && typeof(photos.pages) != "undefined"){
					if(photos.perpage * photos.pages <= handler.request.start + handler.request.count){
						//If the final page of results has been received, it is possible to 
						//know exactly how many photos there are
						maxPhotos = handler.request.start + photos.photo.length;                
					}else{
						//If the final page of results has not yet been received,
						//it is not possible to tell exactly how many photos exist, so
						//return the number of pages multiplied by the number of photos per page.
						maxPhotos = photos.perpage * photos.pages;
					}
					this._maxPhotosPerUser[primaryKey] = maxPhotos;
					onBegin(maxPhotos, handler.request);
				}else if(this._maxPhotosPerUser[primaryKey]){
					onBegin(this._maxPhotosPerUser[primaryKey], handler.request);
				}
			}
			//Call whatever functions the caller has defined on the request object, except for onBegin
			handler.fetchHandler(processedData, handler.request);
			if(onBegin){
				//Replace the onBegin function, if it existed.
				handler.request.onBegin = onBegin;
			}
		});
		
		//Define a callback for the script that iterates through a list of 
		//handlers for this piece of data.  Multiple requests can come into
		//the store for the same data.
		var myHandler = dojo.hitch(this, function(data){
			//The handler should not be called more than once, so disconnect it.
			//if(handle !== null){ dojo.disconnect(handle); }
			if(data.stat != "ok"){
				errorHandler(null, request);
			}else{ //Process the items...
				var handlers = this._handlers[requestKey];
				if(!handlers){
					console.log("FlickrRestStore: no handlers for data", data);
					return;
				}

				this._handlers[requestKey] = null;
				this._prevRequests[requestKey] = data;

				//Process the data once.
				var processedData = this._processFlickrData(data, request, primaryKey);
				if(!this._prevRequestRanges[primaryKey]){
					this._prevRequestRanges[primaryKey] = [];
				}
				this._prevRequestRanges[primaryKey].push({
					start: request.start,
					end: request.start + (data.photoset ? data.photoset.photo.length : data.photos.photo.length)
				});

				//Iterate through the array of handlers, calling each one.
				dojo.forEach(handlers, function(i){
					doHandle(processedData, data, i);
				});
			}
		});

		var data = this._prevRequests[requestKey];
		
		//If the data was previously retrieved, there is no need to fetch it again.
		if(data){
			this._handlers[requestKey] = null;
			doHandle(this._cache[primaryKey], data, thisHandler);
			return;
		}else if(this._checkPrevRanges(primaryKey, request.start, request.count)){
			//If this range of data has already been retrieved, reuse it.
			this._handlers[requestKey] = null;
			doHandle(this._cache[primaryKey], null, thisHandler);
			return;
		}
				
		var deferred = dojo.io.script.get(getArgs);
		deferred.addCallback(myHandler);
		
		//We only set up the errback, because the callback isn't ever really used because we have
		//to link to the jsonFlickrFeed function....
		deferred.addErrback(function(error){
			dojo.disconnect(handle);
			errorHandler(error, request);
		});
	},
	
	getAttributes: function(item){
		//	summary: 
		//      See dojo.data.api.Read.getAttributes()
		return [
			"title", "author", "imageUrl", "imageUrlSmall", "imageUrlMedium",
			"imageUrlThumb", "link", "dateTaken", "datePublished"
		]; 
	},
	
	getValues: function(item, attribute){
		//	summary:
		//      See dojo.data.api.Read.getValue()
		this._assertIsItem(item);
		this._assertIsAttribute(attribute);

		switch(attribute){
			case "title":
				return [ this._unescapeHtml(item.title) ]; // String
			case "author":
				return [ item.ownername ]; // String
			case "imageUrlSmall":
				return [ item.media.s ]; // String
			case "imageUrl":
				return [ item.media.l ]; // String
			case "imageUrlMedium":
				return [ item.media.m ]; // String
			case "imageUrlThumb":
				return [ item.media.t ]; // String
			case "link":
				return [ "http://www.flickr.com/photos/" + item.owner + "/" + item.id ]; // String
			case "dateTaken":
				return [ item.datetaken ];
			case "datePublished":
				return [ item.datepublished ];
			default:
				return undefined;
		}
		
	},

	_processFlickrData: function(/* Object */data, /* Object */request, /* String */ cacheKey){
		// summary: Processes the raw data from Flickr and updates the internal cache.
		// data: 
		//		Data returned from Flickr
		// request: 
		//		The original dojo.data.Request object passed in by the user.
		
		// If the data contains an 'item' object, it has not come from the REST
		// services, so process it using the FlickrStore.
		if(data.items){
			return dojox.data.FlickrStore.prototype._processFlickrData.apply(this,arguments);
		}

		var template = ["http://farm", null, ".static.flickr.com/", null, "/", null, "_", null];
		
		var items = [];
		var photos = (data.photoset ? data.photoset : data.photos);
		if(data.stat == "ok" && photos && photos.photo){
			items = photos.photo;
			
			//Add on the store ref so that isItem can work.
			for(var i = 0; i < items.length; i++){
				var item = items[i];
				item[this._storeRef] = this;
				
				template[1] = item.farm;
				template[3] = item.server;
				template[5] = item.id;
				template[7] = item.secret;
				 
				var base = template.join("");
				item.media = {
					s: base + "_s.jpg",
				 	m: base + "_m.jpg",
				 	l: base + ".jpg",
				 	t: base + "_t.jpg"
				};
				if(!item.owner && data.photoset){
					item.owner = data.photoset.owner;
				}
			}
		}
		var start = request.start ? request.start : 0;
		var arr = this._cache[cacheKey];
		if(!arr){
			this._cache[cacheKey] = arr = [];
		}
		dojo.forEach(items, function(i, idx){
			arr[idx+ start] = i;
		});

		return arr; // Array
	},
	
	_checkPrevRanges: function(primaryKey, start, count){
		var end = start + count;
		var arr = this._prevRequestRanges[primaryKey];
		return (!!arr) && dojo.some(arr, function(item){
			return ((start >= item.start)&&(end <= item.end));
		});
	}
});