"use strict"

define([], function()
{
	var AttachmentsStore = function()
	{
        this._db = null;

        var DB_NAME = "attachments_store";
        var OBJECT_STORE_NAME = "attachments";

		this.isSupported = function()
		{
            if(!window.indexedDB){
                return false;
            }
            return true;
		}

		this.store = function(featureLayerUrl, attachmentId, objectId, attachmentFile, callback)
		{
            try
            {
                var transaction = this._db.transaction([OBJECT_STORE_NAME],"readwrite");

                transaction.oncomplete = function(event) 
                {
                    callback(true);
                };

                transaction.onerror = function(event) 
                {
                    callback(false,event.target.error.message)
                };

                var objectStore = transaction.objectStore(OBJECT_STORE_NAME);
                var request = objectStore.put(
                	{
                		id: attachmentId,
                		objectId: objectId,
                		featureId: featureLayerUrl + "/" + objectId,
                		contentType: attachmentFile.type,
                		name: attachmentFile.name,
                		size: attachmentFile.size,
                		url: 'javascript:alert("show local attached file ' + attachmentFile.name + '");', // TODO -> download the local file
                		content: attachmentFile.content
                	});
                request.onsuccess = function(event) 
                {
                    //console.log("item added to db " + event.target.result);
                };
            }
            catch(err)
            {
                console.log("AttachmentsStore: " + err.stack);
                callback(false,err.stack);
            }
		}

		this.retrieve = function(attachmentId, callback)
		{
            if(this._db != null)
            {
                var objectStore = this._db.transaction([OBJECT_STORE_NAME]).objectStore(OBJECT_STORE_NAME);
                var request = objectStore.get(attachmentId);
                request.onsuccess = function(event)
                {
                    var result = event.target.result;
                    if(result == null){
                        callback(false,"not found");
                    }
                    else{
                        callback(true,result);
                    }
                }
                request.onerror = function(err)
                {
                    console.log(err);
                    callback(false,err);
                }
            }
		}

		this.getAttachmentsByFeatureId = function(featureLayerUrl,objectId,callback)
		{
			var featureId = featureLayerUrl + "/" + objectId;
			var attachments = [];

			var objectStore = this._db.transaction([OBJECT_STORE_NAME]).objectStore(OBJECT_STORE_NAME);
			var index = objectStore.index("featureId");
			var keyRange = IDBKeyRange.only(featureId);
			index.openCursor(keyRange).onsuccess = function(evt)
			{
				var cursor = evt.target.result;
				if(cursor)
				{
					attachments.push( cursor.value );
					cursor.continue();
				}
				else
				{
					callback(attachments);
				}
			}
		}

		this.delete = function(attachmentId)
		{
			console.assert(false, "not implemented");
		}

        this.deleteAll = function(callback)
        {
            if(this._db != null)
            {
                var request = this._db.transaction([OBJECT_STORE_NAME],"readwrite")
                    .objectStore(OBJECT_STORE_NAME)
                    .clear();
                request.onsuccess = function(event)
                {
                    callback(true);
                }
                request.onerror = function(err)
                {
                    callback(false,err);
                }
            }
            else
            {
                callback(false,null);
            }
        }

        this.getUsage = function(callback){
            if(this._db != null){
                var usage = { sizeBytes: 0, attachmentCount: 0 };

                var transaction = this._db.transaction([OBJECT_STORE_NAME])
                    .objectStore(OBJECT_STORE_NAME)
                    .openCursor();

                transaction.onsuccess = function(event){
                    var cursor = event.target.result;
                    if(cursor){
                        var storedObject = cursor.value;
                        var json = JSON.stringify(storedObject);
                        usage.sizeBytes += json.length;
                        usage.attachmentCount += 1;
                        cursor.continue();
                    }
                    else{                        
                        callback(usage,null);
                    }
                }.bind(this);
                transaction.onerror = function(err){
                    callback(null,err);
                }
            }
            else{
                callback(null,null);
            }
        }

		this.init = function(callback)
		{
			console.log("init AttachmentStore");
			
            var request = indexedDB.open(DB_NAME, 11);
            callback = callback? callback : function(success) { console.log("AttachmentsStore::init() success:", success)}.bind(this);

            request.onerror = function(event) 
            {
                console.log("indexedDB error: " + event.target.errorCode);
                callback(false,event.target.errorCode);
            }.bind(this);

            request.onupgradeneeded = function(event) 
            {
                var db = event.target.result;

                if( db.objectStoreNames.contains(OBJECT_STORE_NAME)) 
                {
                    db.deleteObjectStore(OBJECT_STORE_NAME);
                }            

                var objectStore = db.createObjectStore(OBJECT_STORE_NAME, { keyPath: "id" });
                objectStore.createIndex("featureId","featureId", {unique: false});
            }.bind(this);

            request.onsuccess = function(event)
            {
                this._db = event.target.result;
                console.log("database opened successfully");
                callback(true);
            }.bind(this);
        }
	};
	return AttachmentsStore;
})