/src/ZebraFlickr/Core/Processing/Retrieval/PhotosetRetriever.cs

#region License



// Copyright (c) 2012 Gareth Lennox (garethl@dwakn.com)

// All rights reserved.

// 

// Redistribution and use in source and binary forms, with or without modification,

// are permitted provided that the following conditions are met:

// 

//     * Redistributions of source code must retain the above copyright notice,

//       this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above copyright notice,

//       this list of conditions and the following disclaimer in the documentation

//       and/or other materials provided with the distribution.

//     * Neither the name of Gareth Lennox nor the names of its

//       contributors may be used to endorse or promote products derived from this

//       software without specific prior written permission.

//  

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND

// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE

// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.



#endregion



using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

using FlickrNet;

using ZebraFlickr.Core.Store;



namespace ZebraFlickr.Core.Processing.Retrieval

{

    public class PhotosetRetriever : IEnumerable<Tuple<SetEntry, Photoset>>

    {

        private readonly Flickr _flickr;

        private readonly TimeSpan _maxCacheAge;

        private readonly LocalState _state;



        public PhotosetRetriever(LocalState state, UserDetails details, TimeSpan maxCacheAge)

        {

            _state = state;

            _maxCacheAge = maxCacheAge;



            _flickr = FlickrClient.Create(details);

        }



        #region Implementation of IEnumerable



        /// <summary>

        /// Returns an enumerator that iterates through the collection.

        /// </summary>

        /// <returns>

        /// A <see cref="T:System.Collections.Generic.IEnumerator`1"/> that can be used to iterate through the collection.

        /// </returns>

        /// <filterpriority>1</filterpriority>

        public IEnumerator<Tuple<SetEntry, Photoset>> GetEnumerator()

        {

            Log.Info("Retrieving photo sets from flickr...");



            var items = Try.Execute(5,

                               delegate

                                   {

                                       var key = "Flickr_Photosets";

                                       var photoSets = _state.Cache.GetIfYoungerThan<PhotosetCollection>(_maxCacheAge, key);



                                       if (photoSets != null)

                                           return photoSets;



                                       photoSets = _flickr.PhotosetsGetList();



                                       Task.Factory.StartNew(() => _state.Cache.Set(key, photoSets));



                                       return photoSets;

                                   });



            var sortedItems = items.OrderBy(x => x.Title);



            foreach (var item in sortedItems)

            {

                var set = _state.GetSetByFlickrSetId(item.PhotosetId) 

                    ?? _state.CreateSet(item.Title, item.PhotosetId);



                //if it hasn't changed since we last synced it, ignore

                if (set.Synced != null && set.Synced.Value >= item.DateUpdated)

                    continue;



                set.Synced = DateTime.UtcNow;



                yield return Tuple.Create(set, item);

            }



            var noSet = _state.GetSetByFlickrSetId("-1") ?? new SetEntry

                {

                    Name = "Not in set",

                    SetId = "-1"

                };



            noSet.Synced = DateTime.Now;



            yield return Tuple.Create(noSet, (Photoset)null);

        }



        /// <summary>

        /// Returns an enumerator that iterates through a collection.

        /// </summary>

        /// <returns>

        /// An <see cref="T:System.Collections.IEnumerator"/> object that can be used to iterate through the collection.

        /// </returns>

        /// <filterpriority>2</filterpriority>

        IEnumerator IEnumerable.GetEnumerator()

        {

            return GetEnumerator();

        }



        #endregion

    }

}