//
// Copyright (c) 2015 Timotei Dolean
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
using Confuser.Renamer.BAML;
using Fasterflect;
using Mono.Cecil;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Resources;

namespace ILRepacking.Steps.ResourceProcessing
{
    /// <summary>
    /// This collector removes the BAML streams from non-main assemblies and
    /// moves them in a assembly-name directory, to prevent duplication.
    /// </summary>
    internal class BamlStreamCollector : IResProcessor, IEmbeddedResourceProcessor
    {
        private const string GenericThemesBamlName = "themes/generic.baml";

        private readonly ILogger _logger;
        private readonly AssemblyDefinition _primaryAssemblyDefinition;
        private readonly BamlGenerator _bamlGenerator;
        private readonly IDictionary<Res, AssemblyDefinition> _bamlStreams = new Dictionary<Res, AssemblyDefinition>();

        public bool HasBamlStreams => _bamlStreams.Count > 0;

        public BamlStreamCollector(ILogger logger, IRepackContext repackContext)
        {
            _logger = logger;
            _primaryAssemblyDefinition = repackContext.PrimaryAssemblyDefinition;

            _bamlGenerator = new BamlGenerator(
                _logger,
                repackContext.TargetAssemblyMainModule.AssemblyReferences,
                _primaryAssemblyDefinition);
        }

        public bool Process(Res resource, AssemblyDefinition containingAssembly, EmbeddedResource embeddedResource, ResReader resourceReader, ResourceWriter resourceWriter)
        {
            if (!resource.IsBamlStream && !embeddedResource.Name.EndsWith(".g.resources"))
                return false;

            _bamlStreams.Add(resource, containingAssembly);
            return true;
        }

        public void Process(EmbeddedResource embeddedResource, ResourceWriter resourceWriter)
        {
            if (_bamlStreams.Count == 0)
                return;

            WriteCollectedBamlStreams(resourceWriter);
            PatchGenericThemesBaml(resourceWriter);
        }

        private void WriteCollectedBamlStreams(ResourceWriter resourceWriter)
        {
            foreach (var bamlStream in _bamlStreams)
            {
                resourceWriter.AddResourceData(
                    GetResourceName(bamlStream.Key, bamlStream.Value), bamlStream.Key.type, bamlStream.Key.data);
            }
        }

        private void PatchGenericThemesBaml(ResourceWriter resourceWriter)
        {
            byte[] existingGenericBaml;

            var genericThemeResources = _bamlStreams
                    .Where(e => e.Key.name.EndsWith(GenericThemesBamlName, StringComparison.OrdinalIgnoreCase))
                    .Select(e => GetResourceName(e.Key, e.Value).Replace(".baml", ".xaml"));

            if (!TryGetPreserializedData(resourceWriter, GenericThemesBamlName, out existingGenericBaml))
            {
                AddNewGenericThemesXaml(resourceWriter, genericThemeResources);
            }
            else
            {
                PatchExistingGenericThemesXaml(
                    resourceWriter, BamlUtils.FromResourceBytes(existingGenericBaml), genericThemeResources);
            }
        }

        private void PatchExistingGenericThemesXaml(
            ResourceWriter resourceWriter, BamlDocument bamlDocument, IEnumerable<string> genericThemeResources)
        {
            _logger.Info("Patching existing themes/generic.xaml");

            _bamlGenerator.AddMergedDictionaries(bamlDocument, genericThemeResources);

            SetPreserializedData(resourceWriter, GenericThemesBamlName,
                BamlUtils.ToResourceBytes(bamlDocument));
        }

        private void AddNewGenericThemesXaml(
            ResourceWriter resourceWriter, IEnumerable<string> genericThemeResources)
        {
            _logger.Info("Creating new themes/generic.xaml");
            var newBamlDocument = _bamlGenerator.GenerateThemesGenericXaml(genericThemeResources);

            resourceWriter.AddResourceData(
                GenericThemesBamlName, "ResourceTypeCode.Stream",
                BamlUtils.ToResourceBytes(newBamlDocument));
        }

        private string GetResourceName(Res resource, AssemblyDefinition assembly)
        {
            if (assembly == _primaryAssemblyDefinition)
                return resource.name;

            return string.Format("{0}/{1}", assembly.Name.Name.ToLowerInvariant(), resource.name);
        }

        private static bool TryGetPreserializedData(ResourceWriter resourceWriter, string resourceName, out byte[] preserializedData)
        {
            IDictionary resourcesHashtable = (IDictionary)resourceWriter.GetFieldValue("_preserializedData");
            if (resourcesHashtable == null || !resourcesHashtable.Contains(resourceName))
            {
                preserializedData = null;
                return false;
            }

            object precannedResource = resourcesHashtable[resourceName];
            preserializedData = precannedResource.GetFieldValue("Data") as byte[];

            return true;
        }

        private static void SetPreserializedData(ResourceWriter resourceWriter, string resourceName, byte[] data)
        {
            IDictionary resourcesHashtable = (IDictionary)resourceWriter.GetFieldValue("_preserializedData");

            resourcesHashtable[resourceName].SetFieldValue("Data", data);
        }
    }
}