using System;
using System.IO;
using System.Collections.Generic;
using System.Reflection;
using SharedLibraryCore.Interfaces;
using System.Linq;
using SharedLibraryCore;
using IW4MAdmin.Application.API.Master;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using SharedLibraryCore.Configuration;
using ILogger = Microsoft.Extensions.Logging.ILogger;

namespace IW4MAdmin.Application.Misc
{
    /// <summary>
    /// implementation of IPluginImporter
    /// discovers plugins and script plugins
    /// </summary>
    public class PluginImporter : IPluginImporter
    {
        private IEnumerable<PluginSubscriptionContent> _pluginSubscription;
        private static readonly string PLUGIN_DIR = "Plugins";
        private readonly ILogger _logger;
        private readonly IRemoteAssemblyHandler _remoteAssemblyHandler;
        private readonly IMasterApi _masterApi;
        private readonly ApplicationConfiguration _appConfig;

        public PluginImporter(ILogger<PluginImporter> logger, ApplicationConfiguration appConfig, IMasterApi masterApi, IRemoteAssemblyHandler remoteAssemblyHandler)
        {
            _logger = logger;
            _masterApi = masterApi;
            _remoteAssemblyHandler = remoteAssemblyHandler;
            _appConfig = appConfig;
        }

        /// <summary>
        /// discovers all the script plugins in the plugins dir
        /// </summary>
        /// <returns></returns>
        public IEnumerable<Func<IServiceProvider, IPlugin>> DiscoverScriptPlugins()
        {
            var pluginDir = $"{Utilities.OperatingDirectory}{PLUGIN_DIR}{Path.DirectorySeparatorChar}";

            if (!Directory.Exists(pluginDir))
            {
                return Enumerable.Empty<Func<IServiceProvider, IPlugin>>();
            }

            var scriptPluginFiles =
                Directory.GetFiles(pluginDir, "*.js").AsEnumerable().Union(GetRemoteScripts()).ToList();

            _logger.LogDebug("Discovered {count} potential script plugins", scriptPluginFiles.Count);

            return scriptPluginFiles.Select<string, Func<IServiceProvider, IPlugin>>(fileName => serviceProvider =>
            {
                _logger.LogDebug("Discovered script plugin {fileName}", fileName);
                return new ScriptPlugin(_logger,
                    serviceProvider.GetRequiredService<IScriptPluginTimerHelper>(), fileName);
            }).ToList();
        }

        /// <summary>
        /// discovers all the C# assembly plugins and commands
        /// </summary>
        /// <returns></returns>
        public (IEnumerable<Type>, IEnumerable<Type>, IEnumerable<Type>) DiscoverAssemblyPluginImplementations()
        {
            var pluginDir = $"{Utilities.OperatingDirectory}{PLUGIN_DIR}{Path.DirectorySeparatorChar}";
            var pluginTypes = Enumerable.Empty<Type>();
            var commandTypes = Enumerable.Empty<Type>();
            var configurationTypes = Enumerable.Empty<Type>();

            if (Directory.Exists(pluginDir))
            {
                var dllFileNames = Directory.GetFiles(pluginDir, "*.dll");
                _logger.LogDebug("Discovered {count} potential plugin assemblies", dllFileNames.Length);

                if (dllFileNames.Length > 0)
                {
                    // we only want to load the most recent assembly in case of duplicates
                    var assemblies = dllFileNames.Select(_name => Assembly.LoadFrom(_name))
                        .Union(GetRemoteAssemblies())
                        .GroupBy(_assembly => _assembly.FullName).Select(_assembly => _assembly.OrderByDescending(_assembly => _assembly.GetName().Version).First());

                    pluginTypes = assemblies
                        .SelectMany(_asm =>
                        {
                            try
                            {
                                return _asm.GetTypes();
                            }
                            catch
                            {
                                return Enumerable.Empty<Type>();
                            }
                        })
                        .Where(_assemblyType => _assemblyType.GetInterface(nameof(IPlugin), false) != null);

                    _logger.LogDebug("Discovered {count} plugin implementations", pluginTypes.Count());

                    commandTypes = assemblies
                        .SelectMany(_asm =>{
                            try
                            {
                                return _asm.GetTypes();
                            }
                            catch
                            {
                                return Enumerable.Empty<Type>();
                            }
                        })
                        .Where(_assemblyType => _assemblyType.IsClass && _assemblyType.BaseType == typeof(Command));

                    _logger.LogDebug("Discovered {count} plugin commands", commandTypes.Count());

                    configurationTypes = assemblies
                        .SelectMany(asm => {
                            try
                            {
                                return asm.GetTypes();
                            }
                            catch
                            {
                                return Enumerable.Empty<Type>();
                            }
                        })
                        .Where(asmType =>
                            asmType.IsClass && asmType.GetInterface(nameof(IBaseConfiguration), false) != null);

                    _logger.LogDebug("Discovered {count} configuration implementations", configurationTypes.Count());
                }
            }

            return (pluginTypes, commandTypes, configurationTypes);
        }

        private IEnumerable<Assembly> GetRemoteAssemblies()
        {
            try
            {
                if (_pluginSubscription == null)
                    _pluginSubscription = _masterApi.GetPluginSubscription(Guid.Parse(_appConfig.Id), _appConfig.SubscriptionId).Result;

                return _remoteAssemblyHandler.DecryptAssemblies(_pluginSubscription.Where(sub => sub.Type == PluginType.Binary).Select(sub => sub.Content).ToArray());
            }

            catch (Exception ex)
            {
                _logger.LogWarning(ex, "Could not load remote assemblies");
                return Enumerable.Empty<Assembly>();
            }
        }

        private IEnumerable<string> GetRemoteScripts()
        {
            try
            {
                if (_pluginSubscription == null)
                    _pluginSubscription = _masterApi.GetPluginSubscription(Guid.Parse(_appConfig.Id), _appConfig.SubscriptionId).Result;

                return _remoteAssemblyHandler.DecryptScripts(_pluginSubscription.Where(sub => sub.Type == PluginType.Script).Select(sub => sub.Content).ToArray());
            }

            catch (Exception ex)
            {
                _logger.LogWarning(ex,"Could not load remote scripts");
                return Enumerable.Empty<string>();
            }
        }
    }

    public enum PluginType
    {
        Binary,
        Script
    }
}