using MarketAlly.AIPlugin;
using MarketAlly.AIPlugin.Analysis.Plugins;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Threading.Tasks;

namespace MarketAlly.AIPlugin.Analysis.Infrastructure
{
    /// <summary>
    /// Service for discovering and loading analysis plugins
    /// </summary>
    public class PluginDiscoveryService : IPluginDiscovery
    {
        private readonly ILogger<PluginDiscoveryService>? _logger;

        public PluginDiscoveryService(ILogger<PluginDiscoveryService>? logger = null)
        {
            _logger = logger;
        }

        public Task<IEnumerable<IAIPlugin>> DiscoverPluginsAsync(string pluginDirectory)
        {
            _logger?.LogInformation("Discovering plugins in directory: {PluginDirectory}", pluginDirectory);

            var plugins = new List<IAIPlugin>();

            if (!Directory.Exists(pluginDirectory))
            {
                _logger?.LogWarning("Plugin directory does not exist: {PluginDirectory}", pluginDirectory);
                return Task.FromResult<IEnumerable<IAIPlugin>>(plugins);
            }

            var assemblyFiles = Directory.GetFiles(pluginDirectory, "*.dll", SearchOption.AllDirectories);

            foreach (var assemblyFile in assemblyFiles)
            {
                try
                {
                    var assembly = Assembly.LoadFrom(assemblyFile);
                    var pluginTypes = assembly.GetTypes()
                        .Where(t => typeof(IAIPlugin).IsAssignableFrom(t) && !t.IsInterface && !t.IsAbstract);

                    foreach (var pluginType in pluginTypes)
                    {
                        try
                        {
                            var plugin = Activator.CreateInstance(pluginType) as IAIPlugin;
                            if (plugin != null && ValidatePlugin(plugin))
                            {
                                plugins.Add(plugin);
                                _logger?.LogDebug("Loaded plugin: {PluginType} from {AssemblyFile}", 
                                    pluginType.Name, assemblyFile);
                            }
                        }
                        catch (Exception ex)
                        {
                            _logger?.LogError(ex, "Failed to create instance of plugin type: {PluginType}", 
                                pluginType.Name);
                        }
                    }
                }
                catch (Exception ex)
                {
                    _logger?.LogError(ex, "Failed to load assembly: {AssemblyFile}", assemblyFile);
                }
            }

            _logger?.LogInformation("Discovered {PluginCount} plugins", plugins.Count);
            return Task.FromResult<IEnumerable<IAIPlugin>>(plugins);
        }

        public Task<IAIPlugin> LoadPluginAsync(string assemblyPath, string typeName)
        {
            _logger?.LogInformation("Loading specific plugin: {TypeName} from {AssemblyPath}", 
                typeName, assemblyPath);

            if (!File.Exists(assemblyPath))
            {
                throw new FileNotFoundException($"Assembly file not found: {assemblyPath}");
            }

            var assembly = Assembly.LoadFrom(assemblyPath);
            var pluginType = assembly.GetType(typeName);

            if (pluginType == null)
            {
                throw new TypeLoadException($"Type not found: {typeName}");
            }

            if (!typeof(IAIPlugin).IsAssignableFrom(pluginType))
            {
                throw new InvalidOperationException($"Type does not implement IAIPlugin: {typeName}");
            }

            var plugin = Activator.CreateInstance(pluginType) as IAIPlugin;
            if (plugin == null)
            {
                throw new InvalidOperationException($"Failed to create instance of type: {typeName}");
            }

            if (!ValidatePlugin(plugin))
            {
                throw new InvalidOperationException($"Plugin validation failed: {typeName}");
            }

            _logger?.LogInformation("Successfully loaded plugin: {TypeName}", typeName);
            return Task.FromResult(plugin);
        }

        public IEnumerable<IAIPlugin> GetBuiltInPlugins()
        {
            _logger?.LogInformation("Getting built-in analysis plugins");

            var plugins = new List<IAIPlugin>
            {
                new PerformanceAnalyzerPlugin(),
                new ArchitectureValidatorPlugin(),
                new TechnicalDebtPlugin(),
                new ComplexityAnalyzerPlugin(),
                new TestAnalysisPlugin(),
                new BehaviorAnalysisPlugin(),
                new SQLiteSchemaReaderPlugin()
            };

            _logger?.LogInformation("Loaded {PluginCount} built-in plugins", plugins.Count);
            return plugins;
        }

        public bool ValidatePlugin(IAIPlugin plugin)
        {
            if (plugin == null)
            {
                _logger?.LogWarning("Plugin is null");
                return false;
            }

            try
            {
                // Check if plugin has required attributes
                var pluginType = plugin.GetType();
                var aiPluginAttribute = pluginType.GetCustomAttribute<AIPluginAttribute>();
                
                if (aiPluginAttribute == null)
                {
                    _logger?.LogWarning("Plugin missing AIPluginAttribute: {PluginType}", pluginType.Name);
                    return false;
                }

                // Check if SupportedParameters is implemented
                if (plugin.SupportedParameters == null)
                {
                    _logger?.LogWarning("Plugin SupportedParameters is null: {PluginType}", pluginType.Name);
                    return false;
                }

                // Validate that ExecuteAsync method exists and is properly implemented
                var executeMethod = pluginType.GetMethod("ExecuteAsync");
                if (executeMethod == null)
                {
                    _logger?.LogWarning("Plugin missing ExecuteAsync method: {PluginType}", pluginType.Name);
                    return false;
                }

                _logger?.LogDebug("Plugin validation successful: {PluginType}", pluginType.Name);
                return true;
            }
            catch (Exception ex)
            {
                _logger?.LogError(ex, "Plugin validation failed: {PluginType}", plugin.GetType().Name);
                return false;
            }
        }
    }
}