using System;
using System.Net.Http;
using System.Threading.Tasks;
using CodexMcpServer.Tools;
using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using OpenHarbor.MCP.AspNetCore.Extensions;
using OpenHarbor.MCP.Core;

namespace CodexMcpServer;

/// <summary>
/// CODEX MCP Server entry point.
/// Exposes 6 CODEX tools via Model Context Protocol.
/// Supports both HTTP (default) and stdio transports.
/// </summary>
internal class Program
{
    private static async Task Main(string[] args)
    {
        // Check if stdio mode is requested
        bool useStdio = args.Length > 0 && args[0] == "--stdio";

        if (useStdio)
        {
            await RunStdioModeAsync();
        }
        else
        {
            await RunHttpModeAsync(args);
        }
    }

    /// <summary>
    /// Runs the MCP server in HTTP mode (default).
    /// Listens on http://localhost:5050 for MCP requests.
    /// </summary>
    private static async Task RunHttpModeAsync(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);

        // Configure services
        builder.Services.AddSingleton<HttpClient>(sp => new HttpClient
        {
            BaseAddress = new Uri("http://localhost:5099"),
            Timeout = TimeSpan.FromSeconds(30)
        });

        // Create and register MCP server
        var httpClient = new HttpClient
        {
            BaseAddress = new Uri("http://localhost:5099"),
            Timeout = TimeSpan.FromSeconds(30)
        };

        var registry = new ToolRegistry();
        registry.AddTool(new SearchCodexTool(httpClient));
        registry.AddTool(new GetDocumentTool(httpClient));
        registry.AddTool(new ListDocumentsTool(httpClient));
        registry.AddTool(new SearchByTagTool(httpClient));
        registry.AddTool(new GetDocumentSectionsTool(httpClient));
        registry.AddTool(new ListTagsTool(httpClient));

        var server = new McpServer(registry);
        builder.Services.AddMcpServer(server);

        // Configure Kestrel to listen on port 5050
        builder.WebHost.ConfigureKestrel(options =>
        {
            options.ListenLocalhost(5050);
        });

        var app = builder.Build();

        // Map MCP endpoints
        app.MapMcpEndpoints(server);

        Console.WriteLine("=== CODEX MCP Server (HTTP Mode) ===");
        Console.WriteLine("Listening on: http://localhost:5050");
        Console.WriteLine("Endpoints:");
        Console.WriteLine("  POST /mcp/invoke   - MCP JSON-RPC endpoint");
        Console.WriteLine("  GET  /health       - Health check");
        Console.WriteLine();
        Console.WriteLine("Connected to CODEX API: http://localhost:5099");
        Console.WriteLine();
        Console.WriteLine("Available Tools:");
        Console.WriteLine("  - search_codex");
        Console.WriteLine("  - get_document");
        Console.WriteLine("  - list_documents");
        Console.WriteLine("  - search_by_tag");
        Console.WriteLine("  - get_document_sections");
        Console.WriteLine("  - list_tags");
        Console.WriteLine();
        Console.WriteLine("Press Ctrl+C to shutdown");
        Console.WriteLine();

        await app.RunAsync();
    }

    /// <summary>
    /// Runs the MCP server in stdio mode (legacy).
    /// Communicates via stdin/stdout for Claude Desktop integration.
    /// </summary>
    private static async Task RunStdioModeAsync()
    {
        try
        {
            // Initialize HTTP client for CODEX API calls
            var httpClient = new HttpClient
            {
                BaseAddress = new Uri("http://localhost:5099"),
                Timeout = TimeSpan.FromSeconds(30)
            };

            // Create tool registry and register all 6 CODEX tools
            var registry = new ToolRegistry();
            registry.AddTool(new SearchCodexTool(httpClient));
            registry.AddTool(new GetDocumentTool(httpClient));
            registry.AddTool(new ListDocumentsTool(httpClient));
            registry.AddTool(new SearchByTagTool(httpClient));
            registry.AddTool(new GetDocumentSectionsTool(httpClient));
            registry.AddTool(new ListTagsTool(httpClient));

            // Create MCP server
            var server = new McpServer(registry);

            // Create stdio transport (JSON-RPC 2.0 over stdin/stdout)
            using var transport = new StdioTransport(
                Console.OpenStandardInput(),
                Console.OpenStandardOutput()
            );

            // Main request/response loop
            while (true)
            {
                var request = await transport.ReadRequestAsync();
                if (request == null)
                {
                    // End of stream - exit gracefully
                    break;
                }

                var response = await server.HandleRequestAsync(request);
                await transport.WriteResponseAsync(response);
            }
        }
        catch (Exception ex)
        {
            // Log errors to stderr (stdout is reserved for MCP protocol)
            await Console.Error.WriteLineAsync($"Fatal error: {ex.Message}");
            await Console.Error.WriteLineAsync(ex.StackTrace);
            Environment.Exit(1);
        }
    }
}