/*
 * File System MCP Server Example
 *
 * This example demonstrates how to create an MCP server that provides
 * file system resources. It shows how to use the built-in file system
 * resource provider to expose files and directories to MCP clients.
 *
 * Compile with:
 * valac --pkg mcp-vala --pkg json-glib-1.0 --pkg gee-0.8 --pkg posix filesystem-server.vala -o filesystem-server
 */

using Mcp;
using Posix;

/**
 * File system server that provides resources from a local directory.
 */
public class FileSystemServer : GLib.Object {
    private Mcp.Core.Server server;
    private string root_path;
    
    /**
     * Creates a new FileSystemServer.
     *
     * @param root_path The root directory to serve files from
     */
    public FileSystemServer (string root_path) {
        this.root_path = root_path;
        
        // Create server information
        var server_info = new Mcp.Types.Protocol.ServerInfo (
            "filesystem-server",
            "1.0.0"
        );
        server_info.description = "MCP server providing file system resources";
        
        // Create server capabilities with resources enabled
        var capabilities = new Mcp.Types.Protocol.ServerCapabilities ();
        capabilities.logging = true;
        capabilities.resources = new Mcp.Types.Protocol.ResourcesCapabilities ();
        capabilities.resources.subscribe = true;  // Enable resource subscriptions
        capabilities.resources.list_changed = true;  // Enable list change notifications
        
        // Create the server
        server = new Mcp.Core.Server (server_info, capabilities);
        
        // Set up file system resource provider
        setup_filesystem_provider ();
    }
    
    /**
     * Sets up the file system resource provider.
     */
    private void setup_filesystem_provider () {
        // Create a custom file system provider
        var provider = new FileSystemResourceProvider (root_path);
        
        // Register the provider with the resource manager
        server.resource_manager.register_provider ("file", provider);
        
        // File system provider registered for path: %s
    }
    
    /**
     * Runs the server.
     *
     * @return Exit code
     */
    public async int run () {
        try {
            // Starting file system MCP server...
            
            // Start the server
            bool started = yield server.start ();
            if (!started) {
                GLib.stderr.printf ("Failed to start server\n");
                return 1;
            }
            
            // File system server started successfully
            // Serving files from: %s
            // Waiting for MCP client connections...
            
            // Run the main loop
            var main_loop = new MainLoop ();
            
            // Connect shutdown signal
            server.shutdown.connect (() => {
                main_loop.quit ();
            });
            
            main_loop.run ();
            
            return 0;
        } catch (Error e) {
            GLib.stderr.printf ("Server error: %s\n", e.message);
            return 1;
        }
    }
}

/**
 * File system resource provider implementation.
 */
public class FileSystemResourceProvider : Mcp.Resources.BaseProvider {
    private string root_path;
    
    /**
     * Creates a new FileSystemResourceProvider.
     *
     * @param root_path The root directory to serve files from
     */
    public FileSystemResourceProvider (string root_path) {
        this.root_path = root_path;
    }
    
    /**
     * {@inheritDoc}
     */
    public override async Gee.ArrayList<Mcp.Resources.Types.Resource> list_resources (string? cursor) throws Error {
        var resources = new Gee.ArrayList<Mcp.Resources.Types.Resource> ();
        
        // List files in root directory
        var dir = File.new_for_path (root_path);
        if (!dir.query_exists ()) {
            throw new Mcp.Core.McpError.RESOURCE_NOT_FOUND ("Directory not found: %s".printf (root_path));
        }
        
        var enumerator = yield dir.enumerate_children_async (
            "standard::name,standard::type,standard::size,standard::content-type",
            FileQueryInfoFlags.NONE,
            Priority.DEFAULT,
            null
        );
        
        FileInfo? file_info = null;
        while ((file_info = enumerator.next_file ()) != null) {
            if (file_info.get_file_type () == FileType.REGULAR) {
                var file = File.new_for_path (Path.build_filename (root_path, file_info.get_name ()));
                var resource = new Mcp.Resources.Types.Resource (
                    file.get_uri (),
                    file_info.get_name ()
                );
                resource.description = "File: %s".printf (file_info.get_name ());
                
                // Set MIME type if available
                string? content_type = file_info.get_content_type ();
                if (content_type != null) {
                    resource.mime_type = content_type;
                } else {
                    resource.mime_type = guess_mime_type (file_info.get_name ());
                }
                
                resource.size = file_info.get_size ();
                
                resources.add (resource);
            }
        }
        
        return resources;
    }
    
    /**
     * {@inheritDoc}
     */
    public override async Gee.ArrayList<Mcp.Types.Common.ResourceContents> read_resource (string uri) throws Error {
        var file = File.new_for_uri (uri);
        if (!file.query_exists ()) {
            throw new Mcp.Core.McpError.RESOURCE_NOT_FOUND ("File not found: %s".printf (uri));
        }
        
        uint8[] contents;
        string etag;
        yield file.load_contents_async (null, out contents, out etag);
        
        // Check if it's text content
        string? mime_type = null;
        try {
            var info = yield file.query_info_async ("standard::content-type", FileQueryInfoFlags.NONE);
            mime_type = info.get_content_type ();
        } catch (Error e) {
            // Ignore error and try to guess from URI
        }
        
        var result = new Gee.ArrayList<Mcp.Types.Common.ResourceContents> ();
        
        if (mime_type != null && mime_type.has_prefix ("text/")) {
            string text = (string) contents;
            result.add (new Mcp.Types.Common.TextResourceContents (uri, text));
        } else {
            // Return as blob content
            result.add (new Mcp.Types.Common.BlobResourceContents (uri, Base64.encode (contents), mime_type ?? "application/octet-stream"));
        }
        
        return result;
    }
    
    /**
     * Guesses MIME type from filename.
     *
     * @param filename The filename
     * @return The guessed MIME type
     */
    private string guess_mime_type (string filename) {
        string extension = "";
        var last_dot = filename.last_index_of (".");
        if (last_dot != -1) {
            extension = filename.substring (last_dot);
        }
        
        switch (extension) {
            case ".txt":
                return "text/plain";
            case ".json":
                return "application/json";
            case ".xml":
                return "application/xml";
            case ".html":
                return "text/html";
            case ".css":
                return "text/css";
            case ".js":
                return "application/javascript";
            case ".vala":
                return "text/x-vala";
            case ".c":
            case ".h":
                return "text/x-c";
            case ".png":
                return "image/png";
            case ".jpg":
            case ".jpeg":
                return "image/jpeg";
            case ".gif":
                return "image/gif";
            case ".pdf":
                return "application/pdf";
            default:
                return "application/octet-stream";
        }
    }
}

/**
 * Main function.
 *
 * @param args Command line arguments
 * @return Exit code
 */
public static int main (string[] args) {
    string root_path = ".";
    
    // Parse command line arguments
    if (args.length > 1) {
        root_path = args[1];
    }
    
    // Check if the path exists and is accessible
    if (!FileUtils.test (root_path, FileTest.EXISTS | FileTest.IS_DIR)) {
        GLib.stderr.printf ("Error: Path '%s' does not exist or is not a directory\n", root_path);
        return 1;
    }
    
    // Create and run the server
    var server = new FileSystemServer (root_path);
    
    // Handle Ctrl+C to gracefully shutdown
    // For now, we'll skip signal handling to get the build working
    
    var loop = new MainLoop ();
    
    // Run the server
    server.run.begin ((obj, res) => {
        loop.quit ();
    });
    
    // Keep the main loop running
    loop.run ();
    
    return 0;
}