apps/backend/src/mcp/tools/FileSystemTools.ts

import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import { CallToolRequestSchema, ListToolsRequestSchema } from '@modelcontextprotocol/sdk/types.js';
import * as fs from 'fs/promises';
import * as path from 'path';
import { DROPZONE_PATH, VIDENSARKIV_PATH as CONFIG_VIDENSARKIV_PATH } from '../../config.js';

// Constants - use config paths for Docker/HF compatibility
export const SAFE_DESKTOP_PATH = DROPZONE_PATH;
export const SNAPSHOTS_PATH = path.join(SAFE_DESKTOP_PATH, 'snapshots');
export const VIDENSARKIV_PATH = CONFIG_VIDENSARKIV_PATH;
export const ALLOWED_EXTENSIONS = ['.txt', '.md', '.json', '.csv', '.yaml', '.yml', '.xml', '.log'];

interface FileInfo {
    name: string;
    path: string;
    size: number;
    modified: string;
    type: string;
}

// Helpers
export async function ensureSafeZoneExists(): Promise<void> {
    try {
        await fs.access(SAFE_DESKTOP_PATH);
    } catch {
        await fs.mkdir(SAFE_DESKTOP_PATH, { recursive: true });
        console.error(`📁 Created DropZone at: ${SAFE_DESKTOP_PATH}`);
    }
}

export async function listSafeFiles(dirPath: string, recursive: boolean = false): Promise<FileInfo[]> {
    const files: FileInfo[] = [];

    try {
        const entries = await fs.readdir(dirPath, { withFileTypes: true });

        for (const entry of entries) {
            const fullPath = path.join(dirPath, entry.name);

            if (entry.isFile()) {
                const ext = path.extname(entry.name).toLowerCase();
                if (ALLOWED_EXTENSIONS.includes(ext)) {
                    const stats = await fs.stat(fullPath);
                    files.push({
                        name: entry.name,
                        path: fullPath.replace(VIDENSARKIV_PATH, '').replace(SAFE_DESKTOP_PATH, ''),
                        size: stats.size,
                        modified: stats.mtime.toISOString(),
                        type: ext
                    });
                }
            } else if (entry.isDirectory() && recursive) {
                const subFiles = await listSafeFiles(fullPath, true);
                files.push(...subFiles);
            }
        }
    } catch (error: any) {
        if (error.code !== 'ENOENT') {
            throw error;
        }
    }

    return files;
}

// Handlers
async function handleListDropzoneFiles(args: any) {
    const filter = args?.filter;

    await ensureSafeZoneExists();
    const files = await listSafeFiles(SAFE_DESKTOP_PATH);

    const filtered = filter
        ? files.filter(f => f.name.endsWith(filter))
        : files;

    return {
        content: [{
            type: 'text',
            text: JSON.stringify({
                path: SAFE_DESKTOP_PATH,
                files: filtered,
                count: filtered.length
            }, null, 2)
        }]
    };
}

async function handleReadDropzoneFile(args: any) {
    const { filename } = args;

    if (!filename) {
        throw new Error('Filename is required');
    }

    const safePath = path.join(SAFE_DESKTOP_PATH, path.basename(filename));

    if (!safePath.startsWith(SAFE_DESKTOP_PATH)) {
        throw new Error('Access denied: File outside safe zone');
    }

    const ext = path.extname(filename).toLowerCase();
    if (!ALLOWED_EXTENSIONS.includes(ext)) {
        throw new Error(`File type not allowed: ${ext}`);
    }

    try {
        const content = await fs.readFile(safePath, 'utf-8');
        return {
            content: [{
                type: 'text',
                text: content
            }]
        };
    } catch (error: any) {
        if (error.code === 'ENOENT') {
            throw new Error(`File not found: ${filename}`);
        }
        throw error;
    }
}

async function handleListVidensarkiv(args: any) {
    const subfolder = args?.subfolder || '';
    const recursive = args?.recursive ?? false;

    const targetPath = path.join(VIDENSARKIV_PATH, subfolder);

    if (!targetPath.startsWith(VIDENSARKIV_PATH)) {
        throw new Error('Access denied: Path outside vidensarkiv');
    }

    const files = await listSafeFiles(targetPath, recursive);

    return {
        content: [{
            type: 'text',
            text: JSON.stringify({
                path: targetPath,
                files: files,
                count: files.length
            }, null, 2)
        }]
    };
}

async function handleReadVidensarkivFile(args: any) {
    const { filepath } = args;

    if (!filepath) {
        throw new Error('Filepath is required');
    }

    const safePath = path.join(VIDENSARKIV_PATH, filepath);

    if (!safePath.startsWith(VIDENSARKIV_PATH)) {
        throw new Error('Access denied: Path outside vidensarkiv');
    }

    const ext = path.extname(filepath).toLowerCase();
    if (!ALLOWED_EXTENSIONS.includes(ext)) {
        throw new Error(`File type not allowed: ${ext}`);
    }

    try {
        const content = await fs.readFile(safePath, 'utf-8');
        return {
            content: [{
                type: 'text',
                text: content
            }]
        };
    } catch (error: any) {
        if (error.code === 'ENOENT') {
            throw new Error(`File not found: ${filepath}`);
        }
        throw error;
    }
}

export function registerFileSystemTools(server: Server) {
    server.setRequestHandler(ListToolsRequestSchema, async (request) => {
        // Since we are appending to an existing list in the main server, 
        // we can't easily "append" here if the main server handles the schema.
        // Instead, the main server should aggregate definitions.
        // But MCP SDK allows adding handlers? No, `setRequestHandler` overwrites.
        // Strategy: The main server handles `ListToolsRequestSchema` and returns a combined list.
        // We export the tool definitions here.
        return { tools: [] }; // Dummy return, unused by aggregator
    });
}

export const FILE_SYSTEM_TOOLS = [
    {
        name: 'list_dropzone_files',
        description: 'List files in the WidgeTDC DropZone (safe zone for file access)',
        inputSchema: {
            type: 'object',
            properties: {
                filter: {
                    type: 'string',
                    description: 'File extension filter (e.g., ".txt", ".json")'
                }
            }
        },
        handler: handleListDropzoneFiles
    },
    {
        name: 'read_dropzone_file',
        description: 'Read a file from the WidgeTDC DropZone',
        inputSchema: {
            type: 'object',
            properties: {
                filename: {
                    type: 'string',
                    description: 'Name of the file to read'
                }
            },
            required: ['filename']
        },
        handler: handleReadDropzoneFile
    },
    {
        name: 'list_vidensarkiv',
        description: 'List files in the vidensarkiv (knowledge archive)',
        inputSchema: {
            type: 'object',
            properties: {
                subfolder: {
                    type: 'string',
                    description: 'Subfolder path within vidensarkiv'
                },
                recursive: {
                    type: 'boolean',
                    description: 'List files recursively'
                }
            }
        },
        handler: handleListVidensarkiv
    },
    {
        name: 'read_vidensarkiv_file',
        description: 'Read a file from the vidensarkiv (knowledge archive)',
        inputSchema: {
            type: 'object',
            properties: {
                filepath: {
                    type: 'string',
                    description: 'Relative path within vidensarkiv'
                }
            },
            required: ['filepath']
        },
        handler: handleReadVidensarkivFile
    }
];