#!/usr/bin/env node
import { fileURLToPath } from 'node:url';
import { z } from 'zod';
import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
import { decode } from './code.js';
import { AgentClient } from './agent-client.js';
import { loadRegistry, upsertEntry } from './registry.js';

const state = {
  current: null,
  servers: new Map(),
};

function result(obj) {
  return { content: [{ type: 'text', text: JSON.stringify(obj, null, 2) }] };
}

function guard(handler) {
  return async (args) => {
    try {
      return result(await handler(args ?? {}));
    } catch (e) {
      return result({ ok: false, error: String(e && e.message ? e.message : e) });
    }
  };
}

async function requireCurrent(op, args) {
  if (!state.current || !state.current.client || !state.current.client.connected) {
    return { ok: false, error: 'no server connected — call connect_server first' };
  }
  return state.current.client.request(op, args ?? {});
}

const DIAGNOSTIC_TOOLS = [
  {
    name: 'server_health',
    title: 'Server health (one-shot hub)',
    description:
      'THE one-shot diagnostic hub: answers "what is wrong" in a single call by aggregating recent errors, queue state, rotation and system info.',
    op: 'server_health',
    inputSchema: {
      errorLimit: z.number().optional(),
      errorSinceMs: z.number().optional(),
    },
  },
  {
    name: 'read_log',
    title: 'Read a log file',
    description: 'Read a tail of one of the app log files, optionally a rotated backup. grep is a case-insensitive substring filter; separate alternatives with "|" (e.g. "error|timeout|502") to keep any line matching at least one term. Not a regular expression.',
    op: 'read_log',
    inputSchema: {
      name: z.enum(['debug', 'fileuploader', 'accountRotation', 'crash']),
      tailKb: z.number().optional(),
      grep: z.string().optional(),
      backup: z.number().optional(),
    },
  },
  {
    name: 'list_logs',
    title: 'List available logs',
    description: 'List the available log files and their sizes.',
    op: 'list_logs',
    inputSchema: {},
  },
  {
    name: 'list_errors',
    title: 'List recent errors',
    description: 'List recent structured errors, filterable by time window, category and hoster.',
    op: 'list_errors',
    inputSchema: {
      sinceMs: z.number().optional(),
      category: z.string().optional(),
      hoster: z.string().optional(),
      limit: z.number().optional(),
    },
  },
  {
    name: 'get_queue_state',
    title: 'Get queue state',
    description: 'Get the upload queue state, optionally including individual jobs.',
    op: 'get_queue_state',
    inputSchema: {
      includeJobs: z.boolean().optional(),
      maxJobs: z.number().optional(),
    },
  },
  {
    name: 'get_history',
    title: 'Get upload history',
    description: 'Get recent upload history, optionally including file names and URLs.',
    op: 'get_history',
    inputSchema: {
      limit: z.number().optional(),
      includeFiles: z.boolean().optional(),
      includeUrls: z.boolean().optional(),
    },
  },
  {
    name: 'get_config_redacted',
    title: 'Get redacted config',
    description: 'Get the app configuration with secrets redacted. Choose a section to narrow the output.',
    op: 'get_config_redacted',
    inputSchema: {
      section: z.enum(['all', 'hosters', 'hosterSettings', 'globalSettings', 'rotationCursors']).optional(),
    },
  },
  {
    name: 'get_system_info',
    title: 'Get system info',
    description: 'Get system and app version info (OS, app version, uptime).',
    op: 'get_system_info',
    inputSchema: {},
  },
  {
    name: 'get_rotation_state',
    title: 'Get rotation state',
    description: 'Get the per-hoster account rotation state and round-robin cursors.',
    op: 'get_rotation_state',
    inputSchema: {},
  },
  {
    name: 'get_app_events',
    title: 'Get app events',
    description: 'Get recent in-app lifecycle events.',
    op: 'get_app_events',
    inputSchema: {
      limit: z.number().optional(),
    },
  },
];

async function doConnect({ code, host, port, label }) {
  const registry = await loadRegistry();

  let target;
  if (label && registry[label]) {
    const e = registry[label];
    target = { host: e.host, port: e.port, token: e.token, fp: e.fp, label: e.label };
  } else {
    if (!code) {
      return { ok: false, error: 'provide a known label, or a code (the host is taken from the code; pass host only to override)' };
    }
    let payload;
    try {
      payload = decode(code);
    } catch (e) {
      return { ok: false, error: String(e.message ?? e) };
    }
    const effHost = host || payload.host;
    if (!effHost) {
      return { ok: false, error: 'no host in the code and none provided — pass host (e.g. the Tailscale IP/MagicDNS name)' };
    }
    target = {
      host: effHost,
      port: typeof port === 'number' ? port : payload.port,
      token: payload.token,
      fp: payload.fp,
      label: label || payload.label || effHost,
    };
  }

  if (typeof port === 'number') target.port = port;

  const client = new AgentClient(target);
  try {
    await client.connect();
  } catch (e) {
    return { ok: false, error: String(e.message ?? e) };
  }

  let version;
  const info = await client.request('get_system_info', {});
  if (info && info.ok && info.data) {
    const d = info.data;
    version = d.version ?? d.appVersion ?? (d.app && d.app.version) ?? (d.agent && d.agent.version) ?? undefined;
  }

  const id = `${target.label}@${target.host}:${target.port}`;
  if (state.current && state.current.client && state.current.client !== client) {
    state.current.client.close();
  }
  state.servers.set(id, { id, client, target });
  state.current = { id, client, target };

  await upsertEntry({
    host: target.host,
    port: target.port,
    token: target.token,
    fp: target.fp,
    label: target.label,
    version,
    lastConnectedAt: new Date().toISOString(),
  });

  return {
    ok: true,
    server: { label: target.label, host: target.host, port: target.port, version },
  };
}

export function buildServer() {
  const server = new McpServer({ name: 'mhu-diagnostics-gateway', version: '1.0.0' });

  server.registerTool(
    'list_servers',
    {
      title: 'List known servers',
      description: 'List the registry of known diagnostic servers and which one is currently connected.',
      inputSchema: {},
    },
    guard(async () => {
      const registry = await loadRegistry();
      return {
        ok: true,
        servers: Object.values(registry),
        current: state.current ? state.current.id : null,
      };
    }),
  );

  server.registerTool(
    'connect_server',
    {
      title: 'Connect to a diagnostic server',
      description:
        'Connect to a remote diagnostic agent. Use label for a known server, or a code for a new one — the host (e.g. a Tailscale IP/MagicDNS name) is taken from the code. Pass host only to override what the code carries.',
      inputSchema: {
        code: z.string().optional(),
        host: z.string().optional(),
        port: z.number().optional(),
        label: z.string().optional(),
      },
    },
    guard((args) => doConnect(args)),
  );

  server.registerTool(
    'disconnect_server',
    {
      title: 'Disconnect the current server',
      description: 'Close the connection to the currently connected diagnostic server.',
      inputSchema: {},
    },
    guard(async () => {
      if (!state.current) return { ok: true, disconnected: false };
      const id = state.current.id;
      try { state.current.client.close(); } catch {}
      state.servers.delete(id);
      state.current = null;
      return { ok: true, disconnected: true, id };
    }),
  );

  server.registerTool(
    'current_server',
    {
      title: 'Show the current server',
      description: 'Show the currently connected diagnostic target, or null if none.',
      inputSchema: {},
    },
    guard(async () => {
      if (!state.current) return { ok: true, current: null };
      const t = state.current.target;
      return {
        ok: true,
        current: { id: state.current.id, label: t.label, host: t.host, port: t.port },
      };
    }),
  );

  for (const tool of DIAGNOSTIC_TOOLS) {
    server.registerTool(
      tool.name,
      { title: tool.title, description: tool.description, inputSchema: tool.inputSchema },
      guard((args) => requireCurrent(tool.op, args)),
    );
  }

  return server;
}

async function main() {
  const server = buildServer();
  const transport = new StdioServerTransport();
  await server.connect(transport);
  console.error('[mhu-diag] gateway ready (stdio MCP)');
}

if (process.argv[1] && fileURLToPath(import.meta.url) === process.argv[1]) {
  main().catch((e) => {
    console.error('[mhu-diag] fatal:', e);
    process.exit(1);
  });
}