type ToolResult = {
  content: Array<{ type: string; text?: string; source?: { type: string; media_type: string; data: string } }>;
  isError?: boolean;
};

type Params = {
  action: string;
  tab_id?: string;
  url?: string;
  expression?: string;
};

type TabInfo = {
  id: string;
  title: string;
  url: string;
};

const RELAY_AUTH_HEADER = 'x-officer-relay-token';

function getConfig(): { port: number; token: string } | null {
  const port = process.env.OFFICER_BROWSER_RELAY_PORT;
  const token = process.env.OFFICER_BROWSER_RELAY_TOKEN;
  if (!port || !token) return null;
  return { port: Number(port), token };
}

async function listTabs(port: number, token: string): Promise<TabInfo[]> {
  const res = await fetch(`http://127.0.0.1:${port}/json/list`, {
    headers: { [RELAY_AUTH_HEADER]: token },
  });
  if (!res.ok) throw new Error(`Failed to list tabs (${res.status})`);
  const tabs = (await res.json()) as Array<{ id: string; title: string; url: string }>;
  return tabs.map((t) => ({ id: t.id, title: t.title, url: t.url }));
}

async function resolveTab(port: number, token: string, tabId?: string): Promise<TabInfo> {
  const tabs = await listTabs(port, token);
  if (tabs.length === 0) throw new Error('No browser tabs connected. The user needs to attach tabs via the Browser Relay extension.');
  if (tabId) {
    const tab = tabs.find((t) => t.id === tabId);
    if (!tab) throw new Error(`Tab ${tabId} not found. Available tabs: ${tabs.map((t) => t.id).join(', ')}`);
    return tab;
  }
  return tabs[0]!;
}

async function sendCdpCommand(port: number, token: string, tabId: string, method: string, params?: unknown): Promise<unknown> {
  const url = `ws://127.0.0.1:${port}/cdp?token=${encodeURIComponent(token)}`;

  return await new Promise<unknown>((resolve, reject) => {
    const ws = new WebSocket(url);
    let settled = false;
    const timeout = setTimeout(() => {
      if (settled) return;
      settled = true;
      ws.close();
      reject(new Error(`CDP command timeout: ${method}`));
    }, 30_000);

    ws.addEventListener('open', () => {
      const cmd: Record<string, unknown> = { id: 1, method };
      if (params) cmd.params = params;
      cmd.sessionId = tabId;
      ws.send(JSON.stringify(cmd));
    });

    ws.addEventListener('message', (event) => {
      if (settled) return;
      try {
        const msg = JSON.parse(String(event.data)) as { id?: number; result?: unknown; error?: { message: string } };
        if (msg.id === 1) {
          settled = true;
          clearTimeout(timeout);
          ws.close();
          if (msg.error) reject(new Error(msg.error.message));
          else resolve(msg.result);
        }
      } catch {
        // ignore parse errors, wait for correct message
      }
    });

    ws.addEventListener('error', () => {
      if (settled) return;
      settled = true;
      clearTimeout(timeout);
      reject(new Error('CDP WebSocket connection failed — is the Browser Relay running?'));
    });

    ws.addEventListener('close', () => {
      if (settled) return;
      settled = true;
      clearTimeout(timeout);
      reject(new Error('CDP WebSocket closed before response'));
    });
  });
}

// --- Actions ---

async function actionListTabs(port: number, token: string): Promise<ToolResult> {
  const tabs = await listTabs(port, token);
  if (tabs.length === 0) {
    return { content: [{ type: 'text', text: 'No browser tabs connected. The user needs to attach tabs via the Browser Relay extension.' }] };
  }
  const lines = tabs.map((t, i) => `${i + 1}. ${t.title}\n   URL: ${t.url}\n   ID: ${t.id}`);
  return { content: [{ type: 'text', text: `Connected tabs (${tabs.length}):\n\n${lines.join('\n\n')}` }] };
}

async function actionScreenshot(port: number, token: string, tabId?: string): Promise<ToolResult> {
  const tab = await resolveTab(port, token, tabId);
  const result = (await sendCdpCommand(port, token, tab.id, 'Page.captureScreenshot', { format: 'png' })) as { data: string };
  return {
    content: [
      { type: 'text', text: `Screenshot of "${tab.title}" (${tab.url})` },
      { type: 'image', source: { type: 'base64', media_type: 'image/png', data: result.data } },
    ],
  };
}

async function actionNavigate(port: number, token: string, url: string, tabId?: string): Promise<ToolResult> {
  const tab = await resolveTab(port, token, tabId);
  await sendCdpCommand(port, token, tab.id, 'Page.navigate', { url });
  return { content: [{ type: 'text', text: `Navigated tab "${tab.title}" to ${url}` }] };
}

async function actionEvaluate(port: number, token: string, expression: string, tabId?: string): Promise<ToolResult> {
  const tab = await resolveTab(port, token, tabId);
  const result = (await sendCdpCommand(port, token, tab.id, 'Runtime.evaluate', {
    expression,
    returnByValue: true,
    awaitPromise: true,
  })) as { result?: { value?: unknown; description?: string }; exceptionDetails?: { text?: string } };

  if (result.exceptionDetails) {
    return { content: [{ type: 'text', text: `Error evaluating JS: ${result.exceptionDetails.text ?? 'Evaluation failed'}` }], isError: true };
  }

  const value = result.result?.value;
  const text = typeof value === 'string' ? value : JSON.stringify(value, null, 2);
  return { content: [{ type: 'text', text: `Result from "${tab.title}":\n${text}` }] };
}

async function actionPageInfo(port: number, token: string, tabId?: string): Promise<ToolResult> {
  const tab = await resolveTab(port, token, tabId);
  const result = (await sendCdpCommand(port, token, tab.id, 'Runtime.evaluate', {
    expression: 'JSON.stringify({ title: document.title, url: location.href })',
    returnByValue: true,
  })) as { result?: { value?: string } };

  let info: { title: string; url: string };
  try {
    info = JSON.parse(result.result?.value ?? '{}');
  } catch {
    info = { title: tab.title, url: tab.url };
  }

  return { content: [{ type: 'text', text: `Title: ${info.title}\nURL: ${info.url}\nTab ID: ${tab.id}` }] };
}

async function actionActivate(port: number, token: string, tabId?: string): Promise<ToolResult> {
  const tab = await resolveTab(port, token, tabId);
  const res = await fetch(`http://127.0.0.1:${port}/json/activate/${encodeURIComponent(tab.id)}`, {
    headers: { [RELAY_AUTH_HEADER]: token },
  });
  if (!res.ok) throw new Error(`Failed to activate tab (${res.status})`);
  return { content: [{ type: 'text', text: `Activated tab "${tab.title}"` }] };
}

async function actionClose(port: number, token: string, tabId?: string): Promise<ToolResult> {
  const tab = await resolveTab(port, token, tabId);
  const res = await fetch(`http://127.0.0.1:${port}/json/close/${encodeURIComponent(tab.id)}`, {
    headers: { [RELAY_AUTH_HEADER]: token },
  });
  if (!res.ok) throw new Error(`Failed to close tab (${res.status})`);
  return { content: [{ type: 'text', text: `Closed tab "${tab.title}"` }] };
}

// --- Main ---

export async function execute(_toolCallId: string, params: Params): Promise<ToolResult> {
  const config = getConfig();
  if (!config) {
    return {
      content: [{ type: 'text', text: 'Browser Relay is not available. The user needs to connect the Browser Relay extension in Settings → Integrations.' }],
      isError: true,
    };
  }

  const { port, token } = config;
  const { action, tab_id, url, expression } = params;

  try {
    switch (action) {
      case 'list_tabs':
        return await actionListTabs(port, token);
      case 'screenshot':
        return await actionScreenshot(port, token, tab_id);
      case 'navigate':
        if (!url) return { content: [{ type: 'text', text: 'url is required for navigate action' }], isError: true };
        return await actionNavigate(port, token, url, tab_id);
      case 'evaluate':
        if (!expression) return { content: [{ type: 'text', text: 'expression is required for evaluate action' }], isError: true };
        return await actionEvaluate(port, token, expression, tab_id);
      case 'page_info':
        return await actionPageInfo(port, token, tab_id);
      case 'activate':
        return await actionActivate(port, token, tab_id);
      case 'close':
        return await actionClose(port, token, tab_id);
      default:
        return {
          content: [{ type: 'text', text: `Unknown action: ${action}. Use list_tabs, screenshot, navigate, evaluate, page_info, activate, or close.` }],
          isError: true,
        };
    }
  } catch (err) {
    const message = err instanceof Error ? err.message : String(err);
    return { content: [{ type: 'text', text: `Browser error: ${message}` }], isError: true };
  }
}