/**
 * Tool Description Banner — embeds live task status into tool descriptions.
 *
 * When the orchestrating LLM re-fetches the tool list (via
 * notifications/tools/list_changed), the description for respond-task,
 * message-task, and cancel-task includes a compact status footer showing
 * running/completed/question-pending tasks.
 *
 * Hard cap: 500 chars max for the banner to stay within tool description limits.
 */

import type { TaskState } from '../task/task-state.js';
import { TaskStatus, isTerminalStatus } from '../task/task-state.js';

const BANNER_MAX_CHARS = 500;
const RECENTLY_TERMINAL_WINDOW_MS = 5 * 60 * 1000; // 5 minutes

function truncateBanner(text: string): string {
  if (text.length <= BANNER_MAX_CHARS) return text;
  return text.slice(0, BANNER_MAX_CHARS - 3) + '...';
}

/**
 * Build a compact status banner for message-task and cancel-task descriptions.
 * Shows: running count, recently completed tasks, tasks needing answers.
 * Returns '' when nothing to report.
 */
export function buildStatusBanner(allTasks: TaskState[]): string {
  const now = Date.now();
  const running: string[] = [];
  const needsAnswer: string[] = [];
  const recentlyDone: { id: string; status: string; agoMs: number }[] = [];

  for (const task of allTasks) {
    if (task.status === TaskStatus.WAITING_ANSWER) {
      needsAnswer.push(task.id);
    } else if (task.status === TaskStatus.RUNNING || task.status === TaskStatus.PENDING) {
      running.push(task.id);
    } else if (isTerminalStatus(task.status)) {
      const updatedMs = new Date(task.updatedAt).getTime();
      const agoMs = now - updatedMs;
      if (agoMs <= RECENTLY_TERMINAL_WINDOW_MS) {
        recentlyDone.push({ id: task.id, status: task.status, agoMs });
      }
    }
  }

  if (running.length === 0 && needsAnswer.length === 0 && recentlyDone.length === 0) {
    return '';
  }

  const parts: string[] = ['---'];

  // Summary line
  const summaryParts: string[] = [];
  if (running.length > 0) summaryParts.push(`${running.length} running`);
  if (needsAnswer.length > 0) summaryParts.push(`${needsAnswer.length} needs answer`);
  if (recentlyDone.length > 0) summaryParts.push(`${recentlyDone.length} recently finished`);
  parts.push(`AGENT STATUS: ${summaryParts.join(' | ')}`);

  // Tasks needing answers
  for (const id of needsAnswer) {
    parts.push(`- ${id} [waiting_answer] — use respond-task`);
  }

  // Recently terminal tasks (most recent first, limit 3)
  const sorted = recentlyDone.sort((a, b) => a.agoMs - b.agoMs).slice(0, 3);
  for (const t of sorted) {
    const ago = t.agoMs < 60_000 ? `${Math.round(t.agoMs / 1000)}s ago` : `${Math.round(t.agoMs / 60_000)}min ago`;
    parts.push(`- ${t.id} [${t.status}] (${ago})`);
  }

  parts.push('Read task:///all for full details.');

  return truncateBanner(parts.join('\n'));
}

/**
 * Build a status banner specifically for respond-task.
 * Focuses on tasks with pending questions, showing question text and answer format.
 * Returns '' when no questions are pending.
 */
export function buildRespondBanner(allTasks: TaskState[]): string {
  const tasksWithQuestions = allTasks
    .filter(t => t.status === TaskStatus.WAITING_ANSWER && t.pendingQuestions.length > 0);

  if (tasksWithQuestions.length === 0) return '';

  const parts: string[] = ['---'];
  parts.push(`ACTION REQUIRED — ${tasksWithQuestions.length} task(s) waiting for your answer:`);

  for (const task of tasksWithQuestions) {
    const pq = task.pendingQuestions[0]!;
    if (pq.type === 'user_input' && pq.questions.length > 0) {
      const firstQ = pq.questions[0]!;
      let line = `- ${task.id}: "${firstQ.text}"`;
      if (firstQ.options && firstQ.options.length > 0) {
        const choiceStr = firstQ.options.map((c, i) => `${i + 1}) ${String(c)}`).join(' ');
        line += ` Options: ${choiceStr}`;
      }
      parts.push(line);
    } else {
      parts.push(`- ${task.id}: [${pq.type}]`);
    }
  }

  parts.push('Use respond-task { "task_id": "<id>", ... }');

  return truncateBanner(parts.join('\n'));
}