import { NextRequest, NextResponse } from 'next/server';
import { listDueTasks, deleteTask } from '@/lib/task-store';
import { sanitizeHeaders } from '@/lib/ssrf-guard';

const CRON_SECRET = process.env.CRON_SECRET;

export async function GET(request: NextRequest) {
  // Protect cron endpoint: require Authorization header with CRON_SECRET
  const auth = request.headers.get('authorization') || '';
  const expected = CRON_SECRET ? `Bearer ${CRON_SECRET}` : '';
  if (!CRON_SECRET || auth !== expected) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
  }

  const nowSec = Math.floor(Date.now() / 1000);
  let tasks: Awaited<ReturnType<typeof listDueTasks>>;
  try {
    tasks = await listDueTasks(nowSec);
  } catch (e: any) {
    return NextResponse.json({ error: e?.message || 'Failed to fetch tasks' }, { status: 500 });
  }

  const results: Array<{ id: string; ok: boolean; error?: string }> = [];

  for (const task of tasks) {
    let ok = false;
    let lastError: string | undefined;

    for (let attempt = 0; attempt <= task.retries; attempt++) {
      if (attempt > 0) {
        await sleep(task.retryInterval);
      }

      try {
        const bodyBytes = encodePayload(task.payload);
        const res = await fetch(task.url, {
          method: 'POST',
          headers: {
            ...sanitizeHeaders(task.headers),
            'content-type': guessContentType(task.payload),
          },
          body: bodyBytes,
          signal: AbortSignal.timeout(15000),
        });

        if (res.ok) {
          ok = true;
          break;
        }
        lastError = `HTTP ${res.status}`;
      } catch (e: any) {
        lastError = e?.message || 'Network error';
      }
    }

    if (ok) {
      try {
        await deleteTask(task.id);
      } catch {
        // best-effort cleanup
      }
    }

    results.push({ id: task.id, ok, error: ok ? undefined : lastError });
  }

  return NextResponse.json({ executed: results.length, results });
}

function encodePayload(payload: any): string {
  if (payload === null || payload === undefined) return '';
  if (typeof payload === 'string') return payload;
  return JSON.stringify(payload);
}

function guessContentType(payload: any): string {
  if (typeof payload === 'string') return 'text/plain';
  return 'application/json';
}

function sleep(ms: number): Promise<void> {
  return new Promise((resolve) => setTimeout(resolve, ms));
}