import type { APIRoute } from 'astro';
import {
  absoluteUrl,
  getEmailBinding,
  getNewsletterDb,
  getRuntimeEnv,
  readEnv,
  sendCloudflareEmail,
  siteOrigin,
  type NewsletterSubscriber,
} from '../../../../lib/newsletter';

export const prerender = false;

type SendBody = {
  subject?: string;
  text?: string;
  html?: string;
  dryRun?: boolean;
};

function unauthorized(): Response {
  return new Response('Unauthorized', { status: 401 });
}

function authorize(request: Request, runtimeEnv: ReturnType<typeof getRuntimeEnv>): boolean {
  const expected = readEnv('NEWSLETTER_ADMIN_TOKEN', runtimeEnv);
  if (!expected) return false;
  const header = request.headers.get('authorization') || '';
  const bearer = header.toLowerCase().startsWith('bearer ')
    ? header.slice(7).trim()
    : '';
  return bearer === expected;
}

export const POST: APIRoute = async ({ request, locals, url }) => {
  const runtimeEnv = getRuntimeEnv(locals);
  if (!authorize(request, runtimeEnv)) return unauthorized();

  const mode = (readEnv('NEWSLETTER_MODE', runtimeEnv) || readEnv('CONTACT_FORM_MODE', runtimeEnv) || 'dev').toLowerCase();
  let body: SendBody;
  try {
    body = (await request.json()) as SendBody;
  } catch {
    return new Response('Invalid JSON body.', { status: 400 });
  }

  const subject = (body.subject || '').trim();
  const text = (body.text || '').trim();
  const html = (body.html || '').trim();
  if (!subject || !text) {
    return new Response('Fields subject and text are required.', { status: 400 });
  }

  if (mode !== 'live') {
    console.info('[newsletter:dev] Campaign send requested', {
      subject,
      dryRun: Boolean(body.dryRun),
      textPreview: text.slice(0, 120),
    });
    return Response.json({
      mode,
      accepted: true,
      sent: 0,
      failed: 0,
      note: 'Dev mode: campaign not sent.',
    });
  }

  const db = getNewsletterDb(runtimeEnv);
  if (!db) {
    return new Response('Newsletter database binding NEWSLETTER_DB is not configured.', {
      status: 500,
    });
  }

  const emailBinding = getEmailBinding(runtimeEnv);
  const fromEmail =
    readEnv('NEWSLETTER_FROM_EMAIL', runtimeEnv) ||
    readEnv('CONTACT_FORM_FROM_EMAIL', runtimeEnv);

  if (!emailBinding || !fromEmail) {
    return new Response('Missing EMAIL binding or from email for newsletter send.', {
      status: 500,
    });
  }

  const subscribersResult = await db
    .prepare(
      `SELECT * FROM newsletter_subscribers
       WHERE status = 'active'
       ORDER BY id ASC`,
    )
    .all<NewsletterSubscriber>();
  const subscribers = subscribersResult.results ?? [];

  const campaignInsert = await db
    .prepare(
      `INSERT INTO newsletter_campaigns (subject, body_text, body_html, status, created_by)
       VALUES (?, ?, ?, ?, ?)`,
    )
    .bind(subject, text, html || null, body.dryRun ? 'draft' : 'sending', 'admin-api')
    .run();

  const campaignId = Number(campaignInsert.meta.last_row_id);
  const origin = siteOrigin(url, runtimeEnv);

  if (body.dryRun) {
    return Response.json({
      dryRun: true,
      campaignId,
      recipients: subscribers.length,
      sample: subscribers.slice(0, 5).map((s) => s.email),
    });
  }

  let sent = 0;
  let failed = 0;

  for (const subscriber of subscribers) {
    const unsubUrl = absoluteUrl(
      origin,
      `/api/newsletter/unsubscribe?token=${subscriber.unsubscribe_token}`,
    );
    const personalizedText = `${text}\n\n---\nDisiscrizione: ${unsubUrl}\n`;
    const personalizedHtml = html
      ? `${html}<hr /><p style="font-size:12px;color:#666">Disiscrizione: <a href="${unsubUrl}">${unsubUrl}</a></p>`
      : undefined;

    try {
      await sendCloudflareEmail(emailBinding, {
        fromEmail,
        toEmail: subscriber.email,
        subject,
        text: personalizedText,
        html: personalizedHtml,
      });
      await db
        .prepare(
          `INSERT INTO newsletter_campaign_sends
            (campaign_id, subscriber_id, email, status, sent_at)
           VALUES (?, ?, ?, 'sent', datetime('now'))`,
        )
        .bind(campaignId, subscriber.id, subscriber.email)
        .run();
      sent += 1;
    } catch (error) {
      failed += 1;
      const message = error instanceof Error ? error.message : String(error);
      await db
        .prepare(
          `INSERT INTO newsletter_campaign_sends
            (campaign_id, subscriber_id, email, status, error, sent_at)
           VALUES (?, ?, ?, 'failed', ?, datetime('now'))`,
        )
        .bind(campaignId, subscriber.id, subscriber.email, message.slice(0, 500))
        .run();
    }
  }

  await db
    .prepare(
      `UPDATE newsletter_campaigns
       SET status = ?, sent_at = datetime('now')
       WHERE id = ?`,
    )
    .bind(failed > 0 && sent === 0 ? 'failed' : 'sent', campaignId)
    .run();

  return Response.json({
    campaignId,
    recipients: subscribers.length,
    sent,
    failed,
  });
};