import fs from 'node:fs';
import { prepareWechatHtmlDeliveryAtWorkspace } from './mindspace-wechat-html-delivery.mjs';
import { resolveArtifactLocalPath } from './wechat/verify/page-artifact.mjs';
import {
  extractPageTitle,
  repairArtifactSharePreview,
  repairSharePreviewHtml,
} from './wechat/verify/share-preview-repair.mjs';

const MIN_CURSOR_PAGE_BYTES = 512;

export function isWechatCursorChannelReply(reply) {
  return reply?.wechatCursorChannel === true;
}

function padHtmlToMinBytes(html, minBytes = MIN_CURSOR_PAGE_BYTES) {
  let next = String(html ?? '');
  if (Buffer.byteLength(next, 'utf8') >= minBytes) return next;
  const deficit = minBytes - Buffer.byteLength(next, 'utf8') + 32;
  const pad = `<!-- cursor-page-pad -->${' '.repeat(Math.max(0, deficit))}`;
  if (/<\/body>/i.test(next)) {
    return next.replace(/<\/body>/i, `${pad}</body>`);
  }
  if (/<\/html>/i.test(next)) {
    return next.replace(/<\/html>/i, `${pad}</html>`);
  }
  return `${next}${pad}`;
}

function normalizeCursorArtifactForWechatDelivery(artifact, { publishDir, topic }) {
  const localPath = resolveArtifactLocalPath(artifact, publishDir);
  if (!localPath) return artifact;
  try {
    if (!fs.existsSync(localPath)) return artifact;
    const title = extractPageTitle(fs.readFileSync(localPath, 'utf8'));
    let content = fs.readFileSync(localPath, 'utf8');
    content = padHtmlToMinBytes(content);
    content = repairSharePreviewHtml(content, { title, topic });
    fs.writeFileSync(localPath, content, 'utf8');
    repairArtifactSharePreview(
      { ...artifact, localPath },
      { topic, publishDir },
    );
  } catch {
    // Best-effort repair; delivery validation will fail closed if still unusable.
  }
  return artifact;
}

export function prepareWechatCursorPageDelivery({
  reply,
  intent,
  publishDir,
  requestStartedAt,
  buildCanonicalUrl,
  topic = '',
}) {
  const baseReply = {
    ...reply,
    wechatCursorChannel: true,
  };
  if (!String(publishDir ?? '').trim()) {
    return baseReply;
  }

  const prepared = prepareWechatHtmlDeliveryAtWorkspace({
    reply: baseReply,
    intent,
    publishDir,
    requestStartedAt,
    allowRecentArtifacts: true,
    buildCanonicalUrl,
  });

  const candidateArtifacts = [
    ...(prepared.recentArtifacts ?? []),
    ...(prepared.confirmedArtifacts ?? []),
    ...(prepared.publishedArtifacts ?? []),
  ];
  for (const artifact of candidateArtifacts) {
    normalizeCursorArtifactForWechatDelivery(artifact, { publishDir, topic });
  }

  const reprepared = prepareWechatHtmlDeliveryAtWorkspace({
    reply: baseReply,
    intent,
    publishDir,
    requestStartedAt,
    allowRecentArtifacts: true,
    buildCanonicalUrl,
  });
  const confirmedArtifacts = reprepared.confirmedArtifacts ?? [];
  const urls = confirmedArtifacts
    .map((artifact) => String(artifact?.url ?? '').trim())
    .filter(Boolean);
  const uniqueUrls = [...new Set(urls)];

  return {
    ...baseReply,
    text: uniqueUrls.length > 0
      ? [String(baseReply.text ?? '').trim(), ...uniqueUrls].filter(Boolean).join('\n')
      : String(baseReply.text ?? '').trim(),
    cursorPreparedArtifacts: confirmedArtifacts,
  };
}