import crypto from 'node:crypto';
import fs from 'node:fs';
import path from 'node:path';
import { extractImageAssetKey } from './chat-image-turn-scope.mjs';

const WECHAT_MP_PUBLIC_PATH_RE = /\/public\/(wechat-mp\/[^?#\s"'<>]+)/i;
const MINDSPACE_PUBLIC_PATH_RE =
  /\/MindSpace\/[0-9a-f-]{36}\/public\/(wechat-mp\/[^?#\s"'<>]+|images\/[^?#\s"'<>]+)/i;
const HTML_IMG_SRC_RE = /\bsrc\s*=\s*["']([^"']+)["']/gi;
const HTML_COVER_JSON_RE = /name=["']mindspace-cover["']\s+content=['"]([^'"]+)['"]/i;

function formatUtcDateStamp(date = new Date()) {
  return date.toISOString().slice(0, 10);
}

export function extractPublicZoneRelativePath(rawUrl, userId = '') {
  const value = String(rawUrl ?? '').trim();
  if (!value) return null;
  const mindspaceMatch = value.match(MINDSPACE_PUBLIC_PATH_RE);
  if (mindspaceMatch?.[1]) {
    return `public/${mindspaceMatch[1]}`;
  }
  const wechatMatch = value.match(WECHAT_MP_PUBLIC_PATH_RE);
  if (wechatMatch?.[1]) {
    return `public/${wechatMatch[1]}`;
  }
  if (value.startsWith('public/wechat-mp/') || value.startsWith('public/images/')) {
    return value;
  }
  if (value.startsWith('wechat-mp/') || value.startsWith('images/')) {
    return `public/${value}`;
  }
  try {
    const parsed = new URL(
      value,
      value.startsWith('/') ? 'http://local' : undefined,
    );
    const pathname = parsed.pathname;
    const publicIndex = pathname.indexOf('/public/');
    if (publicIndex >= 0) {
      const tail = pathname.slice(publicIndex + '/public/'.length);
      if (tail.startsWith('wechat-mp/') || tail.startsWith('images/')) {
        return `public/${tail}`;
      }
    }
  } catch {
    return null;
  }
  void userId;
  return null;
}

export function materializeWechatPublicImageForEmbed({
  publishDir,
  rawUrl,
  buffer = null,
  mimeType = 'image/jpeg',
  now = new Date(),
} = {}) {
  const publicRelativePath = extractPublicZoneRelativePath(rawUrl);
  if (!publicRelativePath || !String(publishDir ?? '').trim()) {
    return null;
  }
  const sourceAbs = path.join(publishDir, publicRelativePath);
  let sourceBuffer = buffer;
  if (!sourceBuffer) {
    try {
      if (!fs.existsSync(sourceAbs) || !fs.statSync(sourceAbs).isFile()) {
        return null;
      }
      sourceBuffer = fs.readFileSync(sourceAbs);
      if (!mimeType) mimeType = 'image/jpeg';
    } catch {
      return null;
    }
  }
  if (!Buffer.isBuffer(sourceBuffer) || sourceBuffer.length === 0) {
    return null;
  }

  if (publicRelativePath.startsWith('public/images/')) {
    const embedPath = publicRelativePath.slice('public/'.length);
    return {
      publicRelativePath,
      relativeEmbedPath: embedPath,
      embedUrl: embedPath,
      assetKeys: collectEmbedAssetKeys([embedPath, publicRelativePath, rawUrl]),
      materialized: false,
    };
  }

  if (!publicRelativePath.startsWith('public/wechat-mp/')) {
    return null;
  }

  const dateDir = formatUtcDateStamp(now);
  const hash = crypto.createHash('md5').update(sourceBuffer).digest('hex').slice(0, 8);
  const basename = path.posix.basename(publicRelativePath);
  const destPublicRelativePath = `public/images/${dateDir}/${hash}-${basename}`;
  const destAbs = path.join(publishDir, destPublicRelativePath);
  try {
    fs.mkdirSync(path.dirname(destAbs), { recursive: true });
    if (!fs.existsSync(destAbs)) {
      fs.writeFileSync(destAbs, sourceBuffer);
    }
  } catch {
    return null;
  }
  const embedPath = destPublicRelativePath.slice('public/'.length);
  return {
    publicRelativePath: destPublicRelativePath,
    relativeEmbedPath: embedPath,
    embedUrl: embedPath,
    assetKeys: collectEmbedAssetKeys([embedPath, destPublicRelativePath, rawUrl]),
    materialized: true,
    mimeType,
  };
}

export function collectEmbedAssetKeys(values = []) {
  const keys = new Set();
  for (const value of values) {
    const key = extractImageAssetKey(value);
    if (key) keys.add(key);
  }
  return keys;
}

export function buildAllowedPageImageEmbedKeys({
  publishDir,
  imageUrls = [],
  userId = '',
} = {}) {
  const allowed = new Set();
  for (const rawUrl of imageUrls) {
    const materialized = materializeWechatPublicImageForEmbed({
      publishDir,
      rawUrl,
      userId,
    });
    if (materialized?.assetKeys) {
      for (const key of materialized.assetKeys) allowed.add(key);
    } else {
      for (const key of collectEmbedAssetKeys([rawUrl])) allowed.add(key);
    }
  }
  return allowed;
}

export function extractHtmlImageSourceKeys(html) {
  const keys = new Set();
  const value = String(html ?? '');
  if (!value) return keys;

  for (const match of value.matchAll(HTML_IMG_SRC_RE)) {
    for (const key of collectEmbedAssetKeys([match[1]])) keys.add(key);
  }

  const coverMatch = value.match(HTML_COVER_JSON_RE);
  if (coverMatch?.[1]) {
    try {
      const parsed = JSON.parse(
        coverMatch[1]
          .replace(/&quot;/g, '"')
          .replace(/&#39;/g, "'"),
      );
      for (const key of collectEmbedAssetKeys([parsed?.cover, parsed?.image])) {
        if (key) keys.add(key);
      }
    } catch {
      for (const key of collectEmbedAssetKeys([coverMatch[1]])) keys.add(key);
    }
  }

  return keys;
}

export function verifyHtmlImageSourcesAllowed(html, allowedKeys) {
  const allowed = allowedKeys instanceof Set ? allowedKeys : new Set(allowedKeys);
  if (allowed.size === 0) {
    return { ok: true, reason: null, offendingKeys: [] };
  }
  const found = extractHtmlImageSourceKeys(html);
  if (found.size === 0) {
    return {
      ok: false,
      reason: 'missing_required_images',
      offendingKeys: [],
    };
  }
  const offendingKeys = [...found].filter((key) => !allowed.has(key));
  if (offendingKeys.length > 0) {
    return {
      ok: false,
      reason: 'stale_image_source',
      offendingKeys,
    };
  }
  return { ok: true, reason: null, offendingKeys: [] };
}

export const chatImageMaterializeInternals = {
  formatUtcDateStamp,
  HTML_IMG_SRC_RE,
};