import fs from 'node:fs';
import fsPromises from 'node:fs/promises';
import os from 'node:os';
import path from 'node:path';
import { pathToFileURL } from 'node:url';

const DEFAULT_VIEWPORT_WIDTH = 1280;
const DEFAULT_VIEWPORT_HEIGHT = 720;
const MAX_LONG_IMAGE_HEIGHT = 20000;

export function isLongImageDownloadRequest(query) {
  const value = String(query?.download ?? query?.export ?? '').trim().toLowerCase();
  return value === 'long-image' || value === 'long_image' || value === 'png';
}

export function longImagePathForHtml(htmlPath, outputPath = null) {
  return outputPath || String(htmlPath).replace(/\.html$/i, '.long.png');
}

function clampDimension(value, fallback, max) {
  const number = Math.ceil(Number(value) || fallback);
  return Math.max(320, Math.min(number, max));
}

async function launchChromium(chromium) {
  const base = {
    headless: true,
    args: ['--disable-dev-shm-usage', '--hide-scrollbars'],
  };
  if (process.env.PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH) {
    return chromium.launch({
      ...base,
      executablePath: process.env.PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH,
    });
  }
  if (process.env.PLAYWRIGHT_CHROMIUM_CHANNEL) {
    return chromium.launch({ ...base, channel: process.env.PLAYWRIGHT_CHROMIUM_CHANNEL });
  }
  try {
    return await chromium.launch(base);
  } catch (error) {
    if (process.platform === 'darwin') {
      return chromium.launch({ ...base, channel: 'chrome' });
    }
    throw error;
  }
}

export async function renderLongImage({
  htmlPath = null,
  url = null,
  outputPath = null,
  viewportWidth = DEFAULT_VIEWPORT_WIDTH,
  viewportHeight = DEFAULT_VIEWPORT_HEIGHT,
} = {}) {
  if (!htmlPath && !url) throw new Error('缺少 htmlPath 或 url');
  const targetUrl = url || pathToFileURL(path.resolve(htmlPath)).toString();
  const destination = outputPath ? path.resolve(outputPath) : longImagePathForHtml(path.resolve(htmlPath));
  const { chromium } = await import('playwright');
  let browser = null;
  try {
    browser = await launchChromium(chromium);
    const page = await browser.newPage({
      viewport: {
        width: clampDimension(viewportWidth, DEFAULT_VIEWPORT_WIDTH, 2400),
        height: clampDimension(viewportHeight, DEFAULT_VIEWPORT_HEIGHT, MAX_LONG_IMAGE_HEIGHT),
      },
      deviceScaleFactor: 2,
    });
    await page.goto(targetUrl, { waitUntil: 'networkidle', timeout: 30000 });
    await page.evaluate(() => document.fonts?.ready).catch(() => null);
    const size = await page.evaluate(() => ({
      width: Math.max(document.documentElement.scrollWidth, document.body.scrollWidth, 320),
      height: Math.max(document.documentElement.scrollHeight, document.body.scrollHeight, 320),
    }));
    await page.setViewportSize({
      width: clampDimension(size.width, DEFAULT_VIEWPORT_WIDTH, 2400),
      height: Math.min(clampDimension(size.height, DEFAULT_VIEWPORT_HEIGHT, MAX_LONG_IMAGE_HEIGHT), 2400),
    });
    await fsPromises.mkdir(path.dirname(destination), { recursive: true });
    await page.screenshot({
      path: destination,
      fullPage: true,
      type: 'png',
      animations: 'disabled',
      caret: 'hide',
    });
    return {
      outputPath: destination,
      bytes: fs.statSync(destination).size,
    };
  } finally {
    await browser?.close().catch(() => {});
  }
}

export async function renderLongImageBuffer({ url }) {
  const tempDir = await fsPromises.mkdtemp(path.join(os.tmpdir(), 'memind-long-image-'));
  const outputPath = path.join(tempDir, 'page.long.png');
  try {
    await renderLongImage({ url, outputPath });
    return await fsPromises.readFile(outputPath);
  } finally {
    await fsPromises.rm(tempDir, { recursive: true, force: true }).catch(() => {});
  }
}