const fs = require("fs");
const crypto = require("crypto");
const path = require("path");

const fileHashCache = {};
const getFileHash = (file, dir = "css") => {
  const cacheKey = `${dir}/${file}`;
  if (fileHashCache[cacheKey]) return fileHashCache[cacheKey];
  
  const filePath = path.join(__dirname, '..', '..', dir, file);
  try {
    const content = fs.readFileSync(filePath, "utf-8");
    const hash = crypto.createHash("md5").update(content).digest("hex").slice(0, 8);
    fileHashCache[cacheKey] = hash;
    return hash;
  } catch (e) {
    console.warn(`Could not hash file: ${file} in ${dir}`);
    return null;
  }
};

const copyHashedFiles = (sourceDir, outputDir) => {
  if (!fs.existsSync(sourceDir)) return;
  
  if (!fs.existsSync(outputDir)) {
    fs.mkdirSync(outputDir, { recursive: true });
  }
  
  const dirName = path.basename(sourceDir);
  const files = fs.readdirSync(sourceDir);
  for (const file of files) {
    const hash = getFileHash(file, dirName);
    const ext = path.extname(file);
    const base = path.basename(file, ext);
    const hashedName = `${base}${hash == null ? '' : `.${hash}`}${ext}`;
    
    fs.copyFileSync(
      path.join(sourceDir, file),
      path.join(outputDir, hashedName)
    );
  }
};

const cacheBustingPlugin = (eleventyConfig, { rootDir }) => {
  eleventyConfig.addFilter("fileHash", (file, dir = "css") => {
    const hash = getFileHash(file, dir);
    const ext = path.extname(file);
    const base = path.basename(file, ext);
    return `/${dir}/${base}.${hash}${ext}`;
  });

  eleventyConfig.on("eleventy.before", async () => {
    // Copy CSS files with hashes
    const cssDir = path.join(rootDir, "css");
    const outputCssDir = path.join(rootDir, "_site", "css");
    copyHashedFiles(cssDir, outputCssDir);

    // Copy assets files with hashes
    const assetsDir = path.join(rootDir, "assets");
    const outputAssetsDir = path.join(rootDir, "_site", "assets");
    copyHashedFiles(assetsDir, outputAssetsDir);
  });
};

module.exports = {
  cacheBustingPlugin,
  getFileHash,
};