import fs from "node:fs";
import path from "node:path";

const repoRoot = process.cwd();
const distRoot = path.join(repoRoot, "dist");
const htmlAttributes = ["href", "src", "poster", "action"];
const internalHosts = new Set(["familyfed.ie", "www.familyfed.ie", "familyfed.bcgen.ie"]);
const assetExtensions = new Set([
  ".avif",
  ".css",
  ".gif",
  ".ico",
  ".jpeg",
  ".jpg",
  ".js",
  ".pdf",
  ".png",
  ".svg",
  ".webp",
  ".woff",
  ".woff2",
  ".ttf",
  ".eot",
]);
const ignoredProtocols = /^[a-z][a-z0-9+.-]*:/i;
const htmlAttributePattern = new RegExp(
  `\\b(${htmlAttributes.join("|")})\\s*=\\s*(["'])(.*?)\\2`,
  "gis",
);
const srcsetPattern = /\bsrcset\s*=\s*(["'])(.*?)\1/gis;
const cssUrlPattern = /url\(\s*(?:"([^"]*)"|'([^']*)'|([^'")]*))\s*\)/gi;

if (!fs.existsSync(distRoot)) {
  console.error("dist/ does not exist. Run `npm run build` before auditing.");
  process.exit(1);
}

const files = listFiles(distRoot);
const htmlFiles = files.filter((file) => file.endsWith(".html"));
const cssFiles = files.filter((file) => file.endsWith(".css"));
const problems = [];
let checked = 0;

for (const file of htmlFiles) {
  const content = fs.readFileSync(file, "utf8");

  for (const match of content.matchAll(htmlAttributePattern)) {
    checked += checkReference({
      sourceFile: file,
      rawReference: match[3],
      sourceKind: match[1].toLowerCase(),
    });
  }

  for (const match of content.matchAll(srcsetPattern)) {
    for (const entry of parseSrcset(match[2])) {
      checked += checkReference({
        sourceFile: file,
        rawReference: entry,
        sourceKind: "srcset",
      });
    }
  }
}

for (const file of cssFiles) {
  const content = fs.readFileSync(file, "utf8");

  for (const match of content.matchAll(cssUrlPattern)) {
    checked += checkReference({
      sourceFile: file,
      rawReference: match[1] ?? match[2] ?? match[3],
      sourceKind: "css url()",
    });
  }
}

if (problems.length > 0) {
  console.error(`Static link/media audit found ${problems.length} problem(s):`);

  for (const problem of problems) {
    console.error(
      `- ${path.relative(repoRoot, problem.sourceFile)}: ${problem.sourceKind}="${problem.rawReference}" -> ${problem.reason}`,
    );
  }

  process.exit(1);
}

console.log(
  `Static link/media audit passed: checked ${checked} local reference(s) in ${htmlFiles.length} HTML file(s) and ${cssFiles.length} CSS file(s).`,
);

function listFiles(dir) {
  return fs.readdirSync(dir, { withFileTypes: true }).flatMap((entry) => {
    const fullPath = path.join(dir, entry.name);
    return entry.isDirectory() ? listFiles(fullPath) : fullPath;
  });
}

function checkReference({ sourceFile, rawReference, sourceKind }) {
  if ((sourceKind === "href" || sourceKind === "action") && isInternalHtmlPageReference(rawReference)) {
    problems.push({
      sourceFile,
      sourceKind,
      rawReference,
      reason: "internal page links should omit the .html extension",
    });
  }

  const reference = normalizeReference(rawReference);

  if (!reference) {
    return 0;
  }

  const target = resolveTargetPath(sourceFile, reference);

  if (!target) {
    return 0;
  }

  const exists = fs.existsSync(target);
  if (!exists) {
    problems.push({
      sourceFile,
      sourceKind,
      rawReference,
      reason: `missing ${describeReference(reference)} at ${path.relative(repoRoot, target)}`,
    });
    return 1;
  }

  if (isHtmlLikeReference(reference) && fs.statSync(target).isFile()) {
    return 1;
  }

  if (fs.statSync(target).isDirectory()) {
    const indexFile = path.join(target, "index.html");
    if (!fs.existsSync(indexFile)) {
      problems.push({
        sourceFile,
        sourceKind,
        rawReference,
        reason: `directory has no index.html at ${path.relative(repoRoot, target)}`,
      });
    }
  }

  return 1;
}

function isInternalHtmlPageReference(rawReference) {
  const trimmed = rawReference.trim();
  if (
    trimmed === "" ||
    trimmed.startsWith("#") ||
    trimmed.startsWith("data:") ||
    trimmed.startsWith("blob:") ||
    trimmed.startsWith("//") ||
    trimmed.startsWith("?")
  ) {
    return false;
  }

  const absoluteMatch = trimmed.match(/^https?:\/\/([^/?#]+)([^?#]*)(?:[?#].*)?$/i);
  if (absoluteMatch) {
    const [, host, pathname] = absoluteMatch;
    return internalHosts.has(host.toLowerCase()) && pathname.toLowerCase().endsWith(".html");
  }

  if (ignoredProtocols.test(trimmed)) {
    return false;
  }

  const pathname = trimmed.split("#")[0].split("?")[0];
  return pathname.toLowerCase().endsWith(".html");
}

function normalizeReference(rawReference) {
  if (!rawReference) {
    return "";
  }

  const trimmed = rawReference.trim();
  if (
    trimmed === "" ||
    trimmed.startsWith("#") ||
    trimmed.startsWith("data:") ||
    trimmed.startsWith("blob:") ||
    trimmed.startsWith("//") ||
    trimmed.startsWith("?")
  ) {
    return "";
  }

  if (ignoredProtocols.test(trimmed)) {
    return "";
  }

  return decodeURI(trimmed.split("#")[0].split("?")[0]);
}

function resolveTargetPath(sourceFile, reference) {
  if (reference.startsWith("/")) {
    return path.join(distRoot, reference);
  }

  return path.resolve(path.dirname(sourceFile), reference);
}

function isHtmlLikeReference(reference) {
  return path.extname(reference) === "" || reference.endsWith(".html");
}

function describeReference(reference) {
  const extension = path.extname(reference).toLowerCase();

  if (extension === ".pdf") {
    return "PDF";
  }

  if ([".avif", ".gif", ".jpeg", ".jpg", ".png", ".svg", ".webp"].includes(extension)) {
    return "image";
  }

  if (assetExtensions.has(extension)) {
    return "asset";
  }

  return "internal link";
}

function parseSrcset(value) {
  return value
    .split(",")
    .map((candidate) => candidate.trim().split(/\s+/)[0])
    .filter(Boolean);
}