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

const { loadMeals, repoRoot } = require("./lib/meals");

const indexTemplatePath = path.join(repoRoot, "templates", "index.html");
const indexOutputPath = path.join(repoRoot, "index.html");

function detectEol(text) {
  return text.includes("\r\n") ? "\r\n" : "\n";
}

function escapeHtml(value) {
  return value
    .replace(/&/g, "&")
    .replace(/</g, "&lt;")
    .replace(/"/g, "&quot;");
}

function renderGalleryItem(meal, eol) {
  const attrs = [`class="thumbnail"`, `href="images/fulls/${meal.id}.jpg"`];

  if (meal.position) {
    attrs.push(`data-position="${escapeHtml(meal.position)}"`);
  }

  return [
    "\t\t\t\t<article>",
    `\t\t\t\t\t<a ${attrs.join(" ")}><img src="images/thumbs/${meal.id}.jpg" alt="" /></a>`,
    `\t\t\t\t\t<h2>${escapeHtml(meal.title)}</h2>`,
    `\t\t\t\t\t<p>${escapeHtml(meal.description)}</p>`,
    "\t\t\t\t</article>",
  ].join(eol);
}

function renderGallery(meals, eol) {
  return meals.map((meal) => renderGalleryItem(meal, eol)).join(eol);
}

function replaceBlock(template, token, replacement) {
  const pattern = new RegExp(`^[\\t ]*\\{\\{${token}\\}\\}$`, "m");

  if (!pattern.test(template)) {
    throw new Error(`Template is missing required block token "{{${token}}}"`);
  }

  return template.replace(pattern, () => replacement);
}

function buildIndex() {
  const template = fs.readFileSync(indexTemplatePath, "utf8");
  const eol = detectEol(template);
  const meals = loadMeals();

  return replaceBlock(template, "gallery_items", renderGallery(meals, eol));
}

function writeFile(filePath, contents) {
  fs.writeFileSync(filePath, contents);
}

function main() {
  writeFile(indexOutputPath, buildIndex());
}

function buildPages() {
  main();
}

if (require.main === module) {
  buildPages();
}

module.exports = {
  buildPages,
  buildIndex,
};