import {
  access,
  copyFile,
  mkdir,
  readdir,
  readFile,
  writeFile,
} from "node:fs/promises";
import path from "node:path";
import { fileURLToPath } from "node:url";

const blogs = [
  {
    slug: "research",
    label: "Research",
    summary: "Notes from papers, algorithms, computational social choice, and mini-surveys of themes I am learning about.",
  },
  {
    slug: "vibes",
    label: "Vibes",
    summary: "Loose experiments, AI conversations, and work-in-progress thoughts that do not need a formal frame.",
  },
  {
    slug: "puzzles",
    label: "Puzzles",
    summary: "Problems, teaching prompts, contest-style curiosities, and small mathematical rabbit holes.",
  },
  {
    slug: "reflections",
    label: "Reflections",
    summary: "Personal notes on teaching, academia, writing, attention, and the rhythms of intellectual work.",
  },
  {
    slug: "poetry",
    label: "Poetry",
    summary: "Poems, tiny forms, and playful writing around mathematics, code, and ordinary life.",
  },
  {
    slug: "reviews",
    label: "Reviews",
    summary: "Notes on tools, workflows, books, hardware, and objects that shape everyday work.",
  },
  {
    slug: "art",
    label: "Art",
    summary: "Algorithmic sketches, generative art, visual experiments, and mathematical images.",
  },
];

const socialLinks = [
  {
    href: "https://x.com/home",
    label: "X",
    color: "#525252",
    svg: `<path d="M5 5l14 14"></path><path d="M19 5L5 19"></path>`,
  },
  {
    href: "https://bsky.app/profile/neeldhara.bsky.social",
    label: "Bluesky",
    color: "#4f83b8",
    svg: `<path d="M12 13c-2.9-5.2-6-7.2-8.1-6.4-1.6.7-1 4.4 2.3 7.1"></path><path d="M12 13c2.9-5.2 6-7.2 8.1-6.4 1.6.7 1 4.4-2.3 7.1"></path><path d="M12 13c-2.3 1.6-3.6 3.1-3.3 4.6.3 1.4 2.1 1.8 3.3.2"></path><path d="M12 13c2.3 1.6 3.6 3.1 3.3 4.6-.3 1.4-2.1 1.8-3.3.2"></path>`,
  },
  {
    href: "https://www.linkedin.com/in/neeldhara-misra-a54b6920/",
    label: "LinkedIn",
    color: "#496f9e",
    svg: `<rect x="4.5" y="4.5" width="15" height="15" rx="2.5"></rect><path d="M8 10.5v5.5"></path><path d="M11.5 16v-5.5"></path><path d="M11.5 13.1c0-1.7 1-2.7 2.3-2.7 1.5 0 2.2 1 2.2 2.7V16"></path><path d="M8 8h.01"></path>`,
  },
  {
    href: "https://mathstodon.xyz/@neeldhara",
    label: "Mastodon",
    color: "#7464a8",
    svg: `<path d="M7 16.5c1.4.8 3.1 1.1 5.2 1 3.7-.1 5.8-1.7 6.1-4.8l.2-3.6c.2-3.1-1.4-4.7-4.5-4.7h-4c-3.1 0-4.7 1.6-4.5 4.7l.3 5.1c.2 3.4 2.2 5.2 5.9 5.3"></path><path d="M8.5 13V9.6c0-1.1.7-1.8 1.7-1.8.8 0 1.4.4 1.8 1.1.4-.7 1-1.1 1.8-1.1 1 0 1.7.7 1.7 1.8V13"></path><path d="M12 9.4V13"></path>`,
  },
  {
    href: "https://www.youtube.com/@neeldhara",
    label: "YouTube",
    color: "#b55252",
    svg: `<path d="M4.8 8.5c.2-1.2 1.1-2.1 2.3-2.2 1.6-.2 3.2-.3 4.9-.3s3.3.1 4.9.3c1.2.1 2.1 1 2.3 2.2.2 1.1.3 2.2.3 3.5s-.1 2.4-.3 3.5c-.2 1.2-1.1 2.1-2.3 2.2-1.6.2-3.2.3-4.9.3s-3.3-.1-4.9-.3c-1.2-.1-2.1-1-2.3-2.2-.2-1.1-.3-2.2-.3-3.5s.1-2.4.3-3.5Z"></path><path d="M10.5 9.5l4 2.5-4 2.5v-5Z"></path>`,
  },
  {
    href: "https://www.instagram.com/neeldharamisra",
    label: "Instagram",
    color: "#9a6b8c",
    svg: `<rect x="5" y="5" width="14" height="14" rx="4"></rect><circle cx="12" cy="12" r="3.2"></circle><path d="M16.3 7.8h.01"></path>`,
  },
];

const publicHostSuffix = process.env.PUBLIC_HOST_SUFFIX ?? "neeldhara.blog";
const allblogsRoot = new URL("../../allblogs/", import.meta.url);
const contentIndex = new URL("../content/blog-index.json", import.meta.url);
const outDir = new URL("../dist/", import.meta.url);
const fontDir = new URL("../webfonts/", import.meta.url);
const shouldWriteContentIndex = process.argv.includes("--write-content-index");
const contentSource = process.env.BLOG_HOME_CONTENT_SOURCE ?? "auto";
const fontFiles = [
  "heliotrope_3_regular.woff2",
  "heliotrope_3_italic.woff2",
  "heliotrope_3_bold.woff2",
  "heliotrope_3_bold_italic.woff2",
];

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

function parseScalar(value) {
  const trimmed = value.trim();

  if (trimmed === "true") return true;
  if (trimmed === "false") return false;

  if (
    (trimmed.startsWith('"') && trimmed.endsWith('"')) ||
    (trimmed.startsWith("'") && trimmed.endsWith("'"))
  ) {
    return trimmed.slice(1, -1);
  }

  if (trimmed.startsWith("[") && trimmed.endsWith("]")) {
    return trimmed
      .slice(1, -1)
      .split(",")
      .map((item) => parseScalar(item))
      .filter(Boolean);
  }

  return trimmed;
}

function parseFrontmatter(markdown) {
  if (!markdown.startsWith("---")) return {};

  const end = markdown.indexOf("\n---", 3);
  if (end === -1) return {};

  const yaml = markdown.slice(3, end).trim();
  const data = {};

  for (const line of yaml.split(/\r?\n/)) {
    const match = line.match(/^([A-Za-z0-9_-]+):\s*(.*)$/);
    if (!match) continue;

    data[match[1]] = parseScalar(match[2]);
  }

  return data;
}

async function pathExists(filePath) {
  try {
    await access(filePath);
    return true;
  } catch {
    return false;
  }
}

async function findMarkdownFiles(dir) {
  const files = [];
  const entries = await readdir(dir, { withFileTypes: true });

  for (const entry of entries) {
    const fullPath = path.join(dir, entry.name);

    if (entry.isDirectory()) {
      files.push(...(await findMarkdownFiles(fullPath)));
      continue;
    }

    if (entry.isFile() && /\.(md|mdx)$/i.test(entry.name)) {
      files.push(fullPath);
    }
  }

  return files;
}

function slugFromFile(filePath, contentDir) {
  const relative = path.relative(contentDir, filePath).replaceAll(path.sep, "/");
  return relative.replace(/\/index\.mdx?$/i, "").replace(/\.mdx?$/i, "");
}

async function getLocalPosts(blog) {
  const contentDir = fileURLToPath(
    new URL(`sites/${blog.slug}/src/content/${blog.slug}/`, allblogsRoot),
  );

  if (!(await pathExists(contentDir))) {
    return null;
  }

  const files = await findMarkdownFiles(contentDir);
  const posts = [];

  for (const file of files) {
    const data = parseFrontmatter(await readFile(file, "utf8"));
    const pubDate = new Date(`${data.pubDate}T00:00:00Z`);

    if (!data.title || Number.isNaN(pubDate.valueOf())) {
      continue;
    }

    const slug = slugFromFile(file, contentDir);

    posts.push({
      title: data.title,
      link: `https://${blog.slug}.${publicHostSuffix}/${slug}/`,
      date: pubDate.toISOString().slice(0, 10),
      featured: data["main-feature"] === true || data.mainFeature === true,
    });
  }

  return posts.sort((a, b) => b.date.localeCompare(a.date));
}

async function getIndexedPosts() {
  const index = JSON.parse(await readFile(contentIndex, "utf8"));

  return blogs.map((blog) => [blog, index[blog.slug] ?? []]);
}

async function getEntries() {
  if (contentSource === "index") {
    return getIndexedPosts();
  }

  const localEntries = await Promise.all(
    blogs.map(async (blog) => [blog, await getLocalPosts(blog)]),
  );

  if (localEntries.every(([, posts]) => posts !== null)) {
    return localEntries;
  }

  return getIndexedPosts();
}

function renderPost(post) {
  const date = post.date ? new Date(`${post.date}T00:00:00Z`) : null;
  const dateLabel = date
    ? date.toLocaleDateString("en", { month: "short", day: "numeric", timeZone: "UTC" })
    : "";

  return `<li class="post"><span class="date">${escapeHtml(dateLabel)}</span><a href="${escapeHtml(post.link)}">${escapeHtml(post.title)}</a></li>`;
}

function renderFeaturedPost(post) {
  if (!post) return "";

  return `<p class="featured-post"><span>Featured</span><a href="${escapeHtml(post.link)}">${escapeHtml(post.title)}</a></p>`;
}

function renderRssIcon(blog) {
  const href = `https://${blog.slug}.${publicHostSuffix}/rss.xml`;

  return `<a class="icon-link" href="${escapeHtml(href)}" aria-label="${escapeHtml(blog.label)} RSS">
    <svg viewBox="0 0 24 24" aria-hidden="true">
      <circle cx="6.25" cy="17.75" r="1.8"></circle>
      <path d="M4.5 5.5c7.7 0 14 6.3 14 14"></path>
      <path d="M4.5 10.2a9.3 9.3 0 0 1 9.3 9.3"></path>
    </svg>
  </a>`;
}

function renderSiteIcon(blog) {
  const href = `https://${blog.slug}.${publicHostSuffix}/`;

  return `<a class="icon-link" href="${escapeHtml(href)}" aria-label="${escapeHtml(blog.label)} site">
    <svg viewBox="0 0 24 24" aria-hidden="true">
      <circle cx="12" cy="12" r="8.25"></circle>
      <path d="M3.75 12h16.5"></path>
      <path d="M12 3.75c2.2 2.25 3.3 5 3.3 8.25s-1.1 6-3.3 8.25"></path>
      <path d="M12 3.75c-2.2 2.25-3.3 5-3.3 8.25s1.1 6 3.3 8.25"></path>
    </svg>
  </a>`;
}

function renderSocialLinks() {
  return `<nav class="social-links" aria-label="Social links">
    ${socialLinks.map((link) => `<a class="social-link" href="${escapeHtml(link.href)}" aria-label="${escapeHtml(link.label)}" style="--social-color:${escapeHtml(link.color)}" target="_blank" rel="me noopener noreferrer">
      <svg viewBox="0 0 24 24" aria-hidden="true">${link.svg}</svg>
    </a>`).join("\n    ")}
  </nav>`;
}

function renderBlog(blog, posts) {
  const featured = posts.find((post) => post.featured);
  const latest = posts.filter((post) => post !== featured).slice(0, 2);

  return `<details class="blog">
    <summary>
      <span>${escapeHtml(blog.label)}</span>
      <span class="blog-actions">
        ${renderSiteIcon(blog)}
        ${renderRssIcon(blog)}
      </span>
    </summary>
    <p>${escapeHtml(blog.summary)}</p>
    ${renderFeaturedPost(featured)}
    <ul>
      ${latest.map(renderPost).join("\n      ")}
    </ul>
  </details>`;
}

const entries = await getEntries();

if (shouldWriteContentIndex) {
  await mkdir(new URL("../content/", import.meta.url), { recursive: true });
  await writeFile(
    contentIndex,
    `${JSON.stringify(
      Object.fromEntries(entries.map(([blog, posts]) => [blog.slug, posts])),
      null,
      2,
    )}\n`,
  );
}

const html = `<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>neeldhara.blog</title>
    <style>
      @font-face {
        font-family: "Heliotrope";
        src: url("/webfonts/heliotrope_3_regular.woff2") format("woff2");
        font-weight: 400;
        font-style: normal;
        font-display: swap;
      }
      @font-face {
        font-family: "Heliotrope";
        src: url("/webfonts/heliotrope_3_italic.woff2") format("woff2");
        font-weight: 400;
        font-style: italic;
        font-display: swap;
      }
      @font-face {
        font-family: "Heliotrope";
        src: url("/webfonts/heliotrope_3_bold.woff2") format("woff2");
        font-weight: 700;
        font-style: normal;
        font-display: swap;
      }
      @font-face {
        font-family: "Heliotrope";
        src: url("/webfonts/heliotrope_3_bold_italic.woff2") format("woff2");
        font-weight: 700;
        font-style: italic;
        font-display: swap;
      }
      html { color-scheme: light; }
      * { box-sizing: border-box; }
      body {
        margin: 0;
        background: #f0f0f0;
        color: #111;
        font-family: "Heliotrope", ui-serif, Georgia, serif;
        font-size: 15px;
        line-height: 1.45;
      }
      a {
        color: inherit;
        text-decoration-color: #c6c6c6;
        text-underline-offset: 3px;
      }
      a:hover { text-decoration-color: #111; }
      main {
        display: grid;
        grid-template-columns: minmax(0, 1.75fr) minmax(320px, 1fr);
        width: min(1220px, calc(100% - 72px));
        min-height: min(860px, calc(100vh - 144px));
        margin: 72px auto;
        background: #d9d9d9;
      }
      .left,
      .right {
        min-height: inherit;
        padding: 34px 32px;
      }
      .left {
        display: flex;
        flex-direction: column;
        justify-content: space-between;
        gap: 56px;
      }
      .right {
        display: flex;
        flex-direction: column;
        justify-content: space-between;
        background: #fff;
      }
      .mark {
        display: block;
        width: 13px;
        height: 13px;
        border: 2px solid #111;
        border-radius: 50%;
      }
      h1,
      h2,
      p {
        margin: 0;
      }
      h1,
      h2 {
        font-size: 15px;
        font-weight: 700;
        line-height: 1.2;
      }
      .role {
        color: #666;
        font-weight: 500;
      }
      .identity {
        display: grid;
        gap: 7px;
      }
      .social-links {
        display: flex;
        align-items: center;
        gap: 13px;
        margin-top: 7px;
      }
      .social-link {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        width: 22px;
        height: 22px;
        color: #222;
        opacity: 0.72;
        transition: color 180ms ease, opacity 180ms ease, transform 180ms ease;
      }
      .social-link:hover {
        color: var(--social-color);
        opacity: 1;
        transform: translateY(-1px);
      }
      .social-link svg {
        width: 18px;
        height: 18px;
        fill: none;
        stroke: currentColor;
        stroke-width: 1.7;
        stroke-linecap: round;
        stroke-linejoin: round;
      }
      .blog-list {
        display: grid;
        gap: 28px;
      }
      .blog {
        max-width: 650px;
      }
      summary {
        display: flex;
        align-items: center;
        gap: 12px;
        width: 100%;
        cursor: pointer;
        font-weight: 700;
        list-style: none;
      }
      summary::-webkit-details-marker {
        display: none;
      }
      summary::before {
        content: "+";
        width: 18px;
        flex: 0 0 18px;
        color: #666;
        font-weight: 500;
      }
      details[open] summary::before {
        content: "-";
      }
      summary > span {
        flex: 0 1 auto;
      }
      .blog-actions {
        display: inline-flex;
        align-items: center;
        gap: 4px;
      }
      .icon-link {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        width: 22px;
        height: 22px;
        color: #111;
      }
      .icon-link svg {
        width: 16px;
        height: 16px;
        fill: none;
        stroke: currentColor;
        stroke-width: 1.9;
        stroke-linecap: round;
      }
      .icon-link circle {
        fill: none;
      }
      .icon-link[aria-label$="RSS"] circle {
        fill: currentColor;
        stroke: none;
      }
      .blog p {
        max-width: 540px;
        margin-top: 9px;
        color: #555;
      }
      .featured-post {
        display: flex;
        align-items: baseline;
        gap: 12px;
      }
      .featured-post span {
        color: #666;
        font-size: 13px;
      }
      .featured-post a {
        font-weight: 700;
      }
      ul {
        display: grid;
        gap: 7px;
        margin: 14px 0 0;
        padding: 0;
        list-style: none;
      }
      .post {
        display: grid;
        grid-template-columns: 64px minmax(0, 1fr);
        gap: 0;
      }
      .date {
        color: #666;
      }
      .post a {
        font-weight: 700;
      }
      .bio {
        display: grid;
        gap: 24px;
        max-width: 390px;
        font-weight: 400;
      }
      @media (max-width: 860px) {
        main {
          grid-template-columns: 1fr;
          width: min(100%, calc(100% - 28px));
          margin: 14px auto;
        }
        .left,
        .right {
          min-height: auto;
          padding: 28px 26px;
        }
        .left {
          gap: 40px;
        }
        .right {
          gap: 72px;
        }
      }
    </style>
  </head>
  <body>
    <main>
      <section class="left" aria-label="Blog index">
        <span class="mark" aria-hidden="true"></span>
        <div class="blog-list">
          ${entries.map(([blog, posts]) => renderBlog(blog, posts)).join("\n          ")}
        </div>
      </section>
      <aside class="right" aria-label="About">
        <div class="identity">
          <h2>Neeldhara Misra</h2>
          <p class="role">Computer Science and Engineering, IIT Gandhinagar</p>
          ${renderSocialLinks()}
        </div>
        <div class="bio">
          <p>I am a computer science faculty member at IIT Gandhinagar. My academic work is broadly around algorithms, structural graph theory, parameterized complexity, computational social choice, combinatorial games, and fair allocation.</p>
          <p>These blogs separate different kinds of notes: paper-reading and mini-surveys, puzzle-like teaching prompts, reflective essays, poems, reviews of tools and workflows, experiments with AI, and visual or generative art.</p>
          <p>The homepage is deliberately small: each section shows the two newest posts and links to that blog's RSS feed.</p>
        </div>
      </aside>
    </main>
  </body>
</html>
`;

await mkdir(outDir, { recursive: true });
await writeFile(new URL("index.html", outDir), html);
await mkdir(new URL("webfonts/", outDir), { recursive: true });
await Promise.all(
  fontFiles.map((file) => copyFile(new URL(file, fontDir), new URL(`webfonts/${file}`, outDir))),
);