#!/usr/bin/env node
/**
 * Blog build script — converts markdown posts to static HTML.
 *
 * Usage:  node build.js
 * Input:  posts/*.md  (markdown with YAML frontmatter)
 * Output: *.html      (from _template.html + _index_template.html)
 *
 * Zero external dependencies — uses only Node.js built-ins.
 * Markdown conversion is intentionally minimal (handles the subset
 * our posts actually use). For richer formatting, swap in marked/markdown-it.
 */

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

const BLOG_DIR = __dirname;
const POSTS_DIR = path.join(BLOG_DIR, "posts");
const TEMPLATE = fs.readFileSync(path.join(BLOG_DIR, "_template.html"), "utf8");
const INDEX_TEMPLATE = fs.readFileSync(
  path.join(BLOG_DIR, "_index_template.html"),
  "utf8"
);

// ── Frontmatter parser ──────────────────────────────────────────────

function parseFrontmatter(src) {
  const match = src.match(/^---\r?\n([\s\S]*?)\r?\n---\r?\n([\s\S]*)$/);
  if (!match) throw new Error("Missing YAML frontmatter");
  const meta = {};
  for (const line of match[1].split("\n")) {
    const idx = line.indexOf(":");
    if (idx === -1) continue;
    const key = line.slice(0, idx).trim();
    let val = line.slice(idx + 1).trim();
    // strip surrounding quotes
    if ((val.startsWith('"') && val.endsWith('"')) || (val.startsWith("'") && val.endsWith("'"))) {
      val = val.slice(1, -1);
    }
    meta[key] = val;
  }
  return { meta, body: match[2] };
}

// ── Minimal Markdown → HTML ─────────────────────────────────────────

function md(src) {
  const lines = src.split("\n");
  let html = "";
  let inUl = false;
  let inCode = false;
  let codeLang = "";
  let codeLines = [];

  function closeUl() {
    if (inUl) { html += "</ul>\n"; inUl = false; }
  }

  for (let i = 0; i < lines.length; i++) {
    const line = lines[i];

    // Fenced code blocks
    if (line.startsWith("```")) {
      if (!inCode) {
        closeUl();
        inCode = true;
        codeLang = line.slice(3).trim();
        codeLines = [];
        continue;
      } else {
        html += `<pre><code${codeLang ? ` class="language-${codeLang}"` : ""}>${codeLines.join("\n")}</code></pre>\n`;
        inCode = false;
        continue;
      }
    }
    if (inCode) {
      codeLines.push(escapeHtml(line));
      continue;
    }

    // Blank line
    if (line.trim() === "") {
      closeUl();
      continue;
    }

    // Headings
    const hMatch = line.match(/^(#{1,6})\s+(.*)$/);
    if (hMatch) {
      closeUl();
      const level = hMatch[1].length;
      html += `<h${level}>${inline(hMatch[2])}</h${level}>\n`;
      continue;
    }

    // Horizontal rule
    if (/^---+$/.test(line.trim())) {
      closeUl();
      html += "<hr>\n";
      continue;
    }

    // Figure (![alt](src) on its own line)
    const figMatch = line.match(/^!\[([^\]]*)\]\(([^)]+)\)$/);
    if (figMatch) {
      closeUl();
      html += `<figure>\n  <img src="${figMatch[2]}" alt="${escapeHtml(figMatch[1])}">\n  <figcaption>${inline(figMatch[1])}</figcaption>\n</figure>\n`;
      continue;
    }

    // Unordered list
    const liMatch = line.match(/^[-*]\s+(.*)$/);
    if (liMatch) {
      if (!inUl) { html += "<ul>\n"; inUl = true; }
      html += `  <li>${inline(liMatch[1])}</li>\n`;
      continue;
    }

    // Paragraph
    closeUl();
    html += `<p>${inline(line)}</p>\n`;
  }

  closeUl();
  return html;
}

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

function inline(s) {
  // Bold
  s = s.replace(/\*\*(.+?)\*\*/g, "<strong>$1</strong>");
  // Italic
  s = s.replace(/\*(.+?)\*/g, "<em>$1</em>");
  // Inline code
  s = s.replace(/`([^`]+)`/g, "<code>$1</code>");
  // Links
  s = s.replace(/\[([^\]]+)\]\(([^)]+)\)/g, '<a href="$2" style="color: var(--c-accent-l);">$1</a>');
  // Em dash
  s = s.replace(/---/g, "&mdash;");
  s = s.replace(/--/g, "&ndash;");
  return s;
}

// ── Date formatting ─────────────────────────────────────────────────

function formatDate(isoDate) {
  const d = new Date(isoDate + "T00:00:00Z");
  const months = [
    "January", "February", "March", "April", "May", "June",
    "July", "August", "September", "October", "November", "December",
  ];
  return `${d.getUTCDate()} ${months[d.getUTCMonth()]} ${d.getUTCFullYear()}`;
}

// ── Build ───────────────────────────────────────────────────────────

function buildPost(file) {
  const src = fs.readFileSync(path.join(POSTS_DIR, file), "utf8");
  const { meta, body } = parseFrontmatter(src);

  // Split lead (first paragraph) from rest
  const parts = body.split(/\n\n/);
  const lead = parts[0].trim();
  const rest = parts.slice(1).join("\n\n");

  const html = TEMPLATE
    .replace(/\{\{TITLE\}\}/g, meta.title)
    .replace(/\{\{DESCRIPTION\}\}/g, meta.description || meta.title)
    .replace(/\{\{OG_DESCRIPTION\}\}/g, meta.og_description || meta.description || meta.title)
    .replace(/\{\{OG_IMAGE\}\}/g, meta.og_image || "https://www.tinqs.com/img/og-cover.jpg")
    .replace(/\{\{SLUG\}\}/g, meta.slug)
    .replace(/\{\{DATE_ISO\}\}/g, meta.date)
    .replace(/\{\{DATE_DISPLAY\}\}/g, formatDate(meta.date))
    .replace(/\{\{LEAD\}\}/g, inline(lead))
    .replace(/\{\{BODY\}\}/g, md(rest))
    .replace(/\{\{AUTHOR_NAME\}\}/g, meta.author || "Ozan Bozkurt")
    .replace(/\{\{AUTHOR_INITIALS\}\}/g, meta.author_initials || "OB")
    .replace(/\{\{AUTHOR_ROLE\}\}/g, meta.author_role || "CTO & Developer, Tinqs");

  const outPath = path.join(BLOG_DIR, `${meta.slug}.html`);
  fs.writeFileSync(outPath, html);
  console.log(`  ${file} → ${meta.slug}.html`);
  return meta;
}

function buildIndex(posts) {
  // Sort newest first
  posts.sort((a, b) => b.date.localeCompare(a.date));

  const cards = posts
    .map(
      (p) => `
    <a href="${p.slug}" class="blog-card">
      <span class="blog-card__date">${formatDate(p.date)}</span>
      <h2 class="blog-card__title">${p.title}</h2>
      <p class="blog-card__excerpt">${p.excerpt || p.description}</p>
      <span class="blog-card__read">Read &rarr;</span>
    </a>`
    )
    .join("\n");

  const html = INDEX_TEMPLATE.replace("{{CARDS}}", cards);
  fs.writeFileSync(path.join(BLOG_DIR, "index.html"), html);
  console.log("  index.html (listing)");
}

// ── Main ────────────────────────────────────────────────────────────

console.log("Building blog...");

if (!fs.existsSync(POSTS_DIR)) {
  console.error("No posts/ directory found.");
  process.exit(1);
}

const files = fs.readdirSync(POSTS_DIR).filter((f) => f.endsWith(".md")).sort();
const posts = files.map(buildPost);
buildIndex(posts);

console.log(`Done — ${posts.length} posts built.`);