#!/usr/bin/env node

/**
 * Build-time script: scans docs/<subfolder>/*.md and generates
 * src/app/docs/lib/docs-auto-generated.ts with static navigation + search data.
 *
 * This file is imported by both client and server components — NO fs/path imports.
 * Run via: node scripts/docs/generate-docs-index.mjs
 * Automatically runs as prebuild step.
 *
 * Sections come from the on-disk subfolder layout introduced in FASE 3 of the
 * platform overhaul. Order is fixed by SECTION_ORDER below.
 */

import fs from "node:fs";
import path from "node:path";
import matter from "gray-matter";
import { format } from "prettier";
import { fileURLToPath } from "node:url";

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const ROOT = path.resolve(__dirname, "..", "..");
const DOCS_DIR = path.join(ROOT, "docs");
const OUT_FILE = path.join(ROOT, "src", "app", "docs", "lib", "docs-auto-generated.ts");

// Subfolder -> nav section title, in the order they should appear in the sidebar.
const SECTION_ORDER = [
  { dir: "architecture", title: "Architecture" },
  { dir: "guides", title: "Guides" },
  { dir: "reference", title: "Reference" },
  { dir: "frameworks", title: "Frameworks" },
  { dir: "routing", title: "Routing" },
  { dir: "security", title: "Security" },
  { dir: "compression", title: "Compression" },
  { dir: "ops", title: "Ops" },
];

const SECTION_INDEX = Object.fromEntries(SECTION_ORDER.map((s, i) => [s.title, i + 1]));

async function writeGeneratedFile(content) {
  fs.mkdirSync(path.dirname(OUT_FILE), { recursive: true });
  const formatted = await format(content, { parser: "typescript", printWidth: 100 });
  fs.writeFileSync(OUT_FILE, formatted, "utf8");
}

function extractTitleFromContent(content) {
  const match = content.match(/^#\s+(.+)$/m);
  if (match) {
    return match[1]
      .replace(/^📖\s*/, "")
      .replace(/^🌐\s*/, "")
      .replace(/\s*—\s*OmniRoute\s*$/i, "")
      .replace(/\s*—\s*OmniRoute Docs\s*$/i, "")
      .trim();
  }
  return "";
}

function extractHeadings(content) {
  const headings = [];
  const regex = /^(#{2,4})\s+(.+)$/gm;
  let match;
  while ((match = regex.exec(content)) !== null) {
    headings.push(match[2].replace(/\*\*/g, "").replace(/\*/g, "").replace(/`/g, "").trim());
  }
  return headings.slice(0, 10);
}

function extractContentPreview(content) {
  const stripped = content
    .replace(/^---[\s\S]*?---/m, "")
    .replace(/^#{1,6}\s+.+$/gm, "")
    .replace(/```[\s\S]*?```/g, "")
    .replace(/!\[[^\]]*\]\([^)]+\)/g, "")
    .replace(/\[([^\]]+)\]\([^)]+\)/g, "$1")
    .replace(/[*_`~>#|]/g, "")
    .replace(/\s+/g, " ")
    .trim();
  return stripped.slice(0, 300);
}

async function emitEmpty(reason) {
  await writeGeneratedFile(
    `// AUTO-GENERATED by scripts/docs/generate-docs-index.mjs — DO NOT EDIT MANUALLY
// Regenerate with: node scripts/docs/generate-docs-index.mjs

export interface AutoGenDocItem {
  slug: string;
  title: string;
  fileName: string;
}

export interface AutoGenNavSection {
  title: string;
  items: AutoGenDocItem[];
}

export interface AutoGenSearchItem {
  slug: string;
  title: string;
  fileName: string;
  section: string;
  content: string;
  headings: string[];
}

export const autoNavSections: AutoGenNavSection[] = [];

export const autoSearchIndex: AutoGenSearchItem[] = [];

export const autoAllSlugs: string[] = [];
`
  );
  console.warn(`[generate-docs-index] ${reason}; generated empty docs index.`);
}

// ---------- Main ----------

if (!fs.existsSync(DOCS_DIR)) {
  if (fs.existsSync(OUT_FILE)) {
    console.warn(
      `[generate-docs-index] ${DOCS_DIR} not found; keeping existing generated docs index.`
    );
    process.exit(0);
  }
  await emitEmpty(`${DOCS_DIR} not found`);
  process.exit(0);
}

const docs = [];

for (const { dir, title } of SECTION_ORDER) {
  const fullDir = path.join(DOCS_DIR, dir);
  if (!fs.existsSync(fullDir)) continue;
  const entries = fs.readdirSync(fullDir, { withFileTypes: true });
  for (const entry of entries) {
    if (!entry.isFile()) continue;
    if (!entry.name.endsWith(".md") && !entry.name.endsWith(".mdx")) continue;
    if (entry.name === "README.md") continue; // section index, not a doc page

    const absPath = path.join(fullDir, entry.name);
    const fileContent = fs.readFileSync(absPath, "utf8");
    const { data: frontmatter, content } = matter(fileContent);

    const slug =
      frontmatter.slug ||
      entry.name
        .replace(/\.mdx?$/i, "")
        .toLowerCase()
        .replace(/_/g, "-");

    // fileName is relative to docs/ — used by the slug page to read content.
    const fileName = path.posix.join(dir, entry.name);

    const titleStr =
      frontmatter.title || extractTitleFromContent(content) || slug.replace(/-/g, " ");
    const section = frontmatter.section || title;
    const order = frontmatter.order ?? 999;
    const headings = extractHeadings(content);
    const contentPreview = frontmatter.description || extractContentPreview(content);

    docs.push({
      slug,
      title: titleStr,
      fileName,
      section,
      order,
      content: contentPreview,
      headings,
    });
  }
}

if (docs.length === 0) {
  await emitEmpty("no docs discovered in subfolders");
  process.exit(0);
}

docs.sort((a, b) => {
  const sectionA = SECTION_INDEX[a.section] ?? 99;
  const sectionB = SECTION_INDEX[b.section] ?? 99;
  if (sectionA !== sectionB) return sectionA - sectionB;
  return a.order - b.order;
});

// Build navigation sections in the configured order.
const sectionMap = new Map();
for (const doc of docs) {
  const items = sectionMap.get(doc.section) || [];
  items.push(doc);
  sectionMap.set(doc.section, items);
}

const navSections = SECTION_ORDER.map(({ title }) => title)
  .filter((t) => sectionMap.has(t))
  .map((title) => ({
    title,
    items: sectionMap.get(title).map((doc) => ({
      slug: doc.slug,
      title: doc.title,
      fileName: doc.fileName,
    })),
  }));

// Build search index
const searchIndex = docs.map((doc) => ({
  slug: doc.slug,
  title: doc.title,
  fileName: doc.fileName,
  section: doc.section,
  content: doc.content,
  headings: doc.headings,
}));

// Add api-explorer synthetic entry if api-reference exists
if (searchIndex.some((item) => item.slug === "api-reference")) {
  if (!searchIndex.some((item) => item.slug === "api-explorer")) {
    searchIndex.push({
      slug: "api-explorer",
      title: "API Explorer",
      fileName: "reference/API_REFERENCE.md",
      section: "Reference",
      content: "interactive try it live api explorer endpoint test request response curl example",
      headings: ["Try It", "Endpoints"],
    });
  }
}

// ---------- Write output ----------

const output = `// AUTO-GENERATED by scripts/docs/generate-docs-index.mjs — DO NOT EDIT MANUALLY
// Regenerate with: node scripts/docs/generate-docs-index.mjs

export interface AutoGenDocItem {
  slug: string;
  title: string;
  fileName: string;
}

export interface AutoGenNavSection {
  title: string;
  items: AutoGenDocItem[];
}

export interface AutoGenSearchItem {
  slug: string;
  title: string;
  fileName: string;
  section: string;
  content: string;
  headings: string[];
}

export const autoNavSections: AutoGenNavSection[] = ${JSON.stringify(navSections, null, 2)};

export const autoSearchIndex: AutoGenSearchItem[] = ${JSON.stringify(searchIndex, null, 2)};

export const autoAllSlugs: string[] = ${JSON.stringify(
  docs.map((d) => d.slug),
  null,
  2
)};
`;

await writeGeneratedFile(output);
console.log(`✅ Generated ${OUT_FILE} with ${docs.length} docs, ${navSections.length} sections`);