import fs from 'node:fs';
import path from 'node:path';

// Adjust path if needed to point to your actual sidebar file
import { guidesSidebar, apisSidebar, legalSidebar } from '../lib/sidebar-data';

const CONTENT_DIR = path.join(process.cwd(), 'content');

// --- HELPERS ---

function ensureDirectoryExistence(filePath: string) {
  const dirname = path.dirname(filePath);
  if (fs.existsSync(dirname)) {
    return true;
  }
  ensureDirectoryExistence(dirname);
  fs.mkdirSync(dirname);
}

function toTitleCase(str: string) {
  return str
    .replace(/[-_]/g, ' ')
    .replace(/\b\w/g, (char) => char.toUpperCase());
}

/**
 * Clean a path segment.
 * e.g., "docs/guides/overview" -> "guides/overview"
 * e.g., "/guides/overview/" -> "guides/overview"
 */
function cleanPath(p: string) {
  if (!p) return '';
  return p
    .replace(/^\/+/, '')        // Remove leading slash
    .replace(/^docs\//, '')     // Remove leading 'docs/' if present (prevents duplication)
    .replace(/\/+$/, '');       // Remove trailing slash
}

/**
 * Resolve HREF
 */
function getItemHref(item: any, urlPrefix: string): string {
  // Normalize prefix: 
  // If urlPrefix is '', prefix becomes just '/'
  // If urlPrefix is '/v2', prefix becomes '/v2/'
  const prefix = urlPrefix ? (urlPrefix.startsWith('/') ? urlPrefix : `/${urlPrefix}`) : '';

  let segment = '';

  // CASE A: String (Doc ID)
  if (typeof item === 'string') {
    segment = cleanPath(item);
  }
  // CASE B: Link (External or Internal)
  else if (item.type === 'link' && item.href) {
    // If external, return immediately
    if (item.href.startsWith('http')) return item.href;
    // If absolute path provided manually, return it (e.g. /legal/...)
    if (item.href.startsWith('/')) return item.href;
    segment = cleanPath(item.href);
  }
  // CASE C: Doc Object
  else if (item.type === 'doc' && item.id) {
    segment = cleanPath(item.id);
  }
  // CASE D: Category (Link to index)
  else if (item.type === 'category') {
    if (item.link?.slug) {
      segment = cleanPath(item.link.slug);
    } else if (item.link?.id) {
      segment = cleanPath(item.link.id);
    }
  }
  // CASE E: Autogenerated
  else if (item.type === 'autogenerated' && item.dirName) {
    segment = cleanPath(item.dirName);
  }

  if (!segment) return '';

  // Combine prefix and segment
  // Ensure we usually start with / unless prefix was empty and logic demands it
  let finalUrl = prefix ? `${prefix}/${segment}` : `/${segment}`;

  // FINAL SAFETY CHECK: Deduplicate /docs/docs/
  // This catches cases where 'urlPrefix' was empty but 'segment' started with docs/
  finalUrl = finalUrl.replace(/\/docs\/docs\//g, '/docs/');

  return finalUrl;
}

/**
 * Resolve TITLE
 */
function getItemLabel(item: any): string {
  if (typeof item === 'string') {
    const parts = item.split('/');
    return toTitleCase(parts[parts.length - 1]);
  }
  if (item.label) return item.label;
  if (item.id) {
    const parts = item.id.split('/');
    return toTitleCase(parts[parts.length - 1]);
  }
  if (item.type === 'autogenerated' && item.dirName) {
    const parts = item.dirName.split('/');
    return toTitleCase(parts[parts.length - 1]);
  }
  return 'Section';
}

/**
 * Resolve ICON
 */
function getItemIcon(item: any): string {
  if (typeof item === 'string') return '<FileText />';
  if (item.type === 'category') return '<Folder />';
  if (item.type === 'autogenerated') return '<Folder />';
  if (item.type === 'link') return '<LinkIcon />';
  return '<FileText />';
}

// --- GENERATOR ---

function generateContent(title: string, description: string, items: any[], urlPrefix: string) {
  const safeDescription = description
    .replace(/\\/g, '\\\\')
    .replace(/"/g, '\\"');

  const cardsHtml = items
    .map((item) => {
      const href = getItemHref(item, urlPrefix);
      const label = getItemLabel(item);
      const icon = getItemIcon(item);

      if (!href) return null;

      const isExternal = href.startsWith('http');
      const externalProp = isExternal ? ' external' : '';

      return `    <Card title="${label}" href="${href}" icon={${icon}}${externalProp} />`;
    })
    .filter(Boolean)
    .join('\n');

  return `---
title: "${title}"
description: "${safeDescription}"
---

{/* THIS FILE IS AUTO-GENERATED FROM SIDEBAR-DATA.
  ANY MANUAL CHANGES WILL BE OVERWRITTEN.
*/}

import { Card, Cards } from 'fumadocs-ui/components/card';
import { FileText, Folder, Link as LinkIcon } from 'lucide-react';

<Cards>
${cardsHtml}
</Cards>
`;
}

function traverse(items: readonly any[], baseDir: string, urlPrefix: string) {
  items.forEach((item) => {
    // Skip strings (leaves)
    if (typeof item === 'string') return;

    // Generate page only for categories with 'generated-index'
    if (
      item.type === 'category' &&
      item.link &&
      item.link.type === 'generated-index' &&
      item.link.slug
    ) {
      const slug = item.link.slug;

      const cleanSlug = cleanPath(slug);
      const filePath = path.join(baseDir, cleanSlug, 'index.mdx');

      console.log(`[+] Generating Virtual Page: ${path.relative(CONTENT_DIR, filePath)}`);
      ensureDirectoryExistence(filePath);

      const content = generateContent(
        item.link.title || item.label || 'Overview',
        item.link.description || '',
        item.items || [],
        urlPrefix
      );

      fs.writeFileSync(filePath, content);
    }

    // Recursively traverse
    if (item.items) {
      traverse(item.items, baseDir, urlPrefix);
    }
  });
}

// --- EXECUTION ---

const VERSIONS_FILE = path.join(CONTENT_DIR, 'versions.json');

console.log('--- Scanning Sidebar for Virtual Pages ---');

// 1. Generate for Latest
// CRITICAL CHANGE: Pass empty string '' instead of '/docs' 
// This generates href="/guides/..." instead of "/docs/guides/..."
// preventing the double prefix if the Component/Link adds it automatically.
console.log(`\nProcessing: Latest`);
traverse(guidesSidebar, CONTENT_DIR, '');
traverse(apisSidebar, CONTENT_DIR, '');
traverse(legalSidebar, CONTENT_DIR, '');

// 2. Generate for Versions
if (fs.existsSync(VERSIONS_FILE)) {
  const versions = JSON.parse(fs.readFileSync(VERSIONS_FILE, 'utf8'));

  versions.forEach((v: any) => {
    if (!v.param || v.param === 'latest' || !v.param.startsWith('v')) return;

    const versionDir = path.join(CONTENT_DIR, v.param);
    if (!fs.existsSync(versionDir)) return;

    console.log(`\nProcessing: ${v.param}`);

    // For versions, we prefix with just the version param (e.g. /v2)
    // If double docs persist here, change this to just `/${v.param}` or verify version routing.
    traverse(guidesSidebar, versionDir, `/${v.param}`);
    traverse(apisSidebar, versionDir, `/${v.param}`);
    traverse(legalSidebar, versionDir, `/${v.param}`);
  });
}

console.log('--- Done ---');