import { readdirSync, readFileSync, writeFileSync, statSync } from 'node:fs';
import { dirname, join } from 'node:path';
import { fileURLToPath } from 'node:url';

const __dirname = dirname(fileURLToPath(import.meta.url));
const storeDir = join(__dirname, 'src', 'store');
const outputPath = join(__dirname, 'API.md');

// Modules that are exposed on the LibDashStore instance (from src/index.js).
// Order here controls the order of sections in the generated document.
const MODULE_ORDER = [
  'companyuser',
  'company',
  'category',
  'article',
  'lang',
  'tax',
  'unit',
  'companysetting',
  'brand',
  'customergroup',
  'entity',
  'entityaddress',
  'entitycontact',
  'supplier',
  'delivery',
  'quote',
  'order',
  'posterminal',
  'google_auth',
  'pic',
];

// Files that are internal helpers and should not appear as public API entries.
const INTERNAL_FILES = new Set([
  'request.js',
  'slugify.js',
  'initialize.js',
  'purge.js',
  'helpers.js',
  'writeLines.js',
  'shapeSetting.js',
  'shapeUnit.js',
  'ensureDefault.js',
  'ensureLieferantenGroup.js',
  'resolveCompanyAccess.js',
  'resolveCategoryAccess.js',
  'resolveCustomerGroupAccess.js',
  'resolveEntityAccess.js',
  'resolvePicAccess.js',
  'resolveArticleBySku.js',
  'queryBySku.js',
  'queryCategoryArticles.js',
  'getCategoryPosterminalIds.js',
  'nextSku.js',
  'createStore.js',
  'index.js',
]);

/**
 * Extract the leading JSDoc block from a source string.
 * @param {string} source
 * @returns {{ description: string, example: string } | null}
 */
function extractJsDoc(source) {
  const match = source.match(/\/\*\*([\s\S]*?)\*\//);
  if (!match) return null;

  const block = match[1];
  const lines = block
    .split('\n')
    .map((l) => l.replace(/^\s*\*\s?/, '').replace(/^\s*\*/, ''));

  const description = [];
  const example = [];
  let inExample = false;

  for (const line of lines) {
    if (line.trim() === '@example') {
      inExample = true;
      continue;
    }
    if (line.trim().startsWith('@')) {
      inExample = false;
      continue;
    }
    if (inExample) {
      example.push(line);
    } else if (line.trim()) {
      description.push(line.trim());
    }
  }

  return {
    description: description.join(' ').trim(),
    example: example.join('\n').trim(),
  };
}

/**
 * Recursively collect all .js files under a directory.
 * @param {string} dir
 * @returns {string[]} absolute file paths
 */
function collectFiles(dir) {
  const out = [];
  for (const entry of readdirSync(dir)) {
    const full = join(dir, entry);
    if (statSync(full).isDirectory()) {
      out.push(...collectFiles(full));
    } else if (entry.endsWith('.js')) {
      out.push(full);
    }
  }
  return out;
}

/**
 * Build a map of module name -> array of { name, file, description, example }.
 * @returns {Map<string, Array<object>>}
 */
function buildModules() {
  const modules = new Map();

  for (const file of collectFiles(storeDir)) {
    const rel = file.slice(storeDir.length + 1).split('/');
    const moduleName = rel[0];
    const fileName = rel[rel.length - 1];

    if (INTERNAL_FILES.has(fileName)) continue;

    const source = readFileSync(file, 'utf8');
    const doc = extractJsDoc(source);
    if (!doc) continue;

    const fnName = fileName.replace(/\.js$/, '');
    if (!modules.has(moduleName)) {
      modules.set(moduleName, []);
    }
    modules.get(moduleName).push({
      name: fnName,
      file: rel.join('/'),
      description: doc.description,
      example: doc.example,
    });
  }

  return modules;
}

function renderSection(moduleName, entries) {
  const lines = [];
  lines.push(`# ${moduleName}`);
  lines.push('');
  lines.push(
    'This document is auto-generated from the JSDoc comments in `src/store` by running `npm run api-doc`.',
  );
  lines.push('');

  for (const entry of entries) {
    lines.push(`## \`${moduleName}.${entry.name}\``);
    lines.push('');
    lines.push(`*Source: \`src/store/${entry.file}\`*`);
    lines.push('');
    if (entry.description) {
      lines.push(entry.description);
      lines.push('');
    }
    if (entry.example) {
      lines.push('```js');
      lines.push(entry.example);
      lines.push('```');
      lines.push('');
    }
  }

  return lines.join('\n');
}

function render() {
  const modules = buildModules();

  const ordered = MODULE_ORDER.filter((m) => modules.has(m));
  const extra = [...modules.keys()].filter((m) => !MODULE_ORDER.includes(m)).sort();
  const moduleNames = [...ordered, ...extra];

  // Write one file per section: API.<section>.md
  const written = [];
  for (const moduleName of moduleNames) {
    const sectionPath = join(__dirname, `API.${moduleName}.md`);
    const markdown = renderSection(moduleName, modules.get(moduleName));
    writeFileSync(sectionPath, markdown, 'utf8');
    written.push({ moduleName, sectionPath, bytes: markdown.length });
  }

  // Write the index API.md linking to each section file.
  const lines = [];
  lines.push('# LibDashStore API');
  lines.push('');
  lines.push(
    'This document is auto-generated from the JSDoc comments in `src/store` by running `npm run api-doc`.',
  );
  lines.push('');
  lines.push(
    'The store is exposed as a `LibDashStore` instance (see `src/index.js`). Each method is an async function that takes a `pool` (mssql connection pool) at construction time and returns a callable function. Methods are grouped by the namespace they are exposed under.',
  );
  lines.push('');
  lines.push('## Table of Contents');
  lines.push('');

  for (const { moduleName } of written) {
    lines.push(`- [${moduleName}](API.${moduleName}.md)`);
  }

  lines.push('');

  return { index: lines.join('\n'), written };
}

const { index, written } = render();
writeFileSync(outputPath, index, 'utf8');
console.log(`Wrote ${outputPath} (${index.length} bytes)`);
for (const { moduleName, sectionPath, bytes } of written) {
  console.log(`Wrote ${sectionPath} (${bytes} bytes)`);
}