import {
  createMintIgnoreMatcher,
  isMintIgnoredBy,
  processMintIgnoreString,
  type MintIgnoreMatcher,
} from '@mintlify/common';
import { getMintIgnore } from '@mintlify/prebuild';
import { addLog, ErrorLog, SuccessLog } from '@mintlify/previewing';
import fs from 'node:fs/promises';
import path from 'node:path';

import { CMD_EXEC_PATH, terminate } from './helpers.js';

async function getGitIgnore(): Promise<string[]> {
  try {
    const content = await fs.readFile(path.join(CMD_EXEC_PATH, '.gitignore'), 'utf-8');
    return processMintIgnoreString(content);
  } catch {
    return [];
  }
}

async function* walk(dir: string, matcher: MintIgnoreMatcher): AsyncGenerator<string> {
  const entries = await fs.readdir(dir, { withFileTypes: true });
  for (const entry of entries) {
    const full = path.join(dir, entry.name);
    const relative = path.relative(CMD_EXEC_PATH, full).split(path.sep).join('/');
    if (isMintIgnoredBy(relative, matcher, entry.isDirectory())) continue;
    if (entry.isDirectory()) {
      yield* walk(full, matcher);
    } else if (entry.name.endsWith('.mdx')) {
      yield full;
    }
  }
}

export const formatHandler = async (): Promise<void> => {
  const { mdxToPm, pmToMdx, canonicalPmToMdxOptions } = await import('./vendor/converter.js');
  const ignores = [...(await getGitIgnore()), ...(await getMintIgnore(CMD_EXEC_PATH))];
  const matcher = createMintIgnoreMatcher(ignores);
  let total = 0;
  let changed = 0;
  let failed = 0;

  for await (const file of walk(CMD_EXEC_PATH, matcher)) {
    total++;
    const relative = path.relative(CMD_EXEC_PATH, file);
    try {
      const raw = await fs.readFile(file, 'utf-8');
      let formatted = raw;
      let originalFrontmatterKeys = 0;
      for (let pass = 0; pass < 3; pass++) {
        const { doc, frontmatter } = mdxToPm(formatted);
        if (pass === 0) originalFrontmatterKeys = Object.keys(frontmatter).length;
        const next = `${pmToMdx(doc, { frontmatter, ...canonicalPmToMdxOptions })}\n`;
        if (next === formatted) break;
        formatted = next;
      }
      if (originalFrontmatterKeys > 0 && !formatted.startsWith('---')) {
        throw new Error('formatting would remove frontmatter; file left untouched');
      }
      if (formatted !== raw) {
        await fs.writeFile(file, formatted);
        changed++;
      }
    } catch (error) {
      failed++;
      addLog(
        <ErrorLog
          message={`${relative}: ${error instanceof Error ? error.message : 'unknown error'}`}
        />
      );
    }
  }

  addLog(
    <SuccessLog
      message={`formatted ${changed} of ${total} mdx file${total === 1 ? '' : 's'}${failed > 0 ? ` (${failed} failed)` : ''}`}
    />
  );
  await terminate(failed > 0 ? 1 : 0);
};