/**
 * Shared filesystem storage utilities for database providers.
 */

import { join } from 'node:path';
import { promises as fsPromises } from 'node:fs';

export async function safeWrite(filePath, buffer) {
  if (buffer == null) return;
  const buf = Buffer.isBuffer(buffer) ? buffer : Buffer.from(buffer);
  await fsPromises.writeFile(filePath, buf);
}

export async function findFileByHash(dir, hash, ext = '') {
  if (!dir || !hash) return null;
  if (ext) {
    const candidate = join(dir, hash + ext);
    try {
      await fsPromises.access(candidate);
      return candidate;
    } catch {
      // fallback
    }
  }
  const candidateNoExt = join(dir, hash);
  try {
    await fsPromises.access(candidateNoExt);
    return candidateNoExt;
  } catch {
    // fallback
  }
  try {
    const files = await fsPromises.readdir(dir);
    const match = files.find((f) => f === hash || f.startsWith(hash + '.'));
    if (match) return join(dir, match);
  } catch {
    // ignore
  }
  return null;
}

export async function safeReadByHash(dir, hash, ext = '') {
  const filePath = await findFileByHash(dir, hash, ext);
  if (!filePath) return null;
  try {
    return await fsPromises.readFile(filePath);
  } catch (err) {
    if (err.code === 'ENOENT') return null;
    throw err;
  }
}

export async function safeDeleteByHash(dir, hash) {
  if (!dir || !hash) return;
  try {
    const files = await fsPromises.readdir(dir);
    const matches = files.filter((f) => f === hash || f.startsWith(hash + '.'));
    await Promise.all(matches.map((f) => fsPromises.unlink(join(dir, f))));
  } catch (err) {
    if (err.code !== 'ENOENT') throw err;
  }
}

export function extFromMimetype(mimetype) {
  if (!mimetype) return '';
  const type = mimetype.trim().toLowerCase().split(';')[0];
  const map = {
    'application/pdf': '.pdf',
    'text/plain': '.txt',
    'text/csv': '.csv',
    'text/html': '.html',
    'text/markdown': '.md',
    'image/avif': '.avif',
    'image/png': '.png',
    'image/jpeg': '.jpg',
    'image/jpg': '.jpg',
    'image/webp': '.webp',
    'image/gif': '.gif',
    'image/svg+xml': '.svg',
    'application/json': '.json',
    'application/zip': '.zip',
    'application/xml': '.xml',
    'application/octet-stream': '.bin',
  };
  if (map[type]) return map[type];
  if (type.startsWith('image/')) return '.' + type.slice(6).replace('+xml', '');
  if (type.startsWith('text/')) return '.' + type.slice(5);
  return '';
}