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

function toPosix(value) {
  return String(value).replace(/\\/g, '/');
}

function projectPath(root, relativePath) {
  return path.join(root, relativePath);
}

function ensureDir(dir) {
  fs.mkdirSync(dir, { recursive: true });
}

function readJson(file, fallback) {
  try {
    return JSON.parse(fs.readFileSync(file, 'utf8'));
  } catch (error) {
    if (error && error.code === 'ENOENT') return fallback;
    throw error;
  }
}

function writeJson(file, value) {
  ensureDir(path.dirname(file));
  fs.writeFileSync(file, `${JSON.stringify(value, null, 2)}\n`, 'utf8');
}

function appendJsonLine(file, value) {
  ensureDir(path.dirname(file));
  fs.appendFileSync(file, `${JSON.stringify(value)}\n`, 'utf8');
}

function readJsonLines(file) {
  try {
    return fs.readFileSync(file, 'utf8')
      .split(/\r?\n/)
      .filter(Boolean)
      .map((line) => JSON.parse(line));
  } catch (error) {
    if (error && error.code === 'ENOENT') return [];
    throw error;
  }
}

function updateGitignore(root) {
  const gitignore = path.join(root, '.gitignore');
  const needed = ['.qmd-adaptive-search/local/', '.qmd-adaptive-search/logs/'];
  let current = '';
  try {
    current = fs.readFileSync(gitignore, 'utf8');
  } catch (error) {
    if (!error || error.code !== 'ENOENT') throw error;
  }
  const missing = needed.filter((line) => !current.split(/\r?\n/).includes(line));
  if (missing.length === 0) return false;
  const prefix = current && !current.endsWith('\n') ? '\n' : '';
  fs.writeFileSync(gitignore, `${current}${prefix}${missing.join('\n')}\n`, 'utf8');
  return true;
}

function deepMerge(base, patch) {
  if (!patch || typeof patch !== 'object' || Array.isArray(patch)) return patch;
  const output = { ...(base || {}) };
  for (const [key, value] of Object.entries(patch)) {
    if (value && typeof value === 'object' && !Array.isArray(value)) output[key] = deepMerge(output[key], value);
    else output[key] = value;
  }
  return output;
}

export { toPosix, projectPath, ensureDir, readJson, writeJson, appendJsonLine, readJsonLines, updateGitignore, deepMerge };