const path = require('path');
const fm = require('front-matter');
const escapeStringRegexp = require('escape-string-regexp');
const fs = require('fs-extra');

const genPath = path.resolve(__dirname, '../core/generated');
fs.ensureDirSync(genPath);

const genCache = new Map();
async function generate(file, content) {
  const cached = genCache.get(file);
  if (cached !== content) {
    await fs.writeFile(path.join(genPath, file), content);
    genCache.set(file, content);
  }
}

const indexRE = /(^|.*\/)index\.(md|js)$/i;
const extRE = /\.(md|js)$/;

function fileToPath(file) {
  if (indexRE.test(file)) {
    return file.replace(indexRE, '/$1');
  }
  return `/${file.replace(extRE, '').replace(/\\/g, '/')}`;
}

function encodePath(userpath) {
  return userpath
    .split('/')
    .map(item => encodeURIComponent(item))
    .join('/');
}

function fileToComponentName(file) {
  const ext = extRE.exec(file)[1];
  let str = file.replace(extRE, '');
  str = str.replace(/([A-Z])/g, ' $1');
  str = str.replace(/^[\W_]+|[\W_]+$/g, '').toLowerCase();
  str = str.charAt(0).toUpperCase() + str.slice(1);
  str = str.replace(/[\W_]+(\w|$)/g, (_, ch) => ch.toUpperCase());
  return ext ? ext.toUpperCase() + str : str;
}

function idx(target, keyPaths) {
  return (
    target &&
    (Array.isArray(keyPaths)
      ? keyPaths.reduce((obj, key) => obj && obj[key], target)
      : target[keyPaths])
  );
}

function getSubFolder(file, refDir) {
  const separator = escapeStringRegexp(path.sep);
  const baseDir = escapeStringRegexp(path.basename(refDir));
  const regexSubFolder = new RegExp(
    `${baseDir}${separator}(.*?)${separator}.*`
  );
  const match = regexSubFolder.exec(file);
  return match && match[1];
}

function parse(fileString) {
  if (!fm.test(fileString)) {
    return {metadata: null, content: fileString};
  }
  const {attributes: metadata, body: content} = fm(fileString);

  return {metadata, content};
}

module.exports = {
  encodePath,
  generate,
  fileToPath,
  fileToComponentName,
  getSubFolder,
  idx,
  parse
};