'use strict';

const u = require('universalify').fromCallback;
const path = require('path');
const fs = require('graceful-fs');
const mkdir = require('../mkdirs');
const pathExists = require('../path-exists').pathExists;

function createLink(srcpath, dstpath, callback) {
  function makeLink(srcpath, dstpath) {
    fs.link(srcpath, dstpath, (err) => {
      if (err) return callback(err);
      callback(null);
    });
  }

  pathExists(dstpath, (err, destinationExists) => {
    if (err) return callback(err);
    if (destinationExists) return callback(null);
    fs.lstat(srcpath, (err) => {
      if (err) {
        err.message = err.message.replace('lstat', 'ensureLink');
        return callback(err);
      }

      const dir = path.dirname(dstpath);
      pathExists(dir, (err, dirExists) => {
        if (err) return callback(err);
        if (dirExists) return makeLink(srcpath, dstpath);
        mkdir.mkdirs(dir, (err) => {
          if (err) return callback(err);
          makeLink(srcpath, dstpath);
        });
      });
    });
  });
}

function createLinkSync(srcpath, dstpath) {
  const destinationExists = fs.existsSync(dstpath);
  if (destinationExists) return undefined;

  try {
    fs.lstatSync(srcpath);
  } catch (err) {
    err.message = err.message.replace('lstat', 'ensureLink');
    throw err;
  }

  const dir = path.dirname(dstpath);
  const dirExists = fs.existsSync(dir);
  if (dirExists) return fs.linkSync(srcpath, dstpath);
  mkdir.mkdirsSync(dir);

  return fs.linkSync(srcpath, dstpath);
}

module.exports = {
  createLink: u(createLink),
  createLinkSync,
};