'use strict'
 
const u = require('universalify').fromCallback
const path = require('path')
const fs = require('graceful-fs')
const _mkdirs = require('../mkdirs')
const mkdirs = _mkdirs.mkdirs
const mkdirsSync = _mkdirs.mkdirsSync
 
const _symlinkPaths = require('./symlink-paths')
const symlinkPaths = _symlinkPaths.symlinkPaths
const symlinkPathsSync = _symlinkPaths.symlinkPathsSync
 
const _symlinkType = require('./symlink-type')
const symlinkType = _symlinkType.symlinkType
const symlinkTypeSync = _symlinkType.symlinkTypeSync
 
const pathExists = require('../path-exists').pathExists
 
function createSymlink (srcpath, dstpath, type, callback) {
  callback = (typeof type === 'function') ? type : callback
  type = (typeof type === 'function') ? false : type
 
  pathExists(dstpath, (err, destinationExists) => {
    if (err) return callback(err)
    if (destinationExists) return callback(null)
    symlinkPaths(srcpath, dstpath, (err, relative) => {
      if (err) return callback(err)
      srcpath = relative.toDst
      symlinkType(relative.toCwd, type, (err, type) => {
        if (err) return callback(err)
        const dir = path.dirname(dstpath)
        pathExists(dir, (err, dirExists) => {
          if (err) return callback(err)
          if (dirExists) return fs.symlink(srcpath, dstpath, type, callback)
          mkdirs(dir, err => {
            if (err) return callback(err)
            fs.symlink(srcpath, dstpath, type, callback)
          })
        })
      })
    })
  })
}
 
function createSymlinkSync (srcpath, dstpath, type, callback) {
  callback = (typeof type === 'function') ? type : callback
  type = (typeof type === 'function') ? false : type
 
  const destinationExists = fs.existsSync(dstpath)
  if (destinationExists) return undefined
 
  const relative = symlinkPathsSync(srcpath, dstpath)
  srcpath = relative.toDst
  type = symlinkTypeSync(relative.toCwd, type)
  const dir = path.dirname(dstpath)
  const exists = fs.existsSync(dir)
  if (exists) return fs.symlinkSync(srcpath, dstpath, type)
  mkdirsSync(dir)
  return fs.symlinkSync(srcpath, dstpath, type)
}
 
module.exports = {
  createSymlink: u(createSymlink),
  createSymlinkSync
}