import fs from 'fs'
import path from 'path'
import util from 'util'
import crypto from 'crypto'
import Memory from './memory.mjs'

const fsPromise = fs.promises

//
// ### function File (options)
// #### @options {Object} Options for this instance
// Constructor function for the File nconf store, a simple abstraction
// around the Memory store that can persist configuration to disk.
//
const File = function (orgOpts) {
  let options = orgOpts
  if (typeof(options) === 'string') {
    options = { file: options }
  }
  if (!options || !options.file) {
    throw new Error('Missing required option `file`')
  }

  Memory.call(this, options)

  this.file    = options.file
  //  this.dir     = options.dir    || process.cwd()
  this.format  = options.format || JSON
  this.secure  = options.secure
  // this.spacing = options.json_spacing || options.spacing || 2

  if (this.secure) {
    this.secure = typeof(this.secure === 'string')
      ? { secret: this.secure.toString() }
      : this.secure

    this.secure.alg = this.secure.alg || 'aes-256-ctr'
    // if (this.secure.secretPath) {
    //   this.secure.secret = fs.readFileSync(this.secure.secretPath, 'utf8')
    // }

    if (!this.secure.secret) {
      throw new Error('secure.secret option is required')
    }
  }

  // if (options.search) {
  //   this.search(this.dir)
  // }
}

// Inherit from the Memory store
util.inherits(File, Memory)

File.prototype.load = function () {
  this.store = {}

  let fileData
  try {
    fileData = fs.readFileSync(this.file, 'utf8')
  }
  catch (ex) {
    throw new Error('Error opening ' + this.file + ': ' + ex.message)
  }

  // Deals with file that include BOM
  if (fileData.charAt(0) === '\uFEFF') {
    fileData = fileData.substr(1)
  }

  try {
    this.store = this.parse(fileData)
  }
  catch (ex) {
    throw new Error("Error parsing your configuration file: [" + this.file + ']: ' + ex.message)
  }

  return this.store
}

File.prototype.loadAsync = function () {
  this.store = {}

  return fsPromise.readFile(this.file, 'utf8')
  .then(fileData => {
    let data = fileData
    if (data.charAt(0) === '\uFEFF') {
      data = data.substr(1)
    }

    try {
      this.store = this.parse(data)
    } catch (err) {
      return Promise.reject(new Error("Error parsing your configuration file: [" + this.file + ']: ' + err.message))
    }

    return this.store
  }, err => {
    return Promise.reject(new Error('Error opening ' + this.file + ': ' + err.message))
  })
}


//
// ### function parse (contents)
// Returns a decrypted version of the contents IFF
// `this.secure` is enabled.
//
File.prototype.parse = function (contents) {
  let parsed = this.format.parse(contents)

  if (this.secure) {
    parsed = Object.keys(parsed).reduce((acc, key) => {
      let value = parsed[key]
      if (!value.iv) {
        throw new Error(`Encrypted file ${this.file} is outdated (encrypted without iv). Please re-encrypt your file.`)
      }
      let decipher = crypto.createDecipheriv(value.alg, this.secure.secret, Buffer.from(value.iv, 'hex'))
      let plaintext = decipher.update(value.value, 'hex', 'utf8')
      plaintext += decipher.final('utf8')
      acc[key] = this.format.parse(plaintext)
      return acc
    }, {})
  }

  return parsed
}

//
// ### function save (path)
// #### @path {string} The path to the file where we save the configuration to  
// Saves the current configuration object to disk at `this.file`
//
File.prototype.save = function (orgPath) {
  let path = orgPath
  if (!path) {
    path = this.file
  }
  fs.writeFileSync(path, this.stringify())

  return this
}

//
// ### function save (path)
// #### @path {string} The path to the file where we save the configuration to  
// Saves the current configuration object to disk at `this.file`
//
File.prototype.saveAsync = function(orgPath) {
  let path = orgPath
  if (!path) {
    path = this.file
  }

  return fsPromise.writeFile(path, this.stringify()).then(() => {
    return this
  })
}

//
// ### function stringify ()
// Returns an encrypted version of the contents IIF
// `this.secure` is enabled
//
File.prototype.stringify = function () {
  let data = this.store

  if (this.secure) {
    data = Object.keys(data).reduce((acc, key) => {
      let value = this.format.stringify(data[key])
      let iv = crypto.randomBytes(16)
      let cipher = crypto.createCipheriv(this.secure.alg, this.secure.secret, iv)
      let ciphertext = cipher.update(value, 'utf8', 'hex')
      ciphertext += cipher.final('hex')
      acc[key] = { alg: this.secure.alg, value: ciphertext, iv: iv.toString('hex') }
      return acc
    }, {})
  }

  return this.format.stringify(data, null, this.spacing)
}

/*

//
// ### function save (value, callback)
// #### @value {Object} _Ignored_ Left here for consistency
// #### @callback {function} Continuation to respond to when complete.
// Saves the current configuration object to disk at `this.file`
// using the format specified by `this.format`.
//
File.prototype.save = function (value, callback) {
  this.saveToFile(this.file, value, callback)
}

//
// ### function saveToFile (path, value, callback)
// #### @path {string} The path to the file where we save the configuration to  
// #### @format {Object} Optional formatter, default behing the one of the store
// #### @callback {function} Continuation to respond to when complete.
// Saves the current configuration object to disk at `this.file`
// using the format specified by `this.format`.
//
File.prototype.saveToFile = function (path, format, callback) {
  if (!callback) {
    callback = format
    format = this.format
  }

  fs.writeFile(path, this.stringify(format), callback)
}

//
// ### function saveSync (value, callback)
// Saves the current configuration object to disk at `this.file`
// using the format specified by `this.format` synchronously.
//
File.prototype.saveSync = function () {
  fs.writeFileSync(this.file, this.stringify())
  return this.store
}

//
// ### function load (callback)
// #### @callback {function} Continuation to respond to when complete.
// Responds with an Object representing all keys associated in this instance.
//
File.prototype.load = function (callback) {
  let self = this

  exists(self.file, function (exists) {
    if (!exists) {
      return callback(null, {})
    }

    //
    // Else, the path exists, read it from disk
    //
    fs.readFile(self.file, function (err, data) {
      if (err) {
        return callback(err)
      }

      try {
        // Deals with string that include BOM
        let stringData = data.toString()
        if (stringData.charAt(0) === '\uFEFF') {
          stringData = stringData.substr(1)
        }

        self.store = self.parse(stringData)
      }
      catch (ex) {
        return callback(new Error("Error parsing your configuration file: [" + self.file + ']: ' + ex.message))
      }

      callback(null, self.store)
    })
  })
}

//
// ### function loadSync (callback)
// Attempts to load the data stored in `this.file` synchronously
// and responds appropriately.
//
File.prototype.loadSync = function () {
  if (!existsSync(this.file)) {
    this.store = {}
    return this.store
  }

  //
  // Else, the path exists, read it from disk
  //
  try {
    // Deals with file that include BOM
    let fileData = fs.readFileSync(this.file, 'utf8')
    if (fileData.charAt(0) === '\uFEFF') {
      fileData = fileData.substr(1)
    }

    this.store = this.parse(fileData)
  }
  catch (ex) {
    throw new Error("Error parsing your configuration file: [" + this.file + ']: ' + ex.message)
  }

  return this.store
}


//
// ### function search (base)
// #### @base {string} Base directory (or file) to begin searching for the target file.
// Attempts to find `this.file` by iteratively searching up the
// directory structure
//
File.prototype.search = function (base) {
  let looking = true,
      fullpath,
      previous,
      stats

  base = base || process.cwd()

  if (this.file[0] === '/') {
    //
    // If filename for this instance is a fully qualified path
    // (i.e. it starts with a `'/'`) then check if it exists
    //
    try {
      stats = fs.statSync(fs.realpathSync(this.file))
      if (stats.isFile()) {
        fullpath = this.file
        looking = false
      }
    }
    catch (ex) {
      //
      // Ignore errors
      //
    }
  }

  if (looking && base) {
    //
    // Attempt to stat the realpath located at `base`
    // if the directory does not exist then return false.
    //
    try {
      let stat = fs.statSync(fs.realpathSync(base))
      looking = stat.isDirectory()
    }
    catch (ex) {
      return false
    }
  }

  while (looking) {
    //
    // Iteratively look up the directory structure from `base`
    //
    try {
      stats = fs.statSync(fs.realpathSync(fullpath = path.join(base, this.file)))
      looking = stats.isDirectory()
    }
    catch (ex) {
      previous = base
      base = path.dirname(base)

      if (previous === base) {
        //
        // If we've reached the top of the directory structure then simply use
        // the default file path.
        //
        try {
          stats = fs.statSync(fs.realpathSync(fullpath = path.join(this.dir, this.file)))
          if (stats.isDirectory()) {
            fullpath = undefined
          }
        }
        catch (ex) {
          //
          // Ignore errors
          //
        }

        looking = false
      }
    }
  }

  //
  // Set the file for this instance to the fullpath
  // that we have found during the search. In the event that
  // the search was unsuccessful use the original value for `this.file`.
  //
  this.file = fullpath || this.file

  return fullpath
}

*/

export default File