import EventEmitter from 'events'
import ObservableStore from 'obs-store'
import { ethErrors } from 'eth-json-rpc-errors'
import createId from './random-id'
import log from 'loglevel'
import { MESSAGE_TYPE } from './enums'

/**
 * Represents, and contains data about, an 'eth_getEncryptionPublicKey' type request. These are created when
 * an eth_getEncryptionPublicKey call is requested.
 *
 * @typedef {Object} EncryptionPublicKey
 * @property {number} id An id to track and identify the message object
 * @property {Object} msgParams The parameters to pass to the encryptionPublicKey method once the request is
 * approved.
 * @property {Object} msgParams.metamaskId Added to msgParams for tracking and identification within MetaMask.
 * @property {string} msgParams.data A hex string conversion of the raw buffer data of the request
 * @property {number} time The epoch time at which the this message was created
 * @property {string} status Indicates whether the request is 'unapproved', 'approved', 'received' or 'rejected'
 * @property {string} type The json-prc method for which a request has been made. A 'Message' will
 * always have a 'eth_getEncryptionPublicKey' type.
 *
 */

export default class EncryptionPublicKeyManager extends EventEmitter {
  /**
   * Controller in charge of managing - storing, adding, removing, updating - EncryptionPublicKey.
   *
   * @typedef {Object} EncryptionPublicKeyManager
   * @property {Object} memStore The observable store where EncryptionPublicKey are saved with persistance.
   * @property {Object} memStore.unapprovedEncryptionPublicKeyMsgs A collection of all EncryptionPublicKeys in the 'unapproved' state
   * @property {number} memStore.unapprovedEncryptionPublicKeyMsgCount The count of all EncryptionPublicKeys in this.memStore.unapprobedMsgs
   * @property {array} messages Holds all messages that have been created by this EncryptionPublicKeyManager
   *
   */
  constructor () {
    super()
    this.memStore = new ObservableStore({
      unapprovedEncryptionPublicKeyMsgs: {},
      unapprovedEncryptionPublicKeyMsgCount: 0,
    })
    this.messages = []
  }

  /**
   * A getter for the number of 'unapproved' EncryptionPublicKeys in this.messages
   *
   * @returns {number} The number of 'unapproved' EncryptionPublicKeys in this.messages
   *
   */
  get unapprovedEncryptionPublicKeyMsgCount () {
    return Object.keys(this.getUnapprovedMsgs()).length
  }

  /**
   * A getter for the 'unapproved' EncryptionPublicKeys in this.messages
   *
   * @returns {Object} An index of EncryptionPublicKey ids to EncryptionPublicKeys, for all 'unapproved' EncryptionPublicKeys in
   * this.messages
   *
   */
  getUnapprovedMsgs () {
    return this.messages.filter((msg) => msg.status === 'unapproved')
      .reduce((result, msg) => {
        result[msg.id] = msg; return result
      }, {})
  }

  /**
   * Creates a new EncryptionPublicKey with an 'unapproved' status using the passed msgParams. this.addMsg is called to add
   * the new EncryptionPublicKey to this.messages, and to save the unapproved EncryptionPublicKeys from that list to
   * this.memStore.
   *
   * @param {Object} address The param for the eth_getEncryptionPublicKey call to be made after the message is approved.
   * @param {Object} req (optional) The original request object possibly containing the origin
   * @returns {Promise<Buffer>} The raw public key contents
   *
   */
  addUnapprovedMessageAsync (address, req) {
    return new Promise((resolve, reject) => {
      if (!address) {
        reject(new Error('MetaMask Message: address field is required.'))
      }
      const msgId = this.addUnapprovedMessage(address, req)
      this.once(`${msgId}:finished`, (data) => {
        switch (data.status) {
          case 'received':
            return resolve(data.rawData)
          case 'rejected':
            return reject(ethErrors.provider.userRejectedRequest('MetaMask EncryptionPublicKey: User denied message EncryptionPublicKey.'))
          default:
            return reject(new Error(`MetaMask EncryptionPublicKey: Unknown problem: ${JSON.stringify(address)}`))
        }
      })
    })
  }

  /**
   * Creates a new EncryptionPublicKey with an 'unapproved' status using the passed msgParams. this.addMsg is called to add
   * the new EncryptionPublicKey to this.messages, and to save the unapproved EncryptionPublicKeys from that list to
   * this.memStore.
   *
   * @param {Object} address The param for the eth_getEncryptionPublicKey call to be made after the message is approved.
   * @param {Object} _req (optional) The original request object possibly containing the origin
   * @returns {number} The id of the newly created EncryptionPublicKey.
   *
   */
  addUnapprovedMessage (address, req) {
    log.debug(`EncryptionPublicKeyManager addUnapprovedMessage: address`)
    // create txData obj with parameters and meta data
    const time = (new Date()).getTime()
    const msgId = createId()
    const msgData = {
      id: msgId,
      msgParams: address,
      time: time,
      status: 'unapproved',
      type: MESSAGE_TYPE.ETH_GET_ENCRYPTION_PUBLIC_KEY,
    }

    if (req) {
      msgData.origin = req.origin
    }

    this.addMsg(msgData)

    // signal update
    this.emit('update')
    return msgId
  }

  /**
   * Adds a passed EncryptionPublicKey to this.messages, and calls this._saveMsgList() to save the unapproved EncryptionPublicKeys from that
   * list to this.memStore.
   *
   * @param {Message} msg The EncryptionPublicKey to add to this.messages
   *
   */
  addMsg (msg) {
    this.messages.push(msg)
    this._saveMsgList()
  }

  /**
   * Returns a specified EncryptionPublicKey.
   *
   * @param {number} msgId The id of the EncryptionPublicKey to get
   * @returns {EncryptionPublicKey|undefined} The EncryptionPublicKey with the id that matches the passed msgId, or undefined
   * if no EncryptionPublicKey has that id.
   *
   */
  getMsg (msgId) {
    return this.messages.find((msg) => msg.id === msgId)
  }

  /**
   * Approves a EncryptionPublicKey. Sets the message status via a call to this.setMsgStatusApproved, and returns a promise
   * with any the message params modified for proper providing.
   *
   * @param {Object} msgParams The msgParams to be used when eth_getEncryptionPublicKey is called, plus data added by MetaMask.
   * @param {Object} msgParams.metamaskId Added to msgParams for tracking and identification within MetaMask.
   * @returns {Promise<object>} Promises the msgParams object with metamaskId removed.
   *
   */
  approveMessage (msgParams) {
    this.setMsgStatusApproved(msgParams.metamaskId)
    return this.prepMsgForEncryptionPublicKey(msgParams)
  }

  /**
   * Sets a EncryptionPublicKey status to 'approved' via a call to this._setMsgStatus.
   *
   * @param {number} msgId The id of the EncryptionPublicKey to approve.
   *
   */
  setMsgStatusApproved (msgId) {
    this._setMsgStatus(msgId, 'approved')
  }

  /**
   * Sets a EncryptionPublicKey status to 'received' via a call to this._setMsgStatus and updates that EncryptionPublicKey in
   * this.messages by adding the raw data of request to the EncryptionPublicKey
   *
   * @param {number} msgId The id of the EncryptionPublicKey.
   * @param {buffer} rawData The raw data of the message request
   *
   */
  setMsgStatusReceived (msgId, rawData) {
    const msg = this.getMsg(msgId)
    msg.rawData = rawData
    this._updateMsg(msg)
    this._setMsgStatus(msgId, 'received')
  }

  /**
   * Removes the metamaskId property from passed msgParams and returns a promise which resolves the updated msgParams
   *
   * @param {Object} msgParams The msgParams to modify
   * @returns {Promise<object>} Promises the msgParams with the metamaskId property removed
   *
   */
  prepMsgForEncryptionPublicKey (msgParams) {
    delete msgParams.metamaskId
    return Promise.resolve(msgParams)
  }

  /**
   * Sets a EncryptionPublicKey status to 'rejected' via a call to this._setMsgStatus.
   *
   * @param {number} msgId The id of the EncryptionPublicKey to reject.
   *
   */
  rejectMsg (msgId) {
    this._setMsgStatus(msgId, 'rejected')
  }

  /**
   * Sets a TypedMessage status to 'errored' via a call to this._setMsgStatus.
   *
   * @param {number} msgId The id of the TypedMessage to error
   *
   */
  errorMessage (msgId, error) {
    const msg = this.getMsg(msgId)
    msg.error = error
    this._updateMsg(msg)
    this._setMsgStatus(msgId, 'errored')
  }

  /**
   * Updates the status of a EncryptionPublicKey in this.messages via a call to this._updateMsg
   *
   * @private
   * @param {number} msgId The id of the EncryptionPublicKey to update.
   * @param {string} status The new status of the EncryptionPublicKey.
   * @throws A 'EncryptionPublicKeyManager - EncryptionPublicKey not found for id: "${msgId}".' if there is no EncryptionPublicKey
   * in this.messages with an id equal to the passed msgId
   * @fires An event with a name equal to `${msgId}:${status}`. The EncryptionPublicKey is also fired.
   * @fires If status is 'rejected' or 'received', an event with a name equal to `${msgId}:finished` is fired along
   * with the EncryptionPublicKey
   *
   */
  _setMsgStatus (msgId, status) {
    const msg = this.getMsg(msgId)
    if (!msg) {
      throw new Error('EncryptionPublicKeyManager - Message not found for id: "${msgId}".')
    }
    msg.status = status
    this._updateMsg(msg)
    this.emit(`${msgId}:${status}`, msg)
    if (status === 'rejected' || status === 'received') {
      this.emit(`${msgId}:finished`, msg)
    }
  }

  /**
   * Sets a EncryptionPublicKey in this.messages to the passed EncryptionPublicKey if the ids are equal. Then saves the
   * unapprovedEncryptionPublicKeyMsgs index to storage via this._saveMsgList
   *
   * @private
   * @param {msg} EncryptionPublicKey A EncryptionPublicKey that will replace an existing EncryptionPublicKey (with the same
   * id) in this.messages
   *
   */
  _updateMsg (msg) {
    const index = this.messages.findIndex((message) => message.id === msg.id)
    if (index !== -1) {
      this.messages[index] = msg
    }
    this._saveMsgList()
  }

  /**
   * Saves the unapproved EncryptionPublicKeys, and their count, to this.memStore
   *
   * @private
   * @fires 'updateBadge'
   *
   */
  _saveMsgList () {
    const unapprovedEncryptionPublicKeyMsgs = this.getUnapprovedMsgs()
    const unapprovedEncryptionPublicKeyMsgCount = Object.keys(unapprovedEncryptionPublicKeyMsgs).length
    this.memStore.updateState({ unapprovedEncryptionPublicKeyMsgs, unapprovedEncryptionPublicKeyMsgCount })
    this.emit('updateBadge')
  }

}