const log = require('loglevel')
const ethUtil = require('ethereumjs-util')
const BN = ethUtil.BN
const bip39 = require('bip39')
const EventEmitter = require('events').EventEmitter
const ObservableStore = require('obs-store')
const filter = require('promise-filter')
const braveCrypto = require('brave-crypto')
const encryptor = require('browser-passworder')
const sigUtil = require('eth-sig-util')
const normalizeAddress = sigUtil.normalize
// Keyrings:
const SimpleKeyring = require('eth-simple-keyring')
const HdKeyring = require('eth-hd-keyring')
const keyringTypes = [
  SimpleKeyring,
  HdKeyring
]

const KEY_LENGTH = 32 // default key length in bytes
const TextEncoder = window.TextEncoder || require('util').TextEncoder
const TextDecoder = window.TextDecoder || require('util').TextDecoder

const moduleCacheRef = (moduleCache) => {
  if (window.WeakRef) {
    let ref = new window.WeakRef(moduleCache)
    moduleCache = null
    return ref
  }

  try {
    const weak = require('weak-napi')
    let ref = {
      _ref: weak(moduleCache),
      deref () {
        return weak.isDead(this._ref) ? null : this._ref
      }
    }

    moduleCache = null
    return ref
  } catch (e) {
  }

  return {
    deref () { return moduleCache }
  }
}

const clearFromCache = (instance) => {
  const moduleCache = MODULE_CACHE.deref()
  if (!moduleCache) {
    return
  }

  for (let key in moduleCache) {
    if (moduleCache[key].exports === instance) {
      delete moduleCache[key]
      return
    }
  }
}

const MODULE_CACHE = moduleCacheRef(arguments[5])

/**
 * Converts a string to a uint8array
 * @param {str} string
 * @returns {Uint8Array}
 */
const strToUint8Array = (str) => {
  return new TextEncoder('utf-8').encode(str)
}

/**
 * Converts uint8array to string
 * @param {Uint8Array} arr
 * @returns {str}
 */
const uint8ArrayToStr = (arr) => {
  return new TextDecoder('utf-8').decode(arr)
}

/**
 * Generates numBytes of random bytes and converts into a string
 * @param {number} numBytes
 * @returns {string}
 */
const getRandomString = (numBytes) => {
  const arr = braveCrypto.getSeed(numBytes)
  return uint8ArrayToStr(arr)
}


class KeyringController extends EventEmitter {

  // PUBLIC METHODS
  //
  // THE FIRST SECTION OF METHODS ARE PUBLIC-FACING,
  // MEANING THEY ARE USED BY CONSUMERS OF THIS CLASS.
  //
  // THEIR SURFACE AREA SHOULD BE CHANGED WITH GREAT CARE.

  constructor (opts) {
    super()
    const initState = opts.initState || {}
    this.keyringTypes = opts.keyringTypes ? keyringTypes.concat(opts.keyringTypes) : keyringTypes
    this.store = new ObservableStore(initState)
    this.memStore = new ObservableStore({
      isUnlocked: false,
      keyringTypes: this.keyringTypes.map(krt => krt.type),
      keyrings: []
    })

    this.encryptor = opts.encryptor || encryptor
    this.keyrings = []
    this.getNetwork = opts.getNetwork
  }

  // Full Update
  // returns @object state
  //
  // Emits the `update` event and
  // returns a Promise that resolves to the current state.
  //
  // Frequently used to end asynchronous chains in this class,
  // indicating consumers can often either listen for updates,
  // or accept a state-resolving promise to consume their results.
  //
  // Not all methods end with this, that might be a nice refactor.
  fullUpdate () {
    this.emit('update', this.memStore.getState())
    return this.memStore.getState()
  }

  // Create New Vault And Keychain
  // @string password - The password to encrypt the vault with
  //
  // returns Promise( @object state )
  //
  // Destroys any old encrypted storage,
  // creates a new encrypted store with the given password,
  // randomly creates a new HD wallet with 1 account,
  // faucets that account on the testnet.
  createNewVaultAndKeychain (password) {
    return this.persistAllKeyrings(password)
      .then(this.createFirstKeyTree.bind(this, password))
      .then(this.persistAllKeyrings.bind(this, password))
      .then(this.fullUpdate.bind(this))
  }

  // CreateNewVaultAndRestore
  // @string password - The password to encrypt the vault with
  // @string seed - The BIP44-compliant seed phrase.
  //
  // returns Promise( @object state )
  //
  // Destroys any old encrypted storage,
  // creates a new encrypted store with the given password,
  // creates a new HD wallet from the given seed with 1 account.
  createNewVaultAndRestore (password, seed) {
    if (typeof password !== 'string') {
      return Promise.reject('Password must be text.')
    }

    if (!bip39.validateMnemonic(seed)) {
      return Promise.reject(new Error('Seed phrase is invalid.'))
    }

    this.clearKeyrings()

    return this.persistAllKeyrings(password)
    .then(() => {
      return this.addNewKeyring('HD Key Tree', {
        mnemonic: seed,
        numberOfAccounts: 1,
        password
      })
    })
    .then((firstKeyring) => {
      return firstKeyring.getAccounts()
    })
    .then((accounts) => {
      const firstAccount = accounts[0]
      if (!firstAccount) throw new Error('KeyringController - First Account not found.')
      return null
    })
    .then(this.persistAllKeyrings.bind(this, password))
    .then(this.fullUpdate.bind(this))
  }

  // Set Locked
  // returns Promise( @object state )
  //
  // This method deallocates all secrets, and effectively locks metamask.
  async setLocked () {
    // set locked
    this.password = null
    this.masterKey = null
    this.memStore.updateState({ isUnlocked: false })
    // remove keyrings
    this.keyrings = []
    await this._updateMemStoreKeyrings()
    return this.fullUpdate()
  }

  // Submit Password
  // @string password
  //
  // returns Promise( @object state )
  //
  // Attempts to decrypt the current vault and load its keyrings
  // into memory.
  //
  // Temporarily also migrates any old-style vaults first, as well.
  // (Pre MetaMask 3.0.0)
  submitPassword (password) {
    this.masterKey = null
    this.memStore.updateState({ isUnlocked: false })
    return this.unlockKeyrings(password)
    .then((keyrings) => {
      this.keyrings = keyrings
      return this.fullUpdate()
    })
  }

  /**
   * Verify Password
   *
   * Attempts to decrypt the current vault with a given password
   * to verify its validity.
   *
   * @param {string} password
   */
  async verifyPassword (password) {
    this.masterKey = null
    return this.unlockKeyrings(password, false)
    .then((keyrings) => {
      this.keyrings = keyrings
    })
  }

  // Add New Keyring
  // @string type
  // @object opts
  //
  // returns Promise( @Keyring keyring )
  //
  // Adds a new Keyring of the given `type` to the vault
  // and the current decrypted Keyrings array.
  //
  // All Keyring classes implement a unique `type` string,
  // and this is used to retrieve them from the keyringTypes array.
  async addNewKeyring (type, opts) {
    if (opts && opts.password) {
      this.password = opts.password
      opts.encryptionKey = await this._getSubkey('ethwallet-encryptor')
    }
    const Keyring = this.getKeyringClassForType(type)
    const keyring = new Keyring(opts)
    return keyring.getAccounts()
    .then((accounts) => {
      return this.checkForDuplicate(type, accounts)
    })
    .then(() => {
        this.keyrings.push(keyring)
        return this.persistAllKeyrings()
    })
    .then(() => this._updateMemStoreKeyrings())
    .then(() => this.fullUpdate())
    .then(() => {
      return keyring
    })
  }

  // Remove Empty Keyrings
  // returns Void
  //
  // Loops through the keyrings and removes the ones
  // with empty accounts (usually after removing the last / only account)
  // from a keyring
  async removeEmptyKeyrings () {
    const validKeyrings = []

    // Since getAccounts returns a promise
    // We need to wait to hear back form each keyring
    // in order to decide which ones are now valid (accounts.length > 0)

    await Promise.all(this.keyrings.map(async (keyring) => {
      const accounts = await keyring.getAccounts()
      if(accounts.length > 0){
        validKeyrings.push(keyring)
      }
    }))
    this.keyrings = validKeyrings

  }

  // For now just checks for simple key pairs
  // but in the future
  // should possibly add HD and other types
  //
  checkForDuplicate (type, newAccount) {
    return this.getAccounts()
    .then((accounts) => {
      switch (type) {
        case 'Simple Key Pair':
          const isNotIncluded = !accounts.find((key) => key === newAccount[0] || key === ethUtil.stripHexPrefix(newAccount[0]))
          return (isNotIncluded) ? Promise.resolve(newAccount) : Promise.reject(new Error('The account you\'re are trying to import is a duplicate'))
        default:
          return Promise.resolve(newAccount)
      }
    })
  }


  // Add New Account
  // @number keyRingNum
  //
  // returns Promise( @object state )
  //
  // Calls the `addAccounts` method on the Keyring
  // in the keyrings array at index `keyringNum`,
  // and then saves those changes.
  addNewAccount (selectedKeyring) {
    return selectedKeyring.addAccounts(1)
    .then((accounts) => {
      accounts.forEach((hexAccount) => {
        this.emit('newAccount', hexAccount)
      })
    })
    .then(this.persistAllKeyrings.bind(this))
    .then(this._updateMemStoreKeyrings.bind(this))
    .then(this.fullUpdate.bind(this))
  }

  // Export Account
  // @string address
  //
  // returns Promise( @string privateKey )
  //
  // Requests the private key from the keyring controlling
  // the specified address.
  //
  // Returns a Promise that may resolve with the private key string.
  exportAccount (address) {
    try {
      return this.getKeyringForAccount(address)
      .then((keyring) => {
        return keyring.exportAccount(normalizeAddress(address))
      })
    } catch (e) {
      return Promise.reject(e)
    }
  }

  // Remove Account
  // @string address
  //
  // returns Promise( void )
  //
  // Removes a specific account from a keyring
  // If the account is the last/only one then it also removes the keyring.
  //
  // Returns a Promise.
  removeAccount (address) {
    return this.getKeyringForAccount(address)
    .then((keyring) => {
      // Not all the keyrings support this, so we have to check...
      if(typeof keyring.removeAccount === 'function') {
        keyring.removeAccount(address)
        this.emit('removedAccount', address)
        return keyring.getAccounts()

      } else {
        Promise.reject(`Keyring ${keyring.type} doesn't support account removal operations`)
      }
    })
    .then(accounts => {
      // Check if this was the last/only account
      if(accounts.length === 0){
        return this.removeEmptyKeyrings()
      }
    })
    .then(this.persistAllKeyrings.bind(this))
    .then(this._updateMemStoreKeyrings.bind(this))
    .then(this.fullUpdate.bind(this))
    .catch( e => {
      return Promise.reject(e)
    })
  }


  // SIGNING METHODS
  //
  // This method signs tx and returns a promise for
  // TX Manager to update the state after signing

  signTransaction (ethTx, _fromAddress, opts = {}) {
    const fromAddress = normalizeAddress(_fromAddress)
    return this.getKeyringForAccount(fromAddress)
    .then((keyring) => {
      return keyring.signTransaction(fromAddress, ethTx, opts)
    })
  }

  // Sign Message
  // @object msgParams
  //
  // returns Promise(@buffer rawSig)
  //
  // Attempts to sign the provided @object msgParams.
  signMessage (msgParams, opts = {}) {
    const address = normalizeAddress(msgParams.from)
    return this.getKeyringForAccount(address)
    .then((keyring) => {
      return keyring.signMessage(address, msgParams.data, opts)
    })
  }

  // Sign Personal Message
  // @object msgParams
  //
  // returns Promise(@buffer rawSig)
  //
  // Attempts to sign the provided @object msgParams.
  // Prefixes the hash before signing as per the new geth behavior.
  signPersonalMessage (msgParams, opts = {}) {
    const address = normalizeAddress(msgParams.from)
    return this.getKeyringForAccount(address)
    .then((keyring) => {
      return keyring.signPersonalMessage(address, msgParams.data, opts)
    })
  }

  // Get encryption public key
  // @object address
  //
  // returns Promise(@buffer publicKey)
  //
  // Get encryption public key for using in encrypt/decrypt process.
  getEncryptionPublicKey (_address, opts = {}) {
    const address = normalizeAddress(_address)
    return this.getKeyringForAccount(address)
    .then((keyring) => {
      return keyring.getEncryptionPublicKey(address, opts)
    })
  }
  
  // Decrypt Message
  // @object msgParams
  //
  // returns Promise(@buffer rawSig)
  //
  // Attempts to decrypt the provided @object msgParams.
  decryptMessage (msgParams, opts = {}) {
    const address = normalizeAddress(msgParams.from)
    return this.getKeyringForAccount(address)
    .then((keyring) => {
      return keyring.decryptMessage(address, msgParams.data, opts)
    })
  }

  // Sign Typed Message (EIP712 https://github.com/ethereum/EIPs/pull/712#issuecomment-329988454)
  signTypedMessage (msgParams, opts = { version: 'V1' }) {
    const address = normalizeAddress(msgParams.from)
    return this.getKeyringForAccount(address)
      .then((keyring) => {
      return keyring.signTypedData(address, msgParams.data, opts)
    })
  }

  // returns an app key
  async getAppKeyAddress (_address, origin) {
    const address = normalizeAddress(_address)
    const keyring = await this.getKeyringForAccount(address)
    return keyring.getAppKeyAddress(address, origin)
  }

  async exportAppKeyForAddress(_address, origin) {
    const address = normalizeAddress(_address)
    const keyring = await this.getKeyringForAccount(address)
    if (!('exportAccount' in keyring)) {
      throw new Error(`The keyring for address ${_address} does not support exporting.`)
    }
    return keyring.exportAccount(address, { withAppKeyOrigin: origin })
  }

  // PRIVATE METHODS
  //
  // THESE METHODS ARE ONLY USED INTERNALLY TO THE KEYRING-CONTROLLER
  // AND SO MAY BE CHANGED MORE LIBERALLY THAN THE ABOVE METHODS.

  // Create First Key Tree
  // returns @Promise
  //
  // Clears the vault,
  // creates a new one,
  // creates a random new HD Keyring with 1 account,
  // makes that account the selected account,
  // faucets that account on testnet,
  // puts the current seed words into the state tree.
  createFirstKeyTree (password) {
    this.clearKeyrings()
    return this.addNewKeyring('HD Key Tree', { numberOfAccounts: 1, password })
    .then((keyring) => {
      return keyring.getAccounts()
    })
    .then((accounts) => {
      const firstAccount = accounts[0]
      if (!firstAccount) throw new Error('KeyringController - No account found on keychain.')
      const hexAccount = normalizeAddress(firstAccount)
      this.emit('newVault', hexAccount)
      return null
    })
  }

  // Persist All Keyrings
  // @password string
  //
  // returns Promise
  //
  // Iterates the current `keyrings` array,
  // serializes each one into a serialized array,
  // encrypts that array with the provided `password`,
  // and persists that encrypted string to storage.
  async persistAllKeyrings (password = this.password) {
    if (typeof password !== 'string') {
      return Promise.reject('KeyringController - password is not a string')
    }

    this.password = password
    const subkey = await this._getSubkey('metamask-encryptor')
    this.memStore.updateState({ isUnlocked: true })
    return Promise.all(this.keyrings.map((keyring) => {
      return Promise.all([keyring.type, keyring.serialize()])
      .then((serializedKeyringArray) => {
        // Label the output values on each serialized Keyring:
        return {
          type: serializedKeyringArray[0],
          data: serializedKeyringArray[1],
        }
      })
    }))
    .then((serializedKeyrings) => {
      return this.encryptor.encrypt(
        uint8ArrayToStr(subkey),
        serializedKeyrings
      )
    })
    .then((encryptedString) => {
      this.store.updateState({ vault: encryptedString })
      return true
    })
  }

  // Unlock Keyrings
  // @string password
  //
  // returns Promise( @array keyrings )
  //
  // Attempts to unlock the persisted encrypted storage,
  // initializing the persisted keyrings to RAM.
  async unlockKeyrings (password, clearKeyrings = true) {
    const storedState = this.store.getState()
    const encryptedVault = storedState.vault
    const salt = storedState.salt
    const argonParams = storedState.argonParams
    if (!encryptedVault) {
      throw new Error('Cannot unlock without a previous vault.')
    }

    if (clearKeyrings) {
      await this.clearKeyrings()
    }

    this.password = password
    const subkey = await this._getSubkey('metamask-encryptor', salt, argonParams)
    const vault = await this.encryptor.decrypt(
      uint8ArrayToStr(subkey),
      encryptedVault
    )
    this.memStore.updateState({ isUnlocked: true })

    if (clearKeyrings) {
      await Promise.all(vault.map(this.restoreKeyring.bind(this)))
    }

    return this.keyrings
  }

  // Restore Keyring
  // @object serialized
  //
  // returns Promise( @Keyring deserialized )
  //
  // Attempts to initialize a new keyring from the provided
  // serialized payload.
  //
  // On success, returns the resulting @Keyring instance.
  restoreKeyring (serialized) {
    const { type, data } = serialized

    const Keyring = this.getKeyringClassForType(type)
    const keyring = new Keyring()
    return keyring.deserialize(data)
    .then(() => {
      return keyring.getAccounts()
    })
    .then(() => {
      this.keyrings.push(keyring)
      return this._updateMemStoreKeyrings()
    })
    .then(() => {
      return keyring
    })
  }

  // Get Keyring Class For Type
  // @string type
  //
  // Returns @class Keyring
  //
  // Searches the current `keyringTypes` array
  // for a Keyring class whose unique `type` property
  // matches the provided `type`,
  // returning it if it exists.
  getKeyringClassForType (type) {
    return this.keyringTypes.find(kr => kr.type === type)
  }

  getKeyringsByType (type) {
    return this.keyrings.filter((keyring) => keyring.type === type)
  }

  // Get Accounts
  // returns Promise( @Array[ @string accounts ] )
  //
  // Returns the public addresses of all current accounts
  // managed by all currently unlocked keyrings.
  async getAccounts () {
    const keyrings = this.keyrings || []
    const addrs = await Promise.all(keyrings.map(kr => kr.getAccounts()))
    .then((keyringArrays) => {
      return keyringArrays.reduce((res, arr) => {
        return res.concat(arr)
      }, [])
    })
    return addrs.map(normalizeAddress)
  }

  // Get Keyring For Account
  // @string address
  //
  // returns Promise(@Keyring keyring)
  //
  // Returns the currently initialized keyring that manages
  // the specified `address` if one exists.
  getKeyringForAccount (address) {
    const hexed = normalizeAddress(address)
    log.debug(`KeyringController - getKeyringForAccount: ${hexed}`)

    return Promise.all(this.keyrings.map((keyring) => {
      return Promise.all([
        keyring,
        keyring.getAccounts(),
      ])
    }))
    .then((candidates) => {
      const winners = candidates.filter(candidate => {
        const accounts = candidate[1].map(normalizeAddress)
        return accounts.includes(hexed)
      })
      if (winners && winners.length > 0) {
        return winners[0][0]
      } else {
        throw new Error('No keyring found for the requested account.')
      }
    })
  }

  // Display For Keyring
  // @Keyring keyring
  //
  // returns Promise( @Object { type:String, accounts:Array } )
  //
  // Is used for adding the current keyrings to the state object.
  displayForKeyring (keyring) {
    return keyring.getAccounts()
    .then((accounts) => {
      return {
        type: keyring.type,
        accounts: accounts.map(normalizeAddress),
      }
    })
  }

  // Add Gas Buffer
  // @string gas (as hexadecimal value)
  //
  // returns @string bufferedGas (as hexadecimal value)
  //
  // Adds a healthy buffer of gas to an initial gas estimate.
  addGasBuffer (gas) {
    const gasBuffer = new BN('100000', 10)
    const bnGas = new BN(ethUtil.stripHexPrefix(gas), 16)
    const correct = bnGas.add(gasBuffer)
    return ethUtil.addHexPrefix(correct.toString(16))
  }

  // Clear Keyrings
  //
  // Deallocates all currently managed keyrings and accounts.
  // Used before initializing a new vault.
  async clearKeyrings () {
    // clear keyrings from memory
    this.keyrings = []
    this.memStore.updateState({
      keyrings: []
    })
  }

  async _updateMemStoreKeyrings () {
    const keyrings = await Promise.all(this.keyrings.map(this.displayForKeyring))
    return this.memStore.updateState({ keyrings })
  }

  /**
   * Returns argon2id hash of a given string
   * @param {string} str
   * @param {string?} salt
   * @param {object?} argonParams
   */
  async _getArgon2Hash (str, salt, argonParams = {}) {
    if (!str || !salt) {
      throw new Error('Missing password or salt for argon2 hashing.')
    }
    const params = {
      pass: str,
      salt
    }
    // Default argon2 params
    const argon2 = require('argon2-wasm')
    const newArgonParams = {
      hashLen: KEY_LENGTH,
      time: 1, // takes about 1.5s on a top-tier mbp (2017)
      mem: 500000,
      type: argon2.types.Argon2id
    }
    Object.assign(newArgonParams, argonParams)
    const result = await argon2.hash(
      Object.assign(params, newArgonParams)
    )
    this.masterKey = result
    this.salt = salt
    this.store.updateState({ salt })
    this.store.updateState({argonParams: newArgonParams})
    clearFromCache(argon2)
  }

  /**
   * Gets a subkey using hkdf-sha-512
   * @param {str} info
   * @param {string?} salt
   * @param {object?} argonParams
   * @returns {Uint8Array}
   */
  async _getSubkey (info, salt, argonParams) {
    if (!this.masterKey) {
      salt = salt || this.salt || getRandomString(32)
      await this._getArgon2Hash(this.password, salt, argonParams)
    }
    return braveCrypto.getHKDF(this.masterKey.hash, strToUint8Array(info), KEY_LENGTH)
  }
}

module.exports = KeyringController