import { Payment, PaymentOpts } from './index' // eslint-disable-line
import * as bscript from '../script'
import * as bcrypto from '../crypto'
import * as lazy from './lazy'
import { bitcoin as BITCOIN_NETWORK } from '../networks'
const typef = require('typeforce')
const OPS = bscript.OPS
const ecc = require('tiny-secp256k1')

const bech32 = require('bech32')

const EMPTY_BUFFER = Buffer.alloc(0)

// witness: {signature} {pubKey}
// input: <>
// output: OP_0 {pubKeyHash}
export function p2wpkh (a: Payment, opts?: PaymentOpts): Payment {
  if (
    !a.address &&
    !a.hash &&
    !a.output &&
    !a.pubkey &&
    !a.witness
  ) throw new TypeError('Not enough data')
  opts = Object.assign({ validate: true }, opts || {})

  typef({
    address: typef.maybe(typef.String),
    hash: typef.maybe(typef.BufferN(20)),
    input: typef.maybe(typef.BufferN(0)),
    network: typef.maybe(typef.Object),
    output: typef.maybe(typef.BufferN(22)),
    pubkey: typef.maybe(ecc.isPoint),
    signature: typef.maybe(bscript.isCanonicalScriptSignature),
    witness: typef.maybe(typef.arrayOf(typef.Buffer))
  }, a)

  const _address = lazy.value(function () {
    const result = bech32.decode(a.address)
    const version = result.words.shift()
    const data = bech32.fromWords(result.words)
    return {
      version,
      prefix: result.prefix,
      data: Buffer.from(data)
    }
  })

  const network = a.network || BITCOIN_NETWORK
  const o: Payment = { network }

  lazy.prop(o, 'address', function () {
    if (!o.hash) return

    const words = bech32.toWords(o.hash)
    words.unshift(0x00)
    return bech32.encode(network.bech32, words)
  })
  lazy.prop(o, 'hash', function () {
    if (a.output) return a.output.slice(2, 22)
    if (a.address) return _address().data
    if (a.pubkey || o.pubkey) return bcrypto.hash160(a.pubkey! || o.pubkey!)
  })
  lazy.prop(o, 'output', function () {
    if (!o.hash) return
    return bscript.compile([
      OPS.OP_0,
      o.hash
    ])
  })
  lazy.prop(o, 'pubkey', function () {
    if (a.pubkey) return a.pubkey
    if (!a.witness) return
    return a.witness[1]
  })
  lazy.prop(o, 'signature', function () {
    if (!a.witness) return
    return a.witness[0]
  })
  lazy.prop(o, 'input', function () {
    if (!o.witness) return
    return EMPTY_BUFFER
  })
  lazy.prop(o, 'witness', function () {
    if (!a.pubkey) return
    if (!a.signature) return
    return [a.signature, a.pubkey]
  })

  // extended validation
  if (opts.validate) {
    let hash: Buffer = Buffer.from([])
    if (a.address) {
      if (network && network.bech32 !== _address().prefix) throw new TypeError('Invalid prefix or Network mismatch')
      if (_address().version !== 0x00) throw new TypeError('Invalid address version')
      if (_address().data.length !== 20) throw new TypeError('Invalid address data')
      hash = _address().data
    }

    if (a.hash) {
      if (hash.length > 0 && !hash.equals(a.hash)) throw new TypeError('Hash mismatch')
      else hash = a.hash
    }

    if (a.output) {
      if (
        a.output.length !== 22 ||
        a.output[0] !== OPS.OP_0 ||
        a.output[1] !== 0x14) throw new TypeError('Output is invalid')
      if (hash.length > 0 && !hash.equals(a.output.slice(2))) throw new TypeError('Hash mismatch')
      else hash = a.output.slice(2)
    }

    if (a.pubkey) {
      const pkh = bcrypto.hash160(a.pubkey)
      if (hash.length > 0 && !hash.equals(pkh)) throw new TypeError('Hash mismatch')
      else hash = pkh
    }

    if (a.witness) {
      if (a.witness.length !== 2) throw new TypeError('Witness is invalid')
      if (!bscript.isCanonicalScriptSignature(a.witness[0])) throw new TypeError('Witness has invalid signature')
      if (!ecc.isPoint(a.witness[1])) throw new TypeError('Witness has invalid pubkey')

      if (a.signature && !a.signature.equals(a.witness[0])) throw new TypeError('Signature mismatch')
      if (a.pubkey && !a.pubkey.equals(a.witness[1])) throw new TypeError('Pubkey mismatch')

      const pkh = bcrypto.hash160(a.witness[1])
      if (hash.length > 0 && !hash.equals(pkh)) throw new TypeError('Hash mismatch')
    }
  }

  return Object.assign(o, a)
}