text: const lazy = require('./lazy')
  const typef = require('typeforce')
  const OPS = require('bitcoin-ops')
  const ecc = require('tiny-secp256k1')
  
  const bcrypto = require('../crypto')
  const bech32 = require('bech32')
  const bscript = require('../script')
  const BITCOIN_NETWORK = require('../networks').bitcoin
  
  const EMPTY_BUFFER = Buffer.alloc(0)
  
  // witness: {signature} {pubKey}
  // input: <>
  // output: OP_0 {pubKeyHash}
  function p2wpkh (a, opts) {
    if (
      !a.address &&
      !a.hash &&
      !a.output &&
      !a.pubkey &&
      !a.witness
    ) throw new TypeError('Not enough data')
    opts = opts || { validate: true }
  
    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 = { 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
      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 && !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 && !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 && !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 && !hash.equals(pkh)) throw new TypeError('Hash mismatch')
      }
    }
  
    return Object.assign(o, a)
  }
  
  module.exports = p2wpkh
  