import * as bcrypto from '../crypto';
import { bitcoin as BITCOIN_NETWORK } from '../networks';
import * as bscript from '../script';
import { Payment, PaymentOpts, StackFunction } from './index';
import * as lazy from './lazy';
const typef = require('typeforce');
const OPS = bscript.OPS;

const bech32 = require('bech32');

const EMPTY_BUFFER = Buffer.alloc(0);

function stacksEqual(a: Buffer[], b: Buffer[]): boolean {
  if (a.length !== b.length) return false;

  return a.every((x, i) => {
    return x.equals(b[i]);
  });
}

// input: <>
// witness: [redeemScriptSig ...] {redeemScript}
// output: OP_0 {sha256(redeemScript)}
export function p2wsh(a: Payment, opts?: PaymentOpts): Payment {
  if (!a.address && !a.hash && !a.output && !a.redeem && !a.witness)
    throw new TypeError('Not enough data');
  opts = Object.assign({ validate: true }, opts || {});

  typef(
    {
      network: typef.maybe(typef.Object),

      address: typef.maybe(typef.String),
      hash: typef.maybe(typef.BufferN(32)),
      output: typef.maybe(typef.BufferN(34)),

      redeem: typef.maybe({
        input: typef.maybe(typef.Buffer),
        network: typef.maybe(typef.Object),
        output: typef.maybe(typef.Buffer),
        witness: typef.maybe(typef.arrayOf(typef.Buffer)),
      }),
      input: typef.maybe(typef.BufferN(0)),
      witness: typef.maybe(typef.arrayOf(typef.Buffer)),
    },
    a,
  );

  const _address = lazy.value(() => {
    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 _rchunks = lazy.value(() => {
    return bscript.decompile(a.redeem!.input!);
  }) as StackFunction;

  let network = a.network;
  if (!network) {
    network = (a.redeem && a.redeem.network) || BITCOIN_NETWORK;
  }

  const o: Payment = { network };

  lazy.prop(o, 'address', () => {
    if (!o.hash) return;
    const words = bech32.toWords(o.hash);
    words.unshift(0x00);
    return bech32.encode(network!.bech32, words);
  });
  lazy.prop(o, 'hash', () => {
    if (a.output) return a.output.slice(2);
    if (a.address) return _address().data;
    if (o.redeem && o.redeem.output) return bcrypto.sha256(o.redeem.output);
  });
  lazy.prop(o, 'output', () => {
    if (!o.hash) return;
    return bscript.compile([OPS.OP_0, o.hash]);
  });
  lazy.prop(o, 'redeem', () => {
    if (!a.witness) return;
    return {
      output: a.witness[a.witness.length - 1],
      input: EMPTY_BUFFER,
      witness: a.witness.slice(0, -1),
    };
  });
  lazy.prop(o, 'input', () => {
    if (!o.witness) return;
    return EMPTY_BUFFER;
  });
  lazy.prop(o, 'witness', () => {
    // transform redeem input to witness stack?
    if (
      a.redeem &&
      a.redeem.input &&
      a.redeem.input.length > 0 &&
      a.redeem.output &&
      a.redeem.output.length > 0
    ) {
      const stack = bscript.toStack(_rchunks());

      // assign, and blank the existing input
      o.redeem = Object.assign({ witness: stack }, a.redeem);
      o.redeem.input = EMPTY_BUFFER;
      return ([] as Buffer[]).concat(stack, a.redeem.output);
    }

    if (!a.redeem) return;
    if (!a.redeem.output) return;
    if (!a.redeem.witness) return;
    return ([] as Buffer[]).concat(a.redeem.witness, a.redeem.output);
  });
  lazy.prop(o, 'name', () => {
    const nameParts = ['p2wsh'];
    if (o.redeem !== undefined) nameParts.push(o.redeem.name!);
    return nameParts.join('-');
  });

  // extended validation
  if (opts.validate) {
    let hash: Buffer = Buffer.from([]);
    if (a.address) {
      if (_address().prefix !== network.bech32)
        throw new TypeError('Invalid prefix or Network mismatch');
      if (_address().version !== 0x00)
        throw new TypeError('Invalid address version');
      if (_address().data.length !== 32)
        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 !== 34 ||
        a.output[0] !== OPS.OP_0 ||
        a.output[1] !== 0x20
      )
        throw new TypeError('Output is invalid');
      const hash2 = a.output.slice(2);
      if (hash.length > 0 && !hash.equals(hash2))
        throw new TypeError('Hash mismatch');
      else hash = hash2;
    }

    if (a.redeem) {
      if (a.redeem.network && a.redeem.network !== network)
        throw new TypeError('Network mismatch');

      // is there two redeem sources?
      if (
        a.redeem.input &&
        a.redeem.input.length > 0 &&
        a.redeem.witness &&
        a.redeem.witness.length > 0
      )
        throw new TypeError('Ambiguous witness source');

      // is the redeem output non-empty?
      if (a.redeem.output) {
        if (bscript.decompile(a.redeem.output)!.length === 0)
          throw new TypeError('Redeem.output is invalid');

        // match hash against other sources
        const hash2 = bcrypto.sha256(a.redeem.output);
        if (hash.length > 0 && !hash.equals(hash2))
          throw new TypeError('Hash mismatch');
        else hash = hash2;
      }

      if (a.redeem.input && !bscript.isPushOnly(_rchunks()))
        throw new TypeError('Non push-only scriptSig');
      if (
        a.witness &&
        a.redeem.witness &&
        !stacksEqual(a.witness, a.redeem.witness)
      )
        throw new TypeError('Witness and redeem.witness mismatch');
    }

    if (a.witness) {
      if (
        a.redeem &&
        a.redeem.output &&
        !a.redeem.output.equals(a.witness[a.witness.length - 1])
      )
        throw new TypeError('Witness and redeem.output mismatch');
    }
  }

  return Object.assign(o, a);
}