'use strict';

var _ = require('lodash');
var inherits = require('inherits');
var Input = require('./input');
var Output = require('../output');
var $ = require('../../util/preconditions');

var Script = require('../../script');
var Signature = require('../../crypto/signature');
var Sighash = require('../sighash');
var BufferUtil = require('../../util/buffer');

/**
 * @constructor
 */
function MultiSigScriptHashInput(input, pubkeys, threshold) {
  Input.apply(this, arguments);
  var self = this;
  this.publicKeys = _.sortBy(pubkeys, function(publicKey) { return publicKey.toString('hex'); });
  this.redeemScript = Script.buildMultisigOut(this.publicKeys, threshold);
  $.checkState(Script.buildScriptHashOut(this.redeemScript).equals(this.output.script),
               'Provided public keys don\'t hash to the provided output');
  this.publicKeyIndex = {};
  _.each(this.publicKeys, function(publicKey, index) {
    self.publicKeyIndex[publicKey.toString()] = index;
  });
  this.threshold = threshold;
  // Empty array of signatures
  this.signatures = new Array(this.publicKeys.length);
}
inherits(MultiSigScriptHashInput, Input);

MultiSigScriptHashInput.prototype.getSignatures = function(transaction, privateKey, index, sigtype) {
  $.checkState(this.output instanceof Output);
  sigtype = sigtype || Signature.SIGHASH_ALL;

  var self = this;
  var results = [];
  _.each(this.publicKeys, function(publicKey) {
    if (publicKey.toString() === privateKey.publicKey.toString()) {
      results.push({
        publicKey: privateKey.publicKey,
        prevTxId: self.txId,
        outputIndex: self.outputIndex,
        inputIndex: index,
        signature: Sighash.sign(transaction, privateKey, sigtype, index, self.redeemScript),
        sigtype: sigtype
      });
    }
  });
  return results;
};

MultiSigScriptHashInput.prototype.addSignature = function(transaction, signature) {
  $.checkState(!this.isFullySigned(), 'All needed signatures have already been added');
  $.checkArgument(!_.isUndefined(this.publicKeyIndex[signature.publicKey.toString()]),
                  'Signature has no matching public key');
  $.checkState(this.isValidSignature(transaction, signature));
  this.signatures[this.publicKeyIndex[signature.publicKey.toString()]] = signature;
  this._updateScript();
  return this;
};

MultiSigScriptHashInput.prototype._updateScript = function() {
  this.setScript(Script.buildP2SHMultisigIn(
    this.publicKeys,
    this.threshold,
    this._createSignatures(),
    { cachedMultisig: this.redeemScript }
  ));
  return this;
};

MultiSigScriptHashInput.prototype._createSignatures = function() {
  return _.map(
    _.filter(this.signatures, function(signature) { return !_.isUndefined(signature); }),
    function(signature) {
      return BufferUtil.concat([
        signature.signature.toDER(),
        BufferUtil.integerAsSingleByteBuffer(signature.sigtype)
      ]);
    }
  );
};

MultiSigScriptHashInput.prototype.clearSignatures = function() {
  this.signatures = new Array(this.publicKeys.length);
  this._updateScript();
};

MultiSigScriptHashInput.prototype.isFullySigned = function() {
  return this.countSignatures() === this.threshold;
};

MultiSigScriptHashInput.prototype.countMissingSignatures = function() {
  return this.threshold - this.countSignatures();
};

MultiSigScriptHashInput.prototype.countSignatures = function() {
  return _.reduce(this.signatures, function(sum, signature) {
    return sum + (!!signature);
  }, 0);
};

MultiSigScriptHashInput.prototype.publicKeysWithoutSignature = function() {
  var self = this;
  return _.filter(this.publicKeys, function(publicKey) {
    return !(self.signatures[self.publicKeyIndex[publicKey.toString()]]);
  });
};

MultiSigScriptHashInput.prototype.isValidSignature = function(transaction, signature) {
  // FIXME: Refactor signature so this is not necessary
  signature.signature.nhashtype = signature.sigtype;
  return Sighash.verify(
      transaction,
      signature.signature,
      signature.publicKey,
      signature.inputIndex,
      this.redeemScript
  );
};

MultiSigScriptHashInput.OPCODES_SIZE = 7; // serialized size (<=3) + 0 .. N .. M OP_CHECKMULTISIG
MultiSigScriptHashInput.SIGNATURE_SIZE = 74; // size (1) + DER (<=72) + sighash (1)
MultiSigScriptHashInput.PUBKEY_SIZE = 34; // size (1) + DER (<=33)

MultiSigScriptHashInput.prototype._estimateSize = function() {
  return MultiSigScriptHashInput.OPCODES_SIZE +
    this.threshold * MultiSigScriptHashInput.SIGNATURE_SIZE +
    this.publicKeys.length * MultiSigScriptHashInput.PUBKEY_SIZE;
};

module.exports = MultiSigScriptHashInput;