var Opcode = require('./opcode');
var util = require('./util');
var conv = require('./convert');
var Address = require('./address');

var Script = function (data) {
  if (!data) {
    this.buffer = [];
  } else if ("string" == typeof data) {
    this.buffer = Crypto.util.hexToBytes(data);
  } else if (util.isArray(data)) {
    this.buffer = data;
  } else if (data instanceof Script) {
    this.buffer = data.buffer;
  } else {
    throw new Error("Invalid script");
  }

  this.parse();
};

Script.fromPubKey = function(str) {
  var script = new Script();
  var s = str.split(" ");
  for (var i in s) {
    if (Opcode.map.hasOwnProperty(s[i])){
      script.writeOp(Opcode.map[s[i]]);
    } else {
      script.writeBytes(conv.hexToBytes(s[i]));
    }
  }
  return script;
};

Script.fromScriptSig = function(str) {
  var script = new Script();
  var s = str.split(" ");
  for (var i in s) {
    if (Opcode.map.hasOwnProperty(s[i])){
      script.writeOp(Opcode.map[s[i]]);
    } else {
      script.writeBytes(conv.hexToBytes(s[i]));
    }
  }
  return script;
};

/**
 * Update the parsed script representation.
 *
 * Each Script object stores the script in two formats. First as a raw byte
 * array and second as an array of "chunks", such as opcodes and pieces of
 * data.
 *
 * This method updates the chunks cache. Normally this is called by the
 * constructor and you don't need to worry about it. However, if you change
 * the script buffer manually, you should update the chunks using this method.
 */
Script.prototype.parse = function () {
  var self = this;

  this.chunks = [];

  // Cursor
  var i = 0;

  // Read n bytes and store result as a chunk
  function readChunk(n) {
    self.chunks.push(self.buffer.slice(i, i + n));
    i += n;
  };

  while (i < this.buffer.length) {
    var opcode = this.buffer[i++];
    if (opcode >= 0xF0) {
      // Two byte opcode
      opcode = (opcode << 8) | this.buffer[i++];
    }

    var len;
    if (opcode > 0 && opcode < Opcode.map.OP_PUSHDATA1) {
      // Read some bytes of data, opcode value is the length of data
      readChunk(opcode);
    } else if (opcode == Opcode.map.OP_PUSHDATA1) {
      len = this.buffer[i++];
      readChunk(len);
    } else if (opcode == Opcode.map.OP_PUSHDATA2) {
      len = (this.buffer[i++] << 8) | this.buffer[i++];
      readChunk(len);
    } else if (opcode == Opcode.map.OP_PUSHDATA4) {
      len = (this.buffer[i++] << 24) |
        (this.buffer[i++] << 16) |
        (this.buffer[i++] << 8) |
        this.buffer[i++];
      readChunk(len);
    } else {
      this.chunks.push(opcode);
    }
  }
};

/**
 * Compare the script to known templates of scriptPubKey.
 *
 * This method will compare the script to a small number of standard script
 * templates and return a string naming the detected type.
 *
 * Currently supported are:
 * Address:
 *   Paying to a Bitcoin address which is the hash of a pubkey.
 *   OP_DUP OP_HASH160 [pubKeyHash] OP_EQUALVERIFY OP_CHECKSIG
 *
 * Pubkey:
 *   Paying to a public key directly.
 *   [pubKey] OP_CHECKSIG
 * 
 * Strange:
 *   Any other script (no template matched).
 */
Script.prototype.getOutType = function () {
if (this.chunks[this.chunks.length-1] == Opcode.map.OP_CHECKMULTISIG && this.chunks[this.chunks.length-2] <= 3) {
  // Transfer to M-OF-N
  return 'Multisig';
} else if (this.chunks.length == 5 &&
  this.chunks[0] == Opcode.map.OP_DUP &&
  this.chunks[1] == Opcode.map.OP_HASH160 &&
  this.chunks[3] == Opcode.map.OP_EQUALVERIFY &&
  this.chunks[4] == Opcode.map.OP_CHECKSIG) {
  // Transfer to Bitcoin address
  return 'Address';
} else if (this.chunks.length == 2 &&
       this.chunks[1] == Opcode.map.OP_CHECKSIG) {
  // Transfer to IP address
  return 'Pubkey';
} else {
  return 'Strange';
}   
}

/**
 * Returns the affected address hash for this output.
 *
 * For standard transactions, this will return the hash of the pubKey that
 * can spend this output.
 *
 * In the future, for payToScriptHash outputs, this will return the
 * scriptHash. Note that non-standard and standard payToScriptHash transactions
 * look the same 
 *
 * This method is useful for indexing transactions.
 */
Script.prototype.simpleOutHash = function ()
{
  switch (this.getOutType()) {
  case 'Address':
    return this.chunks[2];
  case 'Pubkey':
    return util.sha256ripe160(this.chunks[0]);
  case 'Multisig':
    return util.sha256ripe160(this.buffer);
  default:
    throw new Error("Encountered non-standard scriptPubKey: " + this.getOutType());
  }
};

/**
 * Old name for Script#simpleOutHash.
 *
 * @deprecated
 */
Script.prototype.simpleOutPubKeyHash = Script.prototype.simpleOutHash;

/**
 * Compare the script to known templates of scriptSig.
 *
 * This method will compare the script to a small number of standard script
 * templates and return a string naming the detected type.
 *
 * WARNING: Use this method with caution. It merely represents a heuristic
 * based on common transaction formats. A non-standard transaction could
 * very easily match one of these templates by accident.
 *
 * Currently supported are:
 * Address:
 *   Paying to a Bitcoin address which is the hash of a pubkey.
 *   [sig] [pubKey]
 *
 * Pubkey:
 *   Paying to a public key directly.
 *   [sig]
 *
 * Multisig:
 *   Paying to M-of-N public keys.
 * 
 * Strange:
 *   Any other script (no template matched).
 */
Script.prototype.getInType = function ()
{
  if (this.chunks.length == 1 &&
      util.isArray(this.chunks[0])) {
    // Direct IP to IP transactions only have the signature in their scriptSig.
    // TODO: We could also check that the length of the data is correct.
    return 'Pubkey';
  } else if (this.chunks.length == 2 &&
             util.isArray(this.chunks[0]) &&
             util.isArray(this.chunks[1])) {
    return 'Address';
  } else if (this.chunks[0] == Opcode.map.OP_0 && 
             this.chunks.slice(1).reduce(function(t,chunk,i) {
                return t && util.isArray(chunk) 
                         && (chunk[0] == 48 || i == this.chunks.length - 1);
             },true)) {
    return 'Multisig';
  } else {
    return 'Strange';
  }
};

/**
 * Returns the affected public key for this input.
 *
 * This currently only works with payToPubKeyHash transactions. It will also
 * work in the future for standard payToScriptHash transactions that use a
 * single public key.
 *
 * However for multi-key and other complex transactions, this will only return
 * one of the keys or raise an error. Therefore, it is recommended for indexing
 * purposes to use Script#simpleInHash or Script#simpleOutHash instead.
 *
 * @deprecated
 */
Script.prototype.simpleInPubKey = function ()
{
  switch (this.getInType()) {
  case 'Address':
    return this.chunks[1];
  case 'Pubkey':
    // TODO: Theoretically, we could recover the pubkey from the sig here.
    //       See https://bitcointalk.org/?topic=6430.0
    throw new Error("Script does not contain pubkey.");
  default:
    throw new Error("Encountered non-standard scriptSig");
  }
};

/**
 * Returns the affected address hash for this input.
 *
 * For standard transactions, this will return the hash of the pubKey that
 * can spend this output.
 *
 * In the future, for standard payToScriptHash inputs, this will return the
 * scriptHash.
 *
 * Note: This function provided for convenience. If you have the corresponding
 * scriptPubKey available, you are urged to use Script#simpleOutHash instead
 * as it is more reliable for non-standard payToScriptHash transactions.
 *
 * This method is useful for indexing transactions.
 */
Script.prototype.simpleInHash = function ()
{
  return util.sha256ripe160(this.simpleInPubKey());
};

/**
 * Old name for Script#simpleInHash.
 *
 * @deprecated
 */
Script.prototype.simpleInPubKeyHash = Script.prototype.simpleInHash;

/**
 * Add an op code to the script.
 */
Script.prototype.writeOp = function (opcode)
{
  this.buffer.push(opcode);
  this.chunks.push(opcode);
};

/**
 * Add a data chunk to the script.
 */
Script.prototype.writeBytes = function (data)
{
  if (data.length < Opcode.map.OP_PUSHDATA1) {
    this.buffer.push(data.length);
  } else if (data.length <= 0xff) {
    this.buffer.push(Opcode.map.OP_PUSHDATA1);
    this.buffer.push(data.length);
  } else if (data.length <= 0xffff) {
    this.buffer.push(Opcode.map.OP_PUSHDATA2);
    this.buffer.push(data.length & 0xff);
    this.buffer.push((data.length >>> 8) & 0xff);
  } else {
    this.buffer.push(Opcode.map.OP_PUSHDATA4);
    this.buffer.push(data.length & 0xff);
    this.buffer.push((data.length >>> 8) & 0xff);
    this.buffer.push((data.length >>> 16) & 0xff);
    this.buffer.push((data.length >>> 24) & 0xff);
  }
  this.buffer = this.buffer.concat(data);
  this.chunks.push(data);
};

/**
 * Create an output for an address
 */
Script.createOutputScript = function (address)
{
  var script = new Script();
  // Standard pay-to-pubkey-hash
  if (address.version == 0) {
      script.writeOp(Opcode.map.OP_DUP);
      script.writeOp(Opcode.map.OP_HASH160);
      script.writeBytes(address.hash);
      script.writeOp(Opcode.map.OP_EQUALVERIFY);
      script.writeOp(Opcode.map.OP_CHECKSIG);
  }
  // Standard pay-to-script-hash
  else {
      script.writeOp(Opcode.map.OP_HASH160);
      script.writeBytes(address.hash);
      script.writeOp(Opcode.map.OP_EQUAL);
  }
  return script;
};

/**
 * Extract pubkeys from a multisig script
 */

Script.prototype.extractPubkeys = function() {
    return this.chunks.filter(function(chunk) {
        return (chunk[0] == 4 && chunk.length == 65 
             || chunk[0]  < 4 && chunk.length == 33)
    });
}

/**
 * Create an m-of-n output script
 */
Script.createMultiSigOutputScript = function (m, pubkeys)
{
  var script = new Script();

  pubkeys = pubkeys.sort();
  
  script.writeOp(Opcode.map.OP_1 + m - 1);
  
  for (var i = 0; i < pubkeys.length; ++i) {
    script.writeBytes(pubkeys[i]);
  }
  
  script.writeOp(Opcode.map.OP_1 + pubkeys.length - 1);

  script.writeOp(Opcode.map.OP_CHECKMULTISIG);

  return script;
};

/**
 * Create a standard payToPubKeyHash input.
 */
Script.createInputScript = function (signature, pubKey)
{
  var script = new Script();
  script.writeBytes(signature);
  script.writeBytes(pubKey);
  return script;
};

/**
 * Create a multisig input
 */
Script.createMultiSigInputScript = function(signatures, script)
{
    script = new Script(script);
    var k = script.chunks[0][0];
    if (signatures.length < k) return false; //Not enough sigs
    var inScript = new Script();
    inScript.writeOp(Opcode.map.OP_0);
    signatures.map(inScript.writeBytes.bind(inScript));
    inScript.writeBytes(script.buffer);
    return inScript;
}

Script.prototype.clone = function ()
{
  return new Script(this.buffer);
};

module.exports = Script;