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

var Script = function(data) {
    this.buffer = data || [];
    if(!Array.isArray(this.buffer)) {
      throw new Error('expect Script to be initialized with Array, but got ' + data)
    }
    this.parse();
};

Script.fromHex = function(data) {
    return new Script(convert.hexToBytes(data))
};

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(convert.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(convert.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_EQUAL &&
        this.chunks[0] == Opcode.map.OP_HASH160 &&
        this.chunks.length == 3) {
        // Transfer to M-OF-N
        return 'P2SH';
    } 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 'Pubkey';
    } else {
        return 'Strange';
    }
}

/**
 * Returns the address corresponding to this output in hash160 form.
 * Assumes strange scripts are P2SH
 */
Script.prototype.toScriptHash = function() {
    var outType = this.getOutType();

    if (outType == 'Pubkey') {
        return this.chunks[2]
    }

    if (outType == 'P2SH') {
        return util.sha256ripe160(this.buffer)
    }

    return util.sha256ripe160(this.buffer)
}

//TODO: support testnet
Script.prototype.getToAddress = function() {
    var outType = this.getOutType();

    if (outType == 'Pubkey') {
        return new Address(this.chunks[2])
    }

    if (outType == 'P2SH') {
        return new Address(this.chunks[1], 5)
    }

    return new Address(this.chunks[1], 5)
}

//TODO: support testnet
Script.prototype.getFromAddress = function(){
    return new Address(this.simpleInHash());
}

/**
 * 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 &&
        Array.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 &&
        Array.isArray(this.chunks[0]) &&
        Array.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 && Array.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();
    address = new Address(address);
    if (address.version == network.mainnet.p2shVersion || address.version == network.testnet.p2shVersion) {
        // Standard pay-to-script-hash
        script.writeOp(Opcode.map.OP_HASH160);
        script.writeBytes(address.hash);
        script.writeOp(Opcode.map.OP_EQUAL);
    }
    else {
        // Standard pay-to-pubkey-hash
        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);
    }
    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];

    //Not enough sigs
    if (signatures.length < k) return false;

    var inScript = new Script();
    inScript.writeOp(Opcode.map.OP_0);
    signatures.map(function(sig) {
        inScript.writeBytes(sig)
    });
    inScript.writeBytes(script.buffer);
    return inScript;
}

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

module.exports = Script;