//------------------------------------------------------------------------------
/*
    This file is part of Codius: https://github.com/codius
    Copyright (c) 2014 Ripple Labs Inc.

    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================

var fs = require('fs');
var path = require('path');
var _ = require('lodash');
var extend = require('extend');
var crypto = require('./crypto');
var Runner = require('./contractrunner').ContractRunner;
var Config = require('./config').Config;

var MASTER_SECRET_REGEX = /^[0-9a-fA-F]{64}$/;
var HASH_REGEX = /^[0-9a-fA-F]{64}$/;


function Engine(config) {
  var self = this;

  if (!config) {
    config = new Config();
  }

  self.config = config;

  // Generate the engine secrets used to generate
  // contract-specific secrets and keypairs, as well
  // as the host's keypairs to sign the contracts' public keys
  if (!MASTER_SECRET_REGEX.test(config.MASTER_SECRET)) {
    if (typeof config.MASTER_SECRET === 'undefined') {
      config.logger.warn('No MASTER_SECRET provided! Generating a random secret, please do not do this in production.');
    } else {
      config.logger.warn('Invalid MASTER_SECRET format! Generating a random secret, please do not do this in production.');
    }
    config.MASTER_SECRET = crypto.getRandomMasterSecret();
  }
  self._secrets = self.generateSecrets(config.MASTER_SECRET);

  // All of the APIs the engine has access to
  self._apis = {};

  // Register all of the desired APIs
  config.apis.forEach(function (apiName) {
    // The initialization function is what sets up all of the modules' hooks and modules

    if (apiName === 'secrets') {
      require(path.resolve(config.apisPath, apiName)).init(self, self.config, self._secrets);
    } else {
      require(path.resolve(config.apisPath, apiName)).init(self, self.config);
    }
  });
}

/**
 *  Register a new API module factory with the engine.
 *  When a new contract is run each API module factory will
 *  be called with a reference to the ContractRunner (which
 *  includes the manifest and manifest hash, among other things).
 *  The function registered here should return a new instace
 *  of the API module's class, which should inherit from the 
 *  ApiModule abstract class. 
 *
 *  @param {String} name
 *  @param {Function} moduleFactory
 */
Engine.prototype.registerAPI = function(name, moduleFactory) {
  var self = this;

  self._apis[name] = moduleFactory;
};

/**
 *  Takes a function that will be connected to the
 *  LocalStorage API to provide contracts with persistent storage.
 *  Each function should take the contract hash as the first
 *  parameter. Otherwise, each function follows the browser
 *  LocalStorage API.
 *
 *  @param {Function} contractStorage.getItem
 *  @param {Function} contractStorage.setItem
 *  @param {Function} contractStorage.removeItem
 *  @param {Function} contractStorage.clear
 *  @param {Function} contractStorage.key
 */
Engine.prototype.setContractStorage = function(contractStorage) {
  var self = this;

  if (self._apis.localstorage) {
    self._apis.localstorage = _.partialRight(self._apis.localstorage, contractStorage);
  }
};

/**
 *  Run the contract specified by the given manifest hash.
 *
 *  @param {String} manifest_hash
 *  @param {Object} opts.env Environment variables to expose to sandboxed code
 *
 *  @returns {ContractRunner}
 */
Engine.prototype.runContract = function(manifest_hash, opts) {
  var self = this;

  opts = opts || {};

  var manifest = self._loadManifest(manifest_hash);

  // Load contract environment variables
  var contract_env; 
  if (manifest.env && typeof manifest.env === 'object') {
    contract_env = manifest.env;
  } else {
    contract_env = {};
  }

  if (opts.env) {
    contract_env = extend(contract_env, opts.env);
  }

  if (!contract_env.PORT && self.config.virtual_port) {
    contract_env.PORT = self.config.virtual_port;
  }

  // Create a new runner to run this contract
  var runner = new Runner(self.config, {
    manifest: manifest,
    manifest_hash: manifest_hash,
    additional_libs: self.config.additional_libs,
    env: contract_env,
    instance_id: opts.instance_id || ''
  });

  // Setup available APIs
  // Each runner will get its own instances of all of the APIs
  var contract_apis = {};
  if (typeof manifest.apis === 'object' && manifest.apis.length > 0) {
    manifest.apis.forEach(function(api_name){
      if (self._apis.hasOwnProperty(api_name)) {
        var createApiHandlerInstance = self._apis[api_name];
        contract_apis[api_name] = createApiHandlerInstance(runner);
      }
    });
  }
  runner.setApis(contract_apis);

  runner.run();

  return runner;
};

Engine.prototype._loadManifest = function(manifestHash) {
  var self = this;

  // Load manifest file
  var firstDir = manifestHash.slice(0, 2);
  var secondDir = manifestHash.slice(2, 4);
  var manifest_path = path.join(self.config.contractsFilesystemPath, firstDir, secondDir, manifestHash);
  var manifest = fs.readFileSync(manifest_path, { encoding: 'utf8' });
  try {
    manifest = JSON.parse(manifest);
  } catch(error) {
    throw new Error('Error parsing manifest: ' + error);
  }

  if (manifest.extend && HASH_REGEX.test(manifest.extend)) {
    manifest = extend(manifest, self._loadManifest(manifest.extend));
  }
  
  return manifest;
};

/**
 *  Generate the host's secrets from the MASTER_SECRET
 *
 *  @param {String} MASTER_SECRET
 *
 *  @returns {Object}
 */
Engine.prototype.generateSecrets = function(MASTER_SECRET) {

  var secrets = {};

  secrets.CONTRACT_SECRET_GENERATOR = crypto.deriveSecret(MASTER_SECRET, 'CONTRACT_SECRET_GENERATOR');

  secrets.CONTRACT_KEYPAIR_GENERATOR_ec_secp256k1 = crypto.deriveSecret(MASTER_SECRET, 'CONTRACT_KEYPAIR_GENERATOR_ec_secp256k1', 'sha256');

  secrets.MASTER_KEYPAIR_ec_secp256k1 = crypto.deriveKeypair(MASTER_SECRET, 'MASTER_KEYPAIR_ec_secp256k1', 'ec_secp256k1');

  return secrets;

};

/**
 *  Get the engine's master public key
 *
 *  @param {String} ['ec_secp256k1'] signature_scheme
 *
 *  @returns {String} public_key
 */
Engine.prototype.getMasterPublicKey = function(signature_scheme) {
  var self = this;
  if (!signature_scheme) {
    signature_scheme = 'ec_secp256k1';
  }

  if (signature_scheme === 'ec_secp256k1') {
    return self._secrets.MASTER_KEYPAIR_ec_secp256k1.public;
  } else {
    throw new Error('Signature scheme: ' + signature_scheme + ' not currently supported.');
  }
};


exports.Engine = Engine;