/**
 * This plugin exposes 'evaluateExpression' method which should be used
 * to evaluate natspec description
 * It should be reloaded each time we want to evaluate set of expressions
 * Just because of security reasons
 * TODO: make use of sync api (once it's finished) and remove unnecessary 
 * code from 'getContractMethods'
 * TODO: unify method signature creation with abi.js (and make a separate method from it)
 */

/// Should be called to copy values from object to global context
var copyToContext = function (obj, context) {
    var keys = Object.keys(obj);
    keys.forEach(function (key) {
        context[key] = obj[key];
    });
}

/// Function called to get all contract's storage values
/// @returns hashmap with contract properties which are used
var getContractProperties = function (expression, abi) {
    return {};
};

/// Function called to get all contract's methods
/// @returns hashmap with used contract's methods
var getContractMethods = function (address, abi) {

    var contract = {};
    var inputParser = web3.abi.inputParser(abi);
    var outputParser = web3.abi.outputParser(abi);

    abi.forEach(function (method) {

        var displayName = web3.abi.methodDisplayName(method.name);
        var typeName = web3.abi.methodTypeName(method.name);

        var impl = function () {
            var params = Array.prototype.slice.call(arguments);
            var parsed = inputParser[displayName][typeName].apply(null, params);
            var methodSignature = _natspec.sha3(web3.fromAscii(method.name)).slice(0, 10);
            var output = _natspec.call(JSON.stringify({
                to: address,
                data: methodSignature + parsed
            }));
            return outputParser[displayName][typeName](output);
        };

        if (contract[displayName] === undefined) {
            contract[displayName] = impl;
        }

        contract[displayName][typeName] = impl;
    });

    return contract; 
};

/// Should be called to evaluate single expression
/// Is internally using javascript's 'eval' method
/// Should be checked if it is safe
var evaluateExpression = function (expression) {

    var self = this;
    var abi = web3._currentContractAbi;
    var address = web3._currentContractAddress;

    var storage = getContractProperties(expression, abi); 
    var methods = getContractMethods(address, abi);

    copyToContext(storage, self);
    copyToContext(methods, self);

    // TODO: test if it is safe
    return eval(expression).toString();
};