/*******************************************************************************
 * Copyright 2015 IBM Corp.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *******************************************************************************/
'use strict';
var Probe = require('../lib/probe.js');
var request = require('../lib/request.js');
var util = require('util');

function TraceProbe() {
  Probe.call(this, 'trace');
  this.config = {
    includeModules: [],
    excludeModules: [],
  };
}
util.inherits(TraceProbe, Probe);

TraceProbe.prototype.attach = function(moduleName, target) {
  if (
    moduleName.slice(0, 1) != '.' ||
    stopList[moduleName] ||
    !isAppInnerRequire() ||
    this.config.excludeModules.indexOf(moduleName) != -1
  ) {
    return target;
  }
  if (target.__ddProbeAttached__) {
    return target;
  }
  var ret = target;
  if (typeof target != 'function') {
    instrumentMethods(moduleName, target);
  } else {
    instrumentMethods(moduleName, target.prototype);
    ret = target;
    if (target && target.prototype && Object.keys(target.prototype).length == 0 && Object.keys(target).length == 0) {
      ret = function() {
        var rc = target.apply(this, arguments);
        instrumentMethods(moduleName, rc);
        return rc;
      };
    }
  }

  ret.__ddProbeAttached__ = function() {
    return true;
  };
  return ret;
};

var stopList = { './commands/base_command': true, './aspects': true };

function instrument(target, name, method, fullName) {
  var methodString = '' + method;
  var methodargs = methodString.toString().split(')')[0].split('(')[1].split(',');
  var lastMethodArg = methodargs[methodargs.length - 1].replace(/ /g, '');
  if (lastMethodArg == '') lastMethodArg = 'undefined';

  function generateF(expectedArgCount, fn) {
    switch (expectedArgCount) {
      case 0:
        return function() {
          return fn.apply(this, arguments);
        };
      case 1:
        return function(a) {
          return fn.apply(this, arguments);
        };
      case 2:
        return function(a, b) {
          return fn.apply(this, arguments);
        };
      case 3:
        return function(a, b, c) {
          return fn.apply(this, arguments);
        };
      case 4:
        return function(a, b, c, d) {
          return fn.apply(this, arguments);
        };
      case 5:
        return function(a, b, c, d, e) {
          return fn.apply(this, arguments);
        };
      case 6:
        return function(a, b, c, d, e, f) {
          return fn.apply(this, arguments);
        };
      case 7:
        return function(a, b, c, d, e, f, g) {
          return fn.apply(this, arguments);
        };
      case 8:
        return function(a, b, c, d, e, f, g, h) {
          return fn.apply(this, arguments);
        };
      case 9:
        return function(a, b, c, d, e, f, g, h, i) {
          return fn.apply(this, arguments);
        };

      // Slow case for functions with > 10 args
      default:
        var ident = 'a';
        var argumentList = [];
        for (var i = 0; i < expectedArgCount; i++) {
          argumentList[i] = ident;
          ident = incrementIdentifier(ident);
        }
        /* eslint no-eval: 0 */
        return eval('x = function(' + argumentList.join(',') + ') {return fn.apply(this,arguments);};');
    }

    function incrementIdentifier(identifier) {
      var charArr = identifier.split('');
      var lastChar = charArr[charArr.length - 1];
      if (lastChar == 'z') {
        return identifier + 'a';
      } else {
        var chopped = identifier.substring(0, identifier.length - 1);
        return chopped + String.fromCharCode(lastChar.charCodeAt(0) + 1);
      }
    }
  }

  var f = function() {
    var req = request.startMethod(fullName);
    var args = arguments;

    var cxtFunc = function() {
      var cxt = {};
      for (var i = 0; i < args.length; ++i) {
        var arg = args[i];
        var value;
        if (
          typeof arg == 'function' &&
          Object.keys(arg).length == 0 &&
          arg.prototype &&
          Object.keys(arg.prototype).length == 0
        ) {
          var fName = arg.name != 0 ? arg.name : '<anonymous>';
          value = 'function ' + fName;
        } else if (typeof arg == 'object') {
          value = 'object';
        } else {
          value = '' + arg;
        }
        cxt['arg' + i] = value;
      }
      return cxt;
    };
    var isCallback = false;
    /*
         * if( arguments.length > 0 && typeof(arguments[arguments.length-1]) ==
         * "function" && Object.keys(arguments[arguments.length-1]).length == 0) {
         * console.log('Type is ' +
         * typeof(arguments[arguments.length-1].prototype)); if
         * (typeof(arguments[arguments.length-1].prototype) === 'object') {
         * console.log('Checking object');
         * console.log(Object.keys(arguments[arguments.length-1].prototype)); }
         * else { console.log('Not object'); }
         *  }
         */
    if (
      arguments.length > 0 &&
      typeof arguments[arguments.length - 1] == 'function' &&
      Object.keys(arguments[arguments.length - 1]).length == 0 &&
      // Add to deal with no prototype
      (!arguments[arguments.length - 1].hasOwnProperty('prototype') ||
        (arguments[arguments.length - 1].prototype &&
          Object.keys(arguments[arguments.length - 1].prototype).length == 0)) &&
      methodString.indexOf(lastMethodArg + '.call') < 0 &&
      methodString.indexOf(lastMethodArg + '.apply') < 0 &&
      ('' + arguments[arguments.length - 1]).indexOf('instrumentedMethodKNJ') < 0
    ) {
      isCallback = true;
      if (isResponseMethod(arguments)) {
        var resArg = arguments[arguments.length - 2];
        var sendCb = resArg.send;
        resArg.send = function() {
          req.stop(cxtFunc());
          return sendCb.apply(resArg, arguments);
        };

        var renderCb = resArg.render;
        resArg.render = function() {
          req.stop(cxtFunc());
          return renderCb.apply(resArg, arguments);
        };
      } else {
        var cb = arguments[arguments.length - 1];
        arguments[arguments.length - 1] = function() {
          req.stop(cxtFunc());
          return cb.apply(this, arguments);
        };
      }
    }

    // Call this method using the apply function
    var res = method.apply(this, arguments);
    if (!isCallback) {
      req.stop(cxtFunc());
    }
    return res;
  };
  // use a function replace to call our 'f' function.
  // we ned to use 'generateF' to call f with the correct number of arguments
  target[name] = generateF(method.length, f);
  target[name].prototype = method.prototype;
}

function isResponseMethod(args) {
  if (args.length > 1) {
    var arg = args[args.length - 2];
    if (
      typeof arg == 'object' &&
      arg != null &&
      'send' in arg &&
      'render' in arg &&
      typeof arg['send'] == 'function' &&
      typeof arg['render'] == 'function'
    ) {
      return true;
    }
  }
  return false;
}

function traceMethod(moduleName, target, name) {
  var method = target[name];
  if (method && !method.__ddInstrumented__) {
    var fullName = moduleName + '.' + name;
    //      logger.debug( "instrumenting method", fullName );
    instrument(target, name, method, fullName);

    var p = target[name].prototype;
    for (var item in p) {
      if (
        typeof p[item] == 'function' &&
        Object.keys(p[item]).length == 0 &&
        Object.keys(p[item].prototype).length == 0
      ) {
        var itemName = fullName + '.' + item;
        instrument(p, item, p[item], itemName);
      }
    }
  }
}

function isAppInnerRequire() {
  var trace = {};
  Error.captureStackTrace(trace);
  var callerLine = trace.stack.split('\n'); // This line contains 'node_modules' reference for generic libs
  return callerLine[6].indexOf('node_modules') == -1;
}

function instrumentMethods(moduleName, target) {
  for (var name in target) {
    if (!target.__lookupGetter__(name) && typeof target[name] == 'function') {
      if (
        !target[name].__super__ &&
        (target[name].prototype || (target[name].prototype && Object.keys(target[name].prototype).length == 0)) &&
        Object.keys(target[name]).length == 0
      ) {
        traceMethod(moduleName, target, name);
      }
    }
  }
}

TraceProbe.prototype.enable = function() {};
TraceProbe.prototype.enableRequests = function() {};

module.exports = TraceProbe;