/*
// aop({options});
// By: adamchow2326@yahoo.com.au
// Version: 1.0
// Simple aspect oriented programming module
// support Aspect before, after and around
// usage:
    aop({
      context: myObject,   // scope context of the target function.
      target: "test",     // target function name
      before: function() {  // before function will be run before the target function
        console.log("aop before");
      },
      after: function() {   // after function will be run after the target function
        console.log("aop after");
      },
      around: function() {  // around function will be run before and after the target function
        console.log("aop around");
      }
    });
*/
var aop = (function() {
  var options = {},
    context = window,
    oFn,
    oFnArg,
    targetFn,
    targetFnSelector,
    beforeFn,
    afterFn,
    aroundFn,
    cloneFn = function(Fn) {
      if (typeof Fn === "function") {
        return eval('[' +Fn.toString()+ ']')[0];
      }
      return null;
    },
    checkContext = function() {
      if (options.context) {
        context = options.context;
      }
      if (typeof context[(options.target).name] === "function") {
        targetFnSelector = (options.target).name;
        targetFn = context[targetFnSelector];
      }
      else if (typeof context[options.target] === "function") {
        targetFnSelector = options.target;
        targetFn = context[targetFnSelector];
      }
      if (targetFn) {
        oFn = cloneFn(targetFn);
        oFnArg = new Array(targetFn.length);
        return true;
      }
      else {
        return false;
      }
    },
    run = function() {
      context[targetFnSelector] = function(oFnArg) {
        if (aroundFn){
          aroundFn.apply(this, arguments);
        }
        if (beforeFn){
          beforeFn.apply(this, arguments); // 'this' is context
        }
        oFn.apply(this, arguments);
        if (afterFn){
          afterFn.apply(this, arguments); // 'this' is context
        }
        if (aroundFn){
          aroundFn.apply(this, arguments);
        }
      };
    };
  return function(opt){
    if (opt && typeof opt === "object" && !opt.length) {
      options = opt;
      if (options.target && checkContext()) {
        if (options.before && typeof options.before === "function") {
          beforeFn = options.before;
        }
        if (options.after && typeof options.after === "function") {
          afterFn = options.after;
        }
        if (options.around && typeof options.after === "function") {
          aroundFn = options.around;
        }
        run();
      }
    }
  };
})();
// test examples
// ----------------- aop modify global function ---------------//
function test(name, age) {
  console.log("test fn. name = " + name + " age: " + age);
}
aop({
  target: "test",
  before: function() {
    console.log("aop before");
  },
  after: function() {
    console.log("aop after");
  },
  around: function() {
    console.log("aop around");
  }
});
// run
test("adam", 6);
// ----------------- aop test modify method in an object ---------------//
var myobj = {
  myName: "testName",
  sayName: function() {
    console.log(this.myName);
  },
  childObj: {
    age: 6,
    say: function() {
      console.log(this.age);
    }
  }
};
aop({
  context: myobj,
  target: "sayName",
  before: function() {
    console.log("aop before say name = " + this.myName);
  },
  after: function() {
    console.log("aop after say name = " + this.myName);
  },
  around: function() {
    console.log("aop around say name = " + this.myName);
  }
});
// run
myobj.sayName();
aop({
  context: myobj.childObj,
  target: "say",
  before: function() {
    console.log("aop before say name = " + this.age);
  },
  after: function() {
    console.log("aop after say name = " + this.age);
  },
  around: function() {
    console.log("aop around say name = " + this.age);
  }
});
myobj.childObj.say();