How to chain .then functions and callback success function in Angular.js
<p>I'm trying to chain nested .then functions and call the success functions, but call back is calling in the starting itself.</p>

<pre><code>//public method fn
function fn(callback) {
//calling the 1st API request
fn1()
  .then(function(response) {
    //2nd API request function
    call1(response);
  }, function(error) {
    return $q.reject({
    responseStatus: error.status
  });

  })
  // Returning response
  .then(function(response) {
    callback({
    responseStatus: 200
    });
  }, function(error) {
    callback({
      responseStatus: 500
    });
  });
}

function call1(response) {
  //2nd API
  fn2()
    .then(function(response) {
     //3rd API request function
        call2(response);
      }, function(error) {
        return $q.reject({
        responseStatus: error.status
      });
    });
}


function call2(response) {
  //3rd API request 
  fn3()
    .then(function(response) {
        return lastfunction();
      //here i need to callback the success  response status
      }, function(error) {
        return $q.reject({
        responseStatus: error.status
      });
    });
}


function fn1(){
 //some code 
 }
function fn2(){
//some code 
}
function fn3(){
//some code 
}

//Controller

//i will show response status callback here

if(response.status ==200){
  show output;
 }
 else{
  //response 500
  show errors;
  }
</code></pre>

<p>Basically i need to callback  "200" response status to other controller  on all service calls are successful and even if one request is failed i need to sent "500". with my code 'response status '200' is calling with the first .then function itself. I want to call this service calls as que</p>

<p>Any help would be appreciated.</p>