package misc

import (
	"bytes"
	"errors"
	"io"
	"net/http"
)

//CallAPI sends an HTTP request using "method" to "url".
//For uploading / sending file, caller needs to set the "content".  Otherwise,
//set it to zero length []byte. If Header fields need to be set, then set it in
// "h".  "h" needs to be even numbered, i.e. pairs of field name and the field
//content.
//
//fileContent, err := ioutil.ReadFile("fileName.ext");
//
//resp, err := CallAPI("PUT", "http://domain/hello/", &fileContent,
//"Name", "world")
//
//is similar to: curl -X PUT -H "Name: world" -T fileName.ext
//http://domain/hello/
func CallAPI(method, url string, content *[]byte, h ...string) (*http.Response, error) {
	if len(h)%2 == 1 { //odd #
		return nil, errors.New("syntax err: # header != # of values")
	}
	//I think the above err check is unnecessary and wastes cpu cycle, since
	//len(h) is not determined at run time. If the coder puts in odd # of args,
	//the integration testing should catch it.
	//But hey, things happen, so I decided to add it anyway, although you can
	//comment it out, if you are confident in your test suites.
	var req *http.Request
	var err error
	req, err = http.NewRequest(method, url, nil)
	if err != nil {
		return nil, err
	}
	for i := 0; i < len(h)-1; i = i + 2 {
		req.Header.Set(h[i], h[i+1])
	}
	req.ContentLength = int64(len(*content))
	if req.ContentLength > 0 {
		req.Body = readCloser{bytes.NewReader(*content)}
		//req.Body = *(new(io.ReadCloser)) //these 3 lines do not work but I am
		//req.Body.Read(content)           //keeping them here in case I wonder why
		//req.Body.Close()                 //I did not implement it this way :)
	}
	return (new(http.Client)).Do(req)
}

type readCloser struct {
	io.Reader
}

func (readCloser) Close() error {
	//cannot put this func inside CallAPI; golang disallow nested func
	return nil
}

//CheckStatusCode compares http response header StatusCode against expected
//statuses. Primary function is to ensure StatusCode is in the 20x (return nil).
//Ok: 200. Created: 201. Accepted: 202. No Content: 204.
//Otherwise return error message.
func CheckHttpResponseStatusCode(resp *http.Response) error {
	switch resp.StatusCode {
	case 200, 201, 202, 204:
		return nil
	case 400:
		return errors.New("Error: response == 400 bad request")
	case 401:
		return errors.New("Error: response == 401 unauthorised")
	case 403:
		return errors.New("Error: response == 403 forbidden")
	case 404:
		return errors.New("Error: response == 404 not found")
	case 405:
		return errors.New("Error: response == 405 method not allowed")
	case 409:
		return errors.New("Error: response == 409 conflict")
	case 413:
		return errors.New("Error: response == 413 over limit")
	case 415:
		return errors.New("Error: response == 415 bad media type")
	case 422:
		return errors.New("Error: response == 422 unprocessable")
	case 429:
		return errors.New("Error: response == 429 too many request")
	case 500:
		return errors.New("Error: response == 500 instance fault / server err")
	case 501:
		return errors.New("Error: response == 501 not implemented")
	case 503:
		return errors.New("Error: response == 503 service unavailable")
	}
	return errors.New("Error: unexpected response status code")
}