login-backend/src/handlers/greeting.go

package handlers

import (
	"encoding/json"
	"fmt"
	"io"
	"moffas_go/helper"
	"moffas_go/logger"
	"net/http"
	"net/url"
	"strconv"
	"strings"
)

type HTTPContextKey string

func Greeting(w http.ResponseWriter, r *http.Request) {
	// GENERATE RANDOMIZED reference_id TO IDENTIFY REQUESTS UNIQUELY
	var err error
	var res string
	type reqStruct struct {
		Name       string `json:"name"`
		Password   string `json:"password"`
		Salt       string `json:"salt"`
		Iterations int    `json:"iterations"`
	}

	var req reqStruct = reqStruct{}

	var ctxkey HTTPContextKey = "requsetID"
	reference_id := r.Context().Value(ctxkey).(string)

	defer func() {
		logger.Info(reference_id, "Response body: ", res)
	}()

	// SET THE RESPONSE TYPE TO application/json
	w.Header().Set("Content-Type", "application/json")
	response := map[string]any{
		"error_code":    "000000000",
		"error_message": "",
	}

	// GET THE REQUEST QUERY PARAMS AND THE RAW QUERY STRING
	var queryString string = string(r.URL.RawQuery)
	var query url.Values = r.URL.Query()
	if r.Method == http.MethodGet {
		// GET NAME FROM QUERY PARAMS
		names := query["name"]
		req.Name = strings.Join(names, "")

		// PREPARE THE RESPONSE
		if req.Name == "" {
			response["message"] = "Hello!"
		} else {
			response["message"] = "Hello, " + req.Name + "!"
		}
		response["reference_id"] = reference_id
		response["query_string"] = queryString
		req.Password = query["password"][0]
		req.Salt = query["salt"][0]
		req.Iterations, _ = strconv.Atoi(query["iterations"][0])

		if req.Password == "" {
			req.Password = "rahasia"
		}
		response["password"] = req.Password

		if req.Salt == "" {
			req.Salt, _ = helper.GenerateRandomString(16)
		}
		response["salt"] = req.Salt

		if req.Iterations <= 0 {
			req.Iterations = 10000
		}
		response["iterations"] = req.Iterations
		response["salted_password"] = helper.PBKDF2_SHA256(req.Password, req.Salt, req.Iterations)

		// SEND THE RESPONSE AS JSON
		res, _ = helper.JSONencode(response)
		fmt.Fprint(w, res)
		return

	} else if r.Method == http.MethodPost {
		// THE RECEIVED REQUEST METHOD IS POST
		logger.Info(reference_id, "Request Method: POST")

		// VERIFY THE CONTENT IS JSON
		if contentType := r.Header.Get("Content-Type"); contentType != "application/json" {
			// NOT JSON
			logger.Error(reference_id, "Invalid content-type: ", contentType)
			response["error_code"] = "400000001"
			response["error_message"] = "Bad Request. Not JSON"
			res, _ = helper.JSONencode(response)
			http.Error(w, res, http.StatusBadRequest)
			return
		}

		// READ THE POST BODY
		var body []byte
		body, err = io.ReadAll(r.Body)
		if err != nil {
			// FAILED TO READ BODY
			logger.Error(reference_id, err)
			response["error_code"] = "400000002"
			response["error_message"] = "Bad Request. Can't read POST body"
			// logger.E("ERROR : ", err)
			res, _ = helper.JSONencode(response)
			http.Error(w, res, http.StatusBadRequest)
			return
		}
		bodyString := string(body)
		logger.Info(reference_id, "POST BODY: ", bodyString)

		// EXTRACT DATA FROM JSON BODY
		err = json.Unmarshal(body, &req)
		if err != nil {
			// FAILED TO DECODE JSON
			logger.Error(reference_id, err)
			response["error_code"] = "400000003"
			response["error_message"] = "Bad Request. Invalid JSON"
			// logger.E("ERROR : ", err)
			res, _ = helper.JSONencode(response)
			http.Error(w, res, http.StatusBadRequest)
			return
		}

		if req.Password == "" {
			req.Password = "rahasia"
		}
		response["password"] = req.Password

		if req.Salt == "" {
			req.Salt, _ = helper.GenerateRandomString(16)
		}
		response["salt"] = req.Salt

		if req.Iterations <= 0 {
			req.Iterations = 10000
		}
		response["iterations"] = req.Iterations
		response["salted_password"] = helper.PBKDF2_SHA256(req.Password, req.Salt, req.Iterations)

		// PREPARE THE RESPONSE
		if req.Name == "" {
			response["message"] = "Hello!"
		} else {
			response["message"] = "Hello, " + req.Name + "!"
		}
		response["reference_id"] = reference_id
		response["query_string"] = queryString

		// SEND THE RESPONSE AS JSON
		res, _ = helper.JSONencode(response)
		fmt.Fprint(w, res)
		return

	} else {
		// METHOD NOT ALLOWED (not GET or POST)
		response["error_code"] = "405000001"
		response["error_message"] = "Method Not Allowed"
		res, _ = helper.JSONencode(response)
		http.Error(w, res, http.StatusMethodNotAllowed)
		return
	}
}