package main

import (
	"encoding/json"
	"log"
	"net/http"
	"os"
	"strconv"
)

type ErrorResponse struct {
	Message    string `json:"message"`
	StatusCode int    `json:"statusCode"`
}

type SuccessResponse struct {
	Name string `json:"name"`
}

func handler(w http.ResponseWriter, r *http.Request) {
	log.Println("Running handler...")

	code := getResponseCode(r)

	w.WriteHeader(code)
	w.Header().Set("Content-Type", "application/json")

	if (code != 200) {
		json.NewEncoder(w).Encode(ErrorResponse{
			Message: "There has been an error.",
			StatusCode: code,
		})
	} else {
		json.NewEncoder(w).Encode(SuccessResponse{
			Name: "Oliver Davies",
		})
	}
}

func getResponseCode(r *http.Request) int {
	// If the `force-fail` header is set, get and return its value.
	if failCode := r.Header.Get("force-fail"); failCode != "" {
		log.Println("`force-fail` header set...")

		if code, err := strconv.Atoi(failCode); err == nil {
			log.Printf("Setting the response code to %d...", code)

			return code
		}
	}

	return http.StatusOK
}

func getPort() string {
	port := os.Getenv("PORT")

	if port != "" {
		return port
	}

	return "8080"
}

func main() {
	http.HandleFunc("/", handler)

	addr := ":" + getPort()

	log.Printf("Starting server on %s", addr)

	if err := http.ListenAndServe(addr, nil); err != nil {
		log.Fatal(err)
	}
}