package fizzbuzz

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"net/url"
	"strconv"
)

// Server represents an instance of a fizzbuzz server
type Server struct{}

// Routes returns the routes of the fizzbuzz server
func (s *Server) Routes() http.Handler {
	mux := http.NewServeMux()
	mux.HandleFunc("/", s.handleFizzBuzz)
	return mux
}

func (s *Server) handleFizzBuzz(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/" {
		// The "/" pattern matches everything,
		// so we need to check that we're at the root here
		http.NotFound(w, r)
		return
	}
	in := &inputs{}

	in.string1 = r.URL.Query().Get("string1")
	in.string2 = r.URL.Query().Get("string2")

	var err error
	if in.int1, err = parseInt(r.URL, "int1"); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	if in.int2, err = parseInt(r.URL, "int2"); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	if in.limit, err = parseInt(r.URL, "limit"); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	if err = json.NewEncoder(w).Encode(in.generateFizzbuzz()); err != nil {
		log.Printf("error while encoding '%#v': %s", in, err.Error())
		http.Error(w, "encoding problem", http.StatusInternalServerError)
	}
}

func parseInt(url *url.URL, paramName string) (int, error) {
	if param := url.Query().Get(paramName); param != "" {
		intParam, err := strconv.Atoi(param)
		if err != nil {
			return 0, fmt.Errorf("%s: invalid integer '%s'", paramName, param)
		}
		return intParam, nil
	}
	return 0, nil
}