package servlet

import (
	"html/template"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"regexp"
	"vinegar/vinegarUtil"
)

const (
	defaultLruSize           = int64(1024 * 1024 * 50)
	ContentTypeHeaderKey     = "Content-Type"
	ContentEncodingHeaderKey = "Content-Encoding"
	AcceptEncodingHeaderKey  = "Accept-Encoding"
)

type ErrorResponse struct {
	Code    int
	Message string
}

type (
	VinegarServlet struct {
		Port   string
		Routes []*VinegarRoute
	}

	VinegarRoute struct {
		Pattern *regexp.Regexp
		Handler VinegarHandlerFunction
		Cache   vinegarUtil.Cache
	}

	VinegarHandlerFunction func(w http.ResponseWriter, req *http.Request)
)

func NewServlet(port string) *VinegarServlet {
	srv := VinegarServlet{Port: port}

	return &srv
}

func NewServletRoute(routePattern string, handleFunc VinegarHandlerFunction) *VinegarRoute {

	pattern := regexp.MustCompile(routePattern)

	route := VinegarRoute{Pattern: pattern, Handler: handleFunc, Cache: vinegarUtil.NewLRU(defaultLruSize)}
	return &route
}

func (s *VinegarServlet) AddRoute(route *VinegarRoute) {
	route.Announce()
	s.Routes = append(s.Routes, route)
}

func (s *VinegarServlet) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	path := req.URL.Path
	for _, route := range s.Routes {
		if route.Pattern.MatchString(path) {
			route.Handler(w, req)
			return
		}
	}
}

func (s *VinegarServlet) Start() {
	if len(s.Routes) < 1 {
		log.Fatal("No routes found for server. Nothing to listen and serve.")
		os.Exit(1)
	}

	log.Printf("Listening on [%s]\n", s.Port)

	err := http.ListenAndServe(s.Port, s)

	if err != nil {
		panic(err)
	}

}

func (r *VinegarRoute) Announce() {
	log.Printf("Added route for [%s]\n", r.Pattern.String())
}

func SendError(w http.ResponseWriter, code int, msg string) {
	errorFile := "templates/error.html"
	errorResp := ErrorResponse{code, msg}
	tmplManager := template.New("error")

	f, err := os.OpenFile(errorFile, os.O_RDONLY, 0777)
	if err != nil {
		panic(err)
	}
	defer f.Close()

	content, err := ioutil.ReadAll(f)
	if err != nil {
		panic(err)
	}

	tmpl, err := tmplManager.Parse(string(content))
	if err != nil {
		panic(err)
	}

	w.WriteHeader(code)
	err = tmpl.Execute(w, errorResp)
	if err != nil {
		panic(err)
	}
}