package pkg

import (
	"net/http"
	"path"
	"strings"
)

type ApplicationHandler struct {
	db           *Db
	fileHandler  http.Handler
	loginHandler *LoginHandler
}

func NewApplication(db *Db) http.Handler {
	var handler http.Handler = &ApplicationHandler{
		db:           db,
		fileHandler:  http.FileServer(http.Dir("web/static")),
		loginHandler: &LoginHandler{},
	}
	handler = LocaleSetter(db, handler)
	handler = LoginChecker(db, handler)
	handler = Recoverer(handler)
	handler = Logger(handler)
	return handler
}

func (h *ApplicationHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	var head string
	head, r.URL.Path = shiftPath(r.URL.Path)
	switch head {
	case "static":
		h.fileHandler.ServeHTTP(w, r)
	case "login":
		h.loginHandler.ServeHTTP(w, r)
	case "edit":
		switch r.Method {
		case http.MethodGet:
			mustRenderTemplate(w, r, "editor.gohtml", "web.gohtml", nil)
		default:
			methodNotAllowed(w, r, http.MethodGet)
		}
	case "":
		switch r.Method {
		case http.MethodGet:
			h.serveHomePage(w, r)
		default:
			methodNotAllowed(w, r, http.MethodGet)
		}
	default:
		http.NotFound(w, r)
	}
}

func (h *ApplicationHandler) serveHomePage(w http.ResponseWriter, r *http.Request) {
	mustRenderWebTemplate(w, r, "home.gohtml", nil)
}

func shiftPath(p string) (head, tail string) {
	p = path.Clean("/" + p)
	if i := strings.IndexByte(p[1:], '/') + 1; i <= 0 {
		return p[1:], "/"
	} else {
		return p[1:i], p[i:]
	}
}

func methodNotAllowed(w http.ResponseWriter, _ *http.Request, allowed ...string) {
	w.Header().Set("Allow", strings.Join(allowed, ", "))
	http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
}