package main

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

type imagesHandler struct {
	name   string
	auth   func(*http.Request) bool
	hndlr  http.Handler
	getter func(fname string) (*Picture, error)
}

func ImagesHandler(name string, auth func(*http.Request) bool, hndlr http.Handler, getter func(fname string) (*Picture, error)) imagesHandler {
	return imagesHandler{name, auth, hndlr, getter}
}

func (i imagesHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	log.Printf("Handling %s %s request from %s: %s [%s]\n", r.Method, i.name, r.RemoteAddr, r.URL.Path, r.UserAgent())

	// Don't handle subdirectories
	if strings.Contains(r.URL.Path[1:], "/") {
		http.Error(w, "Image not found.", http.StatusBadRequest)
		return
	}

	// Refuse most methods
	if r.Method != "GET" && r.Method != "HEAD" {
		http.Error(w, "Method not allowed.", http.StatusMethodNotAllowed)
		return
	}

	// Refuse content
	if r.ContentLength != 0 {
		http.Error(w, "This request doesn't accept content.", http.StatusRequestEntityTooLarge)
		return
	}

	// Check rights
	if !i.auth(r) {
		w.Header().Set("WWW-Authenticate", "Basic realm=\"YouP0m\"")
		http.Error(w, "You are not allowed to perform this request.", http.StatusUnauthorized)
		return
	}

	// Search the picture
	if pict, err := i.getter(r.URL.Path[1:]); err != nil {
		http.Error(w, err.Error(), http.StatusNotFound)
		return
	} else {
		r.URL.Path = "/" + pict.path
		i.hndlr.ServeHTTP(w, r)
	}
}