package main

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

type loginChecker struct{
	students []Student
}

type loginUpload struct {
	Username string
	Password string
}

func (l loginChecker) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if addr := r.Header.Get("X-Forwarded-For"); addr != "" {
		r.RemoteAddr = addr
	}
	log.Printf("%s \"%s %s\" [%s]\n", r.RemoteAddr, r.Method, r.URL.Path, r.UserAgent())

	w.Header().Set("Content-Type", "text/plain")

	// Check request type and size
	if r.Method != "POST" {
		http.Error(w,
			"Invalid request",
			http.StatusBadRequest)
		return
	} else if r.ContentLength < 0 || r.ContentLength > 1023 {
		http.Error(w,
			"Request entity too large",
			http.StatusRequestEntityTooLarge)
		return
	}

	dec := json.NewDecoder(r.Body)
	var lu loginUpload
	if err := dec.Decode(&lu); err != nil {
		http.Error(w,
			err.Error(),
			http.StatusBadRequest)
		return
	}

	// Perform login check
	canContinue := false
	for _, std := range l.students {
		if std.Login == lu.Username {
			canContinue = true
		}
	}

	if !canContinue {
		http.Error(w, "Login not found in whitelist.", http.StatusUnauthorized)
		return
	}

	http.Error(w, "Success", http.StatusOK)
}