/*
 * nftables-http-api
 * Copyright (C) 2024 Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>
 *
 *  This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>.
 */

package main

import (
	"encoding/json"
	"flag"
	"github.com/gorilla/mux"
	"gopkg.in/yaml.v3"
	"log"
	"net/http"
	"os"
)

var config Config
var configFile string
var listen string

func init() {
	flag.StringVar(&configFile, "config", "/etc/nft-set-api.yml", "Path to configuration file")
	flag.StringVar(&listen, "listen", "[::1]:8082", "Address and port to listen on")
}

type Config struct {
	TokenSets map[string][]string
}

type authMiddleWareMap struct {
	tokenSets map[string]string
}

func (authMiddleWare *authMiddleWareMap) Middleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		var givenToken = r.Header.Get("TOKEN")
		params := mux.Vars(r)
		givenSet := params["set"]

		if givenToken == "" {
			doReturn(w, http.StatusUnauthorized, "missing token")
			return
		}

		for configToken, configSets := range config.TokenSets {
			if doCheckToken(givenToken, configToken) {
				for _, configSet := range configSets {
					if givenSet == configSet {
						next.ServeHTTP(w, r)
						return
					}
				}
			}
		}

		log.Printf("Not processing unauthenticated request from %s", r.RemoteAddr)

		doReturn(w, http.StatusUnauthorized, "invalid token")

	})
}

type addressPayload struct {
	Address string
}

func main() {
	flag.Parse()
	log.Print("Booting ...")

	buffer, err := os.ReadFile(configFile)
	if err != nil {
		log.Fatalln("Could not read configuration file:", err)
		return
	}

	err = yaml.Unmarshal(buffer, &config)
	if err != nil {
		log.Fatalln("Could not parse configuration file:", err)
		return
	}
	log.Printf("%+v\n", config)

	log.Print("Listening on ", listen)

	router := mux.NewRouter()
	router.HandleFunc("/set/{set}", handleSetRoute).Methods("GET", "POST")

	authMiddleWare := authMiddleWareMap{make(map[string]string)}
	router.Use(authMiddleWare.Middleware)

	http.ListenAndServe(listen, router)
}

func handleSetRoute(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	params := mux.Vars(r)
	method := r.Method
	set := params["set"]
	log.Printf("Processing authorized %s request from %s for set %s", method, r.RemoteAddr, set)

	switch method {
	case "GET":
		nftResult, err := handleNft("get", set, "")
		if err != nil || nftResult == nil {
			doReturn(w, http.StatusInternalServerError, err.Error())
			return
		}
		doReturnSet(w, http.StatusOK, "", nftResult.([]string))

	case "POST":
		var payload addressPayload
		decErr := json.NewDecoder(r.Body).Decode(&payload)
		if decErr != nil {
			doReturn(w, http.StatusBadRequest, decErr.Error())
			return
		}

		nftResult, err := handleNft("add", set, payload.Address)
		if err != nil || nftResult == nil {
			doReturn(w, http.StatusInternalServerError, err.Error())
			return
		}
		switch nftResult {
		case "already":
			doReturn(w, http.StatusOK, "already exists")
		case "added":
			doReturn(w, http.StatusCreated, "ok")
		default:
			doReturn(w, http.StatusInternalServerError, "unhandled result")
		}
	}
}