/*
   Copyright (c) 2015 Andrey Sibiryov <me@kobology.ru>
   Copyright (c) 2015 Other contributors as noted in the AUTHORS file.

   This file is part of GORB - Go Routing and Balancing.

   GORB is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   GORB 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 Lesser General Public License for more details.

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

package main

import (
	"flag"
	"net"
	"net/http"
	"os"

	"github.com/kobolog/gorb/core"
	"github.com/kobolog/gorb/util"

	log "github.com/Sirupsen/logrus"
	"github.com/gorilla/mux"

	"github.com/prometheus/client_golang/prometheus/promhttp"
	"strings"
)

var (
	// Version get dynamically set to git rev by ldflags at build time
	Version          = "DEV"

	debug            = flag.Bool("v", false, "enable verbose output")
	device           = flag.String("i", "eth0", "default interface to bind services on")
	flush            = flag.Bool("f", false, "flush IPVS pools on start")
	listen           = flag.String("l", ":4672", "endpoint to listen for HTTP requests")
	consul           = flag.String("c", "", "URL for Consul HTTP API")
	vipInterface     = flag.String("vipi", "", "interface to add VIPs")
	storeURLs        = flag.String("store", "", "comma delimited list of store urls for sync data. All urls must have" +
		" identical schemes and paths.")
	storeTimeout     = flag.Int64("store-sync-time", 60, "sync-time for store")
	storeServicePath = flag.String("store-service-path", "services", "store service path")
	storeBackendPath = flag.String("store-backend-path", "backends", "store backend path")
)

func main() {
	// Called first to interrupt bootstrap and display usage if the user passed -h.
	flag.Parse()

	if *debug {
		log.SetLevel(log.DebugLevel)
	}

	log.Info("starting GORB Daemon v" + Version)

	if os.Geteuid() != 0 {
		log.Fatalf("this program has to be run with root priveleges to access IPVS")
	}

	hostIPs, err := util.InterfaceIPs(*device)

	if err != nil {
		log.Fatalf("error while obtaining interface addresses: %s", err)
	}

	listenAddr, err := net.ResolveTCPAddr("tcp", *listen)
	listenPort := uint16(0)

	if err != nil {
		log.Fatalf("error while obtaining listening port from '%s': %s", *listen, err)
	} else {
		listenPort = uint16(listenAddr.Port)
	}

	ctx, err := core.NewContext(core.ContextOptions{
		Disco:            *consul,
		Endpoints:        hostIPs,
		Flush:            *flush,
		ListenPort:       listenPort,
		VipInterface:     *vipInterface})

	if err != nil {
		log.Fatalf("error while initializing server context: %s", err)
	}

	// While it's not strictly required, close IPVS socket explicitly.
	defer ctx.Close()

	// sync with external store
	if storeURLs != nil && len(*storeURLs) > 0 {
		urls := strings.Split(*storeURLs, ",")
		store, err := core.NewStore(urls, *storeServicePath, *storeBackendPath, *storeTimeout, ctx)
		if err != nil {
			log.Fatalf("error while initializing external store sync: %s", err)
		}
		defer store.Close()
	}

	core.RegisterPrometheusExporter(ctx)
	r := mux.NewRouter()

	r.Handle("/service/{vsID}", serviceCreateHandler{ctx}).Methods("PUT")
	r.Handle("/service/{vsID}/{rsID}", backendCreateHandler{ctx}).Methods("PUT")
	r.Handle("/service/{vsID}/{rsID}", backendUpdateHandler{ctx}).Methods("PATCH")
	r.Handle("/service/{vsID}", serviceRemoveHandler{ctx}).Methods("DELETE")
	r.Handle("/service/{vsID}/{rsID}", backendRemoveHandler{ctx}).Methods("DELETE")
	r.Handle("/service", serviceListHandler{ctx}).Methods("GET")
	r.Handle("/service/{vsID}", serviceStatusHandler{ctx}).Methods("GET")
	r.Handle("/service/{vsID}/{rsID}", backendStatusHandler{ctx}).Methods("GET")
	r.Handle("/metrics", promhttp.Handler()).Methods("GET")

	log.Infof("setting up HTTP server on %s", *listen)
	log.Fatal(http.ListenAndServe(*listen, r))
}