/*
goircd -- minimalistic simple Internet Relay Chat (IRC) server
Copyright (C) 2014-2020 Sergey Matveev <stargrave@stargrave.org>

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, version 3 of the License.

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 <http://www.gnu.org/licenses/>.
*/

package main

import (
	"crypto/tls"
	"flag"
	"io/ioutil"
	"log"
	"net"
	"os"
	"os/signal"
	"path"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"
)

const (
	Version = "1.9.1"

	StateTopicFilename = "topic"
	StateKeyFilename   = "key"

	EventNew   = iota
	EventDel   = iota
	EventMsg   = iota
	EventTopic = iota
	EventWho   = iota
	EventMode  = iota
	EventTerm  = iota
	EventTick  = iota
)

type ClientEvent struct {
	client    *Client
	eventType int
	text      string
}

type StateEvent struct {
	where string
	topic string
	key   string
}

var (
	hostname       = flag.String("hostname", "localhost", "hostname")
	bind           = flag.String("bind", "[::1]:6667", "address to bind to")
	cloak          = flag.String("cloak", "", "cloak user's host with the given hostname")
	motd           = flag.String("motd", "", "path to MOTD file")
	logdir         = flag.String("logdir", "", "absolute path to directory for logs")
	statedir       = flag.String("statedir", "", "absolute path to directory for states")
	passwords      = flag.String("passwd", "", "optional path to passwords file")
	tlsBind        = flag.String("tlsbind", "", "TLS address to bind to")
	tlsPEM         = flag.String("tlspem", "", "path to TLS certificat+key PEM file")
	permStateDirS  = flag.String("perm-state-dir", "755", "state directory permissions")
	permStateFileS = flag.String("perm-state-file", "600", "state files permissions")
	permLogFileS   = flag.String("perm-log-file", "644", "log files permissions")
	timestamped    = flag.Bool("timestamped", false, "enable timestamps on stderr messages")
	verbose        = flag.Bool("verbose", false, "enable verbose logging")
	debug          = flag.Bool("debug", false, "enable debug (traffic) logging")

	permStateDir  os.FileMode
	permStateFile os.FileMode
	permLogFile   os.FileMode

	stateSink chan StateEvent = make(chan StateEvent)
)

func permParse(s string) os.FileMode {
	r, err := strconv.ParseUint(s, 8, 16)
	if err != nil {
		log.Fatalln(err)
	}
	return os.FileMode(r)
}

func listenerLoop(ln net.Listener, events chan ClientEvent) {
	for {
		conn, err := ln.Accept()
		if err != nil {
			log.Println("error during accept", err)
			continue
		}
		NewClient(conn, events)
	}
}

func main() {
	flag.Parse()
	permStateDir = permParse(*permStateDirS)
	permStateFile = permParse(*permStateFileS)
	permLogFile = permParse(*permLogFileS)

	if *timestamped {
		log.SetFlags(log.Ldate | log.Lmicroseconds | log.Lshortfile)
	} else {
		log.SetFlags(log.Lshortfile)
	}
	log.SetOutput(os.Stdout)

	if *logdir == "" {
		// Dummy logger
		go func() {
			for range logSink {
			}
		}()
	} else {
		if !path.IsAbs(*logdir) {
			log.Fatalln("need absolute path for logdir")
		}
		go Logger(*logdir, logSink)
	}

	if *statedir == "" {
		// Dummy statekeeper
		go func() {
			for range stateSink {
			}
		}()
	} else {
		if !path.IsAbs(*statedir) {
			log.Fatalln("need absolute path for statedir")
		}
		states, err := filepath.Glob(path.Join(*statedir, "#*"))
		if err != nil {
			log.Fatalln("can not read statedir", err)
		}
		for _, state := range states {
			buf, err := ioutil.ReadFile(path.Join(state, StateTopicFilename))
			if err != nil {
				log.Fatalf(
					"can not read state %s/%s: %v",
					state, StateTopicFilename, err,
				)
			}
			room := RoomRegister(path.Base(state))
			room.topic = strings.TrimRight(string(buf), "\n")
			buf, err = ioutil.ReadFile(path.Join(state, StateKeyFilename))
			if err == nil {
				room.key = strings.TrimRight(string(buf), "\n")
			} else {
				if !os.IsNotExist(err) {
					log.Fatalf(
						"can not read state %s/%s: %v",
						state, StateKeyFilename, err,
					)
				}
			}
			log.Println("loaded state for room:", room.name)
		}

		go func() {
			for event := range stateSink {
				statePath := path.Join(*statedir, event.where)
				if _, err := os.Stat(statePath); os.IsNotExist(err) {
					if err := os.Mkdir(statePath, permStateDir); err != nil {
						log.Printf("can not create state %s: %v", statePath, err)
						continue
					}
				}

				topicPath := path.Join(statePath, StateTopicFilename)
				if err := ioutil.WriteFile(
					topicPath,
					[]byte(event.topic+"\n"),
					permStateFile,
				); err != nil {
					log.Printf("can not write statefile %s: %v", topicPath, err)
					continue
				}

				keyPath := path.Join(statePath, StateKeyFilename)
				if err := ioutil.WriteFile(
					keyPath,
					[]byte(event.key+"\n"),
					permStateFile,
				); err != nil {
					log.Printf("can not write statefile %s: %v", keyPath, err)
				}
			}
		}()
	}

	events := make(chan ClientEvent)
	if *bind != "" {
		ln, err := net.Listen("tcp", *bind)
		if err != nil {
			log.Fatalf("can not listen on %s: %v", *bind, err)
		}
		go listenerLoop(ln, events)
	}
	if *tlsBind != "" {
		cert, err := tls.LoadX509KeyPair(*tlsPEM, *tlsPEM)
		if err != nil {
			log.Fatalf("can not load TLS keys from %s: %s", *tlsPEM, err)
		}
		config := tls.Config{Certificates: []tls.Certificate{cert}}
		ln, err := tls.Listen("tcp", *tlsBind, &config)
		if err != nil {
			log.Fatalf("can not listen on %s: %v", *tlsBind, err)
		}
		go listenerLoop(ln, events)
	}
	log.Println("goircd", Version, "started")

	needsShutdown := make(chan os.Signal, 0)
	signal.Notify(needsShutdown, syscall.SIGTERM, syscall.SIGINT)
	go func() {
		<-needsShutdown
		events <- ClientEvent{eventType: EventTerm}
		log.Println("goircd shutting down")
	}()

	finished := make(chan struct{})
	go Processor(events, finished)
	<-finished
}