// Copyright 2014 by Sascha L. Teichmann
// Use of this source code is governed by the MIT license
// that can be found in the LICENSE file.

package main

import (
	"flag"
	"fmt"
	"log"
	"net"
	"os"
	"os/signal"
	"runtime"
	"time"

	"bitbucket.org/s_l_teichmann/mtredisalize/common"
)

const (
	Version    = "0.3"
	GCDuration = "24h"
)

func main() {

	var (
		port       int
		host       string
		driver     string
		cacheSize  int
		version    bool
		gcDuration string
	)

	flag.IntVar(&port, "port", 6379, "port to bind")
	flag.StringVar(&driver, "driver", "leveldb", "type of database (leveldb, sqlite)")
	flag.StringVar(&host, "host", "", "host to bind")
	flag.IntVar(&cacheSize, "cache", 32, "cache size in MB")
	flag.BoolVar(&version, "version", false, "Print version and exit.")
	flag.StringVar(&gcDuration, "gc-duration", GCDuration, "Duration between forced GCs.")
	flag.Parse()

	if version {
		fmt.Printf("Version: %s\n", Version)
		os.Exit(0)
	}

	args := flag.Args()

	if len(args) < 1 {
		log.Fatal("Missing path to world")
	}

	var (
		err     error
		backend Backend
		gcDur   time.Duration
	)

	if gcDur, err = time.ParseDuration(gcDuration); err != nil {
		log.Fatal(err)
	}

	if driver == "sqlite" {
		if backend, err = NewSqliteBackend(
			args[0],
			common.EncodeStringToBytes,
			common.DecodeStringFromBytes); err != nil {
			log.Fatal(err)
		}
	} else {
		if backend, err = NewLeveDBBackend(args[0], cacheSize); err != nil {
			log.Fatal(err)
		}
	}
	defer backend.Shutdown()

	var listener net.Listener

	listener, err = net.Listen("tcp", fmt.Sprintf("%s:%d", host, port))
	if err != nil {
		log.Fatal(err)
	}
	defer listener.Close()
	log.Printf("Server started at %s", listener.Addr())

	connChan := make(chan net.Conn)
	defer close(connChan)
	sigChan := make(chan os.Signal, 1)
	signal.Notify(sigChan, os.Interrupt, os.Kill)

	go func() {
		for {
			conn, err := listener.Accept()
			if err != nil {
				log.Fatal(err)
			}
			log.Printf("Client accepted from: %s", conn.RemoteAddr())
			connChan <- conn
		}
	}()

	log.Printf("Doing garbage collection every: %s", gcDur)
	gcChan := time.Tick(gcDur)

	for {
		select {
		case conn := <-connChan:
			var session Session
			if session, err = backend.NewSession(); err != nil {
				log.Printf("Cannot create session: %s", err)
				conn.Close()
			} else {
				go NewConnection(conn, session).Run()
			}
		case <-sigChan:
			log.Println("Shutting down")
			return
		case <-gcChan:
			log.Println("Starting garbage collection.")
			runtime.GC()
			log.Println("Garbage collection done.")
		}
	}
}