package main

// #include <stdlib.h>
// #include "salticidae/network.h"
// void onTerm(int sig, void *);
// void onReceiveHello(msg_t *, msgnetwork_conn_t *, void *);
// void onReceiveAck(msg_t *, msgnetwork_conn_t *, void *);
// bool connHandler(msgnetwork_conn_t *, bool, void *);
// void errorHandler(SalticidaeCError *, bool, void *);
import "C"

import (
	"fmt"
	"github.com/Determinant/salticidae-go"
	"os"
	"unsafe"
)

const (
	MSG_OPCODE_HELLO salticidae.Opcode = iota
	MSG_OPCODE_ACK
)

func msgHelloSerialize(name string, text string) salticidae.Msg {
	serialized := salticidae.NewDataStream(true)
	serialized.PutU32(salticidae.ToLittleEndianU32(uint32(len(name))))
	serialized.PutData([]byte(name))
	serialized.PutData([]byte(text))
	return salticidae.NewMsgMovedFromByteArray(
		MSG_OPCODE_HELLO, salticidae.NewByteArrayMovedFromDataStream(serialized, true), true)
}

func msgHelloUnserialize(msg salticidae.Msg) (name string, text string) {
	p := msg.GetPayloadByMove()
	succ := true
	length := salticidae.FromLittleEndianU32(p.GetU32(&succ))
	t := p.GetDataInPlace(int(length))
	name = string(t.Get())
	t.Release()
	t = p.GetDataInPlace(p.Size())
	text = string(t.Get())
	t.Release()
	return
}

func msgAckSerialize() salticidae.Msg {
	return salticidae.NewMsgMovedFromByteArray(MSG_OPCODE_ACK, salticidae.NewByteArray(true), true)
}

func checkError(err *salticidae.Error) {
	if err.GetCode() != 0 {
		fmt.Printf("error during a sync call: %s\n", salticidae.StrError(err.GetCode()))
		os.Exit(1)
	}
}

type MyNet struct {
	net   salticidae.MsgNetwork
	name  string
	cname *C.char
}

var (
	alice, bob MyNet
	ec         salticidae.EventContext
)

//export onTerm
func onTerm(_ C.int, _ unsafe.Pointer) {
	ec.Stop()
}

//export onReceiveHello
func onReceiveHello(_msg *C.struct_msg_t, _conn *C.struct_msgnetwork_conn_t, userdata unsafe.Pointer) {
	msg := salticidae.MsgFromC(salticidae.CMsg(_msg))
	conn := salticidae.MsgNetworkConnFromC(salticidae.CMsgNetworkConn(_conn))
	net := conn.GetNet()
	name, text := msgHelloUnserialize(msg)
	myName := C.GoString((*C.char)(userdata))
	fmt.Printf("[%s] %s says %s\n", myName, name, text)
	ack := msgAckSerialize()
	net.SendMsg(ack, conn)
}

//export onReceiveAck
func onReceiveAck(_ *C.struct_msg_t, _conn *C.struct_msgnetwork_conn_t, userdata unsafe.Pointer) {
	myName := C.GoString((*C.char)(userdata))
	fmt.Printf("[%s] the peer knows\n", myName)
}

//export connHandler
func connHandler(_conn *C.struct_msgnetwork_conn_t, connected C.bool, userdata unsafe.Pointer) C.bool {
	conn := salticidae.MsgNetworkConnFromC(salticidae.CMsgNetworkConn(_conn))
	net := conn.GetNet()
	myName := C.GoString((*C.char)(userdata))
	n := alice
	if myName == "bob" {
		n = bob
	}
	if connected {
		if conn.GetMode() == salticidae.CONN_MODE_ACTIVE {
			fmt.Printf("[%s] connected, sending hello.\n", myName)
			hello := msgHelloSerialize(myName, "Hello there!")
			n.net.SendMsg(hello, conn)
		} else {
			fmt.Printf("[%s] accepted, waiting for greetings.\n", myName)
		}
	} else {
		fmt.Printf("[%s] disconnected, retrying.\n", myName)
		net.Connect(conn.GetAddr())
	}
	return true
}

//export errorHandler
func errorHandler(_err *C.struct_SalticidaeCError, fatal C.bool, _ unsafe.Pointer) {
	err := (*salticidae.Error)(unsafe.Pointer(_err))
	s := "recoverable"
	if fatal {
		s = "fatal"
	}
	fmt.Printf("Captured %s error during an async call: %s\n", s, salticidae.StrError(err.GetCode()))
}

func genMyNet(ec salticidae.EventContext,
	name string,
	myAddr salticidae.NetAddr, otherAddr salticidae.NetAddr) MyNet {
	err := salticidae.NewError()
	netconfig := salticidae.NewMsgNetworkConfig()
	net := salticidae.NewMsgNetwork(ec, netconfig, &err)
	checkError(&err)
	n := MyNet{net: net, name: name, cname: C.CString(name)}
	cname := unsafe.Pointer(n.cname)
	n.net.RegHandler(MSG_OPCODE_HELLO, salticidae.MsgNetworkMsgCallback(C.onReceiveHello), cname)
	n.net.RegHandler(MSG_OPCODE_ACK, salticidae.MsgNetworkMsgCallback(C.onReceiveAck), cname)
	n.net.RegConnHandler(salticidae.MsgNetworkConnCallback(C.connHandler), cname)
	n.net.RegErrorHandler(salticidae.MsgNetworkErrorCallback(C.errorHandler), cname)

	n.net.Start()
	n.net.Listen(myAddr, &err)
	checkError(&err)
	n.net.Connect(otherAddr)
	return n
}

func main() {
	ec = salticidae.NewEventContext()
	err := salticidae.NewError()

	aliceAddr := salticidae.NewNetAddrFromIPPortString("127.0.0.1:12345", true, &err)
	bobAddr := salticidae.NewNetAddrFromIPPortString("127.0.0.1:12346", true, &err)

	alice = genMyNet(ec, "alice", aliceAddr, bobAddr)
	bob = genMyNet(ec, "bob", bobAddr, aliceAddr)

	ev_int := salticidae.NewSigEvent(ec, salticidae.SigEventCallback(C.onTerm), nil)
	ev_int.Add(salticidae.SIGINT)
	ev_term := salticidae.NewSigEvent(ec, salticidae.SigEventCallback(C.onTerm), nil)
	ev_term.Add(salticidae.SIGTERM)

	ec.Dispatch()
	alice.net.Stop()
	bob.net.Stop()
	C.free(unsafe.Pointer(alice.cname))
	C.free(unsafe.Pointer(bob.cname))
}