package cmpp

import (
	"encoding/binary"
	"fmt"
	"net"
	"reflect"
	"strings"
	"testing"
	"time"
)

func TestReceiptVersionLayout(t *testing.T) {
	for _, version := range []Type{V20, V21, V30} {
		width, size := 21, 60
		if version == V30 {
			width, size = 32, 71
		}
		original := CmppReceiptPkt{MsgId: ^uint64(0), Stat: "DELIVRD", SubmitTime: "2609201200", DoneTime: "2609201201", DestTerminalId: strings.Repeat("9", width), SmscSequence: ^uint32(0)}
		raw, err := original.PackVersion(version)
		if err != nil {
			t.Fatal(err)
		}
		if len(raw) != size || binary.BigEndian.Uint32(raw[size-4:]) != ^uint32(0) {
			t.Fatalf("wrong layout: %x", raw)
		}
		var decoded CmppReceiptPkt
		if err = decoded.UnpackVersion(raw, version); err != nil || !reflect.DeepEqual(decoded, original) {
			t.Fatalf("roundtrip: %+v %v", decoded, err)
		}
		for _, bad := range [][]byte{raw[:len(raw)-1], append(append([]byte{}, raw...), 0)} {
			if decoded.UnpackVersion(bad, version) == nil {
				t.Fatal("invalid length accepted")
			}
		}
		other := V30
		if version == V30 {
			other = V20
		}
		if decoded.UnpackVersion(raw, other) == nil {
			t.Fatal("wrong version accepted")
		}
		original.DestTerminalId += "1"
		if _, err = original.PackVersion(version); err == nil {
			t.Fatal("truncated destination")
		}
	}
}

// Real TCP peers exercise the bounded reader, not only Pack/Unpack in memory.
func tcpPair(t *testing.T, version Type) (*Conn, net.Conn) {
	t.Helper()
	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	defer listener.Close()
	client, err := net.Dial("tcp", listener.Addr().String())
	if err != nil {
		t.Fatal(err)
	}
	server, err := listener.Accept()
	if err != nil {
		t.Fatal(err)
	}
	conn := NewConn(server, version)
	conn.SetState(CONN_AUTHOK)
	t.Cleanup(func() { conn.Close(); client.Close() })
	return conn, client
}

func TestCMPP3LargeSubmitAndMalformedPackets(t *testing.T) {
	for _, length := range []int{140, 159} {
		p := Cmpp3SubmitReqPkt{DestUsrTl: 99, DestTerminalId: make([]string, 99), MsgLength: uint8(length), MsgContent: strings.Repeat("x", length)}
		if length == 140 {
			p.MsgFmt = 8
		}
		raw, err := p.Pack(^uint32(0))
		if err != nil {
			t.Fatal(err)
		}
		if len(raw) != 3331+length {
			t.Fatalf("size %d", len(raw))
		}
		conn, peer := tcpPair(t, V30)
		go peer.Write(raw)
		pkt, err := conn.RecvAndUnpackPkt(time.Second)
		if err != nil {
			t.Fatal(err)
		}
		decoded := pkt.(*Cmpp3SubmitReqPkt)
		if decoded.SeqId != ^uint32(0) || len(decoded.DestTerminalId) != 99 || decoded.MsgContent != p.MsgContent {
			t.Fatal("wire mismatch")
		}
		var d Cmpp3SubmitReqPkt
		if d.Unpack(raw[8:len(raw)-1]) == nil || d.Unpack(append(raw[8:], 0)) == nil {
			t.Fatal("malformed body accepted")
		}
		p.DestUsrTl = 100
		p.DestTerminalId = append(p.DestTerminalId, "")
		if _, err = p.Pack(0); err == nil {
			t.Fatal("100 destinations accepted")
		}
	}
	for _, size := range []uint32{0, 11, CMPP3_PACKET_MAX + 1, ^uint32(0)} {
		conn, peer := tcpPair(t, V30)
		raw := make([]byte, 4)
		binary.BigEndian.PutUint32(raw, size)
		go peer.Write(raw)
		if _, err := conn.RecvAndUnpackPkt(time.Second); err == nil {
			t.Fatalf("accepted length %d", size)
		}
	}
	p := Cmpp3SubmitReqPkt{DestUsrTl: 1, DestTerminalId: []string{"1"}, MsgFmt: 8, MsgLength: 141, MsgContent: strings.Repeat("a", 141)}
	if _, err := p.Pack(0); err == nil {
		t.Fatal("oversized non-ASCII accepted")
	}
	p.MsgFmt, p.MsgLength, p.MsgContent = 0, 160, strings.Repeat("a", 160)
	if _, err := p.Pack(0); err == nil {
		t.Fatal("ASCII must be strictly shorter than 160 bytes")
	}
}

func TestConnectStatusKeepsAll32Bits(t *testing.T) {
	for _, status := range []uint32{0, 5, 255, 256, ^uint32(0)} {
		t.Run(fmt.Sprint(status), func(t *testing.T) {
			listener, err := net.Listen("tcp", "127.0.0.1:0")
			if err != nil {
				t.Fatal(err)
			}
			defer listener.Close()
			done := make(chan error, 1)
			go func() {
				peer, e := listener.Accept()
				if e != nil {
					done <- e
					return
				}
				conn := NewConn(peer, V30)
				defer conn.Close()
				conn.SetState(CONN_CONNECTED)
				req, e := conn.RecvAndUnpackPkt(time.Second)
				if e == nil {
					e = conn.SendPkt(&Cmpp3ConnRspPkt{Status: status, Version: V30}, req.(*CmppConnReqPkt).SeqId)
				}
				done <- e
			}()
			client := NewClient(V30)
			defer client.Disconnect()
			err = client.Connect(listener.Addr().String(), "123456", "secret", time.Second)
			if status == 0 && err != nil {
				t.Fatal(err)
			}
			if status != 0 && (err == nil || !strings.Contains(err.Error(), fmt.Sprintf("status=%d", status))) {
				t.Fatalf("status truncated: %v", err)
			}
			if e := <-done; e != nil {
				t.Fatal(e)
			}
		})
	}
}

func TestRequestSequenceSkipsInFlightAcrossWrap(t *testing.T) {
	conn, peer := tcpPair(t, V30)
	sequences := make(chan uint32, 3)
	sequences <- ^uint32(0)
	sequences <- 0
	sequences <- 1
	conn.SeqId = sequences
	client := &Client{conn: conn, typ: V30}
	read := make(chan error, 1)
	go func() { raw := make([]byte, 12); _, err := peer.Read(raw); read <- err }()
	seq, err := client.SendReqPktAvailable(&CmppActiveTestReqPkt{}, func(n uint32) bool { return n != ^uint32(0) })
	if err != nil || seq != 0 {
		t.Fatalf("zero lost: %d %v", seq, err)
	}
	if err = <-read; err != nil {
		t.Fatal(err)
	}
}