package usbip

import (
	"bytes"
	"encoding/binary"
	"io"
	"net"
	"testing"
	"time"

	"escpos-emulator/internal/escpos"
)

func startServer(t *testing.T) (*Server, *escpos.Printer) {
	t.Helper()
	prof, _ := escpos.FindProfile("80mm")
	p, err := escpos.NewPrinter(prof)
	if err != nil {
		t.Fatal(err)
	}
	s, err := Listen("127.0.0.1:0", DeviceFromProfile(prof), p)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { s.Close() })
	return s, p
}

func dial(t *testing.T, s *Server) net.Conn {
	t.Helper()
	c, err := net.Dial("tcp", s.Addr().String())
	if err != nil {
		t.Fatal(err)
	}
	_ = c.SetDeadline(time.Now().Add(5 * time.Second))
	t.Cleanup(func() { c.Close() })
	return c
}

func readN(t *testing.T, c net.Conn, n int) []byte {
	t.Helper()
	b := make([]byte, n)
	if _, err := io.ReadFull(c, b); err != nil {
		t.Fatalf("leyendo %d bytes: %v", n, err)
	}
	return b
}

func TestDevlist(t *testing.T) {
	s, _ := startServer(t)
	c := dial(t, s)
	c.Write([]byte{0x01, 0x11, 0x80, 0x05, 0, 0, 0, 0})
	h := readN(t, c, 12)
	if binary.BigEndian.Uint16(h[2:]) != opRepDevlist || binary.BigEndian.Uint32(h[8:]) != 1 {
		t.Fatalf("cabecera DEVLIST inesperada: % X", h)
	}
	dev := readN(t, c, 312+4)
	if got := string(bytes.TrimRight(dev[256:288], "\x00")); got != BusID {
		t.Fatalf("busid = %q", got)
	}
	if !bytes.Equal(dev[312:], []byte{7, 1, 2, 0}) {
		t.Fatalf("interfaz = % X, want clase impresora 07 01 02", dev[312:])
	}
}

type client struct {
	t    *testing.T
	c    net.Conn
	seq  uint32
	isIn map[uint32]bool
}

func attach(t *testing.T, s *Server) *client {
	c := dial(t, s)
	req := []byte{0x01, 0x11, 0x80, 0x03, 0, 0, 0, 0}
	bus := make([]byte, 32)
	copy(bus, BusID)
	c.Write(append(req, bus...))
	h := readN(t, c, 8)
	if binary.BigEndian.Uint32(h[4:]) != 0 {
		t.Fatalf("IMPORT rechazado: % X", h)
	}
	readN(t, c, 312)
	return &client{t: t, c: c, isIn: map[uint32]bool{}}
}

func (cl *client) submit(dir, ep uint32, length int, setup []byte, data []byte) uint32 {
	cl.seq++
	cl.isIn[cl.seq] = dir == dirIn
	h := make([]byte, 48)
	binary.BigEndian.PutUint32(h[0:], cmdSubmit)
	binary.BigEndian.PutUint32(h[4:], cl.seq)
	binary.BigEndian.PutUint32(h[8:], 0x00010002)
	binary.BigEndian.PutUint32(h[12:], dir)
	binary.BigEndian.PutUint32(h[16:], ep)
	binary.BigEndian.PutUint32(h[24:], uint32(length))
	binary.BigEndian.PutUint32(h[32:], 0xFFFFFFFF)
	copy(h[40:], setup)
	cl.c.Write(append(h, data...))
	return cl.seq
}

func (cl *client) ret() (seq uint32, status int32, data []byte) {
	h := readN(cl.t, cl.c, 48)
	seq = binary.BigEndian.Uint32(h[4:])
	status = int32(binary.BigEndian.Uint32(h[20:]))
	if n := int(binary.BigEndian.Uint32(h[24:])); cl.isIn[seq] && n > 0 {
		data = readN(cl.t, cl.c, n)
	}
	return
}
func TestControlAndBulk(t *testing.T) {
	s, p := startServer(t)
	cl := attach(t, s)

	// GET_DESCRIPTOR(DEVICE)
	cl.submit(dirIn, 0, 18, []byte{0x80, 6, 0, 1, 0, 0, 18, 0}, nil)
	_, st, d := cl.ret()
	if st != 0 || len(d) != 18 || d[1] != 1 {
		t.Fatalf("descriptor de dispositivo: status %d, % X", st, d)
	}
	if vid := binary.LittleEndian.Uint16(d[8:]); vid != 0x1209 {
		t.Fatalf("VID = %04X", vid)
	}

	// GET_DESCRIPTOR(CONFIGURATION) con wLength 9: solo la cabecera
	cl.submit(dirIn, 0, 9, []byte{0x80, 6, 0, 2, 0, 0, 9, 0}, nil)
	_, _, d = cl.ret()
	if len(d) != 9 || d[2] != 32 {
		t.Fatalf("configuración: % X", d)
	}

	// GET_DEVICE_ID de la clase impresora
	cl.submit(dirIn, 0, 1024, []byte{0xA1, 0, 0, 0, 0, 0, 0, 4}, nil)
	_, _, d = cl.ret()
	if !bytes.Contains(d, []byte("CMD:ESC/POS")) {
		t.Fatalf("GET_DEVICE_ID = %q", d)
	}

	// DEVICE_QUALIFIER debe dar STALL
	cl.submit(dirIn, 0, 10, []byte{0x80, 6, 0, 6, 0, 0, 10, 0}, nil)
	if _, st, _ = cl.ret(); st != errPipe {
		t.Fatalf("DEVICE_QUALIFIER status = %d, want %d", st, errPipe)
	}

	// Lectura bulk IN pendiente antes de que haya datos
	inSeq := cl.submit(dirIn, epBulkIn, 64, nil, nil)

	// Bulk OUT: texto + DLE EOT 1
	payload := []byte("\x1b@Hola USB\n\x10\x04\x01")
	outSeq := cl.submit(dirOut, epBulkOut, len(payload), nil, payload)

	got := map[uint32][]byte{}
	for i := 0; i < 2; i++ {
		seq, st, data := cl.ret()
		if st != 0 {
			t.Fatalf("seq %d status %d", seq, st)
		}
		got[seq] = data
	}
	if !bytes.Equal(got[inSeq], []byte{0x12}) {
		t.Fatalf("bulk IN = % X, want 12", got[inSeq])
	}
	if _, ok := got[outSeq]; !ok {
		t.Fatal("falta la respuesta del bulk OUT")
	}

	// UNLINK de una lectura pendiente
	pending := cl.submit(dirIn, epBulkIn, 64, nil, nil)
	cl.seq++
	u := make([]byte, 48)
	binary.BigEndian.PutUint32(u[0:], cmdUnlink)
	binary.BigEndian.PutUint32(u[4:], cl.seq)
	binary.BigEndian.PutUint32(u[20:], pending)
	cl.c.Write(u)
	h := readN(t, cl.c, 48)
	if binary.BigEndian.Uint32(h[0:]) != retUnlink || int32(binary.BigEndian.Uint32(h[20:])) != errConnReset {
		t.Fatalf("RET_UNLINK inesperado: % X", h)
	}

	if len(p.Snapshot(0).Connections) != 1 {
		t.Fatal("debería haber una conexión USB activa")
	}
}