package utp

import "testing"

func TestEncodeDecode(t *testing.T) {
	tests := []struct {
		name string
		h    header
	}{
		{
			name: "syn",
			h: header{
				typ:       Syn,
				ver:       1,
				ext:       0,
				connID:    1234,
				timestamp: 12345678,
				timeDiff:  1000,
				wnd:       65535,
				seq:       1,
				ack:       0,
			},
		},
		{
			name: "data",
			h: header{
				typ:       Data,
				ver:       1,
				connID:    5678,
				timestamp: 99999999,
				timeDiff:  500,
				wnd:       32768,
				seq:       100,
				ack:       99,
			},
		},
		{
			name: "state",
			h: header{
				typ:    State,
				ver:    1,
				connID: 1234,
				wnd:    65535,
				seq:    1,
				ack:    1,
			},
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			buf := make([]byte, headerSize)
			encode(&tt.h, buf)
			got := decode(buf)
			if got != tt.h {
				t.Errorf("got %+v, want %+v", got, tt.h)
			}
		})
	}
}

func TestSeqLess(t *testing.T) {
	tests := []struct {
		name string
		a, b uint16
		want bool
	}{
		{"1 < 2", 1, 2, true},
		{"2 > 1", 2, 1, false},
		{"wrap 0xFFFF < 0", 0xFFFF, 0, true},
		{"wrap 0 > 0xFFFF", 0, 0xFFFF, false},
		{"half 0x7FFF > 0", 0x7FFF, 0, false},
		{"half 0 < 0x7FFF", 0, 0x7FFF, true},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := seqLess(tt.a, tt.b)
			if got != tt.want {
				t.Errorf("seqLess(%d, %d) = %v, want %v", tt.a, tt.b, got, tt.want)
			}
		})
	}
}