package imq

import (
	"bytes"
	"errors"
	"testing"
)

// frame encodes a frame as the client does: field 1 the type, field 2 the data.
func frame(t uint64, data []byte) []byte {
	b := append([]byte{0x08}, uvarint(t)...)
	b = append(b, 0x12)
	b = append(b, uvarint(uint64(len(data)))...)
	return append(b, data...)
}

func uvarint(v uint64) []byte {
	var b []byte
	for v >= 0x80 {
		b = append(b, byte(v)|0x80)
		v >>= 7
	}
	return append(b, byte(v))
}

func TestReaderSplitsFrames(t *testing.T) {
	stream := append(frame(1302, []byte("hello")), frame(3103, bytes.Repeat([]byte{1}, 300))...)
	stream = append(stream, frame(1301, nil)...)
	// Fed a byte at a time, the frames still come out whole and in order.
	var r Reader
	var got []Frame
	for i := range stream {
		frames, err := r.Write(stream[i : i+1])
		if err != nil {
			t.Fatal(err)
		}
		got = append(got, frames...)
	}
	want := []Frame{{1302, 5}, {3103, 300}, {1301, 0}}
	if len(got) != len(want) {
		t.Fatalf("got %v, want %v", got, want)
	}
	for i := range want {
		if got[i] != want[i] {
			t.Fatalf("got %v, want %v", got, want)
		}
	}
}

func TestReaderRejectsOtherStreams(t *testing.T) {
	var r Reader
	// A TLS ClientHello isn't IMQ.
	if _, err := r.Write([]byte{0x16, 0x03, 0x01, 0x00, 0xa5}); !errors.Is(err, ErrMalformed) {
		t.Fatalf("got %v, want ErrMalformed", err)
	}
	if _, err := r.Write(frame(1301, nil)); !errors.Is(err, ErrMalformed) {
		t.Fatal("a reader keeps failing after a malformed frame")
	}
}

func TestTypeName(t *testing.T) {
	if TypeName(3104) != "G2cSendMessage" || TypeName(7) != "type 7" {
		t.Fatal(TypeName(3104), TypeName(7))
	}
}