package via

import (
	"encoding/binary"
	"strings"
	"testing"
)

// emptyVialPage is what get_supported returns once the list runs out: the whole
// report is 0xFF padding and no ID is greater than the cursor. A list ends
// because the firmware says so, not because the host ran out of answers.
func emptyVialPage() []byte {
	buf := make([]byte, 32)
	buf[0] = lightingGet
	buf[1] = vialrgbGetSupported
	for i := 2; i < len(buf); i++ {
		buf[i] = 0xFF
	}
	return buf
}

// vialVersionResponse is a Vial keyboard-ID answer: the prefix stays in byte 0
// and the version fills bytes 1 to 4, because Vial's handlers take msg = &data[1].
func vialVersionResponse(version uint32) []byte {
	buf := make([]byte, 32)
	buf[0] = vialPrefix
	binary.LittleEndian.PutUint32(buf[1:5], version)
	return buf
}

// unhandledResponse is stock QMK's answer to a command its switch does not know:
// raw_hid_receive ends with `default: { *command_id = id_unhandled; }`.
func unhandledResponse() []byte {
	buf := make([]byte, 32)
	buf[0] = byte(Unhandled)
	return buf
}

// echoResponse is a keyboard that hands the request straight back. Nothing in
// Vial's or QMK's source rules it out, and it is the answer that would make a
// prefix probe believe anything, so it has to read as "not Vial".
func echoResponse() []byte {
	buf := make([]byte, 32)
	buf[0] = vialPrefix
	buf[1] = vialGetKeyboardID
	return buf
}

func TestVialVersionReadsTheVersionOffAVialKeyboard(t *testing.T) {
	transport := &fakeTransport{queue: [][]byte{vialVersionResponse(0x00000006)}}
	protocol := Protocol{handle: transport}

	version, isVial, err := protocol.VialVersion()
	if err != nil {
		t.Fatalf("VialVersion() error = %v", err)
	}
	if !isVial {
		t.Error("VialVersion() = not Vial, want a keyboard that answered with a version")
	}
	if version != 6 {
		t.Errorf("VialVersion() = %d, want 6", version)
	}
	// The probe has to be the prefixed command, and the rest of the report zeroed,
	// so that an echo cannot look like an answer.
	sent := transport.reports[0]
	if sent[0] != vialPrefix || sent[1] != vialGetKeyboardID {
		t.Errorf("request = %v, want the Vial prefix and the keyboard-ID command", sent[:2])
	}
	for i := 2; i < len(sent); i++ {
		if sent[i] != 0 {
			t.Errorf("request byte %d = %d, want 0 so that an echo cannot pass for a version", i, sent[i])
		}
	}
}

// Stock QMK marks a command it does not know, and that is a keyboard that is not
// Vial rather than a failure to talk to it.
func TestVialVersionTreatsAnUnhandledCommandAsNotVial(t *testing.T) {
	transport := &fakeTransport{queue: [][]byte{unhandledResponse()}}
	protocol := Protocol{handle: transport}

	version, isVial, err := protocol.VialVersion()
	if err != nil {
		t.Fatalf("VialVersion() error = %v, want the unhandled marker read as an answer", err)
	}
	if isVial || version != 0 {
		t.Errorf("VialVersion() = %d, %t, want 0, false", version, isVial)
	}
}

// A keyboard that echoes the request answers with a prefix and a zero. A version
// is never zero, so this must not read as Vial.
func TestVialVersionDoesNotTrustAnEcho(t *testing.T) {
	transport := &fakeTransport{queue: [][]byte{echoResponse()}}
	protocol := Protocol{handle: transport}

	_, isVial, err := protocol.VialVersion()
	if err != nil {
		t.Fatalf("VialVersion() error = %v", err)
	}
	if isVial {
		t.Error("VialVersion() = Vial on an echoed request, which carries no version")
	}
}

// The supported list is a run of u16 from byte 2, padded to the end of the
// report with 0xFF. Reading the padding as an ID would put a name on a number
// the firmware never said was there.
func TestVialEffectIDsStopsAtTheFirmwarePadding(t *testing.T) {
	page := make([]byte, 32)
	page[0] = lightingGet
	page[1] = vialrgbGetSupported
	for i, id := range []uint16{1, 4, 5} {
		binary.LittleEndian.PutUint16(page[2+i*2:], id)
	}
	// get_supported memsets the rest of the report to 0xFF, which is the padding
	// the reader has to stop at.
	for i := 8; i < len(page); i++ {
		page[i] = 0xFF
	}

	transport := &fakeTransport{queue: [][]byte{page, emptyVialPage()}}
	protocol := Protocol{handle: transport}

	ids, err := protocol.VialEffectIDs()
	if err != nil {
		t.Fatalf("VialEffectIDs() error = %v", err)
	}
	want := []uint16{1, 4, 5}
	if len(ids) != len(want) {
		t.Fatalf("VialEffectIDs() = %v, want %v", ids, want)
	}
	for i := range want {
		if ids[i] != want[i] {
			t.Errorf("VialEffectIDs()[%d] = %d, want %d", i, ids[i], want[i])
		}
	}
}

// get_supported fills one report at a time from a cursor the request carries, so
// a list longer than one page takes more than one round trip.
func TestVialEffectIDsFollowsTheCursor(t *testing.T) {
	first := make([]byte, 32)
	first[0] = lightingGet
	first[1] = vialrgbGetSupported
	binary.LittleEndian.PutUint16(first[2:], 40)

	second := make([]byte, 32)
	second[0] = lightingGet
	second[1] = vialrgbGetSupported
	binary.LittleEndian.PutUint16(second[2:], 45)
	for i := 4; i < len(second); i++ {
		second[i] = 0xFF
	}

	transport := &fakeTransport{queue: [][]byte{first, second, emptyVialPage()}}
	protocol := Protocol{handle: transport}

	ids, err := protocol.VialEffectIDs()
	if err != nil {
		t.Fatalf("VialEffectIDs() error = %v", err)
	}
	if len(ids) != 2 || ids[0] != 40 || ids[1] != 45 {
		t.Errorf("VialEffectIDs() = %v, want [40 45]", ids)
	}
	// The second request has to carry what the first page ended on, or the
	// firmware would send the same page again.
	cursor := binary.LittleEndian.Uint16(transport.reports[1][2:4])
	if cursor != 40 {
		t.Errorf("second request cursor = %d, want 40", cursor)
	}
}

// Stock QMK's rgb_matrix get has no default case, so a value ID it does not know
// leaves the report unmarked rather than answering 0xFF. That is why the effect
// IDs must not be asked for before the firmware is known to be Vial: on a stock
// board the answer is an echo, and an echo of this request is bytes that can be
// read as a list.
func TestVialEffectIDsRefusesAListThatDoesNotAscend(t *testing.T) {
	page := make([]byte, 32)
	page[0] = lightingGet
	page[1] = vialrgbGetSupported
	binary.LittleEndian.PutUint16(page[2:], 7)
	binary.LittleEndian.PutUint16(page[4:], 3)

	transport := &fakeTransport{queue: [][]byte{page, emptyVialPage()}}
	protocol := Protocol{handle: transport}

	ids, err := protocol.VialEffectIDs()
	if err != nil {
		t.Fatalf("VialEffectIDs() error = %v, want a list read and then rejected", err)
	}
	if ids != nil {
		t.Errorf("VialEffectIDs() = %v, want nothing from a list that does not ascend", ids)
	}
}

// A firmware that echoes the request answers the second page with the cursor it
// was given, and a cursor that cannot advance would loop forever. That is the case
// the guard is for: an echoing keyboard is not a Vial keyboard, and the loop has
// to end rather than keep asking.
func TestVialEffectIDsStopsWhenTheFirmwareEchoesTheCursor(t *testing.T) {
	page := make([]byte, 32)
	page[0] = lightingGet
	page[1] = vialrgbGetSupported
	binary.LittleEndian.PutUint16(page[2:], 1)
	binary.LittleEndian.PutUint16(page[4:], 4)
	for i := 6; i < len(page); i++ {
		page[i] = 0xFF
	}

	transport := &fakeTransport{queue: [][]byte{page}}
	protocol := Protocol{handle: transport}

	_, err := protocol.VialEffectIDs()
	if err == nil {
		t.Fatal("VialEffectIDs() = nil error, want a failure when the cursor cannot advance")
	}
	if !strings.Contains(err.Error(), "advance") {
		t.Errorf("error = %q, want it to say the list did not advance", err)
	}
}