// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
// SPDX-License-Identifier: GPL-3.0-or-later

package input

import (
	"errors"
	"reflect"
	"testing"
	"time"
)

const (
	testInsertSymbol uint32 = 0xff63
	testF11Symbol    uint32 = 0xffc8
	codeShift        uint8  = 50
	codeControl      uint8  = 37
	codeAlt          uint8  = 64
	codeInsert       uint8  = 118
	codeA            uint8  = 38
	codeR            uint8  = 27
	codeF11          uint8  = 95
)

var testEscape = CommandChord{Symbol: testF11Symbol}

func newTestCaptureRouter(t *testing.T, local CommandBindings) *RemoteCaptureRouter {
	t.Helper()
	router, err := NewRemoteCaptureRouter(testEscape, local, []uint32{testInsertSymbol})
	if err != nil {
		t.Fatal(err)
	}
	return router
}

type captureStep struct {
	key  RemoteCaptureKey
	want RemoteCaptureResult
}

func press(code uint8, symbol uint32) RemoteCaptureKey {
	return RemoteCaptureKey{Keycode: code, Symbol: symbol, Pressed: true}
}
func hold(code uint8, symbol uint32) RemoteCaptureKey {
	return RemoteCaptureKey{Keycode: code, Symbol: symbol, Pressed: true, Repeat: true}
}
func release(code uint8) RemoteCaptureKey { return RemoteCaptureKey{Keycode: code} }
func remote(transitions ...RemoteRepeatTransition) RemoteCaptureResult {
	return RemoteCaptureResult{Remote: transitions}
}

func runCaptureSteps(t *testing.T, router *RemoteCaptureRouter, steps []captureStep) {
	t.Helper()
	for index, step := range steps {
		got, err := router.Route(step.key)
		if err != nil {
			t.Fatalf("step %d: %v", index, err)
		}
		if len(got.Remote) == 0 {
			got.Remote = nil
		}
		if len(step.want.Remote) == 0 {
			step.want.Remote = nil
		}
		if !reflect.DeepEqual(got, step.want) {
			t.Fatalf("step %d: result = %+v, want %+v", index, got, step.want)
		}
	}
}

func TestBehaviorRemoteCaptureForwardsOrdinaryAndReaderChords(t *testing.T) {
	router := newTestCaptureRouter(t, nil)
	runCaptureSteps(t, router, []captureStep{
		{press(codeShift, leftShiftKeySymbol), remote(down(codeShift))},
		{press(codeA, 'a'), remote(down(codeA))},
		{hold(codeA, 'a'), remote(repeat(codeA))},
		{release(codeA), remote(up(codeA))},
		{release(codeShift), remote(up(codeShift))},
		// A Cthulhu/NVDA modifier chord goes to the remote screen reader.
		{press(codeInsert, testInsertSymbol), remote(down(codeInsert))},
		{press(codeA, 'a'), remote(down(codeA))},
		{release(codeA), remote(up(codeA))},
		{release(codeInsert), remote(up(codeInsert))},
		// Releases for keys held before capture are not forwarded.
		{release(codeR), RemoteCaptureResult{}},
	})
	if got := router.Retire(); len(got.Remote) != 0 || len(got.Swallow) != 0 {
		t.Fatalf("retire = %+v", got)
	}
}

func TestBehaviorRemoteCaptureWithdrawsPrefixForLocalChord(t *testing.T) {
	local := CommandBindings{{Symbol: 'r', Modifiers: controlModifier, CthulhuModifier: true}: "tentacle/remote/toggle-remote-focus"}
	router := newTestCaptureRouter(t, local)
	runCaptureSteps(t, router, []captureStep{
		{press(codeInsert, testInsertSymbol), remote(down(codeInsert))},
		{press(codeControl, leftControlKeySymbol), remote(down(codeControl))},
		{hold(codeControl, leftControlKeySymbol), remote(repeat(codeControl))},
		// The local chord releases the forwarded prefix remotely, newest first.
		{press(codeR, 'r'), RemoteCaptureResult{Remote: []RemoteRepeatTransition{up(codeControl), up(codeInsert)}, Local: "tentacle/remote/toggle-remote-focus"}},
		{hold(codeR, 'r'), RemoteCaptureResult{}},
		{hold(codeControl, leftControlKeySymbol), RemoteCaptureResult{}},
		{release(codeR), RemoteCaptureResult{}},
		// A forwarded key while the prefix is still held presses it again.
		{press(codeA, 'a'), remote(down(codeInsert), down(codeControl), down(codeA))},
		{release(codeA), remote(up(codeA))},
		{release(codeControl), remote(up(codeControl))},
		{release(codeInsert), remote(up(codeInsert))},
	})
}

func TestBehaviorRemoteCaptureWithdrawnReleaseIsConsumed(t *testing.T) {
	local := CommandBindings{{Symbol: 'r', Modifiers: controlModifier}: "tentacle/remote/disconnect"}
	router := newTestCaptureRouter(t, local)
	runCaptureSteps(t, router, []captureStep{
		{press(codeControl, rightControlKeySymbol), remote(down(codeControl))},
		{press(codeR, 'r'), RemoteCaptureResult{Remote: []RemoteRepeatTransition{up(codeControl)}, Local: "tentacle/remote/disconnect"}},
		{release(codeControl), RemoteCaptureResult{}}, // Already released remotely.
		{release(codeR), RemoteCaptureResult{}},
		{press(codeR, 'r'), remote(down(codeR))}, // Without Control it is ordinary.
	})
}

func TestBehaviorRemoteCaptureEscapeWinsAndRetireSwallows(t *testing.T) {
	// A local binding on the escape chord cannot replace the escape.
	local := CommandBindings{testEscape: "tentacle/remote/other"}
	router := newTestCaptureRouter(t, local)
	runCaptureSteps(t, router, []captureStep{
		{press(codeShift, leftShiftKeySymbol), remote(down(codeShift))},
		{press(codeA, 'a'), remote(down(codeA))},
		{press(codeAlt, 0xffe9), remote(down(codeAlt))},
		// Shift+Alt+F11 is not the bare escape chord: it is forwarded.
		{press(codeF11, testF11Symbol), remote(down(codeF11))},
		{release(codeF11), remote(up(codeF11))},
		{release(codeAlt), remote(up(codeAlt))},
		{release(codeShift), remote(up(codeShift))},
		{press(codeF11, testF11Symbol), RemoteCaptureResult{Escape: true}},
	})
	got := router.Retire()
	want := RemoteCaptureRetirement{Remote: []RemoteRepeatTransition{up(codeA)}, Swallow: []uint8{codeF11, codeA}}
	if !reflect.DeepEqual(got, want) {
		t.Fatalf("retire = %+v, want %+v", got, want)
	}
	if again := router.Retire(); again.Remote != nil || again.Swallow != nil {
		t.Fatalf("second retire = %+v", again)
	}
	if _, err := router.Route(release(codeA)); !errors.Is(err, ErrRemoteKeyState) {
		t.Fatalf("route after retire = %v", err)
	}
}

func TestBehaviorRemoteCaptureRetireReleasesForwardedPrefixes(t *testing.T) {
	local := CommandBindings{{Symbol: 'r', Modifiers: controlModifier}: "tentacle/remote/menu"}
	router := newTestCaptureRouter(t, local)
	runCaptureSteps(t, router, []captureStep{
		{press(codeShift, leftShiftKeySymbol), remote(down(codeShift))},
		{press(codeControl, leftControlKeySymbol), remote(down(codeControl))},
		{press(codeR, 'r'), remote(down(codeR))}, // Shift+Control+r is not bound.
	})
	got := router.Retire()
	want := RemoteCaptureRetirement{
		Remote:  []RemoteRepeatTransition{up(codeR), up(codeControl), up(codeShift)},
		Swallow: []uint8{codeR, codeControl, codeShift},
	}
	if !reflect.DeepEqual(got, want) {
		t.Fatalf("retire = %+v, want %+v", got, want)
	}
}

func TestBehaviorRemoteCaptureStopsOnInconsistentInput(t *testing.T) {
	for name, keys := range map[string][]RemoteCaptureKey{
		"orphan repeat": {hold(codeA, 'a')},
		"double down":   {press(codeA, 'a'), press(codeA, 'a')},
		"invalid code":  {press(codeA, 'a'), press(7, 'b')},
	} {
		t.Run(name, func(t *testing.T) {
			router := newTestCaptureRouter(t, nil)
			var err error
			for _, key := range keys {
				if _, err = router.Route(key); err != nil {
					break
				}
			}
			if err == nil {
				t.Fatal("inconsistent input accepted")
			}
			if _, err := router.Route(release(codeA)); !errors.Is(err, ErrRemoteKeyState) {
				t.Fatalf("stopped router = %v", err)
			}
			got := router.Retire()
			if len(keys) > 1 && !reflect.DeepEqual(got.Remote, []RemoteRepeatTransition{up(codeA)}) {
				t.Fatalf("retire = %+v", got)
			}
		})
	}
	router := newTestCaptureRouter(t, nil)
	for index := 0; index < RemoteHeldKeyLimit; index++ {
		code := uint8(100 + index)
		if _, err := router.Route(press(code, 'a')); err != nil {
			t.Fatal(err)
		}
	}
	if _, err := router.Route(press(200, 'b')); !errors.Is(err, ErrRemoteKeyLimit) {
		t.Fatalf("overflow = %v", err)
	}
	if got := router.Retire(); len(got.Remote) != RemoteHeldKeyLimit || len(got.Swallow) != RemoteHeldKeyLimit {
		t.Fatalf("retire after overflow = %d/%d", len(got.Remote), len(got.Swallow))
	}
}

func TestBehaviorRemoteCaptureRejectsInvalidChords(t *testing.T) {
	for name, test := range map[string]struct {
		escape CommandChord
		local  CommandBindings
	}{
		"empty escape":    {CommandChord{}, nil},
		"modifier escape": {CommandChord{Symbol: leftShiftKeySymbol}, nil},
		"reader escape":   {CommandChord{Symbol: testInsertSymbol}, nil},
		"modifier local":  {testEscape, CommandBindings{{Symbol: leftControlKeySymbol}: "tentacle/remote/x"}},
	} {
		if _, err := NewRemoteCaptureRouter(test.escape, test.local, []uint32{testInsertSymbol}); !errors.Is(err, ErrRemoteCaptureChord) {
			t.Fatalf("%s: %v", name, err)
		}
	}
}

// Local chords come from resolved bindings filtered to Remote's commands, so a
// user-assigned shortcut is local while ordinary reader commands are forwarded.
func TestBehaviorRemoteCaptureHonorsResolvedRemaps(t *testing.T) {
	suggestions := []BindingOverride{{Layout: DesktopKeyboardLayout, Scope: "global", Command: "tentacle/remote/menu", Keys: []string{"Cthulhu+Ctrl+r"}}}
	remap := []BindingOverride{{Layout: DesktopKeyboardLayout, Scope: "global", Command: "tentacle/remote/menu", Keys: []string{"Cthulhu+Alt+r"}}}
	for name, overrides := range map[string][]BindingOverride{
		"suggested": MergeTentacleBindings(nil, suggestions),
		"remapped":  MergeTentacleBindings(remap, suggestions),
	} {
		t.Run(name, func(t *testing.T) {
			resolved, err := ResolveCommandBindings(DesktopKeyboardLayout, false, overrides)
			if err != nil {
				t.Fatal(err)
			}
			local := CommandBindings{}
			for chord, command := range resolved {
				if command == "tentacle/remote/menu" {
					local[chord] = command
				}
			}
			router := newTestCaptureRouter(t, local)
			modifierCode, modifierSymbol := codeControl, leftControlKeySymbol
			if name == "remapped" {
				modifierCode, modifierSymbol = codeAlt, uint32(0xffe9)
			}
			runCaptureSteps(t, router, []captureStep{
				{press(codeInsert, testInsertSymbol), remote(down(codeInsert))},
				{press(modifierCode, modifierSymbol), remote(down(modifierCode))},
				{press(codeR, 'r'), RemoteCaptureResult{Remote: []RemoteRepeatTransition{up(modifierCode), up(codeInsert)}, Local: "tentacle/remote/menu"}},
			})
			// Local reader commands are not Remote commands: Cthulhu+t
			// reaches the remote screen reader.
			other := newTestCaptureRouter(t, local)
			runCaptureSteps(t, other, []captureStep{
				{press(codeInsert, testInsertSymbol), remote(down(codeInsert))},
				{press(28, 't'), remote(down(28))},
			})
		})
	}
}

// The normalizer and router compose: a classic repeat pair inside a local
// chord produces no remote traffic and no second local command.
func TestBehaviorRemoteCaptureComposesWithNormalizer(t *testing.T) {
	normalizer := newTestNormalizer(t)
	router := newTestCaptureRouter(t, CommandBindings{{Symbol: 'r', Modifiers: controlModifier}: "tentacle/remote/menu"})
	symbols := map[uint8]uint32{codeControl: leftControlKeySymbol, codeR: 'r'}
	var remoteOut []RemoteRepeatTransition
	var commands []Command
	now := time.Unix(1, 0)
	for _, event := range []Event{
		{Keycode: codeControl, Pressed: true, Timestamp: 10},
		{Keycode: codeR, Pressed: true, Timestamp: 20},
		{Keycode: codeR, Pressed: false, Timestamp: 700},
		{Keycode: codeR, Pressed: true, Timestamp: 700},
		{Keycode: codeR, Pressed: false, Timestamp: 800},
		{Keycode: codeControl, Pressed: false, Timestamp: 0},
	} {
		transitions, err := normalizer.Observe(event, now)
		if err != nil {
			t.Fatal(err)
		}
		for _, transition := range transitions {
			result, err := router.Route(RemoteCaptureKey{Keycode: transition.Keycode, Symbol: symbols[transition.Keycode], Pressed: transition.Pressed, Repeat: transition.Repeat})
			if err != nil {
				t.Fatal(err)
			}
			remoteOut = append(remoteOut, result.Remote...)
			if result.Local != "" {
				commands = append(commands, result.Local)
			}
		}
	}
	if want := []RemoteRepeatTransition{down(codeControl), up(codeControl)}; !reflect.DeepEqual(remoteOut, want) {
		t.Fatalf("remote = %+v, want %+v", remoteOut, want)
	}
	if !reflect.DeepEqual(commands, []Command{"tentacle/remote/menu"}) {
		t.Fatalf("commands = %v", commands)
	}
}

func TestBehaviorRemoteCaptureConsumesUnsupportedKeys(t *testing.T) {
	router := newTestCaptureRouter(t, nil)
	runCaptureSteps(t, router, []captureStep{
		{press(codeShift, leftShiftKeySymbol), remote(down(codeShift))},
		{RemoteCaptureKey{Keycode: 121, Symbol: 0x1008ff12, Pressed: true, Unsupported: true}, RemoteCaptureResult{}},
		{hold(121, 0x1008ff12), RemoteCaptureResult{}},
		{release(121), RemoteCaptureResult{}},
		{release(codeShift), remote(up(codeShift))},
	})
	for keysym, want := range map[string]string{"Prior": "Page_Up", "KP_Next": "KP_Page_Down", "a": "a", "A": "", "XF86AudioMute": "XF86AudioMute", "XF86Eject": "", "ISO_Level3_Shift": ""} {
		if got := RemoteCaptureKeyName(keysym); got != want {
			t.Fatalf("%s = %q, want %q", keysym, got, want)
		}
	}
}