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

package app

import (
	"context"
	"encoding/json"
	"errors"
	"log/slog"
	"sync"
	"testing"
	"time"

	"git.stormux.org/storm/cthulhu/internal/input"
	"git.stormux.org/storm/cthulhu/internal/tentacle"
	"git.stormux.org/storm/cthulhu/internal/tentaclewire"
)

// fakeCaptureInput stands in for the Xorg owner; the native test covers the
// grab itself. Ending sends the "requested" marker and closes, as the owner does.
type fakeCaptureInput struct {
	mu      sync.Mutex
	prefix  string
	stream  chan input.RemoteCaptureEvent
	session uint64
	begun   chan struct{}
	ended   chan uint64
	refuse  bool
}

func (fake *fakeCaptureInput) SetTentacleBindings(context.Context, []input.BindingOverride) error {
	return nil
}
func (fake *fakeCaptureInput) TentacleBindings() []input.BindingOverride { return nil }

func (fake *fakeCaptureInput) BeginRemoteCapture(_ context.Context, prefix string) (uint64, <-chan input.RemoteCaptureEvent, error) {
	fake.mu.Lock()
	defer fake.mu.Unlock()
	if fake.refuse {
		return 0, nil, errors.New("grab failed")
	}
	fake.session++
	fake.prefix = prefix
	fake.stream = make(chan input.RemoteCaptureEvent, 16)
	fake.begun <- struct{}{}
	return fake.session, fake.stream, nil
}

func (fake *fakeCaptureInput) EndRemoteCapture(_ context.Context, session uint64) error {
	fake.mu.Lock()
	defer fake.mu.Unlock()
	if fake.stream != nil && session == fake.session {
		fake.stream <- input.RemoteCaptureEvent{Ended: "requested"}
		close(fake.stream)
		fake.stream = nil
		fake.ended <- session
	}
	return nil
}

func (fake *fakeCaptureInput) emit(event input.RemoteCaptureEvent) {
	fake.mu.Lock()
	defer fake.mu.Unlock()
	fake.stream <- event
	if event.Ended != "" {
		close(fake.stream)
		fake.stream = nil
	}
}

func capture_next_event(t *testing.T, session *tentacle.Session) tentaclewire.SessionEvent {
	t.Helper()
	var event tentaclewire.SessionEvent
	if err := json.Unmarshal(keyboard_owner_invoke(t, session, "event", nil), &event); err != nil {
		t.Fatal(err)
	}
	return event
}

func capture_fixture(t *testing.T) (*tentacle.Session, *tentacle.RemotePolicy, *fakeCaptureInput, *tentacleRuntime) {
	t.Helper()
	policy := tentacle.NewRemotePolicy()
	session := keyboard_owner_session(t, policy, []string{"keyboard-capture", "remote-present"})
	fake := &fakeCaptureInput{begun: make(chan struct{}, 4), ended: make(chan uint64, 4)}
	runtime := &tentacleRuntime{logger: slog.New(slog.DiscardHandler), remotePolicy: policy, input: fake,
		output: &tentacleOutput{gate: &focusGate{}}, announcements: make(chan string, 1)}
	ctx, cancel := context.WithCancel(t.Context())
	done := runtime.start_remote_capture(ctx, session)
	t.Cleanup(func() {
		cancel()
		select {
		case <-done:
		case <-time.After(5 * time.Second):
			t.Error("capture owner did not join")
		}
	})
	return session, policy, fake, runtime
}

func capture_open(t *testing.T, session *tentacle.Session) tentaclewire.RemoteLease {
	t.Helper()
	grants := []string{"keyboard-capture"}
	approval, err := session.BeginRemoteApproval("controller", grants)
	if err != nil {
		t.Fatal(err)
	}
	if _, err := session.AuthorizeRemoteWithApproval(approval, "controller", grants); err != nil {
		t.Fatal(err)
	}
	var lease tentaclewire.RemoteLease
	if json.Unmarshal(keyboard_owner_invoke(t, session, "open", nil), &lease) != nil || lease.Epoch == 0 {
		t.Fatal("controller lease did not open")
	}
	return lease
}

func capture_focus(t *testing.T, session *tentacle.Session, lease tentaclewire.RemoteLease, sequence uint64, remote bool) {
	t.Helper()
	request := tentaclewire.RemoteFocusRequest{RemoteOperation: tentaclewire.RemoteOperation{Lease: lease.Lease, Epoch: lease.Epoch, Sequence: sequence}, Remote: remote}
	keyboard_owner_invoke(t, session, "rpc", map[string]any{"Method": "remote.focus", "Params": request})
}

func TestRemoteCaptureForwardsKeysAndReportsFocus(t *testing.T) {
	session, _, fake, _ := capture_fixture(t)
	lease := capture_open(t, session)
	capture_focus(t, session, lease, 1, true)
	<-fake.begun
	if fake.prefix != "tentacle/"+session.Identity()+"/" {
		t.Fatal("capture prefix does not name this Tentacle", fake.prefix)
	}
	if event := capture_next_event(t, session); event.Kind != "remote.focus" || event.Focus != "remote" || event.Reason != "requested" {
		t.Fatal("missing remote focus", event)
	}
	fake.emit(input.RemoteCaptureEvent{Key: &input.RemoteCaptureTransition{Code: 38, Name: "a", Pressed: true}})
	fake.emit(input.RemoteCaptureEvent{Key: &input.RemoteCaptureTransition{Code: 38, Pressed: true, Repeat: true}})
	fake.emit(input.RemoteCaptureEvent{Key: &input.RemoteCaptureTransition{Code: 38}})
	for _, want := range []tentaclewire.RemoteCapturedKey{{Code: 38, Name: "a", Pressed: true}, {Code: 38, Pressed: true, Repeat: true}, {Code: 38}} {
		if event := capture_next_event(t, session); event.Kind != "remote.input" || event.Input == nil || *event.Input != want {
			t.Fatal("captured key changed", event)
		}
	}
	fake.emit(input.RemoteCaptureEvent{Ended: "escape"})
	if event := capture_next_event(t, session); event.Kind != "remote.focus" || event.Focus != "local" || event.Reason != "escape" {
		t.Fatal("escape not reported", event)
	}
	// Re-enter, then leave by request.
	capture_focus(t, session, lease, 2, true)
	<-fake.begun
	capture_next_event(t, session)
	capture_focus(t, session, lease, 3, false)
	<-fake.ended
	if event := capture_next_event(t, session); event.Focus != "local" || event.Reason != "requested" {
		t.Fatal("requested local focus not reported", event)
	}
}

func TestRemoteCaptureRevocationEndsCapture(t *testing.T) {
	session, policy, fake, _ := capture_fixture(t)
	lease := capture_open(t, session)
	capture_focus(t, session, lease, 1, true)
	<-fake.begun
	capture_next_event(t, session)
	policy.SetAvailable(false) // Lock or handoff.
	select {
	case <-fake.ended:
	case <-time.After(5 * time.Second):
		t.Fatal("revocation left capture active")
	}
	policy.SetAvailable(true)
}

func TestRemoteCaptureRefusesUnderReaderPolicyOrGrabFailure(t *testing.T) {
	session, _, fake, runtime := capture_fixture(t)
	lease := capture_open(t, session)
	runtime.output.gate.suspended.Store(true)
	capture_focus(t, session, lease, 1, true)
	if event := capture_next_event(t, session); event.Focus != "local" || event.Reason != "local" {
		t.Fatal("suspended reader entered remote focus", event)
	}
	runtime.output.gate.suspended.Store(false)
	fake.mu.Lock()
	fake.refuse = true
	fake.mu.Unlock()
	capture_focus(t, session, lease, 2, true)
	if event := capture_next_event(t, session); event.Focus != "local" || event.Reason != "unavailable" {
		t.Fatal("failed grab not reported", event)
	}
	if len(fake.begun) != 0 {
		t.Fatal("capture began under policy denial")
	}
}

func TestRemoteCaptureRequiresGrantAndOwner(t *testing.T) {
	policy := tentacle.NewRemotePolicy()
	session := keyboard_owner_session(t, policy, []string{"remote-present"})
	runtime := &tentacleRuntime{logger: slog.New(slog.DiscardHandler), remotePolicy: policy,
		input: &fakeCaptureInput{begun: make(chan struct{}, 1), ended: make(chan uint64, 1)}, output: &tentacleOutput{gate: &focusGate{}}}
	select {
	case <-runtime.start_remote_capture(t.Context(), session):
	case <-time.After(time.Second):
		t.Fatal("ungranted session attached capture")
	}
}