// 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"
	"os"
	"reflect"
	"strings"
	"sync"
	"testing"
	"time"

	"git.stormux.org/storm/cthulhu/internal/atspi"
	"git.stormux.org/storm/cthulhu/internal/braille"
	"git.stormux.org/storm/cthulhu/internal/config"
	"git.stormux.org/storm/cthulhu/internal/tentacle"
	"git.stormux.org/storm/cthulhu/internal/tentaclewire"
)

type fakeVirtualBraille struct {
	mu        sync.Mutex
	requests  []braille.VirtualRequest
	responses chan braille.VirtualResponse
	closed    chan struct{}
	once      sync.Once
}

func (fake *fakeVirtualBraille) Send(request braille.VirtualRequest) error {
	fake.mu.Lock()
	defer fake.mu.Unlock()
	fake.requests = append(fake.requests, request)
	return nil
}
func (fake *fakeVirtualBraille) Responses() <-chan braille.VirtualResponse { return fake.responses }
func (fake *fakeVirtualBraille) Close()                                    { fake.once.Do(func() { close(fake.closed) }) }
func (fake *fakeVirtualBraille) seen() []braille.VirtualRequest {
	fake.mu.Lock()
	defer fake.mu.Unlock()
	return append([]braille.VirtualRequest(nil), fake.requests...)
}

type peerRouteRecorder struct{ routes chan atspi.BrailleRoute }

func (router peerRouteRecorder) RouteBraille(_ context.Context, route atspi.BrailleRoute) error {
	router.routes <- route
	return nil
}

func braille_fixture(t *testing.T, grants []string) (*tentacle.Session, *tentacle.RemotePolicy, *brailleWorker, *fakeVirtualBraille, peerRouteRecorder) {
	t.Helper()
	policy := tentacle.NewRemotePolicy()
	session := keyboard_owner_session(t, policy, grants)
	router := peerRouteRecorder{routes: make(chan atspi.BrailleRoute, 4)}
	worker := &brailleWorker{logger: slog.New(slog.DiscardHandler), wake: make(chan struct{}, 1), cancel: func() {},
		connected: true, cells: 20, router: router, frame: braille.Frame{Cursor: -1}, baseFrame: braille.Frame{Cursor: -1}}
	fake := &fakeVirtualBraille{responses: make(chan braille.VirtualResponse, 4), closed: make(chan struct{})}
	runtime := &tentacleRuntime{logger: slog.New(slog.DiscardHandler), remotePolicy: policy, announcements: make(chan string, 4),
		output: &tentacleOutput{braille: worker, gate: &focusGate{}}, virtualBraille: func() (virtualBraille, error) { return fake, nil }}
	ctx, cancel := context.WithCancel(t.Context())
	done := runtime.start_remote_braille(ctx, session)
	t.Cleanup(func() {
		cancel()
		select {
		case <-done:
		case <-time.After(5 * time.Second):
			t.Error("Braille owner did not join")
		}
	})
	return session, policy, worker, fake, router
}

func braille_open(t *testing.T, session *tentacle.Session, role string, grants []string) tentaclewire.RemoteLease {
	t.Helper()
	approval, err := session.BeginRemoteApproval(role, grants)
	if err != nil {
		t.Fatal(err)
	}
	if _, err := session.AuthorizeRemoteWithApproval(approval, role, 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("lease did not open")
	}
	return lease
}

func braille_call(t *testing.T, session *tentacle.Session, lease tentaclewire.RemoteLease, sequence uint64, value tentaclewire.RemoteBraille) {
	t.Helper()
	request := tentaclewire.RemoteBrailleRequest{RemoteOperation: tentaclewire.RemoteOperation{Lease: lease.Lease, Epoch: lease.Epoch, Sequence: sequence}, Braille: value}
	keyboard_owner_invoke(t, session, "rpc", map[string]any{"Method": "remote.braille", "Params": request})
}

func wait_until(t *testing.T, what string, predicate func() bool) {
	t.Helper()
	deadline := time.Now().Add(5 * time.Second)
	for !predicate() {
		if time.Now().After(deadline) {
			t.Fatal("timed out waiting for", what)
		}
		time.Sleep(2 * time.Millisecond)
	}
}

func TestRemoteBrailleExportsApplicationFramesOnly(t *testing.T) {
	session, policy, worker, fake, router := braille_fixture(t, []string{"braille-stream"})
	route := braille.TextRoute{Start: 0, End: 5, SourceStart: 0, TextLength: 5, BusName: ":1.2", Path: "/text", SourceText: "hello"}
	worker.EnqueueFrame(braille.Frame{Text: "hello", Cursor: -1, Routes: []braille.TextRoute{route}})
	lease := braille_open(t, session, "controlled", []string{"braille-stream"})
	braille_call(t, session, lease, 1, tentaclewire.RemoteBraille{Op: "size", Width: 20})
	wait_until(t, "width and initial frame", func() bool { return len(fake.seen()) >= 2 })
	seen := fake.seen()
	if seen[0].Width == nil || *seen[0].Width != 20 || seen[1].Frame == nil || seen[1].Frame.Text != "hello" || seen[1].Frame.ID == 0 || seen[1].Frame.Routes != nil {
		t.Fatalf("initial export = %+v", seen)
	}
	exportedID := seen[1].Frame.ID
	fake.responses <- braille.VirtualResponse{Cells: []int{1, 3, 9}}
	var event tentaclewire.SessionEvent
	if json.Unmarshal(keyboard_owner_invoke(t, session, "event", nil), &event) != nil || event.Kind != "remote.braille" || !reflect.DeepEqual(event.Braille.Cells, []int{1, 3, 9}) {
		t.Fatal("cells not published", event)
	}
	braille_call(t, session, lease, 2, tentaclewire.RemoteBraille{Op: "gesture", Gesture: "route", Index: 3})
	braille_call(t, session, lease, 3, tentaclewire.RemoteBraille{Op: "gesture", Gesture: "pan-right"})
	wait_until(t, "gestures", func() bool { return len(fake.seen()) >= 4 })
	if seen = fake.seen(); seen[2].Route == nil || *seen[2].Route != 3 || seen[3].Pan != "right" {
		t.Fatalf("gestures = %+v", seen[2:])
	}
	fake.responses <- braille.VirtualResponse{Route: &braille.RoutingEvent{ID: exportedID, Offset: 3}}
	select {
	case routed := <-router.routes:
		if routed.Offset != 3 || routed.Line != "hello" {
			t.Fatal("route changed", routed)
		}
	case <-time.After(5 * time.Second):
		t.Fatal("peer route did not reach the application")
	}
	// Reader UI is never exported; application frames under it are, unroutable.
	worker.SetInternalUIFrame(&braille.Frame{Text: "private form", Cursor: -1})
	worker.EnqueueFrame(braille.Frame{Text: "world", Cursor: -1})
	wait_until(t, "frame under reader UI", func() bool { return len(fake.seen()) >= 5 })
	for _, request := range fake.seen() {
		if request.Frame != nil && request.Frame.Text == "private form" {
			t.Fatal("reader UI frame exported")
		}
	}
	if last := fake.seen()[4]; last.Frame == nil || last.Frame.Text != "world" || last.Frame.ID != 0 {
		t.Fatalf("frame under UI = %+v", last)
	}
	policy.SetAvailable(false)
	select {
	case <-fake.closed:
	case <-time.After(5 * time.Second):
		t.Fatal("revocation did not stop export")
	}
	policy.SetAvailable(true)
	worker.mu.Lock()
	exporter := worker.remoteExport
	worker.mu.Unlock()
	if exporter != nil {
		t.Fatal("exporter left installed")
	}
}

func TestRemoteBrailleControllerShowsPeerCellsAndReportsKeys(t *testing.T) {
	session, policy, worker, _, _ := braille_fixture(t, []string{"braille-stream", "remote-present"})
	worker.EnqueueFrame(braille.Frame{Text: "local", Cursor: -1})
	worker.SetContraction(true, "en-ueb-g2.ctb")
	lease := braille_open(t, session, "controller", []string{"braille-stream"})
	braille_call(t, session, lease, 1, tentaclewire.RemoteBraille{Op: "geometry"})
	var event tentaclewire.SessionEvent
	if json.Unmarshal(keyboard_owner_invoke(t, session, "event", nil), &event) != nil || event.Braille == nil || event.Braille.Op != "geometry" || event.Braille.Width != 20 {
		t.Fatal("geometry not reported", event)
	}
	braille_call(t, session, lease, 2, tentaclewire.RemoteBraille{Op: "cells", Cells: []int{1, 2, 255}})
	wait_until(t, "peer cells", func() bool { return worker.current().Raw })
	frame := worker.current()
	if frame.Text != "⠁⠂⣿" || frame.Contract || frame.Table != "" || frame.WordWrap {
		t.Fatalf("peer frame = %+v", frame)
	}
	// Local application frames continue updating underneath.
	worker.EnqueueFrame(braille.Frame{Text: "newer", Cursor: -1})
	if !worker.current().Raw {
		t.Fatal("application frame replaced peer cells")
	}
	frame = worker.current()
	worker.route(t.Context(), braille.RoutingEvent{ID: frame.ID, Offset: 1})
	worker.route(t.Context(), braille.RoutingEvent{ID: frame.ID, Offset: -1, Pan: "right"})
	worker.route(t.Context(), braille.RoutingEvent{ID: frame.ID + 99, Offset: 0}) // Stale.
	for _, want := range []tentaclewire.RemoteBraille{{Op: "gesture", Gesture: "route", Index: 1}, {Op: "gesture", Gesture: "pan-right"}} {
		if json.Unmarshal(keyboard_owner_invoke(t, session, "event", nil), &event) != nil || event.Braille == nil || !reflect.DeepEqual(*event.Braille, want) {
			t.Fatal("gesture changed", event)
		}
	}
	policy.SetAvailable(false)
	wait_until(t, "local frame restored", func() bool { return !worker.current().Raw })
	if text := worker.current().Text; text != "newer" {
		t.Fatal("restored frame", text)
	}
	policy.SetAvailable(true)
}

func TestRemoteBrailleInitialExportDuringFlashIsUnroutable(t *testing.T) {
	worker := &brailleWorker{cancel: func() {}, connected: true, wake: make(chan struct{}, 1)}
	worker.EnqueueFrame(braille.Frame{Text: "application", Cursor: -1})
	baseID := worker.current().ID
	var exported braille.Frame
	worker.SetRemoteExport(func(frame braille.Frame) { exported = frame })
	if exported.ID != baseID {
		t.Fatal("initial application lost its routing identity")
	}
	worker.FlashConfirmation("message", config.BrailleOptions{FlashMessages: true, FlashPersistent: true})
	worker.SetRemoteExport(func(frame braille.Frame) { exported = frame })
	if exported.Text != "application" || exported.ID != 0 {
		t.Fatalf("flash export = %+v", exported)
	}
	worker.DismissConfirmation()
	worker.SetRemoteExport(func(frame braille.Frame) { exported = frame })
	if exported.ID == 0 || exported.ID != worker.current().ID {
		t.Fatal("restored application lost its routing identity")
	}
}

func TestRemoteBrailleInitialExportSerializedWithUpdates(t *testing.T) {
	worker := &brailleWorker{cancel: func() {}, wake: make(chan struct{}, 1)}
	worker.EnqueueFrame(braille.Frame{Text: "initial", Cursor: -1})
	entered, release, finished := make(chan struct{}), make(chan struct{}), make(chan struct{})
	var frames []string
	go func() {
		worker.SetRemoteExport(func(frame braille.Frame) {
			if frame.Text == "initial" {
				close(entered)
				<-release
			}
			frames = append(frames, frame.Text)
		})
		close(finished)
	}()
	select {
	case <-entered:
	case <-time.After(5 * time.Second):
		close(release)
		t.Fatal("initial export was not offered")
	}
	if worker.mu.TryLock() {
		worker.mu.Unlock()
		close(release)
		<-finished
		t.Fatal("initial export was offered outside the frame lock")
	}
	updated := make(chan struct{})
	go func() { worker.EnqueueFrame(braille.Frame{Text: "newer", Cursor: -1}); close(updated) }()
	close(release)
	<-finished
	<-updated
	if !reflect.DeepEqual(frames, []string{"initial", "newer"}) {
		t.Fatal(frames)
	}
}

func TestRemoteBrailleCancelledRouteHasNoEffect(t *testing.T) {
	router := peerRouteRecorder{routes: make(chan atspi.BrailleRoute, 1)}
	worker := &brailleWorker{cancel: func() {}, wake: make(chan struct{}, 1), router: router}
	worker.EnqueueFrame(braille.Frame{Text: "test", Cursor: -1, Routes: []braille.TextRoute{{Start: 0, End: 4, TextLength: 4}}})
	ctx, cancel := context.WithCancel(t.Context())
	cancel()
	worker.RouteExported(ctx, braille.RoutingEvent{ID: worker.current().ID, Offset: 1})
	select {
	case <-router.routes:
		t.Fatal("cancelled route reached application")
	default:
	}
}

func TestRemoteBrailleWedgedHelperWriteIsBounded(t *testing.T) {
	reader, writer, err := os.Pipe()
	if err != nil {
		t.Fatal(err)
	}
	defer reader.Close()
	defer writer.Close()
	helper := &processVirtualBraille{stdin: writer, encoder: json.NewEncoder(writer)}
	done := make(chan error, 1)
	go func() {
		done <- helper.Send(braille.VirtualRequest{Frame: &braille.Frame{Text: strings.Repeat("x", 1024*1024)}})
	}()
	select {
	case err := <-done:
		if !errors.Is(err, os.ErrDeadlineExceeded) {
			t.Fatalf("blocked write = %v", err)
		}
	case <-time.After(5 * time.Second):
		t.Fatal("wedged helper blocked its owner")
	}
}