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

package atspi

import (
	"bufio"
	"context"
	"fmt"
	"io"
	"os"
	"os/exec"
	"strings"
	"testing"
	"time"

	"github.com/godbus/dbus/v5"
)

func TestBackgroundInvalidationPreservesOtherProviderLines(t *testing.T) {
	owned := NewObjectID(":1.42", "/line")
	other := NewObjectID(":1.43", "/line")
	adapter := New()
	adapter.documentLineCache = map[ObjectID]DocumentCaretText{owned: {}, other: {}}
	adapter.invalidateTreeEvent(TextInsertedEvent, 0, other, ObjectID{})
	if _, ok := adapter.documentLineCache[owned]; !ok {
		t.Fatal("background text change cleared the owned provider's line cache")
	}
	if _, ok := adapter.documentLineCache[other]; ok {
		t.Fatal("changed provider's line cache survived invalidation")
	}
	adapter.invalidateTreeEvent(AccessibleNameEvent, 0, owned, ObjectID{})
	if len(adapter.documentLineCache) != 0 {
		t.Fatal("owned provider change failed to invalidate its lines")
	}
}

func TestNativeBackgroundEventFiltering(t *testing.T) {
	if os.Getenv("CTHULHU_NATIVE_BACKGROUND_EVENTS") != "1" {
		t.Skip("requires private Xorg/AT-SPI session")
	}
	ctx, cancel := context.WithTimeout(context.Background(), 25*time.Second)
	defer cancel()
	adapter := New()
	if err := adapter.Start(ctx); err != nil {
		t.Fatal(err)
	}
	defer adapter.Stop(context.Background())

	type fixture struct {
		input  io.WriteCloser
		output *bufio.Reader
		xid    string
	}
	start := func(name string) fixture {
		command := exec.CommandContext(ctx, "/usr/bin/python3", "../../tests/gtk_background_events.py", name)
		input, err := command.StdinPipe()
		if err != nil {
			t.Fatal(err)
		}
		output, err := command.StdoutPipe()
		if err != nil {
			t.Fatal(err)
		}
		command.Stderr = os.Stderr
		if err := command.Start(); err != nil {
			t.Fatal(err)
		}
		t.Cleanup(func() { input.Close(); command.Process.Kill(); command.Wait() })
		reader := bufio.NewReader(output)
		line, err := reader.ReadString('\n')
		fields := strings.Fields(line)
		if err != nil || len(fields) != 2 || fields[0] != "ready" {
			t.Fatalf("fixture readiness: %q, %v", line, err)
		}
		return fixture{input, reader, fields[1]}
	}
	wait := func(predicate func(Event) bool) Event {
		t.Helper()
		var last Event
		count := 0
		for {
			select {
			case event := <-adapter.Events():
				last = event
				count++
				if predicate(event) {
					return event
				}
			case <-ctx.Done():
				t.Fatalf("native event missing: %v; filtered=%d received=%d last=%s %s %q", ctx.Err(), adapter.backgroundEventsFiltered.Load(), count, last.Type, last.Source.Role, last.Source.Name)
			}
		}
	}
	focus := func(xid string) {
		t.Helper()
		if output, err := exec.CommandContext(ctx, "xdotool", "windowfocus", "--sync", xid).CombinedOutput(); err != nil {
			t.Fatalf("focus: %s, %v", output, err)
		}
	}
	background := start("Background fixture")
	foreground := start("Foreground fixture")
	// Publish the complete AT-SPI cache, including table cells, before flooding.
	if _, err := adapter.CaptureDesktop(ctx); err != nil {
		t.Fatal(err)
	}
	focus(foreground.xid)
	fmt.Fprintln(foreground.input, "edit")
	owned := wait(func(event Event) bool {
		return event.Type == TextInsertedEvent && event.Payload == "Updated text" && !event.ForegroundMismatch
	})

	sessionBus, err := dbus.ConnectSessionBus()
	if err != nil {
		t.Fatal(err)
	}
	defer sessionBus.Close()
	var address string
	if err := sessionBus.Object("org.a11y.Bus", "/org/a11y/bus").CallWithContext(ctx, "org.a11y.Bus.GetAddress", 0).Store(&address); err != nil {
		t.Fatal(err)
	}
	control, err := dbus.Connect(address)
	if err != nil {
		t.Fatal(err)
	}
	defer control.Close()
	monitor, err := dbus.Connect(address)
	if err != nil {
		t.Fatal(err)
	}
	defer monitor.Close()
	if err := monitor.BusObject().CallWithContext(ctx, "org.freedesktop.DBus.Monitoring.BecomeMonitor", 0, []string{"type='method_call'"}, uint32(0)).Err; err != nil {
		t.Fatal(err)
	}
	messages := make(chan *dbus.Message, 65536)
	monitor.Eavesdrop(messages)

	flood := func(generation string, sameProvider bool) {
		t.Helper()
		before := adapter.backgroundEventsFiltered.Load()
		fmt.Fprintln(background.input, "flood "+generation)
		marker := wait(func(event Event) bool {
			return event.Type == TextInsertedEvent && event.Payload == "Flood complete "+generation
		})
		if (marker.Source.BusName == owned.Source.BusName) != sameProvider {
			t.Fatal("fixture provider identity did not match test case")
		}
		if count := adapter.backgroundEventsFiltered.Load() - before; count < 300 {
			t.Fatalf("filtered %d events; want at least 300 real selection updates", count)
		}
		if err := control.Object(marker.Source.BusName, dbus.ObjectPath(marker.Source.Path)).CallWithContext(ctx, "org.freedesktop.DBus.Peer.Ping", 0).Err; err != nil {
			t.Fatal(err)
		}
		queries := 0
	reading:
		for {
			select {
			case message := <-messages:
				if message.Headers[dbus.FieldDestination].Value() != marker.Source.BusName {
					continue
				}
				member := message.Headers[dbus.FieldMember].Value()
				if member == "Ping" {
					break reading
				}
				if message.Headers[dbus.FieldPath].Value() == dbus.ObjectPath(marker.Source.Path) {
					continue
				}
				switch message.Headers[dbus.FieldInterface].Value() {
				case "org.a11y.atspi.Selection", "org.a11y.atspi.Table", "org.a11y.atspi.Text", "org.a11y.atspi.Value":
					queries++
				}
			case <-ctx.Done():
				t.Fatal("monitor barrier missing")
			}
		}
		if queries != 0 {
			t.Fatalf("background flood caused %d selection/table/text/value queries", queries)
		}
		t.Logf("%s: filtered at least 300 updates with zero content queries", generation)
	}
	flood("other-provider", false)

	// The same application can have an inactive sibling on the same bus.
	fmt.Fprintln(background.input, "sibling")
	line, err := background.output.ReadString('\n')
	fields := strings.Fields(line)
	if err != nil || len(fields) != 2 || fields[0] != "sibling" {
		t.Fatalf("sibling readiness: %q, %v", line, err)
	}
	if _, err := adapter.CaptureDesktop(ctx); err != nil {
		t.Fatal(err)
	}
	focus(fields[1])
	owned = wait(func(event Event) bool {
		return !event.ForegroundMismatch && event.Source.Name == "Background fixture sibling entry"
	})
	flood("same-provider", true)

	// Returning to the previously noisy window must read its current selection.
	focus(background.xid)
	fmt.Fprintln(background.input, "focus-table")
	wait(func(event Event) bool {
		return !event.ForegroundMismatch && event.Source.Name == "Result 1" && event.Source.GUITable
	})
	t.Log("returning to the noisy application delivers current table focus")
}