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

package app

import (
	"strings"

	"git.stormux.org/storm/cthulhu/internal/atspi"
)

// windowOwner keeps application, top-level window, and object focus as
// separate lifecycles. The event loop remains the sole owner of this state.
type windowOwner struct {
	applicationBus string
	window         atspi.ObjectID
	focus          atspi.ObjectID
	activated      bool
	title          string
}

func (owner *windowOwner) activate(event atspi.Event) (duplicate bool) {
	window := eventWindow(event)
	if window.Valid() && window == owner.window {
		if owner.activated {
			return true
		}
		owner.activated = true
		owner.title = activationTitle(event)
		return false
	}
	owner.window = window
	owner.applicationBus = window.BusName
	owner.focus = event.Source.ID()
	owner.activated = true
	owner.title = activationTitle(event)
	return false
}

func (owner *windowOwner) follow(event atspi.Event) bool {
	window := eventWindow(event)
	if owner.window.Valid() && window.Valid() && window != owner.window {
		// A focused object can precede window:activate during an actual X11
		// handoff. The native adapter has already rejected objects in a known
		// inactive window, so confirmed focused state may establish the new owner.
		if !event.Source.Focused {
			return false
		}
		owner.window = window
		owner.applicationBus = window.BusName
		owner.activated = false
		owner.title = ""
	}
	if !owner.window.Valid() && window.Valid() {
		owner.window = window
		owner.applicationBus = window.BusName
		owner.activated = false
		owner.title = ""
	}
	owner.focus = event.Source.ID()
	return true
}

func (owner *windowOwner) end(event atspi.Event, consumedCommand bool) bool {
	window := eventWindow(event)
	if !owner.window.Valid() || !window.Valid() || window != owner.window {
		return false
	}
	// Python rechecks active state because passive X11 grabs can emit a
	// transient deactivate/activate pair while the same window stays active.
	if event.Type == atspi.WindowDeactivatedEvent {
		if consumedCommand || event.Source.StatesKnown && event.Source.Active {
			return false
		}
	}
	owner.clear()
	return true
}

// containsLoad permits a document replacement only inside the existing focus
// context. A load completion is not a window activation, even when a provider
// still reports focused or active state for a background document.
func (owner *windowOwner) containsLoad(event atspi.Event) bool {
	window := eventWindow(event)
	if owner.window.Valid() {
		// The old document may become defunct before its replacement loads.
		// Its window still owns the context even though object focus is gone.
		return window == owner.window && event.Source.BusName == owner.applicationBus
	}
	return owner.focus.Valid() && event.Source.BusName == owner.focus.BusName
}

func (owner *windowOwner) defunct(event atspi.Event) (windowEnded, focusEnded bool) {
	if event.Detail1 == 0 {
		return false, false
	}
	id := event.Source.ID()
	if owner.window.Valid() && id == owner.window {
		owner.clear()
		return true, true
	}
	if owner.focus.Valid() && id == owner.focus {
		owner.focus = atspi.ObjectID{}
		return false, true
	}
	return false, false
}

func (owner *windowOwner) clear() {
	owner.applicationBus = ""
	owner.window = atspi.ObjectID{}
	owner.focus = atspi.ObjectID{}
	owner.activated = false
	owner.title = ""
}

func activationTitle(event atspi.Event) string {
	if title := strings.TrimSpace(event.WindowTitle); title != "" {
		return title
	}
	if event.Source.ID() == eventWindow(event) {
		return strings.TrimSpace(event.Source.Name)
	}
	return ""
}

// Track empty names as well so restoring an earlier title is a real change.
func (owner *windowOwner) changeTitle(event atspi.Event) bool {
	if !owner.window.Valid() || event.Source.ID() != owner.window {
		return false
	}
	title := strings.TrimSpace(event.Source.Name)
	if title == owner.title {
		return false
	}
	owner.title = title
	return title != ""
}

func eventWindow(event atspi.Event) atspi.ObjectID {
	if event.Window.Valid() {
		return event.Window
	}
	// Window lifecycle fixtures and older adapters identify the top-level in
	// OriginPath. For object events OriginPath is the object itself, so it must
	// not be promoted to a window owner.
	switch event.Type {
	case atspi.WindowActivatedEvent, atspi.WindowDeactivatedEvent, atspi.WindowDestroyedEvent:
		return atspi.NewObjectID(event.Source.BusName, event.OriginPath)
	default:
		return atspi.ObjectID{}
	}
}