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

package atspi

/*
#include "adapter_native.h"
*/
import "C"

import (
	"context"
	"errors"
	"fmt"
	"git.stormux.org/storm/cthulhu/internal/platform/session"
	"git.stormux.org/storm/cthulhu/internal/platform/xorg"
	"runtime"
	"runtime/cgo"
	"unsafe"
)

func (adapter *Adapter) Start(ctx context.Context) error {
	if !adapter.running.CompareAndSwap(false, true) {
		return errors.New("AT-SPI adapter already started")
	}

	adapter.loopDone = make(chan struct{})
	setupDone := make(chan error, 1)
	go func() {
		runtime.LockOSThread()
		defer runtime.UnlockOSThread()
		if err := adapter.initialize(); err != nil {
			setupDone <- err
			return
		}
		// Xwayland only describes X clients. Its empty or stale foreground
		// must not veto native Wayland windows; use AT-SPI ownership there.
		if !session.Wayland() {
			adapter.foregroundReader = xorg.OpenForegroundReader()
		}
		adapter.promptRefreshWindow = ObjectID{}
		adapter.promptScannedWindow = ObjectID{}
		adapter.promptScannedEpoch = 0
		adapter.refreshForeground()
		adapter.refreshWindowTitle()
		timer := C.start_foreground_timer(C.gpointer(adapter.callbackData))
		setupDone <- nil
		C.atspi_event_main()
		if timer != 0 {
			C.g_source_remove(timer)
		}
		adapter.foregroundReader.Close()
		adapter.foregroundReader = nil
		for _, focus := range adapter.nativeFocus {
			C.g_object_unref(C.gpointer(focus.source))
		}
		adapter.nativeFocus = nil
		for _, known := range adapter.documentWindows {
			C.g_object_unref(C.gpointer(known.source))
		}
		adapter.documentWindows = nil
		adapter.documentWindowIDs = nil
		adapter.clearNativeDocument()
		adapter.clearNativeReview()
		adapter.clearMouseApplication()
		close(adapter.loopDone)
	}()

	select {
	case err := <-setupDone:
		if err != nil {
			adapter.running.Store(false)
			return err
		}
		if err := ctx.Err(); err != nil {
			C.atspi_event_quit()
			<-adapter.loopDone
			adapter.running.Store(false)
			return err
		}
		adapter.ready.Store(true)
		return nil
	case <-ctx.Done():
		err := <-setupDone
		if err != nil {
			adapter.running.Store(false)
			return err
		}
		C.atspi_event_quit()
		<-adapter.loopDone
		adapter.running.Store(false)
		return ctx.Err()
	}
}

func (adapter *Adapter) initialize() error {
	if result := C.atspi_init(); result != 0 {
		return fmt.Errorf("initialize AT-SPI: result %d", int(result))
	}
	// libatspi's ordinary default is 800 ms, but its startup grace period is
	// much longer. Keep both bounded so a newly connected or wedged provider
	// cannot indefinitely hold the event-loop thread during owned-tree capture.
	C.atspi_set_timeout(800, 800)

	callbackHandle := cgo.NewHandle(adapter)
	callbackData := C.cthulhu_callback_data_new(C.uintptr_t(callbackHandle))
	if callbackData == nil {
		callbackHandle.Delete()
		C.atspi_exit()
		return errors.New("allocate AT-SPI callback data")
	}
	adapter.callbackHandle = callbackHandle
	adapter.callbackData = callbackData

	for _, eventType := range eventTypes {
		if err := adapter.registerEvent(eventType); err != nil {
			if cleanupErr := adapter.deregisterEvents(); cleanupErr != nil {
				err = errors.Join(err, cleanupErr)
			}
			C.cthulhu_callback_data_free(callbackData)
			adapter.callbackHandle = 0
			adapter.callbackData = nil
			C.atspi_exit()
			return err
		}
	}

	return nil
}

func (adapter *Adapter) registerEvent(eventType string) error {
	nativeEventType := C.CString(eventType)
	var registerError *C.GError
	registered := C.atspi_event_listener_register_from_callback(
		C.AtspiEventListenerCB(C.cthulhu_event_callback_pointer()),
		unsafe.Pointer(adapter.callbackData),
		nil,
		nativeEventType,
		&registerError,
	)
	C.free(unsafe.Pointer(nativeEventType))
	if registerError != nil {
		err := nativeError("register AT-SPI event listener "+eventType, registerError)
		C.g_error_free(registerError)
		return err
	}
	if registered == 0 {
		return errors.New("register AT-SPI event listener " + eventType)
	}
	return nil
}

func (adapter *Adapter) deregisterEvents() error {
	var stopErr error
	for _, eventType := range eventTypes {
		nativeEventType := C.CString(eventType)
		var deregisterError *C.GError
		C.atspi_event_listener_deregister_from_callback(
			C.AtspiEventListenerCB(C.cthulhu_event_callback_pointer()),
			unsafe.Pointer(adapter.callbackData),
			nativeEventType,
			&deregisterError,
		)
		C.free(unsafe.Pointer(nativeEventType))
		if deregisterError != nil {
			stopErr = errors.Join(stopErr, nativeError("deregister AT-SPI event listener "+eventType, deregisterError))
			C.g_error_free(deregisterError)
		}
	}
	return stopErr
}

func (adapter *Adapter) Stop(ctx context.Context) error {
	adapter.stopMutex.Lock()
	defer adapter.stopMutex.Unlock()
	if !adapter.running.Load() {
		return nil
	}
	adapter.ready.Store(false)

	var stopErr error
	// AT-SPI documents event-loop quit as an event-handler operation. Schedule
	// it on the default GLib context owned by atspi_event_main instead of calling
	// it synchronously from this arbitrary shutdown goroutine.
	if C.cthulhu_request_event_loop_quit() == 0 {
		stopErr = errors.New("request AT-SPI event loop quit")
	}

	select {
	case <-adapter.loopDone:
	case <-ctx.Done():
		return errors.Join(stopErr, fmt.Errorf("wait for AT-SPI event loop: %w", ctx.Err()))
	}
	if result := C.atspi_exit(); result != 0 {
		stopErr = errors.Join(stopErr, fmt.Errorf("exit AT-SPI: result %d", int(result)))
	}
	C.cthulhu_callback_data_free(adapter.callbackData)
	adapter.callbackData = nil
	adapter.callbackHandle.Delete()
	adapter.callbackHandle = 0
	adapter.running.Store(false)
	adapter.invalidateTree()
	return stopErr
}