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

package xorg

/*
#cgo pkg-config: xkbcommon
#cgo pkg-config: xi
#include "commands_native.h"
*/
import "C"

import (
	"context"
	"errors"
	"fmt"

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

type uiReply struct {
	session uint64
	err     error
}
type uiUpdate struct {
	ctx          context.Context
	closeSession uint64
	result       chan uiReply
	localOnly    bool
}

func (listener *CommandListener) InternalUISession() uint64  { return listener.uiSession.Load() }
func (listener *CommandListener) InternalUIActive() bool     { return listener.uiSession.Load() != 0 }
func (listener *CommandListener) InternalUIEchoActive() bool { return listener.uiEcho.Load() }

// BeginInternalUI acknowledges exclusive capture without changing X input
// focus. EndInternalUI waits for physical releases, and cannot close a newer UI.
func (listener *CommandListener) BeginInternalUI(ctx context.Context) (uint64, error) {
	return listener.update_internal_ui(ctx, 0, false)
}

// BeginLocalUI admits only device-backed XI2 events and excludes XTEST. This
// is a core API, never a Tentacle-controlled form flag. It fails on unsupported
// servers; ordinary forms keep their existing input path.
func (listener *CommandListener) BeginLocalUI(ctx context.Context) (uint64, error) {
	return listener.update_internal_ui(ctx, 0, true)
}
func (listener *CommandListener) EndInternalUI(ctx context.Context, session uint64) error {
	if session == 0 {
		return errors.New("missing internal UI session")
	}
	// Revoke promptly even when the acknowledgement must wait for a held key.
	if session > listener.uiSequence.Load() {
		return errors.New("unknown internal UI session")
	}
	for previous := listener.uiClose.Load(); previous < session; previous = listener.uiClose.Load() {
		if listener.uiClose.CompareAndSwap(previous, session) {
			break
		}
	}
	_, err := listener.update_internal_ui(ctx, session, false)
	return err
}
func (listener *CommandListener) update_internal_ui(ctx context.Context, closeSession uint64, localOnly bool) (uint64, error) {
	listener.mutex.Lock()
	done := listener.done
	listener.mutex.Unlock()
	if done == nil {
		return 0, errors.New("command listener is not running")
	}
	update := uiUpdate{ctx: ctx, closeSession: closeSession, result: make(chan uiReply, 1), localOnly: localOnly}
	select {
	case listener.uiUpdates <- update:
	case <-ctx.Done():
		return 0, ctx.Err()
	case <-done:
		return 0, errors.New("command listener stopped")
	}
	select {
	case result := <-update.result:
		return result.session, result.err
	case <-done:
		return 0, errors.New("command listener stopped")
	}
}

func (owner *commandOwner) begin_internal_ui_mode(localOnly bool) (uint64, error) {
	if !owner.commandGrabsAllowed() || owner.learnMode || owner.ocrReview || owner.uiSession != 0 || owner.remote != nil {
		return 0, errors.New("internal UI input unavailable")
	}
	var revert C.int
	C.XGetInputFocus(owner.device.display, &owner.uiFocus, &revert)
	if owner.uiFocus == 0 || owner.uiFocus == 1 {
		return 0, errors.New("no focused application")
	}
	owner.uiWindow = C.read_foreground(owner.device.display).window
	var status C.int
	if localOnly {
		status = C.acquire_local_keyboard(owner.device)
	} else {
		status = C.acquire_internal_keyboard(owner.device)
	}
	if status != 0 {
		return 0, fmt.Errorf("internal keyboard capture failed: %d", int(status))
	}
	owner.uiSession = owner.listener.uiSequence.Add(1)
	owner.listener.uiSession.Store(owner.uiSession)
	owner.listener.uiEcho.Store(true)
	owner.listener.grabActive.Store(true)
	return owner.uiSession, nil
}

func (owner *commandOwner) begin_internal_ui() (uint64, error) {
	return owner.begin_internal_ui_mode(false)
}

func (owner *commandOwner) dismiss_internal_ui() {
	owner.uiSession = 0
	owner.listener.uiSession.Store(0)
	C.reset_internal_compose(owner.device)
	if len(owner.held) == 0 {
		C.release_command_keyboard(owner.device)
		owner.listener.uiEcho.Store(false)
		owner.listener.grabActive.Store(false)
	}
}
func (owner *commandOwner) report_ui_failure(err error) bool {
	owner.listener.failures <- err
	return false
}
func (owner *commandOwner) sync_internal_ui() bool {
	if owner.uiSession != 0 {
		var focus C.Window
		var revert C.int
		C.XGetInputFocus(owner.device.display, &focus, &revert)
		requestedClose := owner.listener.uiClose.Load() == owner.uiSession
		if requestedClose || !owner.commandGrabsAllowed() || focus != owner.uiFocus || C.read_foreground(owner.device.display).window != owner.uiWindow {
			session := owner.uiSession
			owner.dismiss_internal_ui()
			// Retain ownership of the current chord until its releases arrive.
			owner.bound = len(owner.held) != 0
			if !requestedClose && !owner.listener.enqueueSecureCommand(input.CommandEvent{Command: input.InternalUIDismiss, UISession: session}) {
				return owner.report_ui_failure(errors.New("internal UI queue overflow"))
			}
		}
	}
	if len(owner.held) == 0 {
		select {
		case update := <-owner.listener.uiUpdates:
			result := uiReply{err: update.ctx.Err()}
			if result.err == nil {
				if update.closeSession != 0 {
					if update.closeSession == owner.uiSession {
						owner.dismiss_internal_ui()
					}
				} else {
					result.session, result.err = owner.begin_internal_ui_mode(update.localOnly)
				}
			}
			update.result <- result
		default:
		}
	}
	return true
}

func (owner *commandOwner) handle_internal_key(key C.CommandKey) bool {
	owner.bound = true
	owner.router.Handle(uint32(key.symbol), uint16(key.code), uint16(key.modifiers), key.pressed != 0)
	if key.pressed == 0 {
		return true
	}
	symbol := uint32(key.symbol)
	if key.textSymbol != 0 {
		symbol = uint32(key.textSymbol)
	}
	chord := owner.router.Chord(symbol, uint16(key.modifiers))
	// Reader modifiers and their initiating chord never become field contents.
	if owner.router.IsModifier(uint32(key.symbol)) {
		return true
	}
	if chord.CthulhuModifier && uint32(key.symbol) != 0xff1b {
		return true
	}
	event := input.CommandEvent{Command: input.InternalUIKey, UISession: owner.uiSession, Timestamp: uint32(key.timestamp), Chord: chord, Text: C.GoString(&key.text[0])}
	if uint32(key.symbol) == 0xff1b {
		owner.dismiss_internal_ui()
	}
	if !owner.listener.enqueueSecureCommand(event) {
		return owner.report_ui_failure(errors.New("internal UI queue overflow"))
	}
	return true
}