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

package atspi

/*
#cgo pkg-config: atspi-2 glib-2.0 gobject-2.0
#include "adapter_native.h"
*/
import "C"

import (
	"context"
	"unicode/utf8"
)

// BrailleRoute refers to the exact source span which produced the display.
// Revalidate it on the GLib thread so edits or focus changes cannot route a
// delayed hardware key into different content.
type BrailleRoute struct {
	Focus         ObjectID
	Position      ObjectReference // Valid only for document browse routing.
	Line          string
	Start, Offset int
}

func (adapter *Adapter) RouteBraille(ctx context.Context, route BrailleRoute) error {
	_, err := adapter.documentOperation(ctx, treeCaptureRequest{brailleRoute: &route})
	return err
}

func validBrailleRoute(snapshot Snapshot, route BrailleRoute) bool {
	return route.Focus.Valid() && snapshot.ID() == route.Focus && !snapshot.Defunct && snapshot.StatesKnown && snapshot.Focused &&
		snapshot.Role != "password text" && snapshot.TextCaretKnown &&
		snapshot.BrailleLineStart == route.Start && snapshot.BrailleLine == route.Line &&
		route.Start >= 0 && route.Offset >= route.Start &&
		route.Offset-route.Start <= utf8.RuneCountInString(route.Line)
}

func (adapter *Adapter) routeNativeBraille(ctx context.Context, route BrailleRoute) error {
	if err := ctx.Err(); err != nil {
		return err
	}
	if route.Position.Valid() {
		return adapter.route_document_braille(ctx, route)
	}
	if !adapter.nativeFocusIs(route.Focus) {
		return ErrStaleObject
	}
	source := adapter.nativeFocus[len(adapter.nativeFocus)-1].source
	// Request caret capture even for read-only text. Ordinary focus snapshots
	// deliberately avoid querying non-editable text on the event hot path.
	snapshot := snapshotFromNativeWithCaret(source, true, true, false, false)
	if !validBrailleRoute(snapshot, route) {
		return ErrStaleObject
	}
	text := C.atspi_accessible_get_text_iface(source)
	if text == nil {
		return ErrNoDocumentCaret
	}
	defer C.g_object_unref(C.gpointer(text))
	if err := ctx.Err(); err != nil {
		return err
	}
	var nativeErr *C.GError
	placed := C.atspi_text_set_caret_offset(text, C.gint(route.Offset), &nativeErr)
	if nativeErr != nil {
		err := nativeError("route braille caret", nativeErr)
		C.g_error_free(nativeErr)
		return err
	}
	if placed == 0 {
		return ErrNoDocumentCaret
	}
	return nil
}

func (adapter *Adapter) route_document_braille(ctx context.Context, route BrailleRoute) error {
	adapter.treeMutex.Lock()
	tree := adapter.documentTree
	adapter.treeMutex.Unlock()
	if tree == nil || len(adapter.nativeFocus) == 0 {
		return ErrStaleObject
	}
	snapshot, err := tree.Resolve(route.Position)
	if err != nil || snapshot.Role == "password text" || snapshot.Defunct {
		return ErrStaleObject
	}
	if err = documentPositionMatchesFocus(tree, route.Position, route.Focus); err != nil {
		return err
	}
	latest := adapter.nativeFocus[len(adapter.nativeFocus)-1].id
	if err = documentPositionMatchesFocus(tree, route.Position, latest); err != nil {
		return err
	}
	source := adapter.nativeDocument[route.Position.ID()]
	if source == nil {
		return ErrStaleObject
	}
	// Recheck the protected state and foreground before reading fresh content.
	C.atspi_accessible_clear_cache_single(source)
	fresh := snapshotFromNativeWithCaret(source, false, false, false, false)
	if fresh.Role != snapshot.Role || fresh.Defunct || fresh.Role == "password text" {
		return ErrStaleObject
	}
	window := C.cthulhu_window_ancestor(source)
	if window == nil {
		return ErrStaleObject
	}
	foreground := adapter.matchesForeground(window, nativeObjectID(window))
	C.g_object_unref(C.gpointer(window))
	if !foreground {
		return ErrStaleObject
	}
	text := C.atspi_accessible_get_text_iface(source)
	if text == nil {
		return ErrNoDocumentCaret
	}
	defer C.g_object_unref(C.gpointer(text))
	length := utf8.RuneCountInString(route.Line)
	if route.Start < 0 || route.Offset < route.Start || route.Offset > route.Start+length || length == 0 {
		return ErrStaleObject
	}
	count := int(C.atspi_text_get_character_count(text, nil))
	if route.Start+length > count {
		return ErrStaleObject
	}
	var nativeErr *C.GError
	content := C.atspi_text_get_text(text, C.gint(route.Start), C.gint(route.Start+length), &nativeErr)
	if nativeErr != nil {
		err := nativeError("validate document braille text", nativeErr)
		C.g_error_free(nativeErr)
		return err
	}
	unchanged := C.GoString(content) == route.Line
	C.g_free(C.gpointer(content))
	if !unchanged {
		return ErrStaleObject
	}
	return adapter.setNativeDocumentPosition(ctx, route.Position, route.Focus, route.Offset, true)
}