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

package review

import (
	"strings"
	"unicode"
	"unicode/utf8"

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

func wholeCaretNode(snapshot atspi.Snapshot) bool {
	if snapshot.Role == "link" {
		return snapshot.ExplicitName && strings.TrimSpace(snapshot.Name) != ""
	}
	if snapshot.Role == "image" {
		return snapshot.Name != "" || snapshot.Description != ""
	}
	switch snapshot.Role {
	case "button", "check box", "check menu item", "list box", "menu item", "page tab",
		"radio menu item", "radio button", "push button", "toggle button":
		return true
	}
	return false
}

// caret_node_indices preserves provider order and treats whole controls as one
// stop. MoveCaret holds the document cursor lock while using these indices.
func caret_node_indices(nodes []atspi.DocumentNode, object atspi.ObjectReference) ([]int, int) {
	// Container text normally embeds its child text. Whole controls are one
	// caret stop even when their label is a child or they have no text interface.
	// Python's web _treatObjectAsWhole makes the same distinction.
	indices := make([]int, 0, len(nodes))
	current := -1
	skipped := make(map[atspi.ObjectID]bool)
	protected := make(map[atspi.ObjectID]bool, len(nodes))
	var skipChildren func([]atspi.ObjectID)
	children := make(map[atspi.ObjectID][]atspi.ObjectID, len(nodes))
	for _, node := range nodes {
		children[node.Reference.ID()] = node.Children
	}
	skipChildren = func(ids []atspi.ObjectID) {
		for _, id := range ids {
			if skipped[id] {
				continue
			}
			skipped[id] = true
			skipChildren(children[id])
		}
	}
	for index, node := range nodes {
		snapshot := node.Snapshot
		// Icon-font text inside links, controls, editable text or code can
		// carry meaning. Preserve that entire subtree, including static leaves.
		protected[node.Reference.ID()] = protected[node.Parent] || snapshot.Editable ||
			!atspi.IsWebDocumentRole(snapshot.Role) && (snapshot.Focusable || snapshot.SupportsClick || snapshot.ExplicitName) ||
			snapshot.Role == "link" || wholeCaretNode(snapshot) ||
			snapshot.HTMLTag == "pre" || snapshot.HTMLTag == "code" ||
			strings.Contains(" "+snapshot.XMLRoles+" ", " code ")
		if node.Reference == object {
			current = index
		}
		if node.Hidden || skipped[node.Reference.ID()] {
			continue
		}
		if !protected[node.Reference.ID()] && decorative_caret_glyph(node) {
			continue
		}
		if wholeCaretNode(node.Snapshot) {
			indices = append(indices, index)
			skipChildren(node.Children)
		} else if node.Snapshot.Editable &&
			(node.Snapshot.Role == "entry" || node.Snapshot.Role == "text") &&
			(node.Snapshot.CharacterCount == 0 || len(node.Children) == 0) {
			indices = append(indices, index)
		} else if !node.Snapshot.Editable && len(node.Children) == 0 && node.Snapshot.CharacterCount > 0 {
			indices = append(indices, index)
		}
	}
	return indices, current
}

// Python's web hasValidName/isUselessEmptyElement rejects standalone unnamed
// private-use icons. Keep this narrower: only a known non-interactive static
// leaf with one matching name/text character is omitted from browse reading.
func decorative_caret_glyph(node atspi.DocumentNode) bool {
	snapshot := node.Snapshot
	if snapshot.Role != "static" || !snapshot.StatesKnown || snapshot.Focusable ||
		snapshot.Editable || node.ParentEditable || snapshot.SupportsClick || snapshot.ExplicitName ||
		snapshot.Description != "" || len(node.Children) != 0 || snapshot.CharacterCount != 1 ||
		(snapshot.Text != "" && snapshot.Text != snapshot.Name) {
		return false
	}
	character, size := utf8.DecodeRuneInString(snapshot.Name)
	return size == len(snapshot.Name) && unicode.Is(unicode.Co, character)
}