package engine

import "gitea.maximumdirect.net/eric/ConfigKit/internal/document"

// mappingIndex keeps ordered document entries and their lookup positions in
// sync while one composition or overlay is assembled.
type mappingIndex struct {
	byNode map[*document.Node]map[string]int
}

func (m *mappingIndex) entries(node *document.Node) map[string]int {
	if m.byNode == nil {
		m.byNode = make(map[*document.Node]map[string]int)
	}
	if entries, ok := m.byNode[node]; ok {
		return entries
	}
	entries := make(map[string]int, len(node.Mapping))
	for index, entry := range node.Mapping {
		entries[entry.Key] = index
	}
	m.byNode[node] = entries
	return entries
}

func (m *mappingIndex) find(node *document.Node, key string) int {
	if index, ok := m.entries(node)[key]; ok {
		return index
	}
	return -1
}

func (m *mappingIndex) append(node *document.Node, entry document.Entry) {
	entries := m.entries(node)
	entries[entry.Key] = len(node.Mapping)
	node.Mapping = append(node.Mapping, entry)
}