package engine

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

// recursiveMergeHooks lets an assembly owner account for the values changed by
// a recursive mapping overlay without making source roles part of the merge.
// Hooks run before replacement and receive the still-owned incoming subtree.
type recursiveMergeHooks struct {
	added    func(Path, *document.Node)
	combined func(Path, *document.Node)
	replaced func(Path, *document.Node, *document.Node)
}

// mergeRecursiveMappings changes an owned mapping and never aliases incoming
// values into it. Entry order follows the target, then new incoming entries.
func mergeRecursiveMappings(target, incoming *document.Node, current Path, index *mappingIndex, hooks recursiveMergeHooks) {
	for _, entry := range incoming.Mapping {
		path := current.Key(entry.Key)
		position := index.find(target, entry.Key)
		if position < 0 {
			cloned := entry
			cloned.Value = document.Clone(entry.Value)
			index.append(target, cloned)
			if hooks.added != nil {
				hooks.added(path, entry.Value)
			}
			continue
		}

		existing := target.Mapping[position].Value
		if existing.Kind == document.Mapping && entry.Value.Kind == document.Mapping {
			if hooks.combined != nil {
				hooks.combined(path, entry.Value)
			}
			mergeRecursiveMappings(existing, entry.Value, path, index, hooks)
			continue
		}

		if hooks.replaced != nil {
			hooks.replaced(path, existing, entry.Value)
		}
		target.Mapping[position] = entry
		target.Mapping[position].Value = document.Clone(entry.Value)
	}
}