package engine

import (
	"golang.org/x/net/html"
)

// InsertrElement represents an insertr element found in HTML
type InsertrElement struct {
	Node *html.Node
}

// findEditableElements finds all editable elements (.insertr and .insertr-add)
func (e *ContentEngine) findEditableElements(doc *html.Node) ([]InsertrElement, []CollectionElement) {
	// Phase 1: Pure discovery
	insertrElements, collectionElements, containers := e.discoverElements(doc)

	// Phase 2: Container expansion (separate concern)
	expandedElements := e.expandContainers(containers)
	insertrElements = append(insertrElements, expandedElements...)

	return insertrElements, collectionElements
}

// discoverElements performs pure element discovery without transformation
func (e *ContentEngine) discoverElements(doc *html.Node) ([]InsertrElement, []CollectionElement, []*html.Node) {
	var insertrElements []InsertrElement
	var collectionElements []CollectionElement
	var containersToTransform []*html.Node

	// Walk the document and categorize elements
	e.walkNodes(doc, func(n *html.Node) {
		if n.Type == html.ElementNode {
			if hasInsertrClass(n) {
				if isContainer(n) {
					// Container element - mark for transformation
					containersToTransform = append(containersToTransform, n)
				} else {
					// Regular element - add directly
					insertrElements = append(insertrElements, InsertrElement{
						Node: n,
					})
				}
			}
			if e.hasInsertrAddClass(n) {
				// Collection element - add directly (no container transformation for collections)
				collectionElements = append(collectionElements, CollectionElement{
					Node: n,
				})
			}
		}
	})

	return insertrElements, collectionElements, containersToTransform
}

// expandContainers transforms container elements by removing .insertr from containers
// and adding .insertr to their viable children
func (e *ContentEngine) expandContainers(containers []*html.Node) []InsertrElement {
	var expandedElements []InsertrElement

	for _, container := range containers {
		// Remove .insertr class from container
		RemoveClass(container, "insertr")

		// Find viable children and add .insertr class to them
		viableChildren := FindViableChildren(container)
		for _, child := range viableChildren {
			AddClass(child, "insertr")
			expandedElements = append(expandedElements, InsertrElement{
				Node: child,
			})
		}
	}

	return expandedElements
}

// walkNodes walks through all nodes in the document
func (e *ContentEngine) walkNodes(n *html.Node, fn func(*html.Node)) {
	fn(n)
	for c := n.FirstChild; c != nil; c = c.NextSibling {
		e.walkNodes(c, fn)
	}
}