package content

import (
	"fmt"
	"strings"

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

// Injector handles content injection into HTML elements
type Injector struct {
	client ContentClient
	siteID string
}

// NewInjector creates a new content injector
func NewInjector(client ContentClient, siteID string) *Injector {
	return &Injector{
		client: client,
		siteID: siteID,
	}
}

// InjectContent replaces element content with database values and adds content IDs
func (i *Injector) InjectContent(element *Element, contentID string) error {
	// Fetch content from database/API
	contentItem, err := i.client.GetContent(i.siteID, contentID)
	if err != nil {
		return fmt.Errorf("fetching content for %s: %w", contentID, err)
	}

	// If no content found, keep original content but add data attributes
	if contentItem == nil {
		i.addContentAttributes(element.Node, contentID, element.Type)
		return nil
	}

	// Replace element content based on type
	switch element.Type {
	case "text":
		i.injectTextContent(element.Node, contentItem.Value)
	case "markdown":
		i.injectMarkdownContent(element.Node, contentItem.Value)
	case "link":
		i.injectLinkContent(element.Node, contentItem.Value)
	default:
		i.injectTextContent(element.Node, contentItem.Value)
	}

	// Add data attributes for editor functionality
	i.addContentAttributes(element.Node, contentID, element.Type)

	return nil
}

// InjectBulkContent efficiently injects multiple content items
func (i *Injector) InjectBulkContent(elements []ElementWithID) error {
	// Extract content IDs for bulk fetch
	contentIDs := make([]string, len(elements))
	for idx, elem := range elements {
		contentIDs[idx] = elem.ContentID
	}

	// Bulk fetch content
	contentMap, err := i.client.GetBulkContent(i.siteID, contentIDs)
	if err != nil {
		return fmt.Errorf("bulk fetching content: %w", err)
	}

	// Inject each element
	for _, elem := range elements {
		contentItem, exists := contentMap[elem.ContentID]

		// Add content attributes regardless
		i.addContentAttributes(elem.Element.Node, elem.ContentID, elem.Element.Type)

		if !exists {
			// Keep original content if not found in database
			continue
		}

		// Replace content based on type
		switch elem.Element.Type {
		case "text":
			i.injectTextContent(elem.Element.Node, contentItem.Value)
		case "markdown":
			i.injectMarkdownContent(elem.Element.Node, contentItem.Value)
		case "link":
			i.injectLinkContent(elem.Element.Node, contentItem.Value)
		default:
			i.injectTextContent(elem.Element.Node, contentItem.Value)
		}
	}

	return nil
}

// injectTextContent replaces text content in an element
func (i *Injector) injectTextContent(node *html.Node, content string) {
	// Remove all child nodes
	for child := node.FirstChild; child != nil; {
		next := child.NextSibling
		node.RemoveChild(child)
		child = next
	}

	// Add new text content
	textNode := &html.Node{
		Type: html.TextNode,
		Data: content,
	}
	node.AppendChild(textNode)
}

// injectMarkdownContent handles markdown content (for now, just as text)
func (i *Injector) injectMarkdownContent(node *html.Node, content string) {
	// For now, treat markdown as text content
	// TODO: Implement markdown to HTML conversion
	i.injectTextContent(node, content)
}

// injectLinkContent handles link/button content with URL extraction
func (i *Injector) injectLinkContent(node *html.Node, content string) {
	// For now, just inject the text content
	// TODO: Parse content for URL and text components
	i.injectTextContent(node, content)
}

// addContentAttributes adds necessary data attributes for editor functionality
func (i *Injector) addContentAttributes(node *html.Node, contentID string, contentType string) {
	i.setAttribute(node, "data-content-id", contentID)
	i.setAttribute(node, "data-content-type", contentType)
	i.setAttribute(node, "data-insertr-enhanced", "true")
}

// InjectEditorAssets adds editor JavaScript and CSS to HTML document
func (i *Injector) InjectEditorAssets(doc *html.Node, isDevelopment bool, libraryScript string) {
	if !isDevelopment {
		return // Only inject in development mode for now
	}

	// Find the head element
	head := i.findHeadElement(doc)
	if head == nil {
		return
	}

	// Add inline script with embedded library
	// Note: Using html.TextNode for scripts can cause issues with HTML entity encoding
	// Instead, we'll insert the script tag as raw HTML
	scriptHTML := fmt.Sprintf(`<script type="text/javascript">
%s
</script>`, libraryScript)

	// Parse the script HTML and append to head
	scriptNodes, err := html.ParseFragment(strings.NewReader(scriptHTML), head)
	if err == nil && len(scriptNodes) > 0 {
		for _, node := range scriptNodes {
			head.AppendChild(node)
		}
	}
}

// findHeadElement finds the <head> element in the document
func (i *Injector) findHeadElement(node *html.Node) *html.Node {
	if node.Type == html.ElementNode && node.Data == "head" {
		return node
	}

	for child := node.FirstChild; child != nil; child = child.NextSibling {
		if result := i.findHeadElement(child); result != nil {
			return result
		}
	}

	return nil
}

// setAttribute safely sets an attribute on an HTML node
func (i *Injector) setAttribute(node *html.Node, key, value string) {
	// Remove existing attribute if present
	for idx, attr := range node.Attr {
		if attr.Key == key {
			node.Attr = append(node.Attr[:idx], node.Attr[idx+1:]...)
			break
		}
	}

	// Add new attribute
	node.Attr = append(node.Attr, html.Attribute{
		Key: key,
		Val: value,
	})
}

// Element represents a parsed HTML element with metadata
type Element struct {
	Node    *html.Node
	Type    string
	Tag     string
	Classes []string
	Content string
}

// ElementWithID combines an element with its generated content ID
type ElementWithID struct {
	Element   *Element
	ContentID string
}