package ibd

import (
	"strings"

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

func findChildren(node *html.Node, f func(node *html.Node) bool) (found []*html.Node) {
	for c := node.FirstChild; c != nil; c = c.NextSibling {
		if f(c) {
			found = append(found, c)
		}
	}
	return
}

func findChildrenRecursive(node *html.Node, f func(node *html.Node) bool) (found []*html.Node) {
	if f(node) {
		found = append(found, node)
	}

	for c := node.FirstChild; c != nil; c = c.NextSibling {
		found = append(found, findChildrenRecursive(c, f)...)
	}

	return
}

func findClass(node *html.Node, className string) (found *html.Node) {
	if isClass(node, className) {
		return node
	}

	for c := node.FirstChild; c != nil; c = c.NextSibling {
		if found = findClass(c, className); found != nil {
			return
		}
	}

	return
}

func isClass(node *html.Node, className string) bool {
	if node.Type == html.ElementNode {
		for _, attr := range node.Attr {
			if attr.Key != "class" {
				continue
			}
			classes := strings.Fields(attr.Val)
			for _, class := range classes {
				if class == className {
					return true
				}
			}
		}
	}
	return false
}

func extractText(node *html.Node) string {
	var result strings.Builder
	extractTextInner(node, &result)
	return result.String()
}

func extractTextInner(node *html.Node, result *strings.Builder) {
	if node.Type == html.TextNode {
		result.WriteString(node.Data)
	}
	for c := node.FirstChild; c != nil; c = c.NextSibling {
		extractTextInner(c, result)
	}
}

func findId(node *html.Node, id string) (found *html.Node) {
	if isId(node, id) {
		return node
	}

	for c := node.FirstChild; c != nil; c = c.NextSibling {
		if found = findId(c, id); found != nil {
			return
		}
	}

	return
}

func isId(node *html.Node, id string) bool {
	if node.Type == html.ElementNode {
		for _, attr := range node.Attr {
			if attr.Key == "id" && attr.Val == id {
				return true
			}
		}
	}
	return false
}