package html

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

type HtmlNode html.Node

type NodeComparer func(n *HtmlNode) bool

func (n *HtmlNode) GetAttribute(key string) ([]string, bool) {
	if n != nil {
		for _, attr := range n.Attr {
			if attr.Key == key {
				return strings.Split(attr.Val, " "), true
			}
		}
	}
	return []string{}, false
}

func (n *HtmlNode) HasAttributeVal(attr string, val string) NodeComparer {
	return func(n *HtmlNode) bool {
		return n.CheckAttribute(attr, val)
	}
}

func (n *HtmlNode) CheckAttribute(attr string, val string) bool {
	if n != nil && n.Type == html.ElementNode {
		attrvals, ok := n.GetAttribute(attr)
		if ok {
			for _, v := range attrvals {
				if v == val {
					return true
				}
			}
		}
	}
	return false
}

func (f NodeComparer) And(f2 NodeComparer) NodeComparer {
	return func(n *HtmlNode) bool {
		return f(n) && f2(n)
	}
}

func (n *HtmlNode) Find(f NodeComparer) *HtmlNode {
	if n != nil {
		if f(n) {
			return n
		}
		for c := (*HtmlNode)(n.FirstChild); c != nil; c = (*HtmlNode)(c.NextSibling) {
			result := c.Find(f)
			if result != nil {
				return result
			}
		}
	}
	return nil
}

func (n *HtmlNode) FindAll(f NodeComparer) []*HtmlNode {
	all := []*HtmlNode{}
	if n != nil {
		if f(n) {
			return []*HtmlNode{n}
		}
		for c := (*HtmlNode)(n.FirstChild); c != nil; c = (*HtmlNode)(c.NextSibling) {
			result := c.FindAll(f)
			if len(result) > 0 {
				all = append(all, result...)
			}
		}
	}
	return all
}

func IsText() NodeComparer {
	return func(n *HtmlNode) bool { return n.Type == html.TextNode }
}

func IsTag(name string) NodeComparer {
	return func(n *HtmlNode) bool { return n.Type == html.ElementNode && n.Data == name }
}

func HasClass(name string) NodeComparer {
	return func(n *HtmlNode) bool { return n.CheckAttribute("class", name) }
}

func HasID(id string) NodeComparer {
	return func(n *HtmlNode) bool { return n.CheckAttribute("id", id) }
}

func (n *HtmlNode) GetElementById(id string) *HtmlNode {
	if n != nil {
		return n.Find(HasID(id))
	} else {
		return nil
	}
}

func (n *HtmlNode) GetElementsByClass(class string) []*HtmlNode {
	if n != nil {
		return n.FindAll(HasClass(class))
	} else {
		return nil
	}
}

func (n *HtmlNode) Text() string {
	if n == nil {
		return ""
	}
	textNodes := n.FindAll(func(n *HtmlNode) bool { return n.Type == html.TextNode })
	texts := []string{}
	for _, n := range textNodes {
		t := strings.TrimSpace(n.Data)
		if t != "" {
			texts = append(texts, t)
		}
	}
	if len(texts) > 0 {
		return strings.Join(texts, " ")
	} else {
		return ""
	}
}

func (n *HtmlNode) FirstText() string {
	text := n.Find(func(n *HtmlNode) bool { return n.Type == html.TextNode })
	return strings.TrimSpace(text.Data)
}