package main

import (
    "fmt"
    "github.com/ivahaev/go-logger"
    "golang.org/x/net/html"
    "net/http"
)

func getChildren(node *html.Node) []*html.Node {
    var children []*html.Node
    for c := node.FirstChild; c != nil; c = c.NextSibling {
        children = append(children, c)
    }
    return children
}

func getAttr(node *html.Node, key string) string {
    for _, attr := range node.Attr {
        if attr.Key == key {
            return attr.Val
        }
    }
    return ""
}

func isText(node *html.Node) bool {
    return node != nil && node.Type == html.TextNode
}

func isElem(node *html.Node, tag string) bool {
    return node != nil && node.Type == html.ElementNode && node.Data == tag
}

func isDiv(node *html.Node, class string) bool {
    return isElem(node, "div") && getAttr(node, "class") == class
}

func readItem(item *html.Node) *Item {
    if a := item.FirstChild; isElem(a, "a") {
        if cs := getChildren(a); isText(cs[0]) {
            return &Item{
                Ref:   getAttr(a, "href"),
                Time:  getAttr(cs[0], "title"),
                Title: cs[0].Data,
            }
        }
    }
    return nil
}

type Item struct {
    Ref, Time, Title string
}


func downloadNews() []*Item {
    logger.Info("sending request to lenta.ru")
    if response, err := http.Get("http://lenta.ru"); err != nil {
        logger.Error("request to lenta.ru failed", "error", err)
    } else {
        defer response.Body.Close()
        status := response.StatusCode
        logger.Info("got response from lenta.ru", "status", status)
        if status == http.StatusOK {
            if doc, err := html.Parse(response.Body); err != nil {
                logger.Error("invalid HTML from lenta.ru", "error", err)
            } else {

                logger.Info("HTML from lenta.ru parsed successfully")
                items := search(doc)
                return items
            }
        }
    }
    return nil
}

func search(node *html.Node) []*Item {
    if isDiv(node, "b-yellow-box__wrap") {
        logger.Info("====b-yellow-box__wrap check + ====")
        var items []*Item
        for c := node.FirstChild; c != nil; c = c.NextSibling {
            if isDiv(c, "item") {
                if item := readItem(c); item != nil {
                    items = append(items, item)
                }
            }
        }
        return items
    }
    for c := node.FirstChild; c != nil; c = c.NextSibling {
        if items := search(c); items != nil {
            return items
        }
    }
    return nil
}

func main() {
    logger.Info("Downloader started")
    items := downloadNews()
    for _, v:= range items{
        fmt.Println(v.Title)
    }
}