package main

import(
    "fmt"
    "net/http"
    "io/ioutil"
    "regexp"
    "strings"
)

var href_reg *regexp.Regexp

var hrefs_been_found map[string]int

var hrefs_undone []string

func get_all_href(url string)([]string){
    var ret [] string
    resp,err := http.Get(url)
    if err!=nil {
        fmt.Println(err)
        return ret
    }
    defer resp.Body.Close()
    body,_ := ioutil.ReadAll(resp.Body)
    

    hrefs := href_reg.FindAllString(string(body),-1)
    
    for _,v := range hrefs{
        str := strings.Split(v,"\"")[1]
        
        if len(str)<1{
            continue
        }

        switch str[0]{
        case 'h':
            ret = append(ret,str)   
        case '/':
            if len(str)!=1 && str[1]=='/'{
                ret = append(ret,"http:"+str)   
            }
            
            if len(str)!=1 && str[1]!='/'{
                ret = append(ret,url+str[1:])
            }
        default:
            ret = append(ret,url+str)
            
        }
        
    }

    return ret
}

func init_global_var(){
    href_pattern :=   "href=\"(.+?)\""
    href_reg = regexp.MustCompile(href_pattern)

    hrefs_been_found = make(map[string]int)
}

func is_href_been_found(href string)bool{
    _,ok := hrefs_been_found[href]
    return ok
}

func add_hrefs_to_undone_list(hrefs []string){
    for _,value := range hrefs {
        ok := is_href_been_found(value)
        if !ok {
            fmt.Printf("new url:(%s)\n",value);
            hrefs_undone = append(hrefs_undone,value)
            hrefs_been_found[value]=1
        }else{
            hrefs_been_found[value]++
        }
        
    }
}

func main(){
    init_global_var()

    var pos = 0
    var urls = []string{"http://www.baidu.com"}
    add_hrefs_to_undone_list(urls)
    
    for {
        if pos >= len(hrefs_undone) {
            break
        }
        url:= hrefs_undone[0]
        hrefs_undone = hrefs_undone[1:]

        hrefs := get_all_href(url)
        add_hrefs_to_undone_list(hrefs)
    }
}