package main

import (
	"net/http"
	"fmt"
	"os"
	"time"
	"encoding/json"
	"sort"
)

func main(){

	timeout := time.Duration( 10 * time.Second )
	client := http.Client { Timeout: timeout }

	req, err := http.NewRequest("GET", "https://musicbrainz.org/ws/2/artist?query=Metallica", nil)
	req.Header.Set("User-Agent", "Go Application Development")
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")

	if (err != nil) {
		fmt.Println("error creating request\n%v", err)
		os.Exit(1)
	}

	resp, err := client.Do(req)
	if (err != nil) {
		fmt.Println("error opening request\n%v", err)
		os.Exit(1)
	}
	defer resp.Body.Close()
	if (err != nil) {
		fmt.Println("could not read body\n%v", err)
		os.Exit(1)
	}
	var result mb_artist_search
	json.NewDecoder(resp.Body).Decode(&result)

	fmt.Println(result.Artists[0].Name)

	for _, element := range get_artist_tags(&result){
		fmt.Printf("\ntag: %2d: %s", element.Count, element.Name)
	}
}

func get_artist_tags (res *mb_artist_search) []mb_tag{
	var t []mb_tag
	for _, elem := range res.Artists[0].Tags  {
		if int(elem.Count) > 0 {
			t = append(t, elem)
		}
	}
	sort.Sort(ByInverseCount(t))
	return t
}




type mb_artist_search struct {
	Created time.Time `json:"created"`
	Count   int       `json:"count"`
	Offset  int       `json:"offset"`
	Artists []struct {
		ID       string `json:"id"`
		Type     string `json:"type,omitempty"`
		TypeID   string `json:"type-id,omitempty"`
		Score    int    `json:"score"`
		Name     string `json:"name"`
		SortName string `json:"sort-name"`
		Country  string `json:"country,omitempty"`
		Area     struct {
			ID       string `json:"id"`
			Type     string `json:"type"`
			TypeID   string `json:"type-id"`
			Name     string `json:"name"`
			SortName string `json:"sort-name"`
			LifeSpan struct {
				Ended interface{} `json:"ended"`
			} `json:"life-span"`
		} `json:"area,omitempty"`
		BeginArea struct {
			ID       string `json:"id"`
			Type     string `json:"type"`
			TypeID   string `json:"type-id"`
			Name     string `json:"name"`
			SortName string `json:"sort-name"`
			LifeSpan struct {
				Ended interface{} `json:"ended"`
			} `json:"life-span"`
		} `json:"begin-area,omitempty"`
		Isnis    []string `json:"isnis,omitempty"`
		LifeSpan struct {
			Begin string      `json:"begin"`
			Ended interface{} `json:"ended"`
		} `json:"life-span,omitempty"`
		Aliases []struct {
			SortName  string      `json:"sort-name"`
			TypeID    string      `json:"type-id,omitempty"`
			Name      string      `json:"name"`
			Locale    interface{} `json:"locale"`
			Type      string      `json:"type"`
			Primary   interface{} `json:"primary"`
			BeginDate interface{} `json:"begin-date"`
			EndDate   interface{} `json:"end-date"`
		} `json:"aliases,omitempty"`
		Tags []mb_tag   `json:"tags,omitempty"`
		Disambiguation string `json:"disambiguation,omitempty"`
	} `json:"artists"`
}

type mb_tag struct{
	Count int `json:"count"`
	Name string `json:"name"`
}
type ByInverseCount []mb_tag
func (t ByInverseCount) Len() int { return len(t) }
func (t ByInverseCount) Less (i, j int) bool { return t[i].Count >= t[j].Count }
func (t ByInverseCount) Swap (i,j int) { t[i], t[j] = t[j], t[i] }