add basic lastfm hook

lastfm/lastfm.go

@@ -0,0 +1,55 @@
+package lastfm
+
+import (
+	"crypto/md5"
+	"encoding/hex"
+	"encoding/xml"
+	"fmt"
+	"net/http"
+	"net/url"
+	"time"
+)
+
+var (
+	baseURL = "http://ws.audioscrobbler.com/2.0/"
+	client  = &http.Client{
+		Timeout: 10 * time.Second,
+	}
+)
+
+func getParamSignature(params url.Values, secret string) string {
+	toHash := ""
+	for k, v := range params {
+		toHash += k
+		toHash += v[0]
+	}
+	toHash += secret
+	hash := md5.Sum([]byte(toHash))
+	return hex.EncodeToString(hash[:])
+}
+
+func GetSession(apiKey, secret, token string) (error, string) {
+	params := url.Values{}
+	// the first 3 parameters here must be in alphabetical order
+	params.Add("api_key", apiKey)
+	params.Add("method", "auth.getSession")
+	params.Add("token", token)
+	params.Add("api_sig", getParamSignature(params, secret))
+	req, _ := http.NewRequest("GET", baseURL, nil)
+	req.URL.RawQuery = params.Encode()
+	resp, err := client.Do(req)
+	if err != nil {
+		return fmt.Errorf("error when making request to last.fm: %v", err), ""
+	}
+	defer resp.Body.Close()
+	decoder := xml.NewDecoder(resp.Body)
+	var lastfm LastFM
+	err = decoder.Decode(&lastfm)
+	if err != nil {
+		return fmt.Errorf("error when decoding last.fm response: %v", err), ""
+	}
+	if lastfm.Error != nil {
+		return fmt.Errorf("error when parsing last.fm response: %v", lastfm.Error.Value), ""
+	}
+	return nil, lastfm.Session.Key
+}

lastfm/models.go

@@ -0,0 +1,21 @@
+package lastfm
+
+import "encoding/xml"
+
+type LastFM struct {
+	XMLName xml.Name `xml:"lfm"`
+	Status  string   `xml:"status,attr"`
+	Session *Session `xml:"session"`
+	Error   *Error   `xml:"error"`
+}
+
+type Session struct {
+	Name       string `xml:"name"`
+	Key        string `xml:"key"`
+	Subscriber uint   `xml:"subscriber"`
+}
+
+type Error struct {
+	Code  uint   `xml:"code,attr"`
+	Value string `xml:",chardata"`
+}