Add initial last.fm client implementation

core/lastfm/client.go

@@ -0,0 +1,67 @@
+package lastfm
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+)
+
+const (
+	apiBaseUrl = "https://ws.audioscrobbler.com/2.0/"
+)
+
+type HttpClient interface {
+	Do(req *http.Request) (*http.Response, error)
+}
+
+func NewClient(apiKey string, lang string, hc HttpClient) *Client {
+	return &Client{apiKey, lang, hc}
+}
+
+type Client struct {
+	apiKey string
+	lang   string
+	hc     HttpClient
+}
+
+// TODO SimilarArtists()
+func (c *Client) ArtistGetInfo(name string) (*Artist, error) {
+	params := url.Values{}
+	params.Add("method", "artist.getInfo")
+	params.Add("format", "json")
+	params.Add("api_key", c.apiKey)
+	params.Add("artist", name)
+	params.Add("lang", c.lang)
+	req, _ := http.NewRequest("GET", apiBaseUrl, nil)
+	req.URL.RawQuery = params.Encode()
+
+	resp, err := c.hc.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	defer resp.Body.Close()
+	data, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != 200 {
+		return nil, c.parseError(data)
+	}
+
+	var response Response
+	err = json.Unmarshal(data, &response)
+	return &response.Artist, err
+}
+
+func (c *Client) parseError(data []byte) error {
+	var e Error
+	err := json.Unmarshal(data, &e)
+	if err != nil {
+		return err
+	}
+	return fmt.Errorf("last.fm error(%d): %s", e.Code, e.Message)
+}