append metadata tags after saving tracks

also rewrite requests to monochrome using 2 helper methods

monochrome/tracks.go

@@ -5,8 +5,6 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
-	"net/http"
-	"net/url"
 	"strconv"
 )
 
@@ -20,24 +18,21 @@ type TrackInfoResponse struct {
 }
 
 func (c *Client) TrackInfo(id int, quality AudioQuality) (*TrackInfo, error) {
-	req, err := http.NewRequest("GET", c.config.ApiURL+"/track", nil)
+	req, err := c.makeRequest("GET", "/track", nil, map[string]string{
+		"id":      strconv.Itoa(id),
+		"quality": quality,
+	})
 	if err != nil {
 		return nil, fmt.Errorf("failed to create request: %v", err)
 	}
 
-	params := url.Values{}
-	params.Set("id", strconv.Itoa(id))
-	params.Set("quality", quality)
-	req.URL.RawQuery = params.Encode()
-
-	resp, err := http.DefaultClient.Do(req)
+	data, err := c.do(req)
 	if err != nil {
 		return nil, fmt.Errorf("failed to send request: %v", err)
 	}
-	defer resp.Body.Close()
 
 	response := TrackInfoResponse{}
-	if err := json.NewDecoder(resp.Body).Decode(&response); err != nil {
+	if err := json.NewDecoder(bytes.NewReader(data)).Decode(&response); err != nil {
 		return nil, fmt.Errorf("failed to decode json response: %v", err)
 	}