feat(agents): Add Deezer API artist image provider agent (#4180)

* feat(agents): Add Deezer API artist image provider agent

* fix(agents): Use proper naming convention of consts

* fix(agents): Check if json test data can be read

* fix(agents): Use underscores for unused function arguments

* fix(agents): Move int literal to deezerArtistSearchLimit const

* feat: add Deezer configuration option to disable it.

Signed-off-by: Deluan <deluan@navidrome.org>

---------

Signed-off-by: Deluan <deluan@navidrome.org>
Co-authored-by: Deluan Quintão <deluan@navidrome.org>

core/agents/deezer/client.go

@@ -0,0 +1,83 @@
+package deezer
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strconv"
+
+	"github.com/navidrome/navidrome/log"
+)
+
+const apiBaseURL = "https://api.deezer.com"
+
+var (
+	ErrNotFound = errors.New("deezer: not found")
+)
+
+type httpDoer interface {
+	Do(req *http.Request) (*http.Response, error)
+}
+
+type client struct {
+	httpDoer httpDoer
+}
+
+func newClient(hc httpDoer) *client {
+	return &client{hc}
+}
+
+func (c *client) searchArtists(ctx context.Context, name string, limit int) ([]Artist, error) {
+	params := url.Values{}
+	params.Add("q", name)
+	params.Add("limit", strconv.Itoa(limit))
+	req, err := http.NewRequestWithContext(ctx, "GET", apiBaseURL+"/search/artist", nil)
+	if err != nil {
+		return nil, err
+	}
+	req.URL.RawQuery = params.Encode()
+
+	var results SearchArtistResults
+	err = c.makeRequest(req, &results)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(results.Data) == 0 {
+		return nil, ErrNotFound
+	}
+	return results.Data, nil
+}
+
+func (c *client) makeRequest(req *http.Request, response interface{}) error {
+	log.Trace(req.Context(), fmt.Sprintf("Sending Deezer %s request", req.Method), "url", req.URL)
+	resp, err := c.httpDoer.Do(req)
+	if err != nil {
+		return err
+	}
+
+	defer resp.Body.Close()
+	data, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	if resp.StatusCode != 200 {
+		return c.parseError(data)
+	}
+
+	return json.Unmarshal(data, response)
+}
+
+func (c *client) parseError(data []byte) error {
+	var deezerError Error
+	err := json.Unmarshal(data, &deezerError)
+	if err != nil {
+		return err
+	}
+	return fmt.Errorf("deezer error(%d): %s", deezerError.Error.Code, deezerError.Error.Message)
+}