harden deezer quality fallback and metadata handling

Improve Deezer full-quality mode behavior by returning explicit errors when yt-dlp mode fails with fallback disabled, parse structured API errors, and correctly map explicit_lyrics booleans into explicit tags.

internal/provider/deezer/client_test.go

@@ -3,8 +3,10 @@ package deezer
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
 
 	"streamrip-go/internal/config"
@@ -64,3 +66,87 @@ func TestGetDownloadableUsesPreview(t *testing.T) {
 		t.Fatalf("unexpected downloadable: %+v", d)
 	}
 }
+
+func TestGetMetadataSetsExplicitFromBool(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/track/9":
+			_ = json.NewEncoder(w).Encode(map[string]any{
+				"id":              9,
+				"title":           "X",
+				"explicit_lyrics": true,
+				"artist":          map[string]any{"name": "Artist"},
+			})
+		default:
+			w.WriteHeader(http.StatusNotFound)
+		}
+	}))
+	defer ts.Close()
+
+	cfgData := config.DefaultConfigData()
+	c := New(&config.Config{File: cfgData, Session: cfgData})
+	c.loggedIn = true
+	orig := baseURL
+	baseURL = ts.URL
+	defer func() { baseURL = orig }()
+
+	meta, err := c.GetMetadata(context.Background(), "9", "track")
+	if err != nil {
+		t.Fatalf("GetMetadata() error = %v", err)
+	}
+	if explicit, _ := meta["explicit"].(bool); !explicit {
+		t.Fatalf("expected explicit=true, got %#v", meta["explicit"])
+	}
+}
+
+func TestSearchReturnsStructuredAPIError(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/search/track" {
+			_ = json.NewEncoder(w).Encode(map[string]any{"error": map[string]any{"message": "invalid query"}})
+			return
+		}
+		w.WriteHeader(http.StatusNotFound)
+	}))
+	defer ts.Close()
+
+	cfgData := config.DefaultConfigData()
+	c := New(&config.Config{File: cfgData, Session: cfgData})
+	c.loggedIn = true
+	orig := baseURL
+	baseURL = ts.URL
+	defer func() { baseURL = orig }()
+
+	_, err := c.Search(context.Background(), "track", "", 5)
+	if err == nil || !strings.Contains(err.Error(), "invalid query") {
+		t.Fatalf("expected structured deezer error, got %v", err)
+	}
+}
+
+func TestGetDownloadableErrorsWhenFullQualityFailsAndFallbackDisabled(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/track/42" {
+			_ = json.NewEncoder(w).Encode(map[string]any{"id": 42, "title": "X", "preview": "https://cdn.example/p.mp3"})
+			return
+		}
+		w.WriteHeader(http.StatusNotFound)
+	}))
+	defer ts.Close()
+
+	cfgData := config.DefaultConfigData()
+	cfgData.Deezer.UseDeezloader = true
+	cfgData.Deezer.LowerQualityIfNotAvailable = false
+	c := New(&config.Config{File: cfgData, Session: cfgData})
+	c.loggedIn = true
+	c.bin = "definitely-not-a-real-yt-dlp-bin"
+	c.run = func(context.Context, string, ...string) ([]byte, error) {
+		return nil, fmt.Errorf("unexpected run call")
+	}
+	orig := baseURL
+	baseURL = ts.URL
+	defer func() { baseURL = orig }()
+
+	_, err := c.GetDownloadable(context.Background(), "42", 2)
+	if err == nil || !strings.Contains(err.Error(), "full-quality mode failed") {
+		t.Fatalf("expected full-quality failure error, got %v", err)
+	}
+}