Add the Config view: edit and save the settings, applied without a restart

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/arr/client.go

@@ -11,16 +11,34 @@ import (
 	"net/http"
 	"net/url"
 	"strings"
+	"sync"
 	"time"
 )
 
 // Client is a minimal JSON client for the Radarr/Sonarr v3 API.
 type Client struct {
+	mu      sync.RWMutex // guards baseURL and apiKey, which Reconfigure can change
 	baseURL string
 	apiKey  string
 	http    *http.Client
 }
 
+// settings returns the current base URL and API key.
+func (c *Client) settings() (baseURL, apiKey string) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	return c.baseURL, c.apiKey
+}
+
+// Reconfigure points the client at another instance or key. Requests already
+// in flight are not affected.
+func (c *Client) Reconfigure(baseURL, apiKey string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.baseURL = strings.TrimRight(baseURL, "/")
+	c.apiKey = apiKey
+}
+
 // NewClient returns a client for the instance at baseURL (without /api/v3).
 func NewClient(baseURL, apiKey string) *Client {
 	return &Client{
@@ -46,7 +64,8 @@ func (e *APIError) Error() string {
 // Do sends a request to /api/v3/<path>. body (if non-nil) is JSON-encoded and
 // the response is decoded into out (if non-nil).
 func (c *Client) Do(ctx context.Context, method, path string, query url.Values, body, out any) error {
-	u := c.baseURL + "/api/v3/" + strings.TrimLeft(path, "/")
+	base, apiKey := c.settings()
+	u := base + "/api/v3/" + strings.TrimLeft(path, "/")
 	if len(query) > 0 {
 		u += "?" + query.Encode()
 	}
@@ -64,7 +83,7 @@ func (c *Client) Do(ctx context.Context, method, path string, query url.Values,
 	if err != nil {
 		return err
 	}
-	req.Header.Set("X-Api-Key", c.apiKey)
+	req.Header.Set("X-Api-Key", apiKey)
 	req.Header.Set("Accept", "application/json")
 	if body != nil {
 		req.Header.Set("Content-Type", "application/json")

internal/arr/image.go

@@ -26,7 +26,8 @@ func (c *Client) Poster(images []Image, inLibrary bool) (key string, fetch func(
 		}
 		if inLibrary && img.URL != "" {
 			local := img.URL
-			return c.baseURL + "|" + local, func(ctx context.Context) ([]byte, error) {
+			base, _ := c.settings()
+			return base + "|" + local, func(ctx context.Context) ([]byte, error) {
 				// MediaCover has poster-250.jpg next to poster.jpg; fall back to the original.
 				if small := smallVariant(local); small != local {
 					if data, err := c.GetBytes(ctx, small); err == nil {
@@ -68,21 +69,23 @@ func (c *Client) GetBytes(ctx context.Context, ref string) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	req.Header.Set("X-Api-Key", c.apiKey)
+	_, apiKey := c.settings()
+	req.Header.Set("X-Api-Key", apiKey)
 	return doImage(c.http, req)
 }
 
 // resolve joins a server-relative path to the base URL. Radarr/Sonarr include
 // their URL base in image paths, so it must not be added twice.
 func (c *Client) resolve(ref string) (string, error) {
-	base, err := url.Parse(c.baseURL)
+	baseURL, _ := c.settings()
+	base, err := url.Parse(baseURL)
 	if err != nil {
 		return "", err
 	}
 	if base.Path != "" && base.Path != "/" && strings.HasPrefix(ref, strings.TrimRight(base.Path, "/")+"/") {
 		return base.Scheme + "://" + base.Host + ref, nil
 	}
-	return c.baseURL + ref, nil
+	return baseURL + ref, nil
 }
 
 var imageClient = &http.Client{Timeout: 20 * time.Second}

internal/arr/update_test.go

@@ -46,3 +46,39 @@ func TestSetSeasonMonitoredUnknownSeason(t *testing.T) {
 		t.Error("want error")
 	}
 }
+
+func TestReconfigureSwitchesInstanceAndKey(t *testing.T) {
+	var gotKey, gotHost string
+	mk := func(host string) *httptest.Server {
+		return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			gotKey, gotHost = r.Header.Get("X-Api-Key"), host
+			io.WriteString(w, `{"version":"1"}`)
+		}))
+	}
+	a, b := mk("a"), mk("b")
+	defer a.Close()
+	defer b.Close()
+
+	c := NewClient(a.URL, "key-a")
+	var out struct{ Version string }
+	if err := c.Do(context.Background(), http.MethodGet, "system/status", nil, nil, &out); err != nil || gotHost != "a" || gotKey != "key-a" {
+		t.Fatalf("before: host=%q key=%q err=%v", gotHost, gotKey, err)
+	}
+	c.Reconfigure(b.URL+"/", "key-b") // a trailing slash is trimmed like in NewClient
+	if err := c.Do(context.Background(), http.MethodGet, "system/status", nil, nil, &out); err != nil || gotHost != "b" || gotKey != "key-b" {
+		t.Fatalf("after: host=%q key=%q err=%v", gotHost, gotKey, err)
+	}
+	// Used from many goroutines while being changed (run with -race to see it matter).
+	done := make(chan bool)
+	go func() {
+		for i := 0; i < 50; i++ {
+			c.Reconfigure(a.URL, "k")
+			c.Reconfigure(b.URL, "k")
+		}
+		done <- true
+	}()
+	for i := 0; i < 50; i++ {
+		_ = c.Do(context.Background(), http.MethodGet, "system/status", nil, nil, &out)
+	}
+	<-done
+}