fix: address bug in isPluginAvailable() for web and native (#4114)

android/capacitor/src/main/java/com/getcapacitor/JSExport.java

@@ -8,6 +8,9 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
 
 public class JSExport {
 
@@ -40,6 +43,7 @@ public static String getCordovaPluginsFileJS(Context context) {
 
     public static String getPluginJS(Collection<PluginHandle> plugins) {
         List<String> lines = new ArrayList<>();
+        JSONArray pluginArray = new JSONArray();
 
         lines.add("// Begin: Capacitor Plugin JS");
 
@@ -57,21 +61,21 @@ public static String getPluginJS(Collection<PluginHandle> plugins) {
                 "', eventName, callback);\n" +
                 "}"
             );
-
             Collection<PluginMethodHandle> methods = plugin.getMethods();
-
             for (PluginMethodHandle method : methods) {
                 if (method.getName().equals("addListener") || method.getName().equals("removeListener")) {
                     // Don't export add/remove listener, we do that automatically above as they are "special snowflakes"
                     continue;
                 }
-
                 lines.add(generateMethodJS(plugin, method));
             }
+
             lines.add("})(window);\n");
+
+            pluginArray.put(createPluginHeader(plugin));
         }
 
-        return TextUtils.join("\n", lines);
+        return TextUtils.join("\n", lines) + "\nwindow.Capacitor.PluginHeaders = " + pluginArray.toString() + ";";
     }
 
     public static String getCordovaPluginJS(Context context) {
@@ -95,6 +99,40 @@ public static String getFilesContent(Context context, String path) {
         return builder.toString();
     }
 
+    private static JSONObject createPluginHeader(PluginHandle plugin) {
+        JSONObject pluginObj = new JSONObject();
+        Collection<PluginMethodHandle> methods = plugin.getMethods();
+        try {
+            String id = plugin.getId();
+            JSONArray methodArray = new JSONArray();
+            pluginObj.put("name", id);
+
+            for (PluginMethodHandle method : methods) {
+                methodArray.put(createPluginMethodHeader(method));
+            }
+
+            pluginObj.put("methods", methodArray);
+        } catch (JSONException e) {
+            // ignore
+        }
+        return pluginObj;
+    }
+
+    private static JSONObject createPluginMethodHeader(PluginMethodHandle method) {
+        JSONObject methodObj = new JSONObject();
+
+        try {
+            methodObj.put("name", method.getName());
+            if (!method.getReturnType().equals(PluginMethod.RETURN_NONE)) {
+                methodObj.put("rtype", method.getReturnType());
+            }
+        } catch (JSONException e) {
+            // ignore
+        }
+
+        return methodObj;
+    }
+
     private static String generateMethodJS(PluginHandle plugin, PluginMethodHandle method) {
         List<String> lines = new ArrayList<>();
 

android/capacitor/src/main/java/com/getcapacitor/JSInjector.java

@@ -20,10 +20,6 @@ class JSInjector {
     private String cordovaPluginsFileJS;
     private String localUrlJS;
 
-    public JSInjector(String globalJS, String pluginJS) {
-        this(globalJS, pluginJS, ""/* cordovaJS */, ""/* cordovaPluginsJS */, ""/* cordovaPluginsFileJS */, ""/* localUrlJS */);
-    }
-
     public JSInjector(
         String globalJS,
         String pluginJS,

core/src/definitions-internal.ts

@@ -5,6 +5,16 @@ import type {
   PluginResultError,
 } from './definitions';
 
+export interface PluginHeaderMethod {
+  readonly name: string;
+  readonly rtype?: 'promise' | 'callback';
+}
+
+export interface PluginHeader {
+  readonly name: string;
+  readonly methods: readonly PluginHeaderMethod[];
+}
+
 /**
  * Has all instance properties that are available and used
  * by the native layer. The "Capacitor" interface it extends
@@ -23,6 +33,8 @@ export interface CapacitorInstance extends CapacitorGlobal {
     };
   };
 
+  PluginHeaders?: readonly PluginHeader[];
+
   /**
    * Low-level API to send data to the native layer.
    * Prefer using `nativeCallback()` or `nativePromise()` instead.

core/src/runtime.ts

@@ -2,6 +2,7 @@ import { getPlatformId, initBridge } from './bridge';
 import type { CapacitorGlobal, PluginImplementations } from './definitions';
 import type {
   CapacitorInstance,
+  PluginHeader,
   WindowCapacitor,
 } from './definitions-internal';
 import { initEvents } from './events';
@@ -25,8 +26,24 @@ export const createCapacitor = (win: WindowCapacitor): CapacitorInstance => {
 
   const isNativePlatform = () => getPlatformId(win) !== 'web';
 
-  const isPluginAvailable = (pluginName: string) =>
-    Object.prototype.hasOwnProperty.call(Plugins, pluginName);
+  const isPluginAvailable = (pluginName: string): boolean => {
+    const plugin = registeredPlugins.get(pluginName);
+
+    if (plugin && getPlatform() in plugin.implementations) {
+      // JS implementation available for the current platform.
+      return true;
+    }
+
+    if (getPluginHeader(pluginName)) {
+      // Native implementation available.
+      return true;
+    }
+
+    return false;
+  };
+
+  const getPluginHeader = (pluginName: string): PluginHeader | undefined =>
+    cap.PluginHeaders?.find(h => h.name === pluginName);
 
   const convertFileSrc = (filePath: string) =>
     convertFileSrcServerUrl(webviewServerUrl, filePath);
@@ -59,24 +76,29 @@ export const createCapacitor = (win: WindowCapacitor): CapacitorInstance => {
     );
   };
 
+  interface RegisteredPlugin {
+    proxy: any;
+    implementations: PluginImplementations;
+  }
+
   // ensure we do not double proxy the same plugin
-  const registeredPlugins = new Map<string, any>();
+  const registeredPlugins = new Map<string, RegisteredPlugin>();
 
   const registerPlugin = (
     pluginName: string,
     impls: PluginImplementations = {},
   ): any => {
     const registeredPlugin = registeredPlugins.get(pluginName);
     if (registeredPlugin) {
-      return registeredPlugin;
+      return registeredPlugin.proxy;
     }
 
     const nativePluginImpl = Plugins[pluginName];
     if (nativePluginImpl) {
       // the native implementation is already on the global
       // return a proxy that'll also handle any missing methods
       // convert the Capacitor.Plugins.PLUGIN into a proxy and return it
-      const nativePluginProxy = (Plugins[pluginName] = new Proxy<any>(
+      const nativePluginProxy = (Plugins[pluginName] = new Proxy(
         {},
         {
           get(_, prop) {
@@ -101,7 +123,10 @@ export const createCapacitor = (win: WindowCapacitor): CapacitorInstance => {
           },
         },
       ));
-      registeredPlugins.set(pluginName, nativePluginProxy);
+      registeredPlugins.set(pluginName, {
+        implementations: impls,
+        proxy: nativePluginProxy,
+      });
       return nativePluginProxy;
     }
 
@@ -110,7 +135,7 @@ export const createCapacitor = (win: WindowCapacitor): CapacitorInstance => {
 
     // there isn't a native implementation already on the global
     // create a Proxy which is used to lazy load implementations
-    const pluginProxy = (Plugins[pluginName] = new Proxy<any>(
+    const pluginProxy = (Plugins[pluginName] = new Proxy(
       {},
       {
         get(_, prop) {
@@ -229,7 +254,10 @@ export const createCapacitor = (win: WindowCapacitor): CapacitorInstance => {
         },
       },
     ));
-    registeredPlugins.set(pluginName, pluginProxy);
+    registeredPlugins.set(pluginName, {
+      implementations: impls,
+      proxy: pluginProxy,
+    });
     return pluginProxy;
   };
 

core/src/tests/runtime.spec.ts

@@ -22,6 +22,7 @@ describe('runtime', () => {
   it('used existing window.Capacitor.Plugins', () => {
     win.Capacitor = {
       Plugins: { Awesome: {} },
+      PluginHeaders: [{ name: 'Awesome', methods: [] }],
     } as any;
     cap = createCapacitor(win);
     expect(cap.isPluginAvailable('Awesome')).toBe(true);

ios/Capacitor/Capacitor/JSExport.swift

@@ -1,3 +1,13 @@
+internal struct PluginHeaderMethod: Codable {
+    let name: String
+    let rtype: String?
+}
+
+internal struct PluginHeader: Codable {
+    let name: String
+    let methods: [PluginHeaderMethod]
+}
+
 /**
  * PluginExport handles defining JS APIs that map to registered
  * plugins and are responsible for proxying calls to our bridge.
@@ -56,12 +66,38 @@ internal class JSExport {
     })(window);
     """)
 
+        if let data = try? JSONEncoder().encode(createPluginHeader(pluginClassName: pluginClassName, pluginType: pluginType)), let header = String(data: data, encoding: .utf8) {
+            lines.append("""
+                (function(w) {
+                var a = (w.Capacitor = w.Capacitor || {});
+                var h = (a.PluginHeaders = a.PluginHeaders || []);
+                h.push(\(header));
+                })(window);
+                """)
+        }
+
         let js = lines.joined(separator: "\n")
 
         let userScript = WKUserScript(source: js, injectionTime: .atDocumentStart, forMainFrameOnly: true)
         userContentController.addUserScript(userScript)
     }
 
+    private static func createPluginHeader(pluginClassName: String, pluginType: CAPPlugin.Type) -> PluginHeader? {
+        if let bridgeType = pluginType as? CAPBridgedPlugin.Type, let methods = bridgeType.pluginMethods() as? [CAPPluginMethod] {
+            return PluginHeader(name: pluginClassName, methods: methods.map { createPluginHeaderMethod(method: $0) })
+        }
+
+        return nil
+    }
+
+    private static func createPluginHeaderMethod(method: CAPPluginMethod) -> PluginHeaderMethod {
+        var rtype = method.returnType
+        if rtype == "none" {
+            rtype = nil
+        }
+        return PluginHeaderMethod(name: method.name, rtype: rtype)
+    }
+
     private static func generateMethod(pluginClassName: String, method: CAPPluginMethod) -> String {
         let methodName = method.name!
         let returnType = method.returnType!