From 40ada838d7d940fd19429a4ac71b748acb5231be Mon Sep 17 00:00:00 2001
From: John Knox <jknox@fb.com>
Date: Tue, 26 Feb 2019 10:00:57 -0800
Subject: [PATCH] Add isMethodSupported handler

Summary: Allows plugin to check if something is supported by that app, for example an extension command or a new feature, before trying to use it.

Reviewed By: passy

Differential Revision: D14225957

fbshipit-source-id: 3c5a29a06b56fe5f1da772824232547447872344
---
 xplat/Flipper/FlipperClient.cpp                | 16 ++++++++++++++++
 xplat/Flipper/FlipperConnectionImpl.h          |  7 +++++++
 xplat/Flipper/FlipperConnectionManagerImpl.cpp |  2 +-
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/xplat/Flipper/FlipperClient.cpp b/xplat/Flipper/FlipperClient.cpp
index d2c00f536..488686c41 100644
--- a/xplat/Flipper/FlipperClient.cpp
+++ b/xplat/Flipper/FlipperClient.cpp
@@ -231,6 +231,22 @@ void FlipperClient::onMessageReceived(
       return;
     }
 
+    if (method == "isMethodSupported") {
+      const auto identifier = params["api"].getString();
+      if (connections_.find(identifier) == connections_.end()) {
+        std::string errorMessage = "Connection " + identifier +
+            " not found for method " + method.getString();
+        log(errorMessage);
+        responder->error(folly::dynamic::object("message", errorMessage)(
+            "name", "ConnectionNotFound"));
+        return;
+      }
+      const auto& conn = connections_.at(params["api"].getString());
+      bool isSupported = conn->hasReceiver(params["method"].getString());
+      responder->success(dynamic::object("isSupported", isSupported));
+      return;
+    }
+
     dynamic response =
         dynamic::object("message", "Received unknown method: " + method);
     responder->error(response);
diff --git a/xplat/Flipper/FlipperConnectionImpl.h b/xplat/Flipper/FlipperConnectionImpl.h
index 891d23ad6..29fc9ab0d 100644
--- a/xplat/Flipper/FlipperConnectionImpl.h
+++ b/xplat/Flipper/FlipperConnectionImpl.h
@@ -53,6 +53,13 @@ class FlipperConnectionImpl : public FlipperConnection {
     receivers_[method] = receiver;
   }
 
+  /**
+  Runtime check which receivers are supported for this app
+  */
+  bool hasReceiver(const std::string& method) {
+    return receivers_.find(method) != receivers_.end();
+  }
+
  private:
   FlipperConnectionManager* socket_;
   std::string name_;
diff --git a/xplat/Flipper/FlipperConnectionManagerImpl.cpp b/xplat/Flipper/FlipperConnectionManagerImpl.cpp
index 47a7d4f6a..3d924f947 100644
--- a/xplat/Flipper/FlipperConnectionManagerImpl.cpp
+++ b/xplat/Flipper/FlipperConnectionManagerImpl.cpp
@@ -34,7 +34,7 @@ static constexpr int maxPayloadSize = 0xFFFFFF;
 // Not a public-facing version number.
 // Used for compatibility checking with desktop flipper.
 // To be bumped for every core platform interface change.
-static constexpr int sdkVersion = 1;
+static constexpr int sdkVersion = 2;
 
 namespace facebook {
 namespace flipper {