// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#import "flutter/shell/platform/darwin/macos/framework/Source/FlutterThreadSynchronizer.h"

#import "flutter/fml/synchronization/waitable_event.h"
#import "flutter/testing/testing.h"

namespace flutter::testing {

namespace {}  // namespace

}  // namespace flutter::testing

@interface FlutterThreadSynchronizerTestScaffold : NSObject

@property(nonatomic, readonly, nonnull) FlutterThreadSynchronizer* synchronizer;

- (nullable instancetype)init;
- (void)dispatchMainTask:(nonnull void (^)())task;
- (void)dispatchRenderTask:(nonnull void (^)())task;
- (void)joinMain;
- (void)joinRender;
@end

@implementation FlutterThreadSynchronizerTestScaffold {
  dispatch_queue_t _mainQueue;
  std::shared_ptr<fml::AutoResetWaitableEvent> _mainLatch;

  dispatch_queue_t _renderQueue;
  std::shared_ptr<fml::AutoResetWaitableEvent> _renderLatch;

  FlutterThreadSynchronizer* _synchronizer;
}

@synthesize synchronizer = _synchronizer;

- (nullable instancetype)init {
  self = [super init];
  if (self != nil) {
    _mainQueue = dispatch_queue_create("MAIN", DISPATCH_QUEUE_SERIAL);
    _renderQueue = dispatch_queue_create("RENDER", DISPATCH_QUEUE_SERIAL);
    _synchronizer = [[FlutterThreadSynchronizer alloc] initWithMainQueue:_mainQueue];
  }
  return self;
}

- (void)dispatchMainTask:(nonnull void (^)())task {
  dispatch_async(_mainQueue, task);
}

- (void)dispatchRenderTask:(nonnull void (^)())task {
  dispatch_async(_renderQueue, task);
}

- (void)joinMain {
  fml::AutoResetWaitableEvent latch;
  fml::AutoResetWaitableEvent* pLatch = &latch;
  dispatch_async(_mainQueue, ^{
    pLatch->Signal();
  });
  latch.Wait();
}

- (void)joinRender {
  fml::AutoResetWaitableEvent latch;
  fml::AutoResetWaitableEvent* pLatch = &latch;
  dispatch_async(_renderQueue, ^{
    pLatch->Signal();
  });
  latch.Wait();
}

@end

TEST(FlutterThreadSynchronizerTest, RegularCommit) {
  FlutterThreadSynchronizerTestScaffold* scaffold =
      [[FlutterThreadSynchronizerTestScaffold alloc] init];
  FlutterThreadSynchronizer* synchronizer = scaffold.synchronizer;

  // Initial resize: does not block until the first frame.
  __block int notifiedResize = 0;
  [scaffold dispatchMainTask:^{
    [synchronizer registerView:1];
    [synchronizer beginResizeForView:1
                                size:CGSize{5, 5}
                              notify:^{
                                notifiedResize += 1;
                              }];
  }];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);
  [scaffold joinMain];
  EXPECT_EQ(notifiedResize, 1);

  // Still does not block.
  [scaffold dispatchMainTask:^{
    [synchronizer beginResizeForView:1
                                size:CGSize{7, 7}
                              notify:^{
                                notifiedResize += 1;
                              }];
  }];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);
  [scaffold joinMain];
  EXPECT_EQ(notifiedResize, 2);

  // First frame
  __block int notifiedCommit = 0;
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:1
                                  size:CGSize{7, 7}
                                notify:^{
                                  notifiedCommit += 1;
                                }];
  }];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);
  [scaffold joinRender];
  EXPECT_EQ(notifiedCommit, 1);
}

TEST(FlutterThreadSynchronizerTest, ResizingBlocksRenderingUntilSizeMatches) {
  FlutterThreadSynchronizerTestScaffold* scaffold =
      [[FlutterThreadSynchronizerTestScaffold alloc] init];
  FlutterThreadSynchronizer* synchronizer = scaffold.synchronizer;
  // A latch to ensure that a beginResizeForView: call has at least executed
  // something, so that the isWaitingWhenMutexIsAvailable: call correctly stops
  // at either when beginResizeForView: finishes or waits half way.
  fml::AutoResetWaitableEvent begunResizingLatch;
  fml::AutoResetWaitableEvent* begunResizing = &begunResizingLatch;

  // Initial resize: does not block until the first frame.
  [scaffold dispatchMainTask:^{
    [synchronizer registerView:1];
    [synchronizer beginResizeForView:1
                                size:CGSize{5, 5}
                              notify:^{
                              }];
  }];
  [scaffold joinMain];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);

  // First frame.
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:1
                                  size:CGSize{5, 5}
                                notify:^{
                                }];
  }];
  [scaffold joinRender];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);

  // Resize to (7, 7): blocks until the next frame.
  [scaffold dispatchMainTask:^{
    [synchronizer beginResizeForView:1
                                size:CGSize{7, 7}
                              notify:^{
                                begunResizing->Signal();
                              }];
  }];
  begunResizing->Wait();
  EXPECT_TRUE([synchronizer isWaitingWhenMutexIsAvailable]);

  // Render with old size.
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:1
                                  size:CGSize{5, 5}
                                notify:^{
                                }];
  }];
  [scaffold joinRender];
  EXPECT_TRUE([synchronizer isWaitingWhenMutexIsAvailable]);

  // Render with new size.
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:1
                                  size:CGSize{7, 7}
                                notify:^{
                                }];
  }];
  [scaffold joinRender];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);

  [scaffold joinMain];
}

TEST(FlutterThreadSynchronizerTest, ShutdownMakesEverythingNonBlocking) {
  FlutterThreadSynchronizerTestScaffold* scaffold =
      [[FlutterThreadSynchronizerTestScaffold alloc] init];
  FlutterThreadSynchronizer* synchronizer = scaffold.synchronizer;
  fml::AutoResetWaitableEvent begunResizingLatch;
  fml::AutoResetWaitableEvent* begunResizing = &begunResizingLatch;

  // Initial resize
  [scaffold dispatchMainTask:^{
    [synchronizer registerView:1];
    [synchronizer beginResizeForView:1
                                size:CGSize{5, 5}
                              notify:^{
                              }];
  }];
  [scaffold joinMain];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);

  // Push a frame.
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:1
                                  size:CGSize{5, 5}
                                notify:^{
                                }];
  }];
  [scaffold joinRender];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);

  [scaffold dispatchMainTask:^{
    [synchronizer shutdown];
  }];

  // Resize to (7, 7). Should not block any frames since it has shut down.
  [scaffold dispatchMainTask:^{
    [synchronizer beginResizeForView:1
                                size:CGSize{7, 7}
                              notify:^{
                                begunResizing->Signal();
                              }];
  }];
  begunResizing->Wait();
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);
  [scaffold joinMain];

  // All further calls should be unblocking.
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:1
                                  size:CGSize{9, 9}
                                notify:^{
                                }];
  }];
  [scaffold joinRender];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);
}

TEST(FlutterThreadSynchronizerTest, RegularCommitForMultipleViews) {
  FlutterThreadSynchronizerTestScaffold* scaffold =
      [[FlutterThreadSynchronizerTestScaffold alloc] init];
  FlutterThreadSynchronizer* synchronizer = scaffold.synchronizer;
  fml::AutoResetWaitableEvent begunResizingLatch;
  fml::AutoResetWaitableEvent* begunResizing = &begunResizingLatch;

  // Initial resize: does not block until the first frame.
  [scaffold dispatchMainTask:^{
    [synchronizer registerView:1];
    [synchronizer registerView:2];
    [synchronizer beginResizeForView:1
                                size:CGSize{5, 5}
                              notify:^{
                              }];
    [synchronizer beginResizeForView:2
                                size:CGSize{15, 15}
                              notify:^{
                                begunResizing->Signal();
                              }];
  }];
  begunResizing->Wait();
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);
  [scaffold joinMain];

  // Still does not block.
  [scaffold dispatchMainTask:^{
    [synchronizer beginResizeForView:1
                                size:CGSize{7, 7}
                              notify:^{
                                begunResizing->Signal();
                              }];
  }];
  begunResizing->Signal();
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);
  [scaffold joinMain];

  // First frame
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:1
                                  size:CGSize{7, 7}
                                notify:^{
                                }];
    [synchronizer performCommitForView:2
                                  size:CGSize{15, 15}
                                notify:^{
                                }];
  }];
  [scaffold joinRender];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);
}

TEST(FlutterThreadSynchronizerTest, ResizingForMultipleViews) {
  FlutterThreadSynchronizerTestScaffold* scaffold =
      [[FlutterThreadSynchronizerTestScaffold alloc] init];
  FlutterThreadSynchronizer* synchronizer = scaffold.synchronizer;
  fml::AutoResetWaitableEvent begunResizingLatch;
  fml::AutoResetWaitableEvent* begunResizing = &begunResizingLatch;

  // Initial resize: does not block until the first frame.
  [scaffold dispatchMainTask:^{
    [synchronizer registerView:1];
    [synchronizer registerView:2];
    [synchronizer beginResizeForView:1
                                size:CGSize{5, 5}
                              notify:^{
                              }];
    [synchronizer beginResizeForView:2
                                size:CGSize{15, 15}
                              notify:^{
                              }];
  }];
  [scaffold joinMain];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);

  // First frame.
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:1
                                  size:CGSize{5, 5}
                                notify:^{
                                }];
    [synchronizer performCommitForView:2
                                  size:CGSize{15, 15}
                                notify:^{
                                }];
  }];
  [scaffold joinRender];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);

  // Resize view 2 to (17, 17): blocks until the next frame.
  [scaffold dispatchMainTask:^{
    [synchronizer beginResizeForView:2
                                size:CGSize{17, 17}
                              notify:^{
                                begunResizing->Signal();
                              }];
  }];
  begunResizing->Wait();
  EXPECT_TRUE([synchronizer isWaitingWhenMutexIsAvailable]);

  // Render view 1 with the size. Still blocking.
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:1
                                  size:CGSize{5, 5}
                                notify:^{
                                }];
  }];
  [scaffold joinRender];
  EXPECT_TRUE([synchronizer isWaitingWhenMutexIsAvailable]);

  // Render view 2 with the old size. Still blocking.
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:1
                                  size:CGSize{15, 15}
                                notify:^{
                                }];
  }];
  [scaffold joinRender];
  EXPECT_TRUE([synchronizer isWaitingWhenMutexIsAvailable]);

  // Render view 1 with the size.
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:1
                                  size:CGSize{5, 5}
                                notify:^{
                                }];
  }];
  [scaffold joinRender];
  EXPECT_TRUE([synchronizer isWaitingWhenMutexIsAvailable]);

  // Render view 2 with the new size. Unblocks.
  [scaffold dispatchRenderTask:^{
    [synchronizer performCommitForView:2
                                  size:CGSize{17, 17}
                                notify:^{
                                }];
  }];
  [scaffold joinRender];
  [scaffold joinMain];
  EXPECT_FALSE([synchronizer isWaitingWhenMutexIsAvailable]);
}