// Copyright 2021 The Dawn & Tint Authors
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#include "src/dawn/node/binding/AsyncRunner.h"

#include <cassert>
#include <limits>

namespace wgpu::binding {

AsyncRunner::AsyncRunner(dawn::native::Instance* instance) : instance_(instance) {}

void AsyncRunner::Begin(Napi::Env env) {
    assert(count_ != std::numeric_limits<decltype(count_)>::max());
    if (count_++ == 0) {
        QueueTick(env);
    }
}

void AsyncRunner::End() {
    assert(count_ > 0);
    count_--;
}

void AsyncRunner::QueueTick(Napi::Env env) {
    // TODO(crbug.com/dawn/1127): We probably want to reduce the frequency at which this gets
    // called.
    if (tick_queued_) {
        return;
    }
    tick_queued_ = true;
    env.Global()
        .Get("setImmediate")
        .As<Napi::Function>()
        .Call({
            // TODO(crbug.com/dawn/1127): Create once, reuse.
            Napi::Function::New(env,
                                [this, env](const Napi::CallbackInfo&) {
                                    tick_queued_ = false;
                                    if (count_ > 0) {
                                        wgpu::Instance instance = instance_->Get();
                                        instance.ProcessEvents();
                                        QueueTick(env);
                                    }
                                }),
        });
}

void AsyncRunner::Reject(Napi::Env env, interop::Promise<void> promise, Napi::Error error) {
    env.Global()
        .Get("setImmediate")
        .As<Napi::Function>()
        .Call({Napi::Function::New(
            env, [promise, error](const Napi::CallbackInfo&) { promise.Reject(error); })});
}

}  // namespace wgpu::binding