package com.transistorsoft.rnbackgroundfetch;

import android.content.Context;
import android.os.Handler;
import android.util.Log;

import com.facebook.react.ReactApplication;
import com.facebook.react.ReactInstanceManager;
import com.facebook.react.ReactNativeHost;
import com.facebook.react.bridge.ReactContext;
import com.facebook.react.bridge.UiThreadUtil;
import com.facebook.react.bridge.WritableNativeMap;
import com.facebook.react.jstasks.HeadlessJsTaskConfig;
import com.facebook.react.jstasks.HeadlessJsTaskContext;
import com.facebook.react.jstasks.HeadlessJsTaskEventListener;
import com.transistorsoft.tsbackgroundfetch.BackgroundFetch;

/**
 * Created by chris on 2018-01-17.
 */

public class HeadlessTask implements HeadlessJsTaskEventListener {
    private static String HEADLESS_TASK_NAME = "BackgroundFetch";
    private static Handler mHandler = new Handler();
    private ReactNativeHost mReactNativeHost;
    private HeadlessJsTaskContext mActiveTaskContext;

    public HeadlessTask(Context context) {
        try {
            ReactApplication reactApplication = ((ReactApplication) context.getApplicationContext());
            mReactNativeHost = reactApplication.getReactNativeHost();
        } catch (AssertionError e) {
            Log.e(BackgroundFetch.TAG, "Failed to fetch ReactApplication.  Task ignored.");
            return;  // <-- Do nothing.  Just return
        }
        HeadlessJsTaskConfig config = new HeadlessJsTaskConfig(HEADLESS_TASK_NAME, new WritableNativeMap(), 30000);
        startTask(config);
    }

    public void finish() {
        if (mActiveTaskContext != null) {
            mActiveTaskContext.removeTaskEventListener(this);
        }
    }
    @Override
    public void onHeadlessJsTaskStart(int taskId) {
        Log.d(BackgroundFetch.TAG,"onHeadlessJsTaskStart: " + taskId);
    }
    @Override
    public void onHeadlessJsTaskFinish(int taskId) {
        Log.d(BackgroundFetch.TAG, "onHeadlessJsTaskFinish: " + taskId);
        mActiveTaskContext.removeTaskEventListener(this);
    }

    /**
     * Start a task. This method handles starting a new React instance if required.
     *
     * Has to be called on the UI thread.
     *
     * @param taskConfig describes what task to start and the parameters to pass to it
     */
    protected void startTask(final HeadlessJsTaskConfig taskConfig) {
        UiThreadUtil.assertOnUiThread();
        final ReactInstanceManager reactInstanceManager = mReactNativeHost.getReactInstanceManager();
        ReactContext reactContext = reactInstanceManager.getCurrentReactContext();
        if (reactContext == null) {
            reactInstanceManager.addReactInstanceEventListener(new ReactInstanceManager.ReactInstanceEventListener() {
                @Override
                public void onReactContextInitialized(final ReactContext reactContext) {
                    // Hack to fix unknown problem executing asynchronous BackgroundTask when ReactContext is created *first time*.  Fixed by adding short delay before #invokeStartTask
                    mHandler.postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            invokeStartTask(reactContext, taskConfig);
                        }
                    }, 500);
                    reactInstanceManager.removeReactInstanceEventListener(this);
                }
            });
            if (!reactInstanceManager.hasStartedCreatingInitialContext()) {
                reactInstanceManager.createReactContextInBackground();
            }
        } else {
            invokeStartTask(reactContext, taskConfig);
        }
    }

    private void invokeStartTask(ReactContext reactContext, final HeadlessJsTaskConfig taskConfig) {
        final HeadlessJsTaskContext headlessJsTaskContext = HeadlessJsTaskContext.getInstance(reactContext);
        headlessJsTaskContext.addTaskEventListener(this);
        mActiveTaskContext = headlessJsTaskContext;
        UiThreadUtil.runOnUiThread(new Runnable() {
            @Override
            public void run() {
                int taskId = headlessJsTaskContext.startTask(taskConfig);
            }
        });
    }
}