package com.hjq.base;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.IdRes;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import java.lang.reflect.Field;

/**
 *    author : Android 轮子哥
 *    github : https://github.com/getActivity/AndroidProject
 *    time   : 2018/10/18
 *    desc   : Fragment 懒加载基类
 */
public abstract class BaseLazyFragment extends Fragment {

    // Activity对象
    public FragmentActivity mActivity;
    // 根布局
    private View mRootView;
    // 是否进行过懒加载
    private boolean isLazyLoad;
    // Fragment 是否可见
    private boolean isFragmentVisible;
    // 是否是 replace Fragment 的形式
    private boolean isReplaceFragment;

    /**
     * 获得全局的，防止使用getActivity()为空
     */
    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        this.mActivity = (FragmentActivity) context;
    }

    /**
     * 获取Activity，防止出现 getActivity() 为空
     */
    public FragmentActivity getFragmentActivity() {
        return mActivity;
    }

    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // super.onCreateView(inflater, container, savedInstanceState);

        if (mRootView == null && getLayoutId() > 0) {
            mRootView = inflater.inflate(getLayoutId(), null);
        }

        ViewGroup parent = (ViewGroup) mRootView.getParent();
        if (parent != null) {
            parent.removeView(mRootView);
        }

        return mRootView;
    }

    @Override
    public View getView() {
        return mRootView;
    }

    /**
     * 是否进行了懒加载
     */
    protected boolean isLazyLoad() {
        return isLazyLoad;
    }

    /**
     * 当前 Fragment 是否可见
     */
    public boolean isFragmentVisible() {
        return isFragmentVisible;
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        if (isReplaceFragment) {
            if (isFragmentVisible) {
                initLazyLoad();
            }
        }else {
            initLazyLoad();
        }
    }

    // replace Fragment时使用，ViewPager 切换时会回调此方法
    @Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);
        this.isReplaceFragment = true;
        this.isFragmentVisible = isVisibleToUser;
        if (isVisibleToUser && getView() != null) {
            if (!isLazyLoad) {
                initLazyLoad();
            }else {
                // 从不可见到可见
                onRestart();
            }
        }
    }

    /**
     * 初始化懒加载
     */
    protected void initLazyLoad() {
        if (!isLazyLoad) {
            isLazyLoad = true;
            initFragment();
        }
    }

    /**
     * 跟 Activity 的同名方法效果一样
     */
    protected void onRestart() {
        // 从可见的状态变成不可见状态，再从不可见状态变成可见状态时回调
    }

    @Override
    public void onDetach() {
        super.onDetach();
        //解决java.lang.IllegalStateException: Activity has been destroyed 的错误
        try {
            Field childFragmentManager = Fragment.class.getDeclaredField("mChildFragmentManager");
            childFragmentManager.setAccessible(true);
            childFragmentManager.set(this, null);
        } catch (NoSuchFieldException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }
    }

    protected void initFragment() {
        initView();
        initData();
    }

    //引入布局
    protected abstract int getLayoutId();

    //标题栏id
    protected abstract int getTitleBarId();

    //初始化控件
    protected abstract void initView();

    //初始化数据
    protected abstract void initData();

    /**
     * 根据资源 id 获取一个 View 对象
     */
    protected <T extends View> T findViewById(@IdRes int id) {
        return  getView().findViewById(id);
    }

    protected <T extends View> T findActivityViewById(@IdRes int id) {
        return mActivity.findViewById(id);
    }

    /**
     * 跳转到其他Activity
     *
     * @param cls          目标Activity的Class
     */
    public void startActivity(Class<? extends Activity> cls) {
        startActivity(new Intent(getContext(), cls));
    }

    /**
     * 销毁当前 Fragment 所在的 Activity
     */
    public void finish() {
        mActivity.finish();
    }

    /**
     * 获取系统服务
     */
    public Object getSystemService(@NonNull String name) {
        return mActivity.getSystemService(name);
    }

    /**
     * Fragment返回键被按下时回调
     */
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        //默认不拦截按键事件，传递给Activity
        return false;
    }
}