package com.android.app_base.base.view;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.databinding.DataBindingUtil;
import androidx.databinding.ViewDataBinding;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.Observer;
import androidx.lifecycle.ViewModelProvider;

import com.android.app_base.base.StateViewEnum;
import com.android.app_base.base.viewmodel.BaseViewModel;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

/**
 * @author Ljj
 * @date 2023.03.02. 15:50
 * @desc Fragment基类
 */
public abstract class BaseFragment<V extends ViewDataBinding,VM extends BaseViewModel> extends Fragment {
    protected V binding;
    protected VM viewModel;
    private int viewModelId;


    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //页面参数初始化方法
        initParam();
    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        binding = DataBindingUtil.inflate(inflater,getLayoutId(), container, false);
        return binding.getRoot();
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        //绑定 ViewDataBinding 和 ViewModel
        initViewDataBindingAndViewModel();
        //初始化状态视图
        initStateView();
        //页面view初始化方法
        initView();
        //页面数据初始化方法
        initData();
        //页面事件监听的方法，用于ViewModel层转到View层的事件注册
        initLiveDataObserve();
    }
    @Override
    public void onDestroyView() {
        super.onDestroyView();
        //解除Messenger注册
//        Messenger.getDefault().unregister(viewModel);

        if(binding != null){
            binding.unbind();
        }
    }


    /**
     *  ViewDataBinding和 ViewModel的获取及相关绑定
     */
    private void initViewDataBindingAndViewModel() {
        viewModelId = getVariableId();
        viewModel = initViewModel();
        //关联ViewModel
        binding.setVariable(viewModelId, viewModel);
        //支持LiveData绑定xml，数据改变，UI自动会更新
        binding.setLifecycleOwner(this);
        //让ViewModel拥有View的生命周期感应
        getLifecycle().addObserver(viewModel);

    }

    /**
     * 初始化ViewModel
     * @return 返回一个ViewModel
     */
    private VM initViewModel() {
        Class<VM> vmClass;
        Type type = getClass().getGenericSuperclass();
        if (type instanceof ParameterizedType){
            vmClass = (Class) ((ParameterizedType) type).getActualTypeArguments()[1];
        } else {
            //如果没有指定泛型参数，则默认使用BaseViewModel
            vmClass = (Class<VM>) BaseViewModel.class;
        }
        return new ViewModelProvider(this, (ViewModelProvider.Factory) ViewModelProvider.AndroidViewModelFactory.getInstance(requireActivity().getApplication())).get(vmClass);
    }

    /**
     * 对状态视图liveData进行观察监听
     */
    private void initStateView() {
        viewModel.getStateViewLiveData().observe(getViewLifecycleOwner(), new Observer<StateViewEnum>() {
            @Override
            public void onChanged(StateViewEnum stateViewEnum) {
                switch (stateViewEnum) {
                    case DIALOG_LOADING:
                        dialogLoading();
                        break;
                    case DIALOG_DISMISS:
                        dialogDismiss();
                        break;
                    case DATA_LOADING:
                        dataLoading();
                        break;
                    case DATA_ERROR:
                        dataError();
                        break;
                    case DATA_NULL:
                        dataNull();
                        break;
                    case NET_ERROR:
                        netError();
                        break;
                    case HIDE:
                        hide();
                        break;
                    default:
                        break;
                }
            }
        });
    }
    /**
     * 缺省页等状态视图的更新
     * 有需求的，在子类选择重写
     */
    protected void dialogLoading() {
    }
    protected void dialogDismiss() {
    }
    protected void dataLoading() {
    }
    protected void dataError() {
    }
    protected void dataNull() {
    }
    protected void netError() {
    }
    protected void hide() {
    }

    /**
     * 获取根布局的id，由子类实现返回
     * @return layout的id
     */
    public abstract int getLayoutId();

    /**
     * 获取ViewModel的id，由子类实现返回
     * @return BR中viewModel的id
     */
    public abstract int getVariableId();

    /**
     * 初始化页面参数，例如从上一个activity传递过来的参数
     */
    abstract void initParam();

    /**
     * 初始化页面view，例如一些view的隐藏或显示,以及点击逻辑等用户交互
     */
    abstract void initView();

    /**
     * 初始化页面数据
     */
    abstract void initData();

    /**
     * 初始化LiveData的监听
     * 简单的数据展示可通过DataBinding直接双向绑定到xml中
     */
    abstract void initLiveDataObserve();

}