package text.com.gridlayoutdemo;

import android.animation.LayoutTransition;
import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.DragEvent;
import android.view.Gravity;
import android.view.View;
import android.widget.GridLayout;
import android.widget.TextView;

import java.util.List;

/**
 * 定義出一個setitem方法動態(tài)傳遞標題數(shù)據
 * 定義方法 setAllowDrag()控制是否可以拖拽
 * Created by janzen on 2017/11/23.
 */

public class DrageGridiayout extends GridLayout {
    private static final int columnCount = 4;
    private boolean allowDrag;//是否可以拖拽
    private Rect[] mRects;
    private View dragedView;


    public DrageGridiayout(Context context) {
        this(context, null);
    }

    public DrageGridiayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public DrageGridiayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
//        android:animateLayoutChanges="true"
//        android:columnCount="4"
        this.setColumnCount(columnCount);
        this.setLayoutTransition(new LayoutTransition());
    }

    public void setItems(List<String> items) {
        for (String item : items) {
            addItem(item);
        }
    }

    private void addItem(String item) {
        TextView textView = newItemView();
        textView.setText(item);
        this.addView(textView);
    }

    private TextView newItemView() {
        TextView textView = new TextView(getContext());
        textView.setBackgroundResource(R.drawable.selector_tv_bg);
        GridLayout.LayoutParams layoutParams = new GridLayout.LayoutParams();
        int margin = 5;
        layoutParams.width = getResources().getDisplayMetrics().widthPixels / 4 - 2 * margin;
        layoutParams.height = GridLayout.LayoutParams.WRAP_CONTENT;
        textView.setLayoutParams(layoutParams);
        layoutParams.setMargins(margin, margin, margin, margin);
        textView.setGravity(Gravity.CENTER);
        if (this.allowDrag) {
            textView.setOnLongClickListener(olcl);
        }else {
            textView.setOnLongClickListener(null);
        }
        return textView;
    }

    public void setAllowDrag(boolean allowDrag) {
        this.allowDrag = allowDrag;
        if (this.allowDrag) {
            this.setOnDragListener(odl);
        }
    }
    View.OnLongClickListener olcl = new View.OnLongClickListener() {
        @Override
        public boolean onLongClick(View view) {
            dragedView = view;
            view.startDrag(null, new View.DragShadowBuilder(view), null, 0);
            view.setEnabled(false);
            return false;
        }
    };
    View.OnDragListener odl = new View.OnDragListener() {
        @Override
        public boolean onDrag(View view, DragEvent dragEvent) {
            switch (dragEvent.getAction()) {
                case DragEvent.ACTION_DRAG_STARTED:
                    initRects();
                    break;
                case DragEvent.ACTION_DRAG_LOCATION:
                    int touchIndex = getTouchIndex(dragEvent);
                    if (touchIndex > -1 && dragedView != null && dragedView != DrageGridiayout.this.getChildAt(touchIndex)) {
                        DrageGridiayout.this.removeView(dragedView);
                        DrageGridiayout.this.addView(dragedView, touchIndex);
                    }
                    break;
                case DragEvent.ACTION_DRAG_ENDED:
                    if (dragedView != null)
                        dragedView.setEnabled(true);
                    break;
            }
            return true;
        }
    };


    private void initRects() {
        mRects = new Rect[this.getChildCount()];
        for (int i = 0; i < this.getChildCount(); i++) {
            View childView = this.getChildAt(i);
            Rect rect = new Rect(childView.getLeft(), childView.getTop(), childView.getRight(), childView.getBottom());
            mRects[i] = rect;
        }
    }

    private int getTouchIndex(DragEvent dragEvent) {
        for (int i = 0; i < mRects.length; i++) {
            Rect rect = mRects[i];
            if (rect.contains((int) dragEvent.getX(), (int) dragEvent.getY())) {
                return i;
            }
        }
        return -1;
    }
}