import android.annotation.SuppressLint
import android.content.Context
import android.graphics.Color
import android.os.Build
import android.util.AttributeSet
import android.util.TypedValue
import android.view.Gravity
import android.view.MotionEvent
import android.view.View
import android.widget.Scroller
import android.widget.TextView
import androidx.annotation.RequiresApi
import androidx.constraintlayout.widget.ConstraintLayout
import kotlin.math.abs
/**
 * 左劃刪除控件
 * 能在控件實現(xiàn)左滑嗎？如何傳入自定義的布局？
 * 思路：
 * 1、一個容器，左右兩部分，左邊外部導(dǎo)入，右邊刪除框 x 增加層級
 * 2、在 View 右邊追加一個刪除款 x 需要在 View 內(nèi)攔截事件
 * 3、在 ConstraintLayout 內(nèi)部添加一個刪除框，左邊對其 parent 右邊
 *
 * @author silence
 * @date 2022-09-27
 */
class LeftDeleteItemLayout : ConstraintLayout {
    private val mDeleteView: View?
    var mDeleteClickListener: OnClickListener? = null
    //流暢滑動
    private var mScroller = Scroller(context)
    //上次事件的橫坐標(biāo)
    private var mLastX = -1f
    //控制控件結(jié)束的runnable
    private val stopMoveRunnable: Runnable = Runnable { stopMove() }
    constructor(context: Context) : this(context, null, 0)
    constructor(context: Context, attrs: AttributeSet?) : this(context, attrs, 0)
    constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) :
            super(context, attrs, defStyleAttr)
    @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
    constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int, defStyleRes: Int) :
            super(context, attrs, defStyleAttr, defStyleRes)
    init {
        //kotlin的初始化函數(shù)
        mDeleteView = makeDeleteView(context)
        addView(mDeleteView)
    }
    //創(chuàng)建刪除框，設(shè)置好位置對齊自身最右邊
    private fun makeDeleteView(context: Context): View {
        val deleteView = TextView(context)
        //給當(dāng)前控件一個id，用于刪除控件約束
        this.id = generateViewId()
        //設(shè)置布局參數(shù)
        deleteView.layoutParams = LayoutParams(
            dp2px(context, 100f), 0
        ).apply {
            //設(shè)置約束條件
            leftToRight = id
            topToTop = id
            bottomToBottom = id
        }
        //設(shè)置其他參數(shù)
        deleteView.text = "刪除"
        deleteView.gravity = Gravity.CENTER
        deleteView.setTextColor(Color.WHITE)
        deleteView.textSize = sp2px(context,18f).toFloat()
        deleteView.setBackgroundColor(Color.RED)
        //設(shè)置點(diǎn)擊回調(diào)
        deleteView.setOnClickListener(mDeleteClickListener)
        return deleteView
    }
    //攔截事件
    override fun onInterceptTouchEvent(event: MotionEvent?): Boolean {
        event?.let {
            when(event.action) {
                //down事件記錄x，不攔截，當(dāng)move的時候才會用到
                MotionEvent.ACTION_DOWN -> mLastX = event.x
                //攔截本控件內(nèi)的移動事件
                MotionEvent.ACTION_MOVE -> return true
            }
        }
        return super.onInterceptTouchEvent(event)
    }
    //處理事件
    @SuppressLint("ClickableViewAccessibility")
    override fun onTouchEvent(event: MotionEvent?): Boolean {
        event?.let {
            when(event.action) {
                MotionEvent.ACTION_MOVE -> moveItem(event)
                MotionEvent.ACTION_UP -> stopMove()
            }
        }
        return super.onTouchEvent(event)
    }
    private fun moveItem(e: MotionEvent) {
        //Log.e("TAG", "moveItem: mLastX=$mLastX")
        //如果沒有收到down事件，不應(yīng)該移動
        if (mLastX == -1f) return
        val dx = mLastX - e.x
        //更新點(diǎn)擊的橫坐標(biāo)
        mLastX = e.x
        //檢查mItem移動后應(yīng)該在[-deleteLength, 0]內(nèi)
        val deleteWidth = mDeleteView!!.width
        if ((scrollX + dx) <= deleteWidth && (scrollX + dx) >= 0) {
            //觸發(fā)移動
            scrollBy(dx.toInt(), 0)
        }
        //如果一段時間沒有移動時間，mLastX還沒被stopMove重置為-1，那就是移動到其他地方了
        //設(shè)置200毫秒沒有新事件就觸發(fā)stopMove
        removeCallbacks(stopMoveRunnable)
        postDelayed(stopMoveRunnable, 200)
    }
    private fun stopMove() {
        //如果移動過半了，應(yīng)該判定左滑成功
        val deleteWidth = mDeleteView!!.width
        if (abs(scrollX) >= deleteWidth / 2f) {
            //觸發(fā)移動至完全展開
            mScroller.startScroll(scrollX, 0, deleteWidth - scrollX, 0)
        }else {
            //如果移動沒過半應(yīng)該恢復(fù)狀態(tài)，則恢復(fù)到原來狀態(tài)
            mScroller.startScroll(scrollX, 0, - scrollX, 0)
        }
        invalidate()
        //清除狀態(tài)
        mLastX = -1f
    }
    //流暢地滑動
    override fun computeScroll() {
        if (mScroller.computeScrollOffset()) {
            scrollTo(mScroller.currX, mScroller.currY)
            postInvalidate()
        }
    }
    //單位轉(zhuǎn)換
    @Suppress("SameParameterValue")
    private fun dp2px(context: Context, dpVal: Float): Int {
        return TypedValue.applyDimension(
            TypedValue.COMPLEX_UNIT_DIP, dpVal, context.resources
                .displayMetrics
        ).toInt()
    }
    @Suppress("SameParameterValue")
    private fun sp2px(context: Context, spVal: Float): Int {
        val fontScale = context.resources.displayMetrics.scaledDensity
        return (spVal * fontScale + 0.5f).toInt()
    }

    //處理事件
    @SuppressLint("ClickableViewAccessibility")
    override fun onTouchEvent(event: MotionEvent): Boolean {
        when(event.action) {
            MotionEvent.ACTION_DOWN -> return true
            MotionEvent.ACTION_MOVE -> moveItem(event)
            MotionEvent.ACTION_UP -> stopMove()
        }
        return super.onTouchEvent(event)
    }