import android.content.Context
import android.graphics.*
import android.util.AttributeSet
import android.view.MotionEvent
import android.view.View
import java.security.MessageDigest
import kotlin.math.hypot

class PatternLockView(context: Context, attrs: AttributeSet?) : View(context, attrs) {

  interface PatternListener {
    fun onPatternDetected(pattern: List<Int>, hash: String)
  }

  var patternListener: PatternListener? = null
  var showLines: Boolean = true

  private val gridSize = 3
  private val points = Array(gridSize) { Array(gridSize) { PointF() } }

  // 선택된 점 인덱스 및 좌표
  private val selectedIndices = mutableListOf<Int>()
  private val selectedPoints = mutableListOf<PointF>()
  private val selectedIndexSet = mutableSetOf<Int>() // 최적화를 위한 Set (contains 빠름)

  // 점 및 선 색상 설정
  private val defaultPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
    color = Color.GRAY
    style = Paint.Style.FILL
  }

  // 선택된 점 색상
  private val selectedPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
    color = Color.BLUE
    style = Paint.Style.FILL
  }

  private val errorPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
    color = Color.RED
    style = Paint.Style.FILL
  }

  // 이어진 선 색상
  private val linePaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
    color = Color.BLUE
    strokeWidth = 10f
    style = Paint.Style.STROKE
  }

  private val errorLinePaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
    color = Color.RED
    strokeWidth = 10f
    style = Paint.Style.STROKE
  }

  private var currentTouchX = -1f
  private var currentTouchY = -1f
  private var isError = false

  // 뷰 크기 변경 시 각 점 좌표 계산
  override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
    val offsetX = w / (gridSize + 1)
    val offsetY = h / (gridSize + 1)
    for (i in 0 until gridSize) {
      for (j in 0 until gridSize) {
        points[i][j] = PointF((j + 1) * offsetX.toFloat(), (i + 1) * offsetY.toFloat())
      }
    }
  }

  // 점과 선을 그림
  override fun onDraw(canvas: Canvas) {
    super.onDraw(canvas)

    // 점 그리기
    for (i in 0 until gridSize) {
      for (j in 0 until gridSize) {
        val index = i * gridSize + j
        val p = points[i][j]
        val paint = when {
          isError && selectedIndexSet.contains(index) && showLines -> errorPaint
          selectedIndexSet.contains(index) && showLines -> selectedPaint
          else -> defaultPaint
        }
        canvas.drawCircle(p.x, p.y, 30f, paint)
      }
    }

    // 선 그리기
    if (showLines && selectedPoints.isNotEmpty()) {
      val paint = if (isError) errorLinePaint else linePaint
      for (i in 0 until selectedPoints.size - 1) {
        canvas.drawLine(
          selectedPoints[i].x,
          selectedPoints[i].y,
          selectedPoints[i + 1].x,
          selectedPoints[i + 1].y,
          paint
        )
      }

      // 현재 터치 중이면 마지막 점에서 손가락까지 선 그리기
      if (currentTouchX >= 0 && currentTouchY >= 0) {
        val last = selectedPoints.last()
        canvas.drawLine(last.x, last.y, currentTouchX, currentTouchY, paint)
      }
    }
  }

  // 터치 이벤트 처리
  override fun onTouchEvent(event: MotionEvent): Boolean {
    when (event.action) {
      MotionEvent.ACTION_DOWN, MotionEvent.ACTION_MOVE -> {
        currentTouchX = event.x
        currentTouchY = event.y
        val (p, index) = findNearestPoint(event.x, event.y) ?: return true
        if (selectedIndexSet.add(index)) {
          selectedIndices.add(index)
          selectedPoints.add(p)
        }
        invalidate()
      }

      MotionEvent.ACTION_UP -> {
        currentTouchX = -1f
        currentTouchY = -1f
        if (selectedIndices.isNotEmpty()) {
          val hash = hashPattern(selectedIndices)
          patternListener?.onPatternDetected(selectedIndices.toList(), hash)
        }
        resetPattern()
      }
    }
    return true
  }

  // 터치 위치가 가까운 점을 찾음
  private fun findNearestPoint(x: Float, y: Float): Pair<PointF, Int>? {
    for (i in 0 until gridSize) {
      for (j in 0 until gridSize) {
        val p = points[i][j]
        if (hypot(x - p.x, y - p.y) < 50f) {
          val index = i * gridSize + j
          return p to index
        }
      }
    }
    return null
  }

  // 잘못된 패턴 입력 시 애니메이션과 함께 초기화
  fun showErrorAndReset() {
    isError = true
    invalidate()

    this.animate().translationX(30f).setDuration(50).withEndAction {
      this.animate().translationX(-30f).setDuration(50).withEndAction {
        this.animate().translationX(0f).setDuration(50).start()
      }.start()
    }.start()

    postDelayed({
      isError = false
      resetPattern()
    }, 1000)
  }

  // 패턴 리셋
  private fun resetPattern() {
    selectedIndices.clear()
    selectedPoints.clear()
    selectedIndexSet.clear()
    invalidate()
  }

  // 패턴을 해시 문자열로 변환 (SHA-256)
  private fun hashPattern(pattern: List<Int>): String {
    val message = pattern.joinToString("")
    val digest = MessageDigest.getInstance("SHA-256")
    val hashBytes = digest.digest(message.toByteArray())
    return hashBytes.joinToString("") { "%02x".format(it) }
  }
}

import android.os.Bundle
import android.util.Log
import androidx.appcompat.app.AppCompatActivity
import com.example.sample.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

    private val TAG: String = MainActivity::class.java.simpleName

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.patternLockView.patternListener = object : PatternLockView.PatternListener {
            override fun onPatternDetected(pattern: List<Int>, hash: String) {
                Log.e(TAG, "patternNumber=${pattern.joinToString(",")}  hash=$hash")
            }
        }

        binding.checkBox.setOnCheckedChangeListener { _, isChecked ->
            binding.patternLockView.showLines = !isChecked
            binding.patternLockView.invalidate()
        }

    }

}