package com.github.jasonhezz.likesplash.util

import android.content.Context
import android.graphics.Rect
import android.os.Build
import android.support.v4.view.ViewCompat
import android.support.v4.view.WindowInsetsCompat
import android.util.AttributeSet
import android.view.Gravity
import android.view.View
import android.widget.FrameLayout


/**
 * Created by JavaCoder on 2017/11/14.
 */
class WindowInsetsFrameLayout @JvmOverloads constructor(context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = 0,
    defStyleRes: Int = 0) : FrameLayout(context, attrs, defStyleAttr, defStyleRes) {

  init {
    ViewCompat.setOnApplyWindowInsetsListener(this
    ) { v, insets -> setWindowInsets(insets) }
  }

  private fun setWindowInsets(insets: WindowInsetsCompat): WindowInsetsCompat {
    if (Build.VERSION.SDK_INT >= 21 && insets.hasSystemWindowInsets()) {
      if (applySystemWindowInsets21(insets)) {
        return insets.consumeSystemWindowInsets()
      }
    }
    return insets
  }

  override protected fun fitSystemWindows(insets: Rect): Boolean {
    return if (Build.VERSION.SDK_INT >= 19 && Build.VERSION.SDK_INT < 21) {
      applySystemWindowInsets19(insets)
    } else super.fitSystemWindows(insets)
  }

  private fun applySystemWindowInsets19(insets: Rect): Boolean {
    var consumed = false
    for (i in 0 until childCount) {
      val child = getChildAt(i)
      if (!child.fitsSystemWindows) {
        continue
      }
      val childInsets = Rect(insets)
      computeInsetsWithGravity(child, childInsets)
      child.setPadding(childInsets.left, childInsets.top, childInsets.right, childInsets.bottom)
      consumed = true
    }
    return consumed
  }

  private fun applySystemWindowInsets21(insets: WindowInsetsCompat): Boolean {
    var consumed = false
    for (i in 0 until childCount) {
      val child = getChildAt(i)
      if (!child.fitsSystemWindows) {
        continue
      }
      val childInsets = Rect(
          insets.systemWindowInsetLeft,
          insets.systemWindowInsetTop,
          insets.systemWindowInsetRight,
          insets.systemWindowInsetBottom)
      computeInsetsWithGravity(child, childInsets)
      ViewCompat.dispatchApplyWindowInsets(child, insets.replaceSystemWindowInsets(childInsets))
      consumed = true
    }
    return consumed
  }

  private fun computeInsetsWithGravity(view: View, insets: Rect) {
    val lp = view.getLayoutParams() as FrameLayout.LayoutParams
    var gravity = lp.gravity
    /**
     * 因为该方法执行时机早于 FrameLayout.layoutChildren，
     * 而在 {FrameLayout#layoutChildren} 中当 gravity == -1 时会设置默认值为 Gravity.TOP | Gravity.LEFT，
     * 所以这里也要同样设置
     */
    if (gravity == -1) {
      gravity = Gravity.TOP or Gravity.START
    }
    if (lp.width != FrameLayout.LayoutParams.MATCH_PARENT) {
      val horizontalGravity = gravity and Gravity.HORIZONTAL_GRAVITY_MASK
      when (horizontalGravity) {
        Gravity.START -> insets.right = 0
        Gravity.END -> insets.left = 0
      }
    }
    if (lp.height != FrameLayout.LayoutParams.MATCH_PARENT) {
      val verticalGravity = gravity and Gravity.VERTICAL_GRAVITY_MASK
      when (verticalGravity) {
        Gravity.TOP -> insets.bottom = 0
        Gravity.BOTTOM -> insets.top = 0
      }
    }
  }

  /*@TargetApi(Build.VERSION_CODES.KITKAT_WATCH)
  override fun onApplyWindowInsets(insets: WindowInsets): WindowInsets {
    val childCount = childCount
    for (index in 0 until childCount)
      getChildAt(index).dispatchApplyWindowInsets(insets)
    return insets
  }*/
}