package io.sentry.android.replay.viewhierarchy

import android.annotation.SuppressLint
import android.annotation.TargetApi
import android.graphics.Rect
import android.view.SurfaceView
import android.view.View
import android.view.ViewParent
import android.widget.ImageView
import android.widget.TextView
import io.sentry.SentryMaskingOptions
import io.sentry.android.replay.R
import io.sentry.android.replay.util.AndroidTextLayout
import io.sentry.android.replay.util.TextLayout
import io.sentry.android.replay.util.isMaskable
import io.sentry.android.replay.util.isVisibleToUser
import io.sentry.android.replay.util.toOpaque
import io.sentry.android.replay.util.totalPaddingTopSafe
import java.lang.ref.WeakReference

@SuppressLint("UseRequiresApi")
@TargetApi(26)
internal sealed class ViewHierarchyNode(
  val x: Float,
  val y: Float,
  val width: Int,
  val height: Int,
  // Elevation (in px)
  val elevation: Float,
  // Distance to the parent (index)
  val distance: Int,
  val parent: ViewHierarchyNode? = null,
  val shouldMask: Boolean = false,
  // Whether the node is important for content capture (=non-empty container)
  var isImportantForContentCapture: Boolean = false,
  val isVisible: Boolean = false,
  val visibleRect: Rect? = null,
) {
  var children: List<ViewHierarchyNode>? = null

  class GenericViewHierarchyNode(
    x: Float,
    y: Float,
    width: Int,
    height: Int,
    elevation: Float,
    distance: Int,
    parent: ViewHierarchyNode? = null,
    shouldMask: Boolean = false,
    isImportantForContentCapture: Boolean = false,
    isVisible: Boolean = false,
    visibleRect: Rect? = null,
  ) :
    ViewHierarchyNode(
      x,
      y,
      width,
      height,
      elevation,
      distance,
      parent,
      shouldMask,
      isImportantForContentCapture,
      isVisible,
      visibleRect,
    )

  class TextViewHierarchyNode(
    val layout: TextLayout? = null,
    val dominantColor: Int? = null,
    val paddingLeft: Int = 0,
    val paddingTop: Int = 0,
    x: Float,
    y: Float,
    width: Int,
    height: Int,
    elevation: Float,
    distance: Int,
    parent: ViewHierarchyNode? = null,
    shouldMask: Boolean = false,
    isImportantForContentCapture: Boolean = false,
    isVisible: Boolean = false,
    visibleRect: Rect? = null,
  ) :
    ViewHierarchyNode(
      x,
      y,
      width,
      height,
      elevation,
      distance,
      parent,
      shouldMask,
      isImportantForContentCapture,
      isVisible,
      visibleRect,
    )

  class ImageViewHierarchyNode(
    x: Float,
    y: Float,
    width: Int,
    height: Int,
    elevation: Float,
    distance: Int,
    parent: ViewHierarchyNode? = null,
    shouldMask: Boolean = false,
    isImportantForContentCapture: Boolean = false,
    isVisible: Boolean = false,
    visibleRect: Rect? = null,
  ) :
    ViewHierarchyNode(
      x,
      y,
      width,
      height,
      elevation,
      distance,
      parent,
      shouldMask,
      isImportantForContentCapture,
      isVisible,
      visibleRect,
    )

  class SurfaceViewHierarchyNode(
    val surfaceViewRef: WeakReference<SurfaceView>,
    x: Float,
    y: Float,
    width: Int,
    height: Int,
    elevation: Float,
    distance: Int,
    parent: ViewHierarchyNode? = null,
    shouldMask: Boolean = false,
    isImportantForContentCapture: Boolean = false,
    isVisible: Boolean = false,
    visibleRect: Rect? = null,
  ) :
    ViewHierarchyNode(
      x,
      y,
      width,
      height,
      elevation,
      distance,
      parent,
      shouldMask,
      isImportantForContentCapture,
      isVisible,
      visibleRect,
    )

  /**
   * Basically replicating this:
   * https://developer.android.com/reference/android/view/View#isImportantForContentCapture() but
   * for lower APIs and with less overhead. If we take a look at how it's set in Android:
   * https://cs.android.com/search?q=IMPORTANT_FOR_CONTENT_CAPTURE_YES&ss=android%2Fplatform%2Fsuperproject%2Fmain
   * we see that they just set it as important for views containing TextViews, ImageViews and
   * WebViews.
   */
  fun setImportantForCaptureToAncestors(isImportant: Boolean) {
    var parent = this.parent
    while (parent != null) {
      parent.isImportantForContentCapture = isImportant
      parent = parent.parent
    }
  }

  /**
   * Traverses the view hierarchy starting from this node. The traversal is done in a depth-first
   * manner.
   *
   * @param callback a callback that will be called for each node in the hierarchy. If the callback
   *   returns false, the traversal will stop for the current node and its children.
   */
  fun traverse(callback: (ViewHierarchyNode) -> Boolean) {
    val traverseChildren = callback(this)
    if (traverseChildren) {
      if (this.children != null) {
        this.children!!.forEach { it.traverse(callback) }
      }
    }
  }

  /**
   * Checks if the given node is obscured by other nodes in the view hierarchy. A node is considered
   * obscured if it's not visible, or if it's not fully visible because it's behind another node
   * with a higher elevation or distance from the common parent.
   *
   * This method should be called on the root node of the view hierarchy.
   *
   * @param node the node to check if it's obscured by other nodes in the view hierarchy
   */
  fun isObscured(node: ViewHierarchyNode): Boolean {
    require(this.parent == null) {
      "This method should be called on the root node of the view hierarchy."
    }
    node.visibleRect ?: return false

    var isObscured = false

    traverse { otherNode ->
      // if the other node doesn't have a visible rect or the current node is already obscured
      // we can skip the traversal
      if (otherNode.visibleRect == null || isObscured) {
        return@traverse false
      }

      // if the other node is not visible, or not important for content capture (empty container)
      // or doesn't contain the node's visible rect, we can skip it
      if (
        !otherNode.isVisible ||
          !otherNode.isImportantForContentCapture ||
          !otherNode.visibleRect.contains(node.visibleRect)
      ) {
        return@traverse false
      }

      // if otherNode's elevation is higher, we know it's obscuring the node
      if (otherNode.elevation > node.elevation) {
        isObscured = true
        return@traverse false
      } else if (otherNode.elevation == node.elevation) {
        // if otherNode's elevation is the same, we need to find the lowest common ancestor
        // and compare the distances from the common parent
        val (lca, nodeAncestor, otherNodeAncestor) = findLCA(node, otherNode)
        // if otherNode is the LCA, this means it's a parent of the node, so it's not obscuring it
        // otherwise compare the distances from the common parent
        if (lca != otherNode && otherNodeAncestor != null && nodeAncestor != null) {
          isObscured = otherNodeAncestor.distance > nodeAncestor.distance
          return@traverse !isObscured
        }
      }
      return@traverse true
    }
    return isObscured
  }

  /**
   * Find the lowest common ancestor of two nodes in the view hierarchy. Given the following view
   * hierarchy:
   *
   * CoordinatorLayout -FrameLayout --TextView -BottomNavigationView --NavigationItemView
   * --NavigationItemView
   *
   * We want to know if the TextView is obscured by anything. For that we're searching for the
   * lowest common ancestor (common parent) of the TextView and the other node. In this case it'd be
   * CoordinatorLayout.
   *
   * After that we also need to know which subtrees contain both the TextView and the obscuring
   * node. In this case it'd be FrameLayout and BottomNavigationView. Once we have the subtrees, we
   * can compare their distances (indexes) from the common parent. In this case BottomNavigationView
   * will have a higher index than FrameLayout, so we can conclude that it obscures the TextView.
   *
   * This method should be called on the root node of the view hierarchy.
   */
  private fun findLCA(node: ViewHierarchyNode, otherNode: ViewHierarchyNode): LCAResult {
    var nodeSubtree: ViewHierarchyNode? = null
    var otherNodeSubtree: ViewHierarchyNode? = null
    var lca: ViewHierarchyNode? = null

    // Check if the current node is node or otherNode
    if (this == node) {
      nodeSubtree = this
    }
    if (this == otherNode) {
      otherNodeSubtree = this
    }

    // Search for nodes node and otherNode in the children subtrees
    if (children != null) {
      for (child in children!!) {
        val result = child.findLCA(node, otherNode)

        if (result.lca != null) {
          return result // If LCA is found, propagate it up
        }
        if (result.nodeSubtree != null) {
          nodeSubtree = child
        }
        if (result.otherNodeSubtree != null) {
          otherNodeSubtree = child
        }
      }
    }

    // If both node and otherNode are found, and LCA is not already determined, the current node
    // is the LCA
    if (nodeSubtree != null && otherNodeSubtree != null) {
      lca = this
    }

    return LCAResult(lca, nodeSubtree, otherNodeSubtree)
  }

  private data class LCAResult(
    val lca: ViewHierarchyNode?,
    var nodeSubtree: ViewHierarchyNode?,
    var otherNodeSubtree: ViewHierarchyNode?,
  )

  companion object {
    private const val SENTRY_UNMASK_TAG = "sentry-unmask"
    private const val SENTRY_MASK_TAG = "sentry-mask"

    private fun Class<*>.isAssignableFrom(set: Set<String>): Boolean {
      var cls: Class<*>? = this
      while (cls != null) {
        val canonicalName = cls.name
        if (set.contains(canonicalName)) {
          return true
        }
        cls = cls.superclass
      }
      return false
    }

    private fun View.shouldMask(options: SentryMaskingOptions): Boolean {
      if (
        (tag as? String)?.lowercase()?.contains(SENTRY_UNMASK_TAG) == true ||
          getTag(R.id.sentry_privacy) == "unmask"
      ) {
        options.trackCustomMasking()
        return false
      }

      if (
        (tag as? String)?.lowercase()?.contains(SENTRY_MASK_TAG) == true ||
          getTag(R.id.sentry_privacy) == "mask"
      ) {
        options.trackCustomMasking()
        return true
      }

      if (
        !this.isMaskContainer(options) &&
          this.parent != null &&
          this.parent.isUnmaskContainer(options)
      ) {
        return false
      }

      if (this.javaClass.isAssignableFrom(options.unmaskViewClasses)) {
        return false
      }

      return this.javaClass.isAssignableFrom(options.maskViewClasses)
    }

    private fun ViewParent.isUnmaskContainer(options: SentryMaskingOptions): Boolean {
      val unmaskContainer = options.unmaskViewContainerClass ?: return false
      return this.javaClass.name == unmaskContainer
    }

    private fun View.isMaskContainer(options: SentryMaskingOptions): Boolean {
      val maskContainer = options.maskViewContainerClass ?: return false
      return this.javaClass.name == maskContainer
    }

    /**
     * Creates a ViewHierarchyNode from a View using SentryMaskingOptions directly. This allows for
     * reuse with both session replay and screenshot masking.
     */
    @JvmStatic
    fun fromView(
      view: View,
      parent: ViewHierarchyNode?,
      distance: Int,
      options: SentryMaskingOptions,
    ): ViewHierarchyNode {
      val (isVisible, visibleRect) = view.isVisibleToUser()
      val shouldMask = isVisible && view.shouldMask(options)
      when (view) {
        is TextView -> {
          parent?.setImportantForCaptureToAncestors(true)
          return TextViewHierarchyNode(
            layout = view.layout?.let { AndroidTextLayout(it) },
            dominantColor = view.currentTextColor.toOpaque(),
            paddingLeft = view.totalPaddingLeft,
            paddingTop = view.totalPaddingTopSafe,
            x = view.x,
            y = view.y,
            width = view.width,
            height = view.height,
            elevation = (parent?.elevation ?: 0f) + view.elevation,
            shouldMask = shouldMask,
            distance = distance,
            parent = parent,
            isImportantForContentCapture = true,
            isVisible = isVisible,
            visibleRect = visibleRect,
          )
        }

        is ImageView -> {
          parent?.setImportantForCaptureToAncestors(true)
          return ImageViewHierarchyNode(
            x = view.x,
            y = view.y,
            width = view.width,
            height = view.height,
            elevation = (parent?.elevation ?: 0f) + view.elevation,
            distance = distance,
            parent = parent,
            isVisible = isVisible,
            isImportantForContentCapture = true,
            shouldMask = shouldMask && view.drawable?.isMaskable() == true,
            visibleRect = visibleRect,
          )
        }

        is SurfaceView -> {
          parent?.setImportantForCaptureToAncestors(true)
          return SurfaceViewHierarchyNode(
            surfaceViewRef = WeakReference(view),
            x = view.x,
            y = view.y,
            width = view.width,
            height = view.height,
            elevation = (parent?.elevation ?: 0f) + view.elevation,
            distance = distance,
            parent = parent,
            shouldMask = shouldMask,
            isImportantForContentCapture = true,
            isVisible = isVisible,
            visibleRect = visibleRect,
          )
        }
      }

      return GenericViewHierarchyNode(
        view.x,
        view.y,
        view.width,
        view.height,
        (parent?.elevation ?: 0f) + view.elevation,
        distance = distance,
        parent = parent,
        shouldMask = shouldMask,
        isImportantForContentCapture = false, // will be set by children
        isVisible = isVisible,
        visibleRect = visibleRect,
      )
    }
  }
}
