Support animating shared elements on pop (#6385)

This PR introduces support to run shared element transition animations on stack pop.

lib/android/app/src/main/java/com/reactnativenavigation/options/AnimationOptions.kt

@@ -36,13 +36,11 @@ open class AnimationOptions(json: JSONObject?) {
         }
     }
 
-    @JvmField
-    var id: Text = NullText()
-    @JvmField
-    var enabled: Bool = NullBool()
-    @JvmField
-    var waitForRender: Bool = NullBool()
+    @JvmField var id: Text = NullText()
+    @JvmField var enabled: Bool = NullBool()
+    @JvmField var waitForRender: Bool = NullBool()
     private var valueOptions = HashSet<ValueAnimationOptions>()
+
     fun mergeWith(other: AnimationOptions) {
         if (other.id.hasValue()) id = other.id
         if (other.enabled.hasValue()) enabled = other.enabled

lib/android/app/src/main/java/com/reactnativenavigation/options/ElementTransitions.kt

@@ -5,8 +5,6 @@ import org.json.JSONObject
 
 class ElementTransitions {
     var transitions = arrayListOf<ElementTransitionOptions>()
-    val hasValue: Boolean
-        get() = transitions.isNotEmpty()
 
     companion object {
         fun parse(json: JSONObject): ElementTransitions {
@@ -25,10 +23,12 @@ class ElementTransitions {
     }
 
     fun mergeWith(other: ElementTransitions) {
-        if (other.hasValue) transitions = other.transitions
+        if (other.hasValue()) transitions = other.transitions
     }
 
     fun mergeWithDefault(defaultOptions: ElementTransitions) {
-        if (!hasValue) transitions = defaultOptions.transitions
+        if (!hasValue()) transitions = defaultOptions.transitions
     }
+
+    fun hasValue() = transitions.isNotEmpty()
 }

lib/android/app/src/main/java/com/reactnativenavigation/options/SharedElements.kt

@@ -0,0 +1,43 @@
+package com.reactnativenavigation.options
+
+import org.json.JSONException
+import org.json.JSONObject
+import java.util.*
+
+class SharedElements {
+    private var transitions: MutableList<SharedElementTransitionOptions> = ArrayList()
+    fun get(): List<SharedElementTransitionOptions> {
+        return transitions
+    }
+
+    fun hasValue() = transitions.isNotEmpty()
+
+    fun mergeWith(other: SharedElements) {
+        if (other.hasValue()) transitions = other.transitions
+    }
+
+    fun mergeWithDefault(defaultOptions: SharedElements) {
+        if (!hasValue()) transitions = defaultOptions.transitions
+    }
+
+    private fun add(transition: SharedElementTransitionOptions) {
+        transitions.add(transition)
+    }
+
+    companion object {
+        @JvmStatic
+        fun parse(json: JSONObject): SharedElements {
+            val result = SharedElements()
+            return try {
+                val sharedElements = json.getJSONArray("sharedElementTransitions")
+                if (sharedElements == null || sharedElements.length() == 0) return result
+                for (i in 0 until sharedElements.length()) {
+                    result.add(SharedElementTransitionOptions.parse(sharedElements.getJSONObject(i)))
+                }
+                result
+            } catch (e: JSONException) {
+                result
+            }
+        }
+    }
+}