[MBL-19385][All] Fix light mode button disappearing after rotation

libs/pandautils/src/main/java/com/instructure/pandautils/views/CanvasWebViewWrapper.kt

@@ -18,6 +18,9 @@ package com.instructure.pandautils.views
 
 import android.content.Context
 import android.content.res.Configuration
+import android.os.Bundle
+import android.os.Parcel
+import android.os.Parcelable
 import android.util.AttributeSet
 import android.view.LayoutInflater
 import android.widget.LinearLayout
@@ -137,6 +140,13 @@ open class CanvasWebViewWrapper @JvmOverloads constructor(
     }
 
     private fun initVisibility(html: String) {
+        updateButtonVisibility(html)
+        if (binding.themeSwitchButton.visibility == android.view.View.VISIBLE) {
+            changeButtonTheme()
+        }
+    }
+
+    private fun updateButtonVisibility(html: String) {
         val nightModeFlags: Int = context.resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_MASK
         if (nightModeFlags == Configuration.UI_MODE_NIGHT_YES && html.isNotEmpty()) {
             binding.themeSwitchButton.setVisible()
@@ -145,6 +155,57 @@ open class CanvasWebViewWrapper @JvmOverloads constructor(
         }
     }
 
+    override fun onConfigurationChanged(newConfig: Configuration?) {
+        super.onConfigurationChanged(newConfig)
+        html?.let { htmlContent ->
+            updateButtonVisibility(htmlContent)
+            if (binding.themeSwitchButton.visibility == android.view.View.VISIBLE) {
+                changeButtonTheme()
+                changeContentTheme(htmlContent)
+            }
+        }
+    }
+
+    override fun onSaveInstanceState(): Parcelable {
+        val superState = super.onSaveInstanceState()
+        return SavedState(superState).apply {
+            this.themeSwitched = this@CanvasWebViewWrapper.themeSwitched
+        }
+    }
+
+    override fun onRestoreInstanceState(state: Parcelable?) {
+        when (state) {
+            is SavedState -> {
+                super.onRestoreInstanceState(state.superState)
+                themeSwitched = state.themeSwitched
+            }
+            else -> super.onRestoreInstanceState(state)
+        }
+    }
+
+    private class SavedState : BaseSavedState {
+        var themeSwitched: Boolean = false
+
+        constructor(superState: Parcelable?) : super(superState)
+
+        private constructor(parcel: Parcel) : super(parcel) {
+            themeSwitched = parcel.readInt() == 1
+        }
+
+        override fun writeToParcel(out: Parcel, flags: Int) {
+            super.writeToParcel(out, flags)
+            out.writeInt(if (themeSwitched) 1 else 0)
+        }
+
+        companion object {
+            @JvmField
+            val CREATOR = object : Parcelable.Creator<SavedState> {
+                override fun createFromParcel(parcel: Parcel) = SavedState(parcel)
+                override fun newArray(size: Int): Array<SavedState?> = arrayOfNulls(size)
+            }
+        }
+    }
+
     private fun formatHtml(data: String): String {
         val textDarkest = colorResToHexString(if (themeSwitched) R.color.licorice else R.color.textDarkest)
         val textDark = colorResToHexString(if (themeSwitched) R.color.ash else R.color.textDark)