add doc changes

firebase-common/src/jsMain/kotlin/dev/gitlive/firebase/externals.kt

@@ -361,10 +361,18 @@ external object firebase {
 
         open class QuerySnapshot {
             val docs: Array<DocumentSnapshot>
+            fun docChanges(): Array<DocumentChange>
             val empty: Boolean
             val metadata: SnapshotMetadata
         }
 
+        open class DocumentChange {
+            val doc: DocumentSnapshot
+            val newIndex: Int
+            val oldIndex: Int
+            val type: String
+        }
+
         open class DocumentSnapshot {
             val id: String
             val ref: DocumentReference

firebase-firestore/src/androidMain/kotlin/dev/gitlive/firebase/firestore/firestore.kt

@@ -338,6 +338,7 @@ actual open class Query(open val android: com.google.firebase.firestore.Query) {
 }
 
 actual typealias Direction = com.google.firebase.firestore.Query.Direction
+actual typealias ChangeType = com.google.firebase.firestore.DocumentChange.Type
 
 actual class CollectionReference(override val android: com.google.firebase.firestore.CollectionReference) : Query(android) {
 
@@ -364,9 +365,22 @@ actual typealias FirestoreExceptionCode = com.google.firebase.firestore.Firebase
 actual class QuerySnapshot(val android: com.google.firebase.firestore.QuerySnapshot) {
     actual val documents
         get() = android.documents.map { DocumentSnapshot(it) }
+    actual val documentChanges
+        get() = android.documentChanges.map { DocumentChange(it) }
     actual val metadata: SnapshotMetadata get() = SnapshotMetadata(android.metadata)
 }
 
+actual class DocumentChange(val android: com.google.firebase.firestore.DocumentChange) {
+    actual val document: DocumentSnapshot
+        get() = DocumentSnapshot(android.document)
+    actual val newIndex: Int
+        get() = android.newIndex
+    actual val oldIndex: Int
+        get() = android.oldIndex
+    actual val type: ChangeType
+        get() = android.type
+}
+
 @Suppress("UNCHECKED_CAST")
 actual class DocumentSnapshot(val android: com.google.firebase.firestore.DocumentSnapshot) {
 

firebase-firestore/src/commonMain/kotlin/dev/gitlive/firebase/firestore/firestore.kt

@@ -164,9 +164,23 @@ expect enum class Direction {
 
 expect class QuerySnapshot {
     val documents: List<DocumentSnapshot>
+    val documentChanges: List<DocumentChange>
     val metadata: SnapshotMetadata
 }
 
+expect enum class ChangeType {
+    ADDED ,
+    MODIFIED,
+    REMOVED
+}
+
+expect class DocumentChange {
+    val document: DocumentSnapshot
+    val newIndex: Int
+    val oldIndex: Int
+    val type: ChangeType
+}
+
 expect class DocumentSnapshot {
 
     inline fun <reified T> get(field: String): T

firebase-firestore/src/iosMain/kotlin/dev/gitlive/firebase/firestore/firestore.kt

@@ -5,6 +5,7 @@
 package dev.gitlive.firebase.firestore
 
 import cocoapods.FirebaseFirestore.*
+import cocoapods.FirebaseFirestore.FIRDocumentChangeType.*
 import dev.gitlive.firebase.*
 import kotlinx.cinterop.*
 import kotlinx.coroutines.CompletableDeferred
@@ -288,6 +289,12 @@ actual enum class Direction {
     DESCENDING
 }
 
+actual enum class ChangeType(internal val ios: FIRDocumentChangeType) {
+    ADDED(FIRDocumentChangeTypeAdded),
+    MODIFIED(FIRDocumentChangeTypeModified),
+    REMOVED(FIRDocumentChangeTypeRemoved)
+}
+
 fun NSError.toException() = when(domain) {
     FIRFirestoreErrorDomain -> when(code) {
         FIRFirestoreErrorCodeOK -> FirestoreExceptionCode.OK
@@ -315,9 +322,22 @@ fun NSError.toException() = when(domain) {
 actual class QuerySnapshot(val ios: FIRQuerySnapshot) {
     actual val documents
         get() = ios.documents.map { DocumentSnapshot(it as FIRDocumentSnapshot) }
+    actual val documentChanges
+        get() = ios.documentChanges.map { DocumentChange(it as FIRDocumentChange) }
     actual val metadata: SnapshotMetadata get() = SnapshotMetadata(ios.metadata)
 }
 
+actual class DocumentChange(val ios: FIRDocumentChange) {
+    actual val document: DocumentSnapshot
+        get() = DocumentSnapshot(ios.document)
+    actual val newIndex: Int
+        get() = ios.newIndex.toInt()
+    actual val oldIndex: Int
+        get() = ios.oldIndex.toInt()
+    actual val type: ChangeType
+        get() = ChangeType.values().first { it.ios == ios.type }
+}
+
 @Suppress("UNCHECKED_CAST")
 actual class DocumentSnapshot(val ios: FIRDocumentSnapshot) {
 

firebase-firestore/src/jsMain/kotlin/dev/gitlive/firebase/firestore/firestore.kt

@@ -344,9 +344,22 @@ actual val FirebaseFirestoreException.code: FirestoreExceptionCode get() = code
 actual class QuerySnapshot(val js: firebase.firestore.QuerySnapshot) {
     actual val documents
         get() = js.docs.map { DocumentSnapshot(it) }
+    actual val documentChanges
+        get() = js.docChanges().map { DocumentChange(it) }
     actual val metadata: SnapshotMetadata get() = SnapshotMetadata(js.metadata)
 }
 
+actual class DocumentChange(val js: firebase.firestore.DocumentChange) {
+    actual val document: DocumentSnapshot
+        get() = DocumentSnapshot(js.doc)
+    actual val newIndex: Int
+        get() = js.newIndex
+    actual val oldIndex: Int
+        get() = js.oldIndex
+    actual val type: ChangeType
+        get() = ChangeType.values().first { it.jsString == js.type }
+}
+
 actual class DocumentSnapshot(val js: firebase.firestore.DocumentSnapshot) {
 
     actual val id get() = rethrow { js.id }
@@ -423,6 +436,12 @@ actual enum class Direction(internal val jsString : String) {
     DESCENDING("desc");
 }
 
+actual enum class ChangeType(internal val jsString : String) {
+    ADDED("added"),
+    MODIFIED("modified"),
+    REMOVED("removed");
+}
+
 inline fun <T, R> T.rethrow(function: T.() -> R): R = dev.gitlive.firebase.firestore.rethrow { function() }
 
 inline fun <R> rethrow(function: () -> R): R {