Find nick from source; fix #1137

mirai-core/src/commonMain/kotlin/message/atImpl.kt

@@ -14,12 +14,40 @@ import kotlinx.io.core.readBytes
 import net.mamoe.mirai.contact.Group
 import net.mamoe.mirai.contact.nameCardOrNick
 import net.mamoe.mirai.internal.network.protocol.data.proto.ImMsgBody
-import net.mamoe.mirai.message.data.At
-import net.mamoe.mirai.message.data.AtAll
+import net.mamoe.mirai.message.data.*
+import net.mamoe.mirai.utils.safeCast
 
 
-internal fun At.toJceData(group: Group?): ImMsgBody.Text {
-    val text = "@${group?.members?.get(this.target)?.nameCardOrNick ?: target}"
+internal fun At.toJceData(
+    group: Group?,
+    source: MessageSource?,
+    isForward: Boolean,
+): ImMsgBody.Text {
+    fun findFromGroup(g: Group?): String? {
+        return g?.members?.get(this.target)?.nameCardOrNick
+    }
+
+    fun findFromSource(): String? {
+        return when (source) {
+            is OnlineMessageSource -> {
+                return findFromGroup(source.target.safeCast())
+            }
+            is OfflineMessageSource -> {
+                if (source.kind == MessageSourceKind.GROUP) {
+                    return findFromGroup(group?.bot?.getGroup(source.targetId))
+                } else null
+            }
+            else -> null
+        }
+    }
+
+    val text = "@${
+        if (isForward) {
+            findFromSource() ?: findFromGroup(group)
+        } else {
+            findFromGroup(group) ?: findFromSource()
+        } ?: target
+    }"
     return ImMsgBody.Text(
         str = text,
         attr6Buf = buildPacket {

mirai-core/src/commonMain/kotlin/message/messageToElems.kt

@@ -34,7 +34,8 @@ internal val UNSUPPORTED_VOICE_MESSAGE_PLAIN = PlainText("收到语音消息，
 @Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
 internal fun MessageChain.toRichTextElems(
     messageTarget: ContactOrBot?,
-    withGeneralFlags: Boolean
+    withGeneralFlags: Boolean,
+    isForward: Boolean = false,
 ): MutableList<ImMsgBody.Elem> {
     val forGroup = messageTarget is Group
     val elements = ArrayList<ImMsgBody.Elem>(this.size)
@@ -114,7 +115,15 @@ internal fun MessageChain.toRichTextElems(
                 )
             }
             is At -> {
-                elements.add(ImMsgBody.Elem(text = currentMessage.toJceData(messageTarget.safeCast())))
+                elements.add(
+                    ImMsgBody.Elem(
+                        text = currentMessage.toJceData(
+                            messageTarget.safeCast(),
+                            this[MessageSource],
+                            isForward,
+                        )
+                    )
+                )
                 // elements.add(ImMsgBody.Elem(text = ImMsgBody.Text(str = " ")))
                 // removed by https://github.com/mamoe/mirai/issues/524
                 // 发送 QuoteReply 消息时无可避免的产生多余空格 #524

mirai-core/src/commonMain/kotlin/network/protocol/packet/chat/MultiMsg.kt

@@ -86,7 +86,11 @@ internal fun Collection<ForwardMessage.INode>.calculateValidationData(
             msgBody = ImMsgBody.MsgBody(
                 richText = ImMsgBody.RichText(
                     elems = chain.messageChain.toMessageChain()
-                        .toRichTextElems(handler.contact, withGeneralFlags = false).toMutableList()
+                        .toRichTextElems(
+                            handler.contact,
+                            withGeneralFlags = false,
+                            isForward = true,
+                        ).toMutableList()
                 )
             )
         )