feat: support gif reverse and fix get image bug

src/main/kotlin/cn/rtast/fancybot/commands/misc/ReverseGIFCommand.kt

@@ -0,0 +1,49 @@
+/*
+ * Copyright © 2024 RTAkland
+ * Author: RTAkland
+ * Date: 2024/9/8
+ */
+
+
+package cn.rtast.fancybot.commands.misc
+
+import cn.rtast.fancybot.util.str.encodeToBase64
+import cn.rtast.rob.entity.GetMessage
+import cn.rtast.rob.enums.ArrayMessageType
+import cn.rtast.rob.util.ob.MessageChain
+import cn.rtast.rob.util.ob.OBMessage
+import com.madgag.gif.fmsware.AnimatedGifEncoder
+import com.madgag.gif.fmsware.GifDecoder
+import java.io.ByteArrayOutputStream
+import java.net.URI
+
+object ReverseGIFCommand {
+
+    private fun reverseGif(gifUrl: String): String {
+        val gifStream = URI(gifUrl).toURL().openStream()
+        val decoder = GifDecoder()
+        decoder.read(gifStream)
+        val frames = (0 until decoder.frameCount).map { decoder.getFrame(it) }.reversed()
+        val byteArrayOutputStream = ByteArrayOutputStream()
+        val encoder = AnimatedGifEncoder()
+        encoder.start(byteArrayOutputStream)
+        encoder.setRepeat(0)
+        for (i in frames.indices) {
+            encoder.setDelay(decoder.getDelay(decoder.frameCount - i - 1))
+            encoder.addFrame(frames[i])
+        }
+        encoder.finish()
+        val gifBytes = byteArrayOutputStream.toByteArray()
+        return gifBytes.encodeToBase64()
+    }
+
+    suspend fun callback(listener: OBMessage, message: GetMessage) {
+        val gifUrl = message.data.message.find { it.type == ArrayMessageType.mface }!!.data.url!!
+        val base64String = this.reverseGif(gifUrl)
+        val msg = MessageChain.Builder()
+            .addReply(message.data.messageId)
+            .addImage(base64String, true)
+            .build()
+        listener.sendGroupMessage(message.data.groupId!!, msg)
+    }
+}