feat: add query mc skin command

src/main/kotlin/cn/rtast/fancybot/commands/lookup/MCSkinCommand.kt

@@ -0,0 +1,89 @@
+/*
+ * Copyright © 2024 RTAkland
+ * Author: RTAkland
+ * Date: 2024/10/2
+ */
+
+
+package cn.rtast.fancybot.commands.lookup
+
+import cn.rtast.fancybot.entity.mc.DecodedSkin
+import cn.rtast.fancybot.entity.mc.Skin
+import cn.rtast.fancybot.entity.mc.Username
+import cn.rtast.fancybot.util.Http
+import cn.rtast.fancybot.util.isFullyTransparent
+import cn.rtast.fancybot.util.scaleImage
+import cn.rtast.fancybot.util.str.decodeToString
+import cn.rtast.fancybot.util.str.encodeToBase64
+import cn.rtast.fancybot.util.str.fromJson
+import cn.rtast.fancybot.util.toByteArray
+import cn.rtast.rob.entity.GroupMessage
+import cn.rtast.rob.util.BaseCommand
+import cn.rtast.rob.util.ob.MessageChain
+import cn.rtast.rob.util.ob.OneBotListener
+import java.awt.AlphaComposite
+import java.awt.image.BufferedImage
+import java.net.URI
+import javax.imageio.ImageIO
+
+class MCSkinCommand : BaseCommand() {
+    override val commandNames = listOf("/skin")
+
+    private val uuidQueryUrl = "https://api.mojang.com/users/profiles/minecraft"
+    private val skinUrl = "https://sessionserver.mojang.com/session/minecraft/profile"
+
+    private fun String.isUsername(): Boolean {
+        val usernamePattern = Regex("^[a-zA-Z][a-zA-Z0-9_]{2,15}$")
+        return usernamePattern.matches(this)
+    }
+
+    /**
+     * 截取整张皮肤中的头部部分, 如果是单层皮肤则直接截取脸部
+     * 如果是双层皮肤也就将脸部作为背景图层, 将头发绘制在脸部上
+     * 代码来自`YeeeesMOTD`
+     * `https://github.com/RTAkland/YeeeesMOTD/blob/main/core/src/main/kotlin/cn/rtast/yeeeesmotd/utils/ImageUtil.kt`
+     */
+    private fun getSkinHead(skinUrl: String): String {
+        val url = URI(skinUrl).toURL()
+        val image = ImageIO.read(url)
+        var subImage = image.getSubimage(8, 8, 8, 8)
+
+        if (subImage.isFullyTransparent()) {
+            subImage = image.getSubimage(40, 8, 8, 8)
+        } else {
+            val hairLayer = image.getSubimage(40, 8, 8, 8)
+            val combined = BufferedImage(subImage.width, subImage.height, BufferedImage.TYPE_INT_ARGB)
+            val g2d = combined.createGraphics()
+            g2d.drawImage(subImage, 0, 0, null)
+            g2d.composite = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1.0f)
+            g2d.drawImage(hairLayer, 0, 0, null)
+            g2d.dispose()
+            subImage = combined
+        }
+        val zoom = subImage.scaleImage(128 to 128)
+        return zoom.toByteArray().encodeToBase64()
+    }
+
+    override suspend fun executeGroup(listener: OneBotListener, message: GroupMessage, args: List<String>) {
+        if (args.isEmpty()) {
+            message.reply("发送`/skin <uuid/游戏名称>`即可查询他的皮肤~ (仅限Java版)")
+            return
+        }
+        try {
+            val nameOrUUID = args.first().trim()
+            val uuid = if (nameOrUUID.isUsername()) Http.get<Username>("$uuidQueryUrl/$nameOrUUID").id
+            else nameOrUUID
+            val skinUrl = Http.get<Skin>("$skinUrl/$uuid")
+                .properties.first().value.decodeToString().fromJson<DecodedSkin>()
+                .textures.skin.url
+            val headBase64 = this.getSkinHead(skinUrl)
+            val msg = MessageChain.Builder()
+                .addImage(headBase64, true)
+                .addText(skinUrl)
+                .build()
+            message.reply(msg)
+        } catch (_: Exception) {
+            message.reply("输入错误, 检查一下是否输入正确吧~")
+        }
+    }
+}