///

app/src/main/kotlin/bums/lunatic/launcher/utils/CommonUtils.kt

@@ -12,6 +12,8 @@ import kotlinx.coroutines.withContext
 import okhttp3.OkHttpClient
 import okhttp3.Request
 import java.io.File
+import java.net.URLConnection
+import java.util.regex.Pattern
 
 object CommonUtils {
     fun dpToPx(context: Context, dp: Float): Int {
@@ -27,48 +29,90 @@ object CommonUtils {
         return Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP
     }
 
-    fun getFileTypeBySignature(file: File): String? {
-        val buffer = ByteArray(12)  // 동영상 포맷 확인용으로 충분히 크게 버퍼 확장
-        file.inputStream().use { it.read(buffer, 0, buffer.size) }
 
-        // GIF
+
-        if (buffer.sliceArray(0..5).contentEquals("GIF87a".toByteArray()) ||
+    fun getFileTypeBySignature(file: File): String? {
-            buffer.sliceArray(0..5).contentEquals("GIF89a".toByteArray())) {
+        val buffer = ByteArray(12)
+        val readBytes = file.inputStream().use { it.read(buffer, 0, buffer.size) }
+
+        // 1. 시그니처 검사 (기존 방식)
+        if (readBytes >= 6) {
+            val gifSignature1 = "GIF87a".toByteArray(Charsets.US_ASCII)
+            val gifSignature2 = "GIF89a".toByteArray(Charsets.US_ASCII)
+            if (buffer.copyOfRange(0, 6).contentEquals(gifSignature1)
+                || buffer.copyOfRange(0, 6).contentEquals(gifSignature2)
+            ) {
                 return "gif"
             }
-        // JPEG
+        }
-        if (buffer[0] == 0xFF.toByte() && buffer[1] == 0xD8.toByte() && buffer[2] == 0xFF.toByte()) {
+
+        if (readBytes >= 3 &&
+            buffer[0] == 0xFF.toByte() && buffer[1] == 0xD8.toByte() && buffer[2] == 0xFF.toByte()
+        ) {
             return "jpg"
         }
-        // PNG
+
-        if (buffer.sliceArray(0..7).contentEquals(byteArrayOf(0x89.toByte(),'P'.toByte(),'N'.toByte(),'G'.toByte(),0x0D,0x0A,0x1A,0x0A))) {
+        if (readBytes >= 8 &&
+            buffer.copyOfRange(0, 8).contentEquals(
+                byteArrayOf(
+                    0x89.toByte(), 'P'.toByte(), 'N'.toByte(), 'G'.toByte(),
+                    0x0D, 0x0A, 0x1A, 0x0A
+                )
+            )
+        ) {
             return "png"
         }
 
-        // MP4 (ftyp... 브랜드 체크, 보통 4~8바이트 확인)
+        if (readBytes >= 12 &&
-        // "ftyp"는 4바이트 offset 4 ~ 7에 위치
+            buffer.copyOfRange(4, 8).contentEquals("ftyp".toByteArray(Charsets.US_ASCII))
-        if (buffer.size >= 12 && buffer.sliceArray(4..7).contentEquals("ftyp".toByteArray())) {
+        ) {
             return "mp4"
         }
 
-        // AVI (큰 헤더 "RIFF....AVI ")
+        if (readBytes >= 12 &&
-        if (buffer.size >= 12 &&
+            buffer.copyOfRange(0, 4).contentEquals("RIFF".toByteArray(Charsets.US_ASCII)) &&
-            buffer.sliceArray(0..3).contentEquals("RIFF".toByteArray()) &&
+            buffer.copyOfRange(8, 12).contentEquals("AVI ".toByteArray(Charsets.US_ASCII))
-            buffer.sliceArray(8..11).contentEquals("AVI ".toByteArray())) {
+        ) {
             return "avi"
         }
 
-        // MKV (Matroska) - EBML 헤더: 0x1A 0x45 0xDF 0xA3
+        if (readBytes >= 4 &&
-        if (buffer.size >= 4 &&
+            buffer[0] == 0x1A.toByte() &&
-            buffer[0] == 0x1A.toByte() && buffer[1] == 0x45.toByte() &&
+            buffer[1] == 0x45.toByte() &&
-            buffer[2] == 0xDF.toByte() && buffer[3] == 0xA3.toByte()) {
+            buffer[2] == 0xDF.toByte() &&
+            buffer[3] == 0xA3.toByte()
+        ) {
             return "mkv"
         }
 
+        // 2. MIME 타입 검사 (Optional, 정확도 향상)
+        val mimeType = URLConnection.guessContentTypeFromStream(file.inputStream())
+        if (mimeType != null) {
+            when {
+                mimeType.equals("image/gif", ignoreCase = true) -> return "gif"
+                mimeType.equals("image/jpeg", ignoreCase = true) -> return "jpg"
+                mimeType.equals("image/png", ignoreCase = true) -> return "png"
+                mimeType.startsWith("video/mp4", ignoreCase = true) -> return "mp4"
+                mimeType.startsWith("video/x-msvideo", ignoreCase = true) -> return "avi"
+                mimeType.startsWith("video/x-matroska", ignoreCase = true) -> return "mkv"
+            }
+        }
+
+        // 3. 정규식 기반 시그니처 검사 (GIF 전용 예)
+        if (readBytes >= 6) {
+            val sigStr = String(buffer, 0, 6, Charsets.US_ASCII)
+            val gifPattern = Pattern.compile("GIF8[79]a")
+            if (gifPattern.matcher(sigStr).matches()) {
+                return "gif"
+            }
+        }
+
         return null
     }
 
 
+
+
     fun downloadFileWithOkHttp(context: Context,refferer : Uri,  fileUrl: String) {
         android.app.AlertDialog.Builder(context)
             .setTitle("파일 다운로드")
@@ -95,15 +139,12 @@ object CommonUtils {
                                 ).show()
                             }
                         } else {
-
-
                             // Content-Type에서 확장자 추출
                             val contentType = response.header("Content-Type")
                             Blog.LOGE("downloadFileWithOkHttp contentType $contentType")
                             var extension = contentType?.let {
                                 MimeTypeMap.getSingleton().getExtensionFromMimeType(it)
                             }
-
                             // 확장자 없으면 URL에서 추출하거나 기본값 "dat" 사용
                             if (extension.isNullOrBlank()) {
                                 extension = MimeTypeMap.getFileExtensionFromUrl(fileUrl)
@@ -112,9 +153,6 @@ object CommonUtils {
                                 }
                             }
                             Blog.LOGE("downloadFileWithOkHttp extension $extension")
-//                if (extension.equals("bin")){
-////                    extension = "jpg"
-//                }
                             val fileName =
                                 "${
                                     refferer.host?.replace(
@@ -133,6 +171,7 @@ object CommonUtils {
 
                             val resultFile = if (extension in listOf("bin", "dat")) {
                                 val realExt = getFileTypeBySignature(file)
+                                Blog.LOGE("downloadFileWithOkHttp extension $realExt")
                                 when {
                                     realExt.isNullOrBlank() -> file
                                     realExt == extension -> file
@@ -142,7 +181,7 @@ object CommonUtils {
                                                 ",",
                                                 "_"
                                             )
-                                        }_${System.currentTimeMillis()}.$extension")
+                                        }_${System.currentTimeMillis()}.$realExt")
                                         if (file.renameTo(newFile)) newFile else file
                                     }
                                 }