1 files changed, 36 insertions, 0 deletions
diff --git a/Hotline/Library/Extensions.swift b/Hotline/Library/Extensions.swift
index 469676c..b6a4b68 100644
--- a/Hotline/Library/Extensions.swift
+++ b/Hotline/Library/Extensions.swift
@@ -22,6 +22,42 @@ extension Data {
     }
     return false
   }
+  
+  enum ImageFormat {
+    case gif
+    case jpeg
+    case png
+    case webp
+    case unknown
+  }
+  
+  var detectedImageFormat: ImageFormat {
+    guard self.count >= 12 else { return .unknown }
+    
+    let bytes = [UInt8](self.prefix(12))
+    
+    // GIF: "GIF8"
+    if bytes[0] == 0x47 && bytes[1] == 0x49 && bytes[2] == 0x46 && bytes[3] == 0x38 {
+      return .gif
+    }
+    
+    // JPEG: FF D8 FF
+    if bytes[0] == 0xFF && bytes[1] == 0xD8 && bytes[2] == 0xFF {
+      return .jpeg
+    }
+    
+    // PNG: 89 50 4E 47 0D 0A 1A 0A
+    if bytes[0] == 0x89 && bytes[1] == 0x50 && bytes[2] == 0x4E && bytes[3] == 0x47 && bytes[4] == 0x0D && bytes[5] == 0x0A && bytes[6] == 0x1A && bytes[7] == 0x0A {
+      return .png
+    }
+    
+    // WebP: "RIFF" at 0-3 and "WEBP" at 8-11
+    if bytes[0] == 0x52 && bytes[1] == 0x49 && bytes[2] == 0x46 && bytes[3] == 0x46 && bytes[8] == 0x57 && bytes[9] == 0x45 && bytes[10] == 0x42 && bytes[11] == 0x50 {
+      return .webp
+    }
+    
+    return .unknown
+  }
 }
 
 // MARK: -