Return updated cap when deleting image

Sources/App/CapServer+Routes.swift

@@ -4,6 +4,8 @@ import Foundation
 /// The decoder to extract caps from JSON payloads given to the `cap` route.
 private let decoder = JSONDecoder()
 
+private let encoder = JSONEncoder()
+
 /// The date formatter to decode dates in requests
 private let dateFormatter: DateFormatter = {
     let df = DateFormatter()
@@ -113,9 +115,10 @@ extension CapServer {
 
             try self.ensureOperability()
             try authenticator.authorize(request)
-            guard self.deleteImage(version: version, for: cap) else {
+            guard let cap = self.deleteImage(version: version, for: cap) else {
                 throw Abort(.gone)
             }
+            return try encoder.encode(cap)
         }
     }
 }

Sources/App/CapServer.swift

@@ -221,6 +221,12 @@ final class CapServer {
         }
     }
     
+    /**
+     Rearrange images of a cap to ensure that an image exists for each number from 0 to `image count - 1`.
+     This is done by using the last images to fill in possible gaps in the sequence.
+     E.g. If there are images `0`, `2`, `3`, then `3` will be renamed to `1`.
+     - Note: The main image is also changed, if the main image is renamed.
+     */
     private func organizeImages(for cap: Cap) {
         var cap = cap
         let folderUrl = folder(of: cap.id)
@@ -268,7 +274,14 @@ final class CapServer {
             }
             sorted.insert((version, newUrl), at: version)
         }
+
         cap.count = sorted.count
+
+        // Fix invalid main image
+        if cap.mainImage >= cap.count || cap.mainImage < 0 {
+            cap.mainImage = 0
+        }
+
         caps[cap.id] = cap
     }
 
@@ -478,18 +491,18 @@ final class CapServer {
         log("Updated cap \(existingCap.id)")
     }
     
-    func deleteImage(version: Int, for capId: Int) -> Bool {
+    func deleteImage(version: Int, for capId: Int) -> Cap? {
         guard let cap = caps[capId] else {
             log("Attempting to delete image \(version) of unknown cap \(capId)")
-            return false
+            return nil
         }
         let capImageUrl = imageUrl(of: capId, version: version)
         guard exists(capImageUrl) else {
             log("Attempting to delete missing image \(version) of cap \(capId)")
-            return false
+            return nil
         }
         organizeImages(for: cap)
-        return true
+        return caps[capId]!
     }
     
     // MARK: Classifier