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Sources/App/CapServer.swift

@@ -22,6 +22,8 @@ final class CapServer: ServerOwner {
     
     private let fm = FileManager.default
     
+    private let changedImageEntryDateFormatter: DateFormatter
+    
     // MARK: Caps
 
     private var writers: Set<String>
@@ -77,6 +79,8 @@ final class CapServer: ServerOwner {
         self.classifierFile = folder.appendingPathComponent("classifier.mlmodel")
         self.changedImagesFile = folder.appendingPathComponent("changes.txt")
         self.writers = Set(writers)
+        self.changedImageEntryDateFormatter = DateFormatter()
+        changedImageEntryDateFormatter.dateFormat = "yy-MM-dd-HH-mm-ss"
     }
 
     func loadData() throws {
@@ -303,9 +307,7 @@ final class CapServer: ServerOwner {
             unwrittenImageChanges = entries
             try? handle.close()
         }
-        let df = DateFormatter()
-        df.dateFormat = "yy-MM-dd-HH-mm-ss"
-        let dateString = df.string(from: Date())
+        let dateString = changedImageEntryDateFormatter.string(from: Date())
         while let entry = entries.popLast() {
             let content = "\(dateString):\(entry.cap):\(entry.image)\n".data(using: .utf8)!
             try handle.write(contentsOf: content)
@@ -333,11 +335,25 @@ final class CapServer: ServerOwner {
         }
     }
     
-    func emptyChangedImageListFile() {
+    func removeAllEntriesInImageChangeList(before date: Date) {
         do {
-            try Data().write(to: changedImagesFile)
+            try String(contentsOf: changedImagesFile)
+                .components(separatedBy: "\n")
+                .filter { $0 != "" }
+                .compactMap { line -> String? in
+                    guard let entryDate = changedImageEntryDateFormatter.date(from: line.components(separatedBy: ":").first!) else {
+                        return nil
+                    }
+                    guard entryDate > date else {
+                        return nil
+                    }
+                    return line
+                }
+                .joined(separator: "\n")
+                .data(using: .utf8)!
+                .write(to: changedImagesFile)
         } catch {
-            log("Failed to empty changed images file: \(error)")
+            log("Failed to update changed images file: \(error)")
         }
     }
     

Sources/App/routes.swift

@@ -4,6 +4,13 @@ import Foundation
 /// The decoder to extract caps from JSON payloads given to the `cap` route.
 private let decoder = JSONDecoder()
 
+/// The date formatter to decode dates in requests
+private let dateFormatter: DateFormatter = {
+    let df = DateFormatter()
+    df.dateFormat = "yy-MM-dd-HH-mm-ss"
+    return df
+}()
+
 private func authorize(_ request: Request) throws {
     guard let key = request.headers.first(name: "key") else {
         throw Abort(.badRequest) // 400
@@ -65,7 +72,16 @@ func routes(_ app: Application) {
     }
     
     // Update the trained classes
-    app.postCatching("classes") { request in
+    app.postCatching("classes", ":date") { request in
+        guard let dateString = request.parameters.get("date") else {
+            log("Invalid parameter for date")
+            throw Abort(.badRequest)
+        }
+        guard let date = dateFormatter.date(from: dateString) else {
+            log("Invalid date specification")
+            throw Abort(.badRequest)
+        }
+        
         try authorize(request)
         guard let buffer = request.body.data else {
             log("Missing body data: \(request.body.description)")
@@ -77,6 +93,6 @@ func routes(_ app: Application) {
             throw CapError.invalidBody
         }
         server.updateTrainedClasses(content: content)
-        server.emptyChangedImageListFile()
+        server.removeAllEntriesInImageChangeList(before: date)
     }
 }