Give mixed selections something to do

A Drag of different kinds showed an empty wheel, because the catalog only
answers for a single category. Filee's answer is a mixed profile, so add
Zip (one archive, flat names) and Merge (non-PDFs are converted to PDF
first); a multi-file drag of one kind gets Zip too.

Sources/Konverter/Core/Tools.swift

@@ -20,7 +20,7 @@ enum ToolID: String, CaseIterable, Identifiable, Codable {
     // Subtitles
     case shiftSubtitle
     // Archives
-    case extractArchive, listArchive
+    case extractArchive, listArchive, createArchive
     // Media metadata
     case mediaInfo
 
@@ -65,6 +65,7 @@ enum ToolID: String, CaseIterable, Identifiable, Codable {
         case .shiftSubtitle: return "Shift Time"
         case .extractArchive: return "Extract"
         case .listArchive: return "List Contents"
+        case .createArchive: return "Zip"
         case .mediaInfo: return "Info"
         }
     }
@@ -100,6 +101,7 @@ enum ToolID: String, CaseIterable, Identifiable, Codable {
         case .shiftSubtitle: return "clock.arrow.circlepath"
         case .extractArchive: return "archivebox"
         case .listArchive: return "list.bullet.rectangle"
+        case .createArchive: return "doc.zipper"
         }
     }
 
@@ -122,7 +124,7 @@ enum ToolID: String, CaseIterable, Identifiable, Codable {
             return .spreadsheet
         case .shiftSubtitle:
             return .subtitle
-        case .extractArchive, .listArchive:
+        case .extractArchive, .listArchive, .createArchive:
             return .archive
         case .mediaInfo:
             return .video
@@ -131,7 +133,10 @@ enum ToolID: String, CaseIterable, Identifiable, Codable {
 
     /// Tools that only make sense for a multi-file selection.
     var requiresMultipleFiles: Bool {
-        self == .mergePDF || self == .imagesToPDF || self == .collageImages
+        switch self {
+        case .mergePDF, .imagesToPDF, .collageImages, .createArchive: return true
+        default: return false
+        }
     }
 
     var minimumFileCount: Int { requiresMultipleFiles ? 2 : 1 }
@@ -151,6 +156,26 @@ enum ToolID: String, CaseIterable, Identifiable, Codable {
     static func tools(for category: FileCategory) -> [ToolID] {
         allCases.filter { $0.category == category }
     }
+
+    /// Tools that accept a drag of mixed kinds. When a selection cannot become
+    /// one format, there is still something useful to do with it: Filee calls
+    /// this a mixed profile, and it is why its donut is never empty.
+    static func combineTools(for urls: [URL]) -> [ToolID] {
+        guard urls.count >= 2 else { return [] }
+        var tools: [ToolID] = []
+        if urls.allSatisfy(canBecomePDF) { tools.append(.mergePDF) }
+        tools.append(.createArchive)
+        return tools
+    }
+
+    /// Kinds that `Converter` knows how to turn into a PDF, which is what
+    /// ``mergePDF`` needs from anything that is not a PDF already.
+    static func canBecomePDF(_ url: URL) -> Bool {
+        switch FileKind.category(of: url) {
+        case .image, .pdf, .document, .slides, .spreadsheet, .ebook: return true
+        default: return false
+        }
+    }
 }
 
 /// One editable field in a tool's options form.
@@ -256,6 +281,8 @@ extension ToolID {
             ]
         case .shiftSubtitle:
             return [ToolField("offset", "Shift by", .decimal(min: -600, max: 600), default: "1", unit: "s")]
+        case .createArchive:
+            return [ToolField("name", "Archive name", .text, default: "Archive", help: "Saved beside the first file")]
         case .listArchive, .extractArchive, .wordCount, .mediaInfo, .readQR, .stripMetadata,
              .grayscaleImage, .normalizeAudio, .extractPDFText, .documentToPDF, .sheetsToCSV,
              .muteVideo, .mergePDF, .imagesToPDF:

Sources/Konverter/Core/WheelOption.swift

@@ -59,7 +59,12 @@ enum WheelBuilder {
     private static func conversionItems(urls: [URL]) -> [WheelItem] {
         let categories = urls.map { FileKind.category(of: $0) }
         let formats = ConversionCatalog.outputs(for: categories)
-        guard let category = categories.first, !formats.isEmpty else { return [] }
+        // A mixed drag has no single output format, but it can still become one
+        // file, so the convert wheel offers the combine tools instead of
+        // vanishing (this is Filee's mixed profile).
+        guard let category = categories.first, !formats.isEmpty else {
+            return combineItems(urls: urls)
+        }
 
         return formats.compactMap { format in
             guard !ConversionCatalog.isRedundant(format, urls: urls) else { return nil }
@@ -77,26 +82,41 @@ enum WheelBuilder {
 
     private static func toolItems(urls: [URL]) -> [WheelItem] {
         let categories = Set(urls.map { FileKind.category(of: $0) })
-        guard categories.count == 1, let category = categories.first else { return [] }
-
-        return ToolID.tools(for: category).compactMap { tool in
-            guard urls.count >= tool.minimumFileCount else { return nil }
-            var availability = Availability.ok
-            if tool.producesArtifacts, urls.count > 1 {
-                availability = .ok
-            }
-            if requiresFFmpeg(tool), !Toolchain.hasFFmpeg {
-                availability = .unavailable("Needs ffmpeg — brew install ffmpeg")
-            }
-            return WheelItem(
-                id: "tool-\(tool.rawValue)",
-                payload: .tool(tool),
-                title: tool.title,
-                subtitle: availability.isAvailable ? nil : availability.reason,
-                symbol: tool.symbol,
-                availability: availability
-            )
+        if categories.count == 1, let category = categories.first,
+           category != .folder, category != .unknown {
+            var tools = ToolID.tools(for: category)
+            // Any multi-file selection can be packed into one archive.
+            if urls.count >= 2 { tools.append(.createArchive) }
+            return tools.compactMap { item(for: $0, urls: urls) }
         }
+        return combineItems(urls: urls)
+    }
+
+    /// The slices a selection of mixed kinds can still act on.
+    private static func combineItems(urls: [URL]) -> [WheelItem] {
+        let subtitles: [ToolID: String] = [
+            .mergePDF: "One PDF",
+            .createArchive: "One ZIP"
+        ]
+        return ToolID.combineTools(for: urls).compactMap { tool in
+            item(for: tool, urls: urls, subtitle: subtitles[tool])
+        }
+    }
+
+    private static func item(for tool: ToolID, urls: [URL], subtitle: String? = nil) -> WheelItem? {
+        guard urls.count >= tool.minimumFileCount else { return nil }
+        var availability = Availability.ok
+        if requiresFFmpeg(tool), !Toolchain.hasFFmpeg {
+            availability = .unavailable("Needs ffmpeg — brew install ffmpeg")
+        }
+        return WheelItem(
+            id: "tool-\(tool.rawValue)",
+            payload: .tool(tool),
+            title: tool.title,
+            subtitle: availability.isAvailable ? subtitle : availability.reason,
+            symbol: tool.symbol,
+            availability: availability
+        )
     }
 
     private static func requiresFFmpeg(_ tool: ToolID) -> Bool {