Add CSV export for days

TempTrack/Storage/CsvConverter.swift

@@ -0,0 +1,40 @@
+import Foundation
+
+struct CsvConverter {
+
+    private let dateFormatter: DateFormatter
+
+    init() {
+        dateFormatter = .init()
+        dateFormatter.dateStyle = .short
+        dateFormatter.timeStyle = .medium
+    }
+
+    private var header: String {
+        "Index;Date;Sensor 0;Sensor 1\n"
+    }
+
+    func convert(measurements: [TemperatureMeasurement]) -> String {
+        header + measurements.enumerated().map { (index, measurement) -> String in
+            let parts: [String] = [
+                "\(index)",
+                dateFormatter.string(from: measurement.date),
+                convert(measurement.sensor0),
+                convert(measurement.sensor1)
+            ]
+
+            return parts.joined(separator: ";")
+        }.joined(separator: "\n")
+    }
+
+    private func convert(_ value: TemperatureValue) -> String {
+        switch value {
+        case .notFound:
+            return ""
+        case .invalidMeasurement:
+            return "?"
+        case .value(let value):
+            return String(format:"%.1f", value)
+        }
+    }
+}

TempTrack/Views/DayView.swift

@@ -1,4 +1,5 @@
 import SwiftUI
+import SFSafeSymbols
 
 private let df: DateFormatter = {
     let df = DateFormatter()
@@ -21,19 +22,45 @@ struct DayView: View {
     @EnvironmentObject
     var storage: PersistentStorage
 
+    @State
+    private var showShareSheet = false
+
+    private let title: String
+
+    init(dateIndex: Int) {
+        self.dateIndex = dateIndex
+        self.title = Date(dateIndex: dateIndex)
+            .formatted(date: .abbreviated, time: .omitted)
+    }
+
     var entries: [TemperatureMeasurement] {
         storage.loadMeasurements(for: dateIndex)
     }
 
     var body: some View {
-        TemperatureDayOverview(points: entries)
-        List(entries) { entry in
-            HStack {
-                Text(df.string(from: entry.date))
-                Spacer()
-                Text(entry.displayText)
+        VStack {
+            TemperatureDayOverview(points: entries)
+            List(entries) { entry in
+                HStack {
+                    Text(entry.date.formatted(date: .omitted, time: .standard))
+                    Spacer()
+                    Text(entry.displayText)
+                }
             }
         }
+        .navigationTitle(title)
+        .navigationBarTitleDisplayMode(.large)
+        .toolbar {
+            ToolbarItem {
+                Button(action: { showShareSheet = true }) {
+                    Label("Export", systemSymbol: .arrowUpDoc)
+                }
+            }
+        }
+        .sheet(isPresented: $showShareSheet) {
+            ShareCsvSheet(isPresented: $showShareSheet,
+                          measurements: entries)
+        }
     }
 }
 

TempTrack/Views/ExportSheet.swift

@@ -39,6 +39,7 @@ struct ExportSheet: View {
                 Button("Delete archive", action: deleteArchive)
                     .padding()
             }
+            Button("Dismiss", action: { isPresented = false })
         }
         .padding()
     }

TempTrack/Views/ShareCsvSheet.swift

@@ -0,0 +1,91 @@
+import SwiftUI
+
+struct ShareCsvSheet: View {
+
+    @Binding var isPresented: Bool
+
+    @State
+    private var isCreatingFile = false
+
+    @State var url: URL?
+
+    @State var error: String?
+
+    @EnvironmentObject
+    private var storage: PersistentStorage
+
+    let measurements: [TemperatureMeasurement]
+
+    var body: some View {
+        VStack {
+            Text("Export")
+                .font(.title)
+            Text("Create a CSV file of all measurements for the day")
+            if isCreatingFile {
+                ProgressView()
+                Text("Creating file...")
+            }
+            if let error {
+                Text(error)
+                    .foregroundStyle(.red)
+            }
+            Spacer()
+            Button("Create file", action: createFile)
+                .disabled(isCreatingFile)
+                .padding()
+            if let url {
+                ShareLink(item: url) {
+                    Label("Share file", systemImage: "square.and.arrow.up")
+                }
+                .padding()
+                Button("Delete file", action: deleteFile)
+                    .padding()
+            }
+            Button("Dismiss", action: { isPresented = false })
+        }
+        .padding()
+    }
+
+    private func createFile() {
+        guard !isCreatingFile else {
+            return
+        }
+        isCreatingFile = true
+        DispatchQueue.main.async {
+            do {
+                let url = FileManager.default.temporaryDirectory.appendingPathComponent("export.csv")
+                let converter = CsvConverter()
+                let content = converter.convert(measurements: measurements)
+                try content.write(to: url, atomically: true, encoding: .utf8)
+                DispatchQueue.main.async {
+                    self.url = url
+                    self.error = nil
+                    self.isCreatingFile = false
+                }
+            } catch {
+                DispatchQueue.main.async {
+                    self.error = "Failed to save file: \(error.localizedDescription)"
+                    self.isCreatingFile = false
+                }
+            }
+        }
+    }
+
+    private func deleteFile() {
+        guard let url else {
+            return
+        }
+        do {
+            try FileManager.default.removeItem(at: url)
+            self.error = nil
+            self.url = nil
+        } catch {
+            self.error = "Failed to delete archive: \(error.localizedDescription)"
+        }
+    }
+}
+
+#Preview {
+    ShareCsvSheet(isPresented: .constant(true),
+                  measurements: [])
+}