feat: add timer presets and completion state

Alarm/Views/TimerView.swift

@@ -2,9 +2,12 @@ import SwiftUI
 import Combine
 
 struct TimerView: View {
+    private let presets = [60, 5 * 60, 10 * 60, 25 * 60]
+
     @State private var durationSeconds: Int = 300
     @State private var remainingSeconds: Int = 300
     @State private var isRunning = false
+    @State private var didComplete = false
     private let ticker = Timer.publish(every: 1, on: .main, in: .common).autoconnect()
 
     var body: some View {
@@ -18,6 +21,12 @@ struct TimerView: View {
                         .font(.system(size: 68, weight: .light, design: .rounded))
                         .monospacedDigit()
 
+                    Text(statusText)
+                        .font(.system(size: 15, weight: .regular))
+                        .foregroundStyle(Color(white: 0.42))
+
+                    presetRow
+
                     Stepper("时长：\(durationSeconds / 60) 分钟", value: $durationSeconds, in: 60 ... 24 * 3600, step: 60)
                         .font(.system(size: 16, weight: .regular))
                         .disabled(isRunning)
@@ -44,33 +53,102 @@ struct TimerView: View {
                 .padding()
             }
             .navigationTitle("计时器")
+            .alert("计时结束", isPresented: $didComplete) {
+                Button("确定", role: .cancel) {}
+            } message: {
+                Text("本轮 \(durationSummary(durationSeconds)) 已完成。")
+            }
             .onReceive(ticker) { _ in
                 guard isRunning else { return }
-                if remainingSeconds > 0 {
+                if remainingSeconds > 1 {
                     remainingSeconds -= 1
-                } else {
-                    stop()
+                    return
                 }
+
+                complete()
             }
         }
         .preferredColorScheme(.light)
     }
 
     private func start() {
         guard remainingSeconds > 0 else { return }
+        didComplete = false
         isRunning = true
     }
 
     private func stop() {
         isRunning = false
     }
 
+    private func complete() {
+        stop()
+        remainingSeconds = 0
+        didComplete = true
+    }
+
     private func format(_ seconds: Int) -> String {
         let h = seconds / 3600
         let m = (seconds % 3600) / 60
         let s = seconds % 60
         return String(format: "%02d:%02d:%02d", h, m, s)
     }
+
+    private var presetRow: some View {
+        HStack(spacing: 10) {
+            ForEach(presets, id: \.self) { preset in
+                Button {
+                    applyPreset(preset)
+                } label: {
+                    Text(durationSummary(preset))
+                        .font(.system(size: 14, weight: .medium))
+                        .foregroundStyle(durationSeconds == preset ? .white : Color(white: 0.2))
+                        .padding(.horizontal, 14)
+                        .padding(.vertical, 10)
+                        .background(
+                            Capsule()
+                                .fill(durationSeconds == preset ? Color.orange : Color.white)
+                        )
+                }
+                .buttonStyle(.plain)
+                .disabled(isRunning)
+                .opacity(isRunning ? 0.45 : 1)
+            }
+        }
+    }
+
+    private var statusText: String {
+        if didComplete {
+            return "本轮倒计时已完成"
+        }
+        if isRunning {
+            return "进行中 · 剩余 \(durationSummary(remainingSeconds))"
+        }
+        if remainingSeconds == durationSeconds {
+            return "选择常用时长后即可开始"
+        }
+        return "已暂停，可继续或重置"
+    }
+
+    private func applyPreset(_ preset: Int) {
+        guard !isRunning else { return }
+        durationSeconds = preset
+        remainingSeconds = preset
+        didComplete = false
+    }
+
+    private func durationSummary(_ seconds: Int) -> String {
+        if seconds < 3600 {
+            return "\(seconds / 60) 分钟"
+        }
+
+        let hours = seconds / 3600
+        let minutes = (seconds % 3600) / 60
+        if minutes == 0 {
+            return "\(hours) 小时"
+        }
+        return "\(hours) 小时 \(minutes) 分钟"
+    }
 }
 
 #Preview {