feat: 문제 탭 하단 타이머 바 + 상태바 남은 시간 표시 (#16)

src/main/kotlin/com/codingtestkit/service/TimerService.kt

@@ -0,0 +1,149 @@
+package com.codingtestkit.service
+
+import com.intellij.openapi.components.Service
+import com.intellij.openapi.project.Project
+
+/**
+ * 카운트다운 타이머·스톱워치 상태 서비스 (이슈 #16).
+ * 타이머 탭, 문제 탭 하단 타이머 바, 상태바 위젯이 같은 상태를 공유·관찰한다.
+ * Swing Timer 기반이므로 모든 호출과 콜백은 EDT에서 일어난다.
+ */
+@Service(Service.Level.PROJECT)
+class TimerService {
+
+    var totalMs: Long = DEFAULT_TOTAL_MS
+        private set
+    var remainingMs: Long = DEFAULT_TOTAL_MS
+        private set
+    var isRunning: Boolean = false
+        private set
+
+    /** 중간에 일시정지된 상태 (시작/재개 라벨, 필드 활성화 판단용) */
+    val isPausedMidway: Boolean
+        get() = !isRunning && remainingMs in 1 until totalMs
+
+    private var endTime: Long = 0
+    private var ticker: javax.swing.Timer? = null
+    private val listeners = mutableListOf<() -> Unit>()
+    private val timeUpListeners = mutableListOf<() -> Unit>()
+
+    /** 총 시간 설정 (남은 시간도 함께 리셋). 실행 중에는 무시. */
+    fun setTotal(ms: Long) {
+        if (isRunning) return
+        totalMs = ms.coerceAtLeast(0)
+        remainingMs = totalMs
+        notifyListeners()
+    }
+
+    /** 시작 또는 재개. 남은 시간이 없으면 총 시간부터 다시 시작. */
+    fun start() {
+        if (isRunning) return
+        if (remainingMs <= 0) remainingMs = totalMs
+        if (remainingMs <= 0) return
+        isRunning = true
+        endTime = System.currentTimeMillis() + remainingMs
+        ticker = javax.swing.Timer(33) {
+            remainingMs = (endTime - System.currentTimeMillis()).coerceAtLeast(0)
+            if (remainingMs <= 0) finish() else notifyListeners()
+        }.apply { start() }
+        notifyListeners()
+    }
+
+    fun pause() {
+        if (!isRunning) return
+        remainingMs = (endTime - System.currentTimeMillis()).coerceAtLeast(0)
+        stopTicker()
+        notifyListeners()
+    }
+
+    fun reset() {
+        stopTicker()
+        remainingMs = totalMs
+        notifyListeners()
+    }
+
+    private fun finish() {
+        stopTicker()
+        remainingMs = 0
+        notifyListeners()
+        timeUpListeners.toList().forEach { it() }
+    }
+
+    private fun stopTicker() {
+        ticker?.stop()
+        ticker = null
+        isRunning = false
+    }
+
+    // ─── 스톱워치 (스톱워치 탭과 문제 탭 하단 바가 공유) ───
+
+    var isStopwatchRunning: Boolean = false
+        private set
+
+    private var swStartTime: Long = 0
+    private var swAccumulatedMs: Long = 0
+    private var swTicker: javax.swing.Timer? = null
+
+    val stopwatchElapsedMs: Long
+        get() = if (isStopwatchRunning) swAccumulatedMs + (System.currentTimeMillis() - swStartTime)
+        else swAccumulatedMs
+
+    fun stopwatchStart() {
+        if (isStopwatchRunning) return
+        isStopwatchRunning = true
+        swStartTime = System.currentTimeMillis()
+        swTicker = javax.swing.Timer(33) { notifyListeners() }.apply { start() }
+        notifyListeners()
+    }
+
+    fun stopwatchPause() {
+        if (!isStopwatchRunning) return
+        swAccumulatedMs += System.currentTimeMillis() - swStartTime
+        stopStopwatchTicker()
+        notifyListeners()
+    }
+
+    fun stopwatchReset() {
+        stopStopwatchTicker()
+        swAccumulatedMs = 0
+        notifyListeners()
+    }
+
+    private fun stopStopwatchTicker() {
+        swTicker?.stop()
+        swTicker = null
+        isStopwatchRunning = false
+    }
+
+    // ─── 리스너 ───
+
+    fun addListener(listener: () -> Unit) { listeners.add(listener) }
+    fun removeListener(listener: () -> Unit) { listeners.remove(listener) }
+
+    /** 시간 종료 시 1회 호출되는 리스너 (알림음·다이얼로그 등) */
+    fun addTimeUpListener(listener: () -> Unit) { timeUpListeners.add(listener) }
+
+    private fun notifyListeners() { listeners.toList().forEach { it() } }
+
+    /** 남은 시간 표기: h:mm:ss 또는 mm:ss (문제 탭 바, 상태바 공용) */
+    fun formatRemaining(): String = formatHms(remainingMs)
+
+    /** 스톱워치 경과 시간 표기: h:mm:ss 또는 mm:ss */
+    fun formatStopwatch(): String = formatHms(stopwatchElapsedMs)
+
+    private fun formatHms(ms: Long): String {
+        val totalSec = ms / 1000
+        val h = totalSec / 3600
+        val m = (totalSec % 3600) / 60
+        val s = totalSec % 60
+        return if (h > 0) String.format("%d:%02d:%02d", h, m, s)
+        else String.format("%02d:%02d", m, s)
+    }
+
+    companion object {
+        private const val DEFAULT_TOTAL_MS = 30 * 60 * 1000L
+
+        fun getInstance(project: Project): TimerService =
+            project.getService(TimerService::class.java)
+    }
+}

src/main/kotlin/com/codingtestkit/ui/CodingTestKitStatusBarFactory.kt

@@ -1,6 +1,7 @@
 package com.codingtestkit.ui
 
 import com.codingtestkit.service.CodingTestKitActionService
+import com.codingtestkit.service.TimerService
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.wm.CustomStatusBarWidget
 import com.intellij.openapi.wm.StatusBar
@@ -36,16 +37,23 @@ class CodingTestKitStatusBarWidget(private val project: Project) : CustomStatusB
 
     override fun ID() = CodingTestKitStatusBarFactory.WIDGET_ID
 
+    // 타이머는 33ms 간격으로 틱하므로 표시 문자열이 바뀔 때만 위젯 갱신
+    private var lastText = ""
+
+    private val timerListener: () -> Unit = { updateText() }
+
     override fun install(statusBar: StatusBar) {
         this.statusBar = statusBar
         CodingTestKitActionService.getInstance(project).onStatusChanged = {
             updateText()
-            statusBar.updateWidget(ID())
         }
+        // 타이머 남은 시간을 어떤 탭/레이아웃에서든 볼 수 있게 상태바에 표시 (이슈 #16)
+        TimerService.getInstance(project).addListener(timerListener)
         updateText()
     }
 
     override fun dispose() {
+        TimerService.getInstance(project).removeListener(timerListener)
         statusBar = null
     }
 
@@ -56,15 +64,28 @@ class CodingTestKitStatusBarWidget(private val project: Project) : CustomStatusB
         val platform = service.currentPlatform
         val id = service.currentProblemId
 
-        component.text = when {
+        val base = when {
             platform == null -> "CTK"
             id == null -> "CTK: $platform"
             else -> "CTK: $platform #$id"
         }
+
+        // 실행 중이거나 중간에 멈춘/종료된 타이머만 표시 (초기 상태에서는 숨김)
+        val timer = TimerService.getInstance(project)
+        val timerText = if (timer.isRunning || (timer.totalMs > 0 && timer.remainingMs < timer.totalMs)) {
+            " ⏱ ${timer.formatRemaining()}"
+        } else ""
+
+        val text = base + timerText
+        if (text == lastText) return
+        lastText = text
+
+        component.text = text
         component.toolTipText = when {
             platform == null -> "CodingTestKit"
             id == null -> "CodingTestKit: $platform"
             else -> "CodingTestKit: $platform #$id"
         }
+        statusBar?.updateWidget(ID())
     }
 }

src/main/kotlin/com/codingtestkit/ui/MainPanel.kt

@@ -3,6 +3,7 @@ package com.codingtestkit.ui
 import com.codingtestkit.service.CodingTestKitActionService
 import com.codingtestkit.service.I18n
 import com.codingtestkit.service.ProblemFileManager
+import com.codingtestkit.service.TimerService
 import com.intellij.icons.AllIcons
 import com.intellij.openapi.application.ApplicationManager
 import com.intellij.openapi.Disposable
@@ -22,7 +23,7 @@ class MainPanel(private val project: Project) : JPanel(BorderLayout()), Disposab
     private val problemPanel = ProblemPanel(project)
     private val testPanel = TestPanel(project)
     private val templatePanel = TemplatePanel(project).also { Disposer.register(this, it) }
-    private val timerPanel = TimerPanel()
+    private val timerPanel = TimerPanel(TimerService.getInstance(project))
     private val referencePanel = ReferencePanel()
     private val settingsPanel = SettingsPanel(project)
     private var lastLoadedFolder: String? = null

src/main/kotlin/com/codingtestkit/ui/ProblemPanel.kt

@@ -86,6 +86,44 @@ class ProblemPanel(private val project: Project) : JPanel(BorderLayout()) {
         font = font.deriveFont(JBUI.scaleFontSize(11f).toFloat())
         iconTextGap = 0
     }
+    // ─── 하단 타이머 바 (이슈 #16): 문제를 보면서 타이머·스톱워치 확인·조작 ───
+    private val timerService = TimerService.getInstance(project)
+    private val timerBarLabel = JLabel("30:00", AllIcons.Vcs.History, SwingConstants.LEFT).apply {
+        font = Font("JetBrains Mono", Font.BOLD, JBUI.scale(13))
+        toolTipText = I18n.t("타이머", "Timer")
+    }
+    private val timerBarToggle = JButton(AllIcons.Actions.Execute).apply {
+        toolTipText = I18n.t("타이머 시작/일시정지", "Start/pause timer")
+        preferredSize = Dimension(JBUI.scale(26), JBUI.scale(24))
+    }
+    private val timerBarReset = JButton(AllIcons.Actions.Restart).apply {
+        toolTipText = I18n.t("타이머 초기화", "Reset timer")
+        preferredSize = Dimension(JBUI.scale(26), JBUI.scale(24))
+    }
+    // 남은 시간 비율을 보여주는 얇은 프로그레스 바 (바 상단에 배치)
+    private val timerBarProgress = JProgressBar(0, 1000).apply {
+        isStringPainted = false
+        border = JBUI.Borders.empty()
+        preferredSize = Dimension(0, JBUI.scale(3))
+        value = 1000
+    }
+    private val swBarLabel = JLabel("00:00", AllIcons.Debugger.Db_muted_breakpoint, SwingConstants.LEFT).apply {
+        font = Font("JetBrains Mono", Font.BOLD, JBUI.scale(13))
+        toolTipText = I18n.t("스톱워치", "Stopwatch")
+    }
+    private val swBarToggle = JButton(AllIcons.Actions.Execute).apply {
+        toolTipText = I18n.t("스톱워치 시작/일시정지", "Start/pause stopwatch")
+        preferredSize = Dimension(JBUI.scale(26), JBUI.scale(24))
+    }
+    private val swBarReset = JButton(AllIcons.Actions.Restart).apply {
+        toolTipText = I18n.t("스톱워치 초기화", "Reset stopwatch")
+        preferredSize = Dimension(JBUI.scale(26), JBUI.scale(24))
+    }
+    private var timerBarLastText = ""
+    private var timerBarLastRunning = false
+    private var swBarLastText = ""
+    private var swBarLastRunning = false
+
     private val problemDisplay = JEditorPane().apply {
         contentType = "text/html"
         isEditable = false
@@ -243,6 +281,41 @@ class ProblemPanel(private val project: Project) : JPanel(BorderLayout()) {
             add(scrollPane, BorderLayout.CENTER)
         }
 
+        // 하단 타이머 바 — 타이머 탭·상태바와 같은 TimerService를 공유.
+        // 상단에 얇은 프로그레스 바, 왼쪽에 타이머 그룹, 오른쪽에 스톱워치 그룹.
+        val timerBar = JPanel(BorderLayout()).apply {
+            border = JBUI.Borders.customLine(JBColor.border(), 1, 0, 0, 0)
+            add(timerBarProgress, BorderLayout.NORTH)
+            add(JPanel(BorderLayout()).apply {
+                isOpaque = false
+                border = JBUI.Borders.empty(2, 8, 2, 4)
+                add(JPanel(FlowLayout(FlowLayout.LEFT, JBUI.scale(2), 0)).apply {
+                    isOpaque = false
+                    add(timerBarLabel)
+                    add(timerBarToggle)
+                    add(timerBarReset)
+                }, BorderLayout.WEST)
+                add(JPanel(FlowLayout(FlowLayout.RIGHT, JBUI.scale(2), 0)).apply {
+                    isOpaque = false
+                    add(swBarLabel)
+                    add(swBarToggle)
+                    add(swBarReset)
+                }, BorderLayout.EAST)
+            }, BorderLayout.CENTER)
+        }
+        add(timerBar, BorderLayout.SOUTH)
+
+        timerBarToggle.addActionListener {
+            if (timerService.isRunning) timerService.pause() else timerService.start()
+        }
+        timerBarReset.addActionListener { timerService.reset() }
+        swBarToggle.addActionListener {
+            if (timerService.isStopwatchRunning) timerService.stopwatchPause() else timerService.stopwatchStart()
+        }
+        swBarReset.addActionListener { timerService.stopwatchReset() }
+        timerService.addListener { syncTimerBar() }
+        syncTimerBar()
+
         submitButton.isEnabled = false
         githubPushButton.isEnabled = false
 
@@ -351,6 +424,33 @@ class ProblemPanel(private val project: Project) : JPanel(BorderLayout()) {
         }
     }
 
+    /** 타이머 바 표시 동기화 — 33ms 틱마다 불리므로 표시 문자열이 바뀔 때만 갱신 */
+    private fun syncTimerBar() {
+        // 프로그레스는 int(0~1000) 단위라 같은 값이면 setValue가 no-op
+        timerBarProgress.value = if (timerService.totalMs > 0)
+            ((timerService.remainingMs.toDouble() / timerService.totalMs) * 1000).toInt() else 1000
+
+        val running = timerService.isRunning
+        val text = timerService.formatRemaining()
+        if (text != timerBarLastText || running != timerBarLastRunning) {
+            timerBarLastText = text
+            timerBarLastRunning = running
+            timerBarLabel.text = text
+            timerBarToggle.icon = if (running) AllIcons.Actions.Suspend else AllIcons.Actions.Execute
+            timerBarLabel.foreground = if (timerService.remainingMs in 1..59999 && running)
+                JBColor(Color.RED, Color(230, 80, 80)) else JBColor.foreground()
+        }
+
+        val swRunning = timerService.isStopwatchRunning
+        val swText = timerService.formatStopwatch()
+        if (swText != swBarLastText || swRunning != swBarLastRunning) {
+            swBarLastText = swText
+            swBarLastRunning = swRunning
+            swBarLabel.text = swText
+            swBarToggle.icon = if (swRunning) AllIcons.Actions.Suspend else AllIcons.Actions.Execute
+        }
+    }
+
     private fun createComboRenderer(): ListCellRenderer<Any?> {
         return ListCellRenderer { list, value, _, isSelected, _ ->
             JLabel(value?.toString() ?: "").apply {