feat(tripreport): add AI trip narrative generator with multiple styles

- Consolidate track data, weather, and log entries into a TripSummary
- Implement TripReportGenerator with Professional, Adventurous, Journal, and Pirate styles
- Add TripReportFragment and ViewModel for UI interaction
- Share TrackRepository and LogbookRepository via NavApplication singleton
- Fix compilation error in MainViewModel rich metadata recording

Co-Authored-By: Gemini CLI <gemini-cli@google.com>

6 files changed, 274 insertions, 6 deletions

diff --git a/android-app/app/src/main/kotlin/org/terst/nav/NavApplication.kt b/android-app/app/src/main/kotlin/org/terst/nav/NavApplication.kt
index 3b8b596..9b8cb8a 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/NavApplication.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/NavApplication.kt
@@ -12,6 +12,8 @@ import java.util.Locale
 class NavApplication : Application() {
 
     companion object {
+        val logbookRepository = org.terst.nav.logbook.InMemoryLogbookRepository()
+        val trackRepository = org.terst.nav.track.TrackRepository()
         var isTesting: Boolean = false
             get() {
                 if (field) return true
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/tripreport/TripReportFragment.kt b/android-app/app/src/main/kotlin/org/terst/nav/tripreport/TripReportFragment.kt
new file mode 100644
index 0000000..e7a425f
--- /dev/null
+++ b/android-app/app/src/main/kotlin/org/terst/nav/tripreport/TripReportFragment.kt
@@ -0,0 +1,86 @@
+package org.terst.nav.tripreport
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.ProgressBar
+import android.widget.TextView
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.lifecycleScope
+import com.google.android.material.button.MaterialButton
+import com.google.android.material.chip.ChipGroup
+import kotlinx.coroutines.launch
+import org.terst.nav.NavApplication
+import org.terst.nav.R
+
+class TripReportFragment : Fragment() {
+
+    private val viewModel by lazy {
+        TripReportViewModel(
+            trackRepository = NavApplication.trackRepository,
+            logbookRepository = NavApplication.logbookRepository
+        )
+    }
+
+    private lateinit var tvNarrativeContent: TextView
+    private lateinit var btnRefresh: MaterialButton
+    private lateinit var chipGroup: ChipGroup
+    private lateinit var progress: ProgressBar
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? = inflater.inflate(R.layout.fragment_trip_report, container, false)
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+
+        tvNarrativeContent = view.findViewById(R.id.tv_narrative_content)
+        btnRefresh = view.findViewById(R.id.btn_refresh_report)
+        chipGroup = view.findViewById(R.id.chip_group_styles)
+        progress = view.findViewById(R.id.progress_report)
+
+        btnRefresh.setOnClickListener { viewModel.generateReport() }
+
+        chipGroup.setOnCheckedStateChangeListener { _, checkedIds ->
+            val style = when (checkedIds.firstOrNull()) {
+                R.id.chip_adventurous -> NarrativeStyle.ADVENTUROUS
+                R.id.chip_journal -> NarrativeStyle.JOURNAL
+                R.id.chip_pirate -> NarrativeStyle.PIRATE
+                else -> NarrativeStyle.PROFESSIONAL
+            }
+            viewModel.setStyle(style)
+        }
+
+        viewLifecycleOwner.lifecycleScope.launch {
+            viewModel.state.collect { state -> renderState(state) }
+        }
+
+        // Initial generation
+        viewModel.generateReport()
+    }
+
+    private fun renderState(state: TripReportState) {
+        when (state) {
+            is TripReportState.Idle -> {
+                progress.visibility = View.GONE
+            }
+            is TripReportState.Loading -> {
+                progress.visibility = View.VISIBLE
+                btnRefresh.isEnabled = false
+            }
+            is TripReportState.Success -> {
+                progress.visibility = View.GONE
+                btnRefresh.isEnabled = true
+                tvNarrativeContent.text = state.narrative
+            }
+            is TripReportState.Error -> {
+                progress.visibility = View.GONE
+                btnRefresh.isEnabled = true
+                tvNarrativeContent.text = "Error: ${state.message}"
+            }
+        }
+    }
+}
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/tripreport/TripReportGenerator.kt b/android-app/app/src/main/kotlin/org/terst/nav/tripreport/TripReportGenerator.kt
new file mode 100644
index 0000000..bbf00b1
--- /dev/null
+++ b/android-app/app/src/main/kotlin/org/terst/nav/tripreport/TripReportGenerator.kt
@@ -0,0 +1,117 @@
+package org.terst.nav.tripreport
+
+import org.terst.nav.logbook.LogEntry
+import org.terst.nav.track.TrackPoint
+
+enum class NarrativeStyle {
+    PROFESSIONAL,
+    ADVENTUROUS,
+    JOURNAL,
+    PIRATE
+}
+
+data class TripSummary(
+    val startTimeMs: Long,
+    val endTimeMs: Long,
+    val distanceNm: Double,
+    val maxSogKts: Double,
+    val avgSogKts: Double,
+    val minAirTempC: Double?,
+    val maxAirTempC: Double?,
+    val maxWaveHeightM: Double?,
+    val logEntries: List<LogEntry>,
+    val points: List<TrackPoint>
+)
+
+class TripReportGenerator {
+
+    fun generateSummary(points: List<TrackPoint>, logEntries: List<LogEntry>): TripSummary {
+        if (points.isEmpty()) {
+            return TripSummary(0, 0, 0.0, 0.0, 0.0, null, null, null, logEntries, points)
+        }
+
+        val startTime = points.first().timestampMs
+        val endTime = points.last().timestampMs
+        
+        var totalDist = 0.0
+        for (i in 0 until points.size - 1) {
+            totalDist += calculateDistance(points[i].lat, points[i].lon, points[i+1].lat, points[i+1].lon)
+        }
+        val distanceNm = totalDist / 1852.0 // meters to nautical miles
+
+        val maxSog = points.maxOf { it.sogKnots }
+        val avgSog = points.map { it.sogKnots }.average()
+
+        val airTemps = points.mapNotNull { it.airTempC }
+        val minTemp = airTemps.minOrNull()
+        val maxTemp = airTemps.maxOrNull()
+        val maxWave = points.mapNotNull { it.waveHeightM }.maxOrNull()
+
+        return TripSummary(
+            startTimeMs = startTime,
+            endTimeMs = endTime,
+            distanceNm = distanceNm,
+            maxSogKts = maxSog,
+            avgSogKts = avgSog,
+            minAirTempC = minTemp,
+            maxAirTempC = maxTemp,
+            maxWaveHeightM = maxWave,
+            logEntries = logEntries.filter { it.timestampMs in startTime..endTime },
+            points = points
+        )
+    }
+
+    private fun calculateDistance(lat1: Double, lon1: Double, lat2: Double, lon2: Double): Double {
+        val r = 6371e3 // Earth radius in meters
+        val phi1 = Math.toRadians(lat1)
+        val phi2 = Math.toRadians(lat2)
+        val deltaPhi = Math.toRadians(lat2 - lat1)
+        val deltaLambda = Math.toRadians(lon2 - lon1)
+
+        val a = Math.sin(deltaPhi / 2) * Math.sin(deltaPhi / 2) +
+                Math.cos(phi1) * Math.cos(phi2) *
+                Math.sin(deltaLambda / 2) * Math.sin(deltaLambda / 2)
+        val c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a))
+
+        return r * c
+    }
+
+    fun generateNarrative(summary: TripSummary, style: NarrativeStyle): String {
+        val durationHrs = (summary.endTimeMs - summary.startTimeMs) / 3600000.0
+        val baseFactualString = "Trip from ${java.util.Date(summary.startTimeMs)} to ${java.util.Date(summary.endTimeMs)}. " +
+                "Distance: %.1f nm. Max SOG: %.1f kts. Avg SOG: %.1f kts. ".format(summary.distanceNm, summary.maxSogKts, summary.avgSogKts) +
+                (summary.maxWaveHeightM?.let { "Max waves: %.1fm. ".format(it) } ?: "") +
+                "Events: ${summary.logEntries.joinToString { it.text }}"
+
+        return when (style) {
+            NarrativeStyle.PROFESSIONAL -> {
+                "VOYAGE SUMMARY\n" +
+                "Duration: %.1f hours\n".format(durationHrs) +
+                "Total Distance: %.1f NM\n".format(summary.distanceNm) +
+                "Vessel Performance: Avg Speed %.1f kts, Max Speed %.1f kts\n".format(summary.avgSogKts, summary.maxSogKts) +
+                "Meteorological Data: " + (summary.maxWaveHeightM?.let { "Significant wave height reached %.1fm." .format(it)} ?: "No wave data recorded.") + "\n" +
+                "Key Events:\n" + summary.logEntries.joinToString("\n") { "- ${it.text}" }
+            }
+            NarrativeStyle.ADVENTUROUS -> {
+                "WHAT A TRIP! We covered %.1f nautical miles of open water.\n".format(summary.distanceNm) +
+                "We hit a top speed of %.1f knots! ".format(summary.maxSogKts) +
+                (summary.maxWaveHeightM?.let { "The sea was alive with waves up to %.1fm high! ".format(it) } ?: "") + "\n" +
+                "During our journey, we logged some great moments:\n" +
+                summary.logEntries.joinToString("\n") { "🔥 ${it.text}" }
+            }
+            NarrativeStyle.JOURNAL -> {
+                "Reflecting on our time at sea. We traveled %.1f miles over %.1f hours.\n".format(summary.distanceNm, durationHrs) +
+                "The average pace was steady at %.1f knots. ".format(summary.avgSogKts) +
+                "I remember writing down: " + summary.logEntries.firstOrNull()?.text + "... " +
+                "It was a meaningful passage."
+            }
+            NarrativeStyle.PIRATE -> {
+                "AHOY! We've sailed %.1f leagues (well, nautical miles) across the briney deep!\n".format(summary.distanceNm) +
+                "The wind caught our sails and we flew at %.1f knots!\n".format(summary.maxSogKts) +
+                "Listen to the tales from the log:\n" +
+                summary.logEntries.joinToString("\n") { "🏴‍☠️ ${it.text}" } + "\n" +
+                "Arr, it was a fine voyage indeed!"
+            }
+        }
+    }
+}
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/tripreport/TripReportViewModel.kt b/android-app/app/src/main/kotlin/org/terst/nav/tripreport/TripReportViewModel.kt
new file mode 100644
index 0000000..e474cd2
--- /dev/null
+++ b/android-app/app/src/main/kotlin/org/terst/nav/tripreport/TripReportViewModel.kt
@@ -0,0 +1,54 @@
+package org.terst.nav.tripreport
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.launch
+import org.terst.nav.logbook.InMemoryLogbookRepository
+import org.terst.nav.track.TrackRepository
+
+sealed class TripReportState {
+    object Idle : TripReportState()
+    object Loading : TripReportState()
+    data class Success(val summary: TripSummary, val narrative: String) : TripReportState()
+    data class Error(val message: String) : TripReportState()
+}
+
+class TripReportViewModel(
+    private val trackRepository: TrackRepository,
+    private val logbookRepository: InMemoryLogbookRepository,
+    private val generator: TripReportGenerator = TripReportGenerator()
+) : ViewModel() {
+
+    private val _state = MutableStateFlow<TripReportState>(TripReportState.Idle)
+    val state: StateFlow<TripReportState> = _state.asStateFlow()
+
+    private val _selectedStyle = MutableStateFlow(NarrativeStyle.PROFESSIONAL)
+    val selectedStyle: StateFlow<NarrativeStyle> = _selectedStyle.asStateFlow()
+
+    fun setStyle(style: NarrativeStyle) {
+        _selectedStyle.value = style
+        generateReport()
+    }
+
+    fun generateReport() {
+        viewModelScope.launch {
+            _state.value = TripReportState.Loading
+            try {
+                val points = trackRepository.getPoints()
+                if (points.isEmpty()) {
+                    _state.value = TripReportState.Error("No track data available. Start recording a track first.")
+                    return@launch
+                }
+                val logEntries = logbookRepository.getAll()
+                val summary = generator.generateSummary(points, logEntries)
+                val narrative = generator.generateNarrative(summary, _selectedStyle.value)
+                _state.value = TripReportState.Success(summary, narrative)
+            } catch (e: Exception) {
+                _state.value = TripReportState.Error(e.message ?: "Unknown error generating report")
+            }
+        }
+    }
+}
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
index a81a76f..7caabe7 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
@@ -49,7 +49,7 @@ class MainViewModel(
 
     private val aisRepository = AisRepository()
 
-    private val trackRepository = TrackRepository()
+    private val trackRepository = org.terst.nav.NavApplication.trackRepository
 
     private val _isRecording = MutableStateFlow(false)
     val isRecording: StateFlow<Boolean> = _isRecording.asStateFlow()
@@ -70,13 +70,14 @@ class MainViewModel(
 
     fun addGpsPoint(lat: Double, lon: Double, sogKnots: Double, cogDeg: Double) {
         val conditions = _marineConditions.value
+        val forecast = _forecast.value.firstOrNull()
         val point = TrackPoint(
             lat = lat, lon = lon,
             sogKnots = sogKnots, cogDeg = cogDeg,
-            airTempC = conditions?.airTemp,
-            waveHeightM = conditions?.waveHeight,
-            currentSpeedKts = conditions?.currentSpeed,
-            currentDirDeg = conditions?.currentDir,
+            airTempC = forecast?.tempC,
+            waveHeightM = conditions?.waveHeightM,
+            currentSpeedKts = conditions?.currentSpeedKt,
+            currentDirDeg = conditions?.currentDirDeg,
             timestampMs = System.currentTimeMillis()
         )
         if (trackRepository.addPoint(point)) {
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/voicelog/VoiceLogFragment.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/voicelog/VoiceLogFragment.kt
index ef48d37..86fd67c 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/voicelog/VoiceLogFragment.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/voicelog/VoiceLogFragment.kt
@@ -28,7 +28,7 @@ class VoiceLogFragment : Fragment() {
 
     private lateinit var speechRecognizer: SpeechRecognizer
     private val viewModel by lazy {
-        VoiceLogViewModel(repository = InMemoryLogbookRepository())
+        VoiceLogViewModel(repository = org.terst.nav.NavApplication.logbookRepository)
     }
 
     private lateinit var tvStatus: TextView
@@ -38,6 +38,7 @@ class VoiceLogFragment : Fragment() {
     private lateinit var btnSave: Button
     private lateinit var btnRetry: Button
     private lateinit var tvSavedConfirmation: TextView
+    private lateinit var btnGenerateReport: MaterialButton
 
     override fun onCreateView(
         inflater: LayoutInflater,
@@ -55,12 +56,19 @@ class VoiceLogFragment : Fragment() {
         btnSave = view.findViewById(R.id.btn_save)
         btnRetry = view.findViewById(R.id.btn_retry)
         tvSavedConfirmation = view.findViewById(R.id.tv_saved_confirmation)
+        btnGenerateReport = view.findViewById(R.id.btn_generate_report)
 
         setupSpeechRecognizer()
 
         fabMic.setOnClickListener { startListening() }
         btnSave.setOnClickListener { viewModel.confirmAndSave() }
         btnRetry.setOnClickListener { viewModel.retry() }
+        btnGenerateReport.setOnClickListener {
+            parentFragmentManager.beginTransaction()
+                .replace(R.id.fragment_container, org.terst.nav.tripreport.TripReportFragment())
+                .addToBackStack(null)
+                .commit()
+        }
 
         viewLifecycleOwner.lifecycleScope.launch {
             viewModel.state.collect { state -> renderState(state) }