feat: LoTW confirmed-grids sync card — fetch confirmed QSO grids directly from ARRL LoTW (lotwreport.adi) and merge with Wavelog grids; credentials stored locally

core/data/src/main/java/com/rtbishop/look4sat/core/data/injection/MainContainer.kt

@@ -36,6 +36,7 @@ import com.rtbishop.look4sat.core.data.repository.SelectionRepo
 import com.rtbishop.look4sat.core.data.repository.SensorsRepo
 import com.rtbishop.look4sat.core.data.repository.SettingsRepo
 import com.rtbishop.look4sat.core.data.repository.UpdateRepository
+import com.rtbishop.look4sat.core.data.repository.LoTWRepository
 import com.rtbishop.look4sat.core.data.repository.WavelogRepository
 import com.rtbishop.look4sat.core.data.source.LocalSource
 import com.rtbishop.look4sat.core.data.source.RemoteSource
@@ -49,6 +50,7 @@ import com.rtbishop.look4sat.core.domain.repository.IMainContainer
 import com.rtbishop.look4sat.core.domain.repository.IRadioController
 import com.rtbishop.look4sat.core.domain.repository.IRadioTrackingService
 import com.rtbishop.look4sat.core.domain.repository.IReporter
+import com.rtbishop.look4sat.core.domain.repository.ILoTWRepository
 import com.rtbishop.look4sat.core.domain.repository.ISatelliteRepo
 import com.rtbishop.look4sat.core.domain.repository.ISelectionRepo
 import com.rtbishop.look4sat.core.domain.repository.ISensorsRepo
@@ -84,6 +86,7 @@ class MainContainer(private val context: Context) : IMainContainer {
     override val amSatRepo by lazy { AmSatRepository(remoteSource, appScope) }
     override val updateRepo by lazy { UpdateRepository(remoteSource) }
     override val wavelogRepo: IWavelogRepository by lazy { WavelogRepository() }
+    override val lotwRepo: ILoTWRepository by lazy { LoTWRepository() }
     override val radioTrackingService: IRadioTrackingService by lazy {
         val manager = context.getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
         RadioTrackingService(appScope, manager, satelliteRepo, settingsRepo)

core/data/src/main/java/com/rtbishop/look4sat/core/data/repository/LoTWRepository.kt

@@ -0,0 +1,93 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.core.data.repository
+
+import com.rtbishop.look4sat.core.domain.repository.ILoTWRepository
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import java.net.HttpURLConnection
+import java.net.URL
+import java.net.URLEncoder
+
+/**
+ * Fetches confirmed gridsquares directly from ARRL LoTW via the official report endpoint:
+ *   GET https://lotw.arrl.org/lotwuser/lotwreport.adi?login=<call>&password=<pwd>
+ *       &qso_query=1&qso_qsl=yes&qso_qsldetail=yes&qso_mydetail=yes&qso_qslsince=<date>
+ *
+ * Only QSL_RCVD=Y records are returned by LoTW for qso_qsl=yes, so every grid in the
+ * report is a *confirmed* grid (green on the map). GRIDSQUARE may be a 4- or 6-char
+ * value; VUCC_GRIDS ("EN52en,EN53fa") also yields 4-char fields. All values are
+ * truncated/expanded to the 4-char form used by the map overlay.
+ *
+ * ARRL rate-limits the report endpoint (roughly once per hour per account), which is
+ * fine for a manual sync button.
+ */
+class LoTWRepository : ILoTWRepository {
+
+    override suspend fun fetchConfirmedGrids(callsign: String, password: String): Set<String>? =
+        withContext(Dispatchers.IO) {
+            val call = callsign.trim().uppercase()
+            val pwd = password.trim()
+            if (call.isBlank() || pwd.isBlank()) return@withContext null
+            val query = buildString {
+                append("login=").append(URLEncoder.encode(call, "UTF-8"))
+                append("&password=").append(URLEncoder.encode(pwd, "UTF-8"))
+                append("&qso_query=1&qso_qsl=yes&qso_qsldetail=yes&qso_mydetail=yes")
+            }
+            try {
+                val connection = URL("$BASE_URL?$query").openConnection() as HttpURLConnection
+                connection.connectTimeout = 15_000
+                connection.readTimeout = 60_000
+                connection.requestMethod = "GET"
+                val code = connection.responseCode
+                if (code !in 200..299) {
+                    connection.disconnect()
+                    return@withContext null
+                }
+                val body = connection.inputStream.bufferedReader().use { it.readText() }
+                connection.disconnect()
+                if (body.contains(" password=") && !body.startsWith("ARRL")) return@withContext null
+                parseConfirmedGrids(body)
+            } catch (e: Exception) {
+                println("LoTWRepository fetch failure: $e")
+                null
+            }
+        }
+
+    internal fun parseConfirmedGrids(body: String): Set<String>? {
+        // LoTW answers with ADIF text; on bad credentials it returns a short error page
+        // containing "password=?" or an <eoh>-less block. Treat anything without a header
+        // marker as failure so the caller can show a sensible message.
+        if (!body.contains("<ADIF_VERS") && !body.contains("<EOH>")) return null
+        val grids = mutableSetOf<String>()
+        for (raw in body.lineSequence()) {
+            val line = raw.trim()
+            val value = when {
+                line.startsWith("<GRIDSQUARE:") -> line.substringAfter('>')
+                line.startsWith("<VUCC_GRIDS:") -> line.substringAfter('>')
+                else -> continue
+            }.substringBefore("E<").trim().uppercase()
+            if (value.length >= 4) grids.add(value.take(4))
+        }
+        return grids
+    }
+
+    private companion object {
+        const val BASE_URL = "https://lotw.arrl.org/lotwuser/lotwreport.adi"
+    }
+}

core/data/src/main/java/com/rtbishop/look4sat/core/data/repository/SettingsRepo.kt

@@ -178,6 +178,31 @@ class SettingsRepo(
         grids.sorted().forEach { array.put(it) }
         preferences.edit { putString(keyWorkedGrids, array.toString()) }
     }
+
+    // LoTW credentials (stored locally on the device only)
+    private val keyLoTWCall = "lotwCallsign"
+    private val keyLoTWPass = "lotwPassword"
+
+    override val lotwSettings: kotlinx.coroutines.flow.StateFlow<com.rtbishop.look4sat.core.domain.model.LoTWSettings>
+        get() = _lotwSettings
+    private val _lotwSettings = MutableStateFlow(getLoTWSettings())
+
+    override fun updateLoTWSettings(settings: com.rtbishop.look4sat.core.domain.model.LoTWSettings) {
+        preferences.edit {
+            putString(keyLoTWCall, settings.callsign.trim().uppercase())
+            putString(keyLoTWPass, settings.password)
+        }
+        _lotwSettings.value = settings.copy(
+            callsign = settings.callsign.trim().uppercase(),
+            password = settings.password
+        )
+    }
+
+    private fun getLoTWSettings(): com.rtbishop.look4sat.core.domain.model.LoTWSettings =
+        com.rtbishop.look4sat.core.domain.model.LoTWSettings(
+            callsign = preferences.getString(keyLoTWCall, null).orEmpty(),
+            password = preferences.getString(keyLoTWPass, null).orEmpty()
+        )
     //endregion
 
     //region # Transceivers settings

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/model/Settings.kt

@@ -84,6 +84,13 @@ data class WavelogSettings(
     val isConfigured: Boolean get() = url.isNotBlank() && token.isNotBlank()
 }
 
+data class LoTWSettings(
+    val callsign: String = "",
+    val password: String = ""
+) {
+    val isConfigured: Boolean get() = callsign.isNotBlank() && password.isNotBlank()
+}
+
 data class RadioControlSettings(
     val enabled: Boolean,
     val radioModel: String,

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/repository/ILoTWRepository.kt

@@ -0,0 +1,28 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.core.domain.repository
+
+/** Fetches confirmed gridsquares directly from ARRL LoTW. */
+interface ILoTWRepository {
+
+    /**
+     * Fetch all confirmed (QSL_RCVD=Y) gridsquares for the given LoTW account.
+     * Returns the 4-char grid set, or null on any failure (network / bad credentials).
+     */
+    suspend fun fetchConfirmedGrids(callsign: String, password: String): Set<String>?
+}

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/repository/IMainContainer.kt

@@ -33,6 +33,7 @@ interface IMainContainer {
     val amSatRepo: IAmSatRepository
     val updateRepo: IUpdateRepository
     val wavelogRepo: IWavelogRepository
+    val lotwRepo: com.rtbishop.look4sat.core.domain.repository.ILoTWRepository
     val radioTrackingService: IRadioTrackingService
     val mutualPassData: StateFlow<MutualPassData>
     fun setMutualPassData(data: MutualPassData)

core/domain/src/main/java/com/rtbishop/look4sat/core/domain/repository/ISettingsRepo.kt

@@ -100,4 +100,9 @@ interface ISettingsRepo {
     fun getWorkedGrids(): Set<String>
     fun setWorkedGrids(grids: Set<String>)
     //endregion
+
+    //region # LoTW confirmed-grids settings
+    val lotwSettings: StateFlow<com.rtbishop.look4sat.core.domain.model.LoTWSettings>
+    fun updateLoTWSettings(settings: com.rtbishop.look4sat.core.domain.model.LoTWSettings)
+    //endregion
 }

core/presentation/src/main/res/values-zh/strings.xml

@@ -148,6 +148,13 @@
     <string name="prefs_wavelog_hint">已同步网格数：%1$d。格式：API key:日志ID。请先保存，再点同步。</string>
     <string name="prefs_wavelog_sync">立即同步</string>
     <string name="prefs_wavelog_syncing">同步中…</string>
+    <string name="prefs_lotw_title">LoTW 已确认网格</string>
+    <string name="prefs_lotw_callsign">LoTW 呼号</string>
+    <string name="prefs_lotw_password">LoTW 密码</string>
+    <string name="prefs_lotw_hint">直接从 ARRL LoTW 拉取已确认 QSO 的网格并与 Wavelog 网格合并（当前 %1$d 个）。密码仅保存在手机本地。请先保存，再点同步。</string>
+    <string name="prefs_lotw_sync">立即同步</string>
+    <string name="prefs_lotw_syncing">同步中…</string>
+    <string name="prefs_lotw_not_configured">未配置 — 直接登录 ARRL LoTW 拉取已确认 QSO 的网格，无需自建服务器</string>
     <string name="prefs_locator_text">使用梅登黑德网格设置站点位置</string>
 
     <string name="prefs_data_title">卫星数据更新</string>

core/presentation/src/main/res/values/strings.xml

@@ -183,6 +183,13 @@
     <string name="prefs_wavelog_hint">Worked grids synced: %1$d. Format: API key, colon, logbook ID. Save first, then tap Sync.</string>
     <string name="prefs_wavelog_sync">Sync now</string>
     <string name="prefs_wavelog_syncing">Syncing…</string>
+    <string name="prefs_lotw_title">LoTW confirmed grids</string>
+    <string name="prefs_lotw_callsign">LoTW callsign</string>
+    <string name="prefs_lotw_password">LoTW password</string>
+    <string name="prefs_lotw_hint">Fetch confirmed-QSO grids directly from ARRL LoTW and merge them with Wavelog grids (currently %1$d). The password is stored on this device only. Save first, then tap Sync.</string>
+    <string name="prefs_lotw_sync">Sync now</string>
+    <string name="prefs_lotw_syncing">Syncing…</string>
+    <string name="prefs_lotw_not_configured">Not configured — pull confirmed grids directly from ARRL LoTW, no self-hosted server needed</string>
     <string name="prefs_locator_text">Set station\'s position using locator</string>
 
     <string name="prefs_data_title">Satellite data</string>

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsDialog.kt

@@ -219,6 +219,69 @@ fun WavelogDialog(
     }
 }
 
+@Composable
+fun LoTWDialog(
+    initialSettings: com.rtbishop.look4sat.core.domain.model.LoTWSettings,
+    workedGridsCount: Int,
+    isSyncing: Boolean,
+    message: String?,
+    dismiss: () -> Unit,
+    onSave: (com.rtbishop.look4sat.core.domain.model.LoTWSettings) -> Unit,
+    onSync: () -> Unit
+) {
+    val call = rememberSaveable { mutableStateOf(initialSettings.callsign) }
+    val pass = rememberSaveable { mutableStateOf(initialSettings.password) }
+    SharedDialog(
+        title = stringResource(R.string.prefs_lotw_title),
+        onCancel = dismiss,
+        onAccept = {
+            onSave(com.rtbishop.look4sat.core.domain.model.LoTWSettings(call.value, pass.value))
+            dismiss()
+        }
+    ) {
+        OutlinedTextField(
+            value = call.value,
+            onValueChange = { call.value = it.uppercase() },
+            label = { Text(text = stringResource(id = R.string.prefs_lotw_callsign)) },
+            placeholder = { Text(text = "BA7OPF") },
+            singleLine = true,
+            modifier = Modifier.fillMaxWidth().padding(horizontal = LocalSpacing.current.large),
+        )
+        OutlinedTextField(
+            value = pass.value,
+            onValueChange = { pass.value = it },
+            label = { Text(text = stringResource(id = R.string.prefs_lotw_password)) },
+            placeholder = { Text(text = "********") },
+            visualTransformation = androidx.compose.ui.text.input.PasswordVisualTransformation(),
+            singleLine = true,
+            modifier = Modifier.fillMaxWidth().padding(horizontal = LocalSpacing.current.large),
+        )
+        Text(
+            text = stringResource(R.string.prefs_lotw_hint, workedGridsCount),
+            style = MaterialTheme.typography.bodySmall,
+            modifier = Modifier.padding(horizontal = LocalSpacing.current.large)
+        )
+        if (message != null) {
+            Text(
+                text = message,
+                color = MaterialTheme.colorScheme.error,
+                style = MaterialTheme.typography.bodySmall,
+                modifier = Modifier.padding(horizontal = LocalSpacing.current.large)
+            )
+        }
+        Row(
+            horizontalArrangement = Arrangement.End,
+            modifier = Modifier.fillMaxWidth().padding(horizontal = LocalSpacing.current.large)
+        ) {
+            TextButton(onClick = onSync, enabled = !isSyncing) {
+                Text(text = if (isSyncing) stringResource(R.string.prefs_lotw_syncing)
+                else stringResource(R.string.prefs_lotw_sync))
+            }
+        }
+        Spacer(modifier = Modifier.height(0.dp))
+    }
+}
+
 @Preview(showBackground = true)
 @Composable
 private fun TransceiversDialogPreview() {

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsScreen.kt

@@ -215,6 +215,18 @@ private fun SettingsScreen(uiState: SettingsState, onAction: (SettingsAction) ->
         )
     }
 
+    if (dialogs.lotw) {
+        LoTWDialog(
+            initialSettings = uiState.lotwSettings,
+            workedGridsCount = uiState.workedGridsCount,
+            isSyncing = uiState.lotwSyncing,
+            message = uiState.lotwMessage,
+            dismiss = { dialogs.lotw = false },
+            onSave = { onAction(SettingsAction.UpdateLoTW(it)) },
+            onSync = { onAction(SettingsAction.SyncLoTWGrids) }
+        )
+    }
+
     // URLs for top bar
     val uriHandler = LocalUriHandler.current
     val appUrl = stringResource(R.string.prefs_app_url)
@@ -325,6 +337,13 @@ private fun SettingsScreen(uiState: SettingsState, onAction: (SettingsAction) ->
                     showWavelogDialog = { dialogs.wavelog = true }
                 )
             }
+            item {
+                LoTWCard(
+                    settings = uiState.lotwSettings,
+                    workedGridsCount = uiState.workedGridsCount,
+                    showLoTWDialog = { dialogs.lotw = true }
+                )
+            }
             item { OtherCard(uiState.otherSettings, onAction) }
             item { CardCredits() }
             item(span = { GridItemSpan(maxLineSpan) }) {
@@ -600,6 +619,38 @@ private fun WavelogCard(
     }
 }
 
+@Composable
+private fun LoTWCard(
+    settings: com.rtbishop.look4sat.core.domain.model.LoTWSettings,
+    workedGridsCount: Int,
+    showLoTWDialog: () -> Unit
+) {
+    ElevatedCard(modifier = Modifier.fillMaxWidth()) {
+        Column(modifier = Modifier.padding(horizontal = 8.dp, vertical = 4.dp)) {
+            Text(
+                text = stringResource(id = R.string.prefs_lotw_title),
+                color = MaterialTheme.colorScheme.primary
+            )
+            Spacer(modifier = Modifier.height(2.dp))
+            Text(
+                text = if (settings.isConfigured) {
+                    stringResource(R.string.prefs_wavelog_configured, workedGridsCount)
+                } else {
+                    stringResource(R.string.prefs_lotw_not_configured)
+                },
+                style = MaterialTheme.typography.bodySmall,
+                maxLines = 2
+            )
+            Spacer(modifier = Modifier.height(4.dp))
+            CardButton(
+                onClick = showLoTWDialog,
+                text = stringResource(id = R.string.prefs_wavelog_configure),
+                modifier = Modifier.fillMaxWidth()
+            )
+        }
+    }
+}
+
 @Composable
 private fun formatUpdateTime(updateTime: Long): String {
     val timePattern = stringResource(id = R.string.prefs_updated_time)
@@ -720,6 +771,7 @@ private class DialogVisibility {
     var bluetooth by mutableStateOf(false)
     var radioControl by mutableStateOf(false)
     var wavelog by mutableStateOf(false)
+    var lotw by mutableStateOf(false)
 }
 
 @Composable
@@ -727,12 +779,13 @@ private fun rememberDialogVisibility(): DialogVisibility {
     return rememberSaveable(saver = run {
         androidx.compose.runtime.saveable.Saver(
             save = {
-                listOf(it.position, it.locator, it.dataSources, it.network, it.bluetooth, it.radioControl, it.wavelog)
+                listOf(it.position, it.locator, it.dataSources, it.network, it.bluetooth, it.radioControl, it.wavelog, it.lotw)
             },
             restore = {
                 DialogVisibility().apply {
                     position = it[0]; locator = it[1]; dataSources = it[2]
                     network = it[3]; bluetooth = it[4]; radioControl = it[5]; wavelog = it[6]
+                    lotw = it.getOrElse(7) { false }
                 }
             }
         )

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsState.kt

@@ -59,6 +59,9 @@ data class SettingsState(
     val workedGridsCount: Int = 0,
     val wavelogSyncing: Boolean = false,
     val wavelogMessage: String? = null,
+    val lotwSettings: com.rtbishop.look4sat.core.domain.model.LoTWSettings = com.rtbishop.look4sat.core.domain.model.LoTWSettings(),
+    val lotwSyncing: Boolean = false,
+    val lotwMessage: String? = null,
     val updateChecker: UpdateCheckerState = UpdateCheckerState()
 )
 
@@ -95,6 +98,10 @@ sealed interface SettingsAction {
     data class UpdateWavelog(val settings: WavelogSettings) : SettingsAction
     data object SyncWorkedGrids : SettingsAction
 
+    // LoTW confirmed grids
+    data class UpdateLoTW(val settings: com.rtbishop.look4sat.core.domain.model.LoTWSettings) : SettingsAction
+    data object SyncLoTWGrids : SettingsAction
+
     // Update checker
     data object CheckForUpdate : SettingsAction
     data object DownloadUpdate : SettingsAction

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsViewModel.kt

@@ -41,6 +41,7 @@ class SettingsViewModel(
     private val settingsRepo: ISettingsRepo,
     private val updateRepo: IUpdateRepository,
     private val wavelogRepo: IWavelogRepository,
+    private val lotwRepo: com.rtbishop.look4sat.core.domain.repository.ILoTWRepository,
     private val apkFile: File,
     private val showToast: IShowToast
 ) : ViewModel() {
@@ -116,6 +117,11 @@ class SettingsViewModel(
                 _uiState.update { it.copy(wavelogSettings = settings) }
             }
         }
+        viewModelScope.launch {
+            settingsRepo.lotwSettings.collect { settings ->
+                _uiState.update { it.copy(lotwSettings = settings) }
+            }
+        }
     }
 
 
@@ -150,6 +156,9 @@ class SettingsViewModel(
             // Wavelog worked grids
             is SettingsAction.UpdateWavelog -> settingsRepo.updateWavelogSettings(action.settings)
             SettingsAction.SyncWorkedGrids -> syncWorkedGrids()
+            // LoTW confirmed grids
+            is SettingsAction.UpdateLoTW -> settingsRepo.updateLoTWSettings(action.settings)
+            SettingsAction.SyncLoTWGrids -> syncLoTWGrids()
             // Update checker
             SettingsAction.CheckForUpdate -> checkForUpdate()
             SettingsAction.DownloadUpdate -> downloadUpdate()
@@ -181,6 +190,28 @@ class SettingsViewModel(
         }
     }
 
+    private fun syncLoTWGrids() {
+        val settings = _uiState.value.lotwSettings
+        if (!settings.isConfigured) {
+            _uiState.update { it.copy(lotwMessage = "LoTW callsign/password not configured") }
+            return
+        }
+        _uiState.update { it.copy(lotwSyncing = true, lotwMessage = null) }
+        viewModelScope.launch {
+            val lotwGrids = lotwRepo.fetchConfirmedGrids(settings.callsign, settings.password)
+            _uiState.update { state ->
+                if (lotwGrids == null) {
+                    state.copy(lotwSyncing = false, lotwMessage = "LoTW sync failed — check callsign/password/network")
+                } else {
+                    // Merge with Wavelog grids: union of both sources, all confirmed/worked
+                    val merged = settingsRepo.getWorkedGrids() + lotwGrids
+                    settingsRepo.setWorkedGrids(merged)
+                    state.copy(lotwSyncing = false, workedGridsCount = merged.size, lotwMessage = null)
+                }
+            }
+        }
+    }
+
     // endregion
 
     // region Update checker
@@ -305,6 +336,7 @@ class SettingsViewModel(
                     settingsRepo = container.settingsRepo,
                     updateRepo = container.updateRepo,
                     wavelogRepo = container.wavelogRepo,
+                    lotwRepo = container.lotwRepo,
                     apkFile = File(context.cacheDir, "look4sat-update.apk"),
                     showToast = container.provideShowToast()
                 )