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