Add Android 7 to 11 network mode controllers

- Added a dedicated legacy network mode backend.
- Added transactional mode writes and cellular modem restart.
- Added airplane mode radio-list preservation and restoration.
- Added clean up traps and post operation verification.

Author: Dhangofa

app/src/main/java/com/dhangofa/networktoggle/telephony/LegacyNetworkModeController.java

@@ -0,0 +1,181 @@
+package com.dhangofa.networktoggle.telephony;
+
+import android.content.Context;
+import android.provider.Settings;
+import android.telephony.TelephonyManager;
+
+import com.dhangofa.networktoggle.command.CommandExecutor;
+import com.dhangofa.networktoggle.command.CommandExecutorFactory;
+import com.dhangofa.networktoggle.model.CommandResult;
+import com.dhangofa.networktoggle.model.ExecutionMode;
+import com.dhangofa.networktoggle.model.NetworkMode;
+
+final class LegacyNetworkModeController {
+    private static final int MODEM_RESTART_DELAY_SECONDS = 2;
+
+    private final Context context;
+    private final SimResolver simResolver;
+
+    LegacyNetworkModeController(Context context, SimResolver simResolver) {
+        this.context = context.getApplicationContext();
+        this.simResolver = simResolver;
+    }
+
+    CommandResult apply(NetworkMode networkMode, ExecutionMode executionMode) {
+        if (networkMode == null || networkMode == NetworkMode.UNKNOWN
+                || networkMode.getLegacyMode() < 0) {
+            return CommandResult.failed("", "Invalid legacy network mode selected.");
+        }
+
+        if (isAirplaneModeEnabled()) {
+            return CommandResult.failed("",
+                    "Disable Airplane mode before changing the network mode.");
+        }
+
+        SimResolver.SimInfo simInfo = simResolver.resolveTargetSimInfo(executionMode);
+        if (simInfo == null || !simResolver.isValidSlotIndex(simInfo.slotIndex)
+                || !simResolver.isValidSubId(simInfo.subId)) {
+            return CommandResult.failed("", "Unable to resolve the target SIM.");
+        }
+
+        Integer[] currentModes = readCombinedModes();
+        int requiredEntries = getRequiredCombinedEntries(simInfo.slotIndex);
+        if (currentModes.length < requiredEntries) {
+            return CommandResult.failed("",
+                    "Unable to preserve the current mode of every SIM slot.");
+        }
+
+        for (int i = 0; i < requiredEntries; i++) {
+            if (currentModes[i] == null) {
+                return CommandResult.failed("",
+                        "Unable to read the current mode for SIM slot " + (i + 1) + ".");
+            }
+        }
+
+        currentModes[simInfo.slotIndex] = networkMode.getLegacyMode();
+        String combinedModes = buildCombinedModes(currentModes, requiredEntries);
+        String originalRadios = readAirplaneModeRadios();
+        String restoreRadios = originalRadios == null
+                ? "settings delete global airplane_mode_radios"
+                : "settings put global airplane_mode_radios " + shellEscape(originalRadios);
+
+        String command = buildTransactionCommand(
+                simInfo.subId,
+                networkMode.getLegacyMode(),
+                combinedModes,
+                restoreRadios
+        );
+
+        CommandExecutor executor = CommandExecutorFactory.forMode(executionMode);
+        if (executor == null) {
+            return CommandResult.failed(command, "No execution mode selected.");
+        }
+
+        CommandResult result = executor.execute(command);
+        if (!result.isSuccess()) return result;
+
+        return verifyResult(command, simInfo, networkMode.getLegacyMode(),
+                originalRadios, requiredEntries);
+    }
+
+    private Integer[] readCombinedModes() {
+        String value = Settings.Global.getString(
+                context.getContentResolver(), "preferred_network_mode");
+        if (value == null || value.trim().isEmpty()
+                || value.trim().equalsIgnoreCase("null")) {
+            return new Integer[0];
+        }
+
+        String[] parts = value.trim().split(",", -1);
+        Integer[] modes = new Integer[parts.length];
+        for (int i = 0; i < parts.length; i++) {
+            modes[i] = ShellValueParser.extractFirstInt(parts[i]);
+        }
+        return modes;
+    }
+
+    private int getRequiredCombinedEntries(int targetSlot) {
+        TelephonyManager manager = (TelephonyManager)
+                context.getSystemService(Context.TELEPHONY_SERVICE);
+        int phoneCount = manager == null ? 1 : manager.getPhoneCount();
+        return Math.max(targetSlot + 1, Math.min(phoneCount, 2));
+    }
+
+    private String buildCombinedModes(Integer[] modes, int count) {
+        StringBuilder value = new StringBuilder();
+        for (int i = 0; i < count; i++) {
+            if (i > 0) value.append(',');
+            value.append(modes[i]);
+        }
+        return value.toString();
+    }
+
+    private boolean isAirplaneModeEnabled() {
+        return Settings.Global.getInt(
+                context.getContentResolver(), Settings.Global.AIRPLANE_MODE_ON, 0) == 1;
+    }
+
+    private String readAirplaneModeRadios() {
+        return Settings.Global.getString(
+                context.getContentResolver(), Settings.Global.AIRPLANE_MODE_RADIOS);
+    }
+
+    private String buildTransactionCommand(int subId, int requestedMode,
+                                           String combinedModes, String restoreRadios) {
+        return "cleanup() { "
+                + "cmd connectivity airplane-mode disable >/dev/null 2>&1; "
+                + restoreRadios + " >/dev/null 2>&1; "
+                + "}; "
+                + "trap cleanup EXIT INT TERM; "
+                + "settings put global airplane_mode_radios cell || exit 20; "
+                + "settings put global preferred_network_mode" + subId + " "
+                + requestedMode + " || exit 21; "
+                + "settings put global preferred_network_mode " + combinedModes
+                + " || exit 22; "
+                + "cmd connectivity airplane-mode enable || exit 23; "
+                + "sleep " + MODEM_RESTART_DELAY_SECONDS + "; "
+                + "cmd connectivity airplane-mode disable || exit 24; "
+                + "sleep " + MODEM_RESTART_DELAY_SECONDS + "; "
+                + restoreRadios + " || exit 25; "
+                + "trap - EXIT INT TERM; "
+                + "exit 0";
+    }
+
+    private CommandResult verifyResult(String command, SimResolver.SimInfo simInfo,
+                                       int requestedMode, String originalRadios,
+                                       int requiredEntries) {
+        String subValue = Settings.Global.getString(
+                context.getContentResolver(),
+                "preferred_network_mode" + simInfo.subId);
+        Integer finalSubMode = ShellValueParser.extractFirstInt(subValue);
+        Integer[] finalCombinedModes = readCombinedModes();
+        String finalRadios = readAirplaneModeRadios();
+
+        if (isAirplaneModeEnabled()) {
+            return CommandResult.failed(command,
+                    "Legacy mode was written, but Airplane mode is still enabled.");
+        }
+        if (finalSubMode == null || finalSubMode != requestedMode) {
+            return CommandResult.failed(command,
+                    "Legacy per-subscription mode verification failed.");
+        }
+        if (finalCombinedModes.length < requiredEntries
+                || finalCombinedModes[simInfo.slotIndex] == null
+                || finalCombinedModes[simInfo.slotIndex] != requestedMode) {
+            return CommandResult.failed(command,
+                    "Legacy combined mode verification failed.");
+        }
+        if (originalRadios == null ? finalRadios != null
+                : !originalRadios.equals(finalRadios)) {
+            return CommandResult.failed(command,
+                    "Original Airplane mode radio configuration was not restored.");
+        }
+
+        return CommandResult.completed(command, 0,
+                "Legacy network mode applied and verified.", "");
+    }
+
+    private String shellEscape(String value) {
+        return "'" + value.replace("'", "'\\''") + "'";
+    }
+}