SystemUI: fix NFC tile sometimes hiding

- Check whether NFC is supported based on device features

- Don't hold a reference to the NFC adapter - query it when we need it
  (not using getDefault, but the internal method, if we use the default,
  querying for the adapter before the service was spun up would lead to
  systemui never having a valid refernce to an adpater).

Ticket: CYNGNOS-1943, CYNGNOS-2866
Change-Id: Iba8b668406ca96183aafcf9a55d60c6d89d70061
Signed-off-by: Roman Birg <roman@cyngn.com>

2 files changed, 66 insertions, 28 deletions

diff --git a/packages/SystemUI/AndroidManifest_cm.xml b/packages/SystemUI/AndroidManifest_cm.xml
index e269159..b29c39f 100644
--- a/packages/SystemUI/AndroidManifest_cm.xml
+++ b/packages/SystemUI/AndroidManifest_cm.xml
@@ -50,6 +50,9 @@
      <!-- Weather Provider -->
     <uses-permission android:name="cyanogenmod.permission.READ_WEATHER" />
 
+    <!-- NFC Tile -->
+    <uses-permission android:name="android.permission.NFC" />
+
     <application>
         <provider android:name=".cm.SpamMessageProvider"
                   android:permission="android.permission.INTERACT_ACROSS_USERS_FULL"
diff --git a/packages/SystemUI/src/com/android/systemui/qs/tiles/NfcTile.java b/packages/SystemUI/src/com/android/systemui/qs/tiles/NfcTile.java
index 1bfbb8f..a5ffd23 100644
--- a/packages/SystemUI/src/com/android/systemui/qs/tiles/NfcTile.java
+++ b/packages/SystemUI/src/com/android/systemui/qs/tiles/NfcTile.java
@@ -22,12 +22,14 @@ import android.content.Intent;
 import android.content.IntentFilter;
 import android.nfc.NfcAdapter;
 
+import android.util.Log;
 import com.android.systemui.R;
 import com.android.systemui.qs.QSTile;
 import org.cyanogenmod.internal.logging.CMMetricsLogger;
+import org.cyanogenmod.internal.util.QSUtils;
 
 public class NfcTile extends QSTile<QSTile.BooleanState> {
-    private NfcAdapter mNfcAdapter;
+
     private boolean mListening;
 
     private BroadcastReceiver mReceiver = new BroadcastReceiver() {
@@ -36,10 +38,11 @@ public class NfcTile extends QSTile<QSTile.BooleanState> {
             refreshState();
         }
     };
+    private final boolean mSupportsNfc;
 
     public NfcTile(Host host) {
         super(host);
-        mNfcAdapter = NfcAdapter.getDefaultAdapter(mContext);
+        mSupportsNfc = QSUtils.deviceSupportsNfc(mContext);
     }
 
     @Override
@@ -49,7 +52,9 @@ public class NfcTile extends QSTile<QSTile.BooleanState> {
 
     @Override
     protected void handleClick() {
-        toggleState();
+        boolean newState = !getState().value;
+        setState(newState);
+        refreshState();
     }
 
     @Override
@@ -57,23 +62,45 @@ public class NfcTile extends QSTile<QSTile.BooleanState> {
         mHost.startActivityDismissingKeyguard(new Intent("android.settings.NFC_SETTINGS"));
     }
 
-    protected void toggleState() {
-        int state = getNfcState();
-        switch (state) {
-            case NfcAdapter.STATE_TURNING_ON:
-            case NfcAdapter.STATE_ON:
-                mNfcAdapter.disable();
-                break;
-            case NfcAdapter.STATE_TURNING_OFF:
-            case NfcAdapter.STATE_OFF:
-                mNfcAdapter.enable();
-                break;
+    private void setState(boolean on) {
+        try {
+            NfcAdapter nfcAdapter = NfcAdapter.getNfcAdapter(mContext);
+            if (nfcAdapter == null) {
+                Log.e(TAG, "tried to set NFC state, but no NFC adapter was found");
+                return;
+            }
+            if (on) {
+                nfcAdapter.enable();
+            } else {
+                nfcAdapter.disable();
+            }
+        } catch (UnsupportedOperationException e) {
+            // ignore
+        }
+    }
+
+    private int getNfcAdapterState() {
+        try {
+            NfcAdapter nfcAdapter = NfcAdapter.getNfcAdapter(mContext);
+            if (nfcAdapter == null) {
+                Log.e(TAG, "tried to get NFC state, but no NFC adapter was found");
+                return NfcAdapter.STATE_OFF;
+            }
+            return nfcAdapter.getAdapterState();
+        } catch (UnsupportedOperationException e) {
+            // ignore
+            return NfcAdapter.STATE_OFF;
         }
     }
 
-    private boolean isEnabled() {
-        int state = getNfcState();
-        switch (state) {
+    /**
+     * Helper method to encapsulate intermediate states (turning off/on) to help determine whether
+     * the adapter will be on or off.
+     * @param nfcState The current NFC adapter state.
+     * @return boolean representing what state the adapter is/will be in
+     */
+    private static boolean isEnabled(int nfcState) {
+        switch (nfcState) {
             case NfcAdapter.STATE_TURNING_ON:
             case NfcAdapter.STATE_ON:
                 return true;
@@ -84,17 +111,28 @@ public class NfcTile extends QSTile<QSTile.BooleanState> {
         }
     }
 
-    private int getNfcState() {
-        return mNfcAdapter.getAdapterState();
+    /**
+     * Helper method to determine intermediate states
+     * @param nfcState The current NFC adapter state.
+     * @return boolean representing if the adapter is in an intermediate state
+     */
+    private static boolean isEnablingDisabling(int nfcState) {
+        switch (nfcState) {
+            case NfcAdapter.STATE_TURNING_OFF:
+            case NfcAdapter.STATE_TURNING_ON:
+                return true;
+            default:
+                return false;
+        }
     }
 
     @Override
     protected void handleUpdateState(BooleanState state, Object arg) {
-        if (mNfcAdapter == null) {
-            mNfcAdapter = NfcAdapter.getDefaultAdapter(mContext);
-        }
-        state.visible = mNfcAdapter != null;
-        state.value = mNfcAdapter != null && isEnabled();
+        state.visible = mSupportsNfc;
+        final int nfcState = getNfcAdapterState();
+        state.value = mSupportsNfc && isEnabled(nfcState);
+        state.enabled = mSupportsNfc && !isEnablingDisabling(nfcState);
+
         state.icon = ResourceIcon.get(state.value ?
                 R.drawable.ic_qs_nfc_on : R.drawable.ic_qs_nfc_off);
         state.label = mContext.getString(R.string.quick_settings_nfc_label);
@@ -110,12 +148,9 @@ public class NfcTile extends QSTile<QSTile.BooleanState> {
         if (mListening == listening) return;
         mListening = listening;
         if (listening) {
-            if (mNfcAdapter == null) {
-                mNfcAdapter = NfcAdapter.getDefaultAdapter(mContext);
-                refreshState();
-            }
             mContext.registerReceiver(mReceiver,
                     new IntentFilter(NfcAdapter.ACTION_ADAPTER_STATE_CHANGED));
+            refreshState();
         } else {
             mContext.unregisterReceiver(mReceiver);
         }