Add "canDial" check.

For bug #3164802.

CallManager allow a new phone call only if ALL of the following are true:

- Phone is not powered off
- There's no incoming or waiting call
- There's available call slot in either foreground or background
- The foreground call is ACTIVE or IDLE or DISCONNECTED.

Change-Id: I0124d600fd8c63b8c608301f3889b3faec47f1db

telephony/java/com/android/internal/telephony/CallManager.java

@@ -695,6 +695,10 @@ public final class CallManager {
             Log.d(LOG_TAG, this.toString());
         }
 
+        if (!canDial(phone)) {
+            throw new CallStateException("cannot dial in current state");
+        }
+
         if ( hasActiveFgCall() ) {
             Phone activePhone = getActiveFgCall().getPhone();
             boolean hasBgCall = !(activePhone.getBackgroundCall().isIdle());
@@ -747,6 +751,32 @@ public final class CallManager {
         }
     }
 
+    /**
+     * Phone can make a call only if ALL of the following are true:
+     *        - Phone is not powered off
+     *        - There's no incoming or waiting call
+     *        - There's available call slot in either foreground or background
+     *        - The foreground call is ACTIVE or IDLE or DISCONNECTED.
+     *          (We mainly need to make sure it *isn't* DIALING or ALERTING.)
+     * @param phone
+     * @return true if the phone can make a new call
+     */
+    private boolean canDial(Phone phone) {
+        int serviceState = phone.getServiceState().getState();
+        boolean hasRingingCall = hasActiveRingingCall();
+        boolean hasActiveCall = hasActiveFgCall();
+        boolean hasHoldingCall = hasActiveBgCall();
+        boolean allLinesTaken = hasActiveCall && hasHoldingCall;
+        Call.State fgCallState = getActiveFgCallState();
+
+        return (serviceState != ServiceState.STATE_POWER_OFF
+                && !hasRingingCall
+                && !allLinesTaken
+                && ((fgCallState == Call.State.ACTIVE)
+                    || (fgCallState == Call.State.IDLE)
+                    || (fgCallState == Call.State.DISCONNECTED)));
+            }
+
     /**
      * Whether or not the phone can do explicit call transfer in the current
      * phone state--that is, one call holding and one call active.