Use mapped IDs for calls

With this CL each client gets a unique ID to represent calls.
This has a couple of benefits:
  - avoids one client from modifying another clients call
  - allows for stricter validation of input
  - allows a call to handed off to a different call service
    (with a different call ID)

Bug: 13643568
Change-Id: I6e2039aead5723d01f9442a4e54f5e616711a3b3
diff --git a/src/com/android/telecomm/CallIdMapper.java b/src/com/android/telecomm/CallIdMapper.java
new file mode 100644
index 0000000..e5ed286
--- /dev/null
+++ b/src/com/android/telecomm/CallIdMapper.java
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.telecomm;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.HashBiMap;
+
+import java.util.UUID;
+
+/** Utility to map {@link Call} objects to unique IDs. IDs are generated when a call is added. */
+class CallIdMapper {
+    private final HashBiMap<String, Call> mCalls = HashBiMap.create();
+    private final String mCallIdPrefix;
+
+    CallIdMapper(String callIdPrefix) {
+        ThreadUtil.checkOnMainThread();
+        mCallIdPrefix = callIdPrefix + "@";
+    }
+
+    void addCall(Call call) {
+        ThreadUtil.checkOnMainThread();
+        Preconditions.checkNotNull(call);
+        String callId = mCallIdPrefix + UUID.randomUUID();
+        mCalls.put(callId, call);
+    }
+
+    void removeCall(Call call) {
+        ThreadUtil.checkOnMainThread();
+        Preconditions.checkNotNull(call);
+        mCalls.inverse().remove(call);
+    }
+
+    String getCallId(Call call) {
+        ThreadUtil.checkOnMainThread();
+        Preconditions.checkNotNull(call);
+        return mCalls.inverse().get(call);
+    }
+
+    Call getCall(Object objId) {
+        ThreadUtil.checkOnMainThread();
+
+        String callId = null;
+        if (objId instanceof String) {
+            callId = (String) objId;
+        }
+        Preconditions.checkArgument(isValidCallId(callId));
+
+        return mCalls.get(callId);
+    }
+
+    void checkValidCallId(String callId) {
+        // Note, no need for thread check, this method is thread safe.
+        if (!isValidCallId(callId)) {
+            Log.wtf(this, "%s is not a valid call ID", callId);
+            throw new IllegalArgumentException("Invalid call ID.");
+        }
+    }
+
+    boolean isValidCallId(String callId) {
+        // Note, no need for thread check, this method is thread safe.
+        return callId != null && callId.startsWith(mCallIdPrefix);
+    }
+}