Expose the battery information through the BatteryModule class

The battery capacity is read through the Android base framework.

Change-Id: I17fb88fdc55c52ace5caa450af495cd36fc7e05f
diff --git a/Android.mk b/Android.mk
index 03e1f15..455895d 100644
--- a/Android.mk
+++ b/Android.mk
@@ -25,6 +25,8 @@
 LOCAL_SRC_FILES := \
         $(call all-subdir-java-files)
 
+LOCAL_JAVA_LIBRARIES := framework
+
 LOCAL_MODULE_TAGS := optional
 
 LOCAL_MODULE := com.fairphone.common
diff --git a/java/com/fairphone/common/modules/BatteryModule.java b/java/com/fairphone/common/modules/BatteryModule.java
new file mode 100644
index 0000000..e5c8cc4
--- /dev/null
+++ b/java/com/fairphone/common/modules/BatteryModule.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2018 Fairphone B.V.
+ *
+ * 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.fairphone.common.modules;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.content.Context;
+import android.util.Log;
+
+import com.android.internal.os.PowerProfile;
+
+/**
+ * A Fairphone 2 battery (module).
+ */
+public class BatteryModule extends Module {
+
+    private enum Battery {
+
+        BAT01("FP2-BAT01", 2420),
+        BAT02("FP2-BAT02", 2440);
+
+        /** Battery pack version identifier. */
+        @NonNull
+        final String versionId;
+
+        /** Battery pack design capacity in milliampere-hour. */
+        final int capacity;
+
+        Battery(@NonNull String versionId, int capacity) {
+            this.versionId = versionId;
+            this.capacity = capacity;
+        }
+    }
+
+    private static final String TAG = "BatteryModule";
+
+    /** Installed battery design capacity in milliampere-hour. */
+    private final int mDesignCapacity;
+
+    /**
+     * @return A fresh instance holding the installed battery module information, or {@code null}
+     * if the battery was not recognised.
+     */
+    @Nullable
+    public static BatteryModule getModule(@NonNull Context context) {
+        Battery battery = null;
+
+        final int capacity = (int) new PowerProfile(context).getBatteryCapacity();
+
+        for (Battery temp : Battery.values()) {
+            if (capacity == temp.capacity) {
+                battery = temp;
+                break;
+            }
+        }
+
+        if (battery == null) {
+            Log.e(TAG, "Unknown battery capacity: " + capacity);
+            return null;
+        } else {
+            return new BatteryModule(battery);
+        }
+    }
+
+    /**
+     * Create a new instance holding the installed battery module information.
+     */
+    private BatteryModule(@NonNull Battery battery) {
+        super(battery.versionId);
+
+        mDesignCapacity = battery.capacity;
+    }
+
+    /**
+     * @return The installed battery design capacity in milliampere-hour.
+     */
+    public int getDesignCapacity() {
+        return mDesignCapacity;
+    }
+
+}
diff --git a/java/com/fairphone/common/modules/Module.java b/java/com/fairphone/common/modules/Module.java
index 71f8e11..7eb072f 100644
--- a/java/com/fairphone/common/modules/Module.java
+++ b/java/com/fairphone/common/modules/Module.java
@@ -20,8 +20,6 @@
 
 /**
  * A Fairphone 2 module.
- * <p>
- * A plain old Java object that holds information about a module.
  */
 public abstract class Module {
 
@@ -29,16 +27,15 @@
     @NonNull
     private final String mVersionId;
 
-    /* package */ Module(@NonNull String versionId) {
+    Module(@NonNull String versionId) {
         mVersionId = versionId;
     }
 
     /**
-     * @return The installed, non-translatable module version identifier or
-     * <code>null</code>.
+     * @return The installed, non-translatable module version identifier or {@code null}.
      */
     @NonNull
-    public String getVersionId() {
+    public final String getVersionId() {
         return mVersionId;
     }