/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.server;
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import android.annotation.NonNull;
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import android.annotation.Nullable;
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import android.os.FileUtils;
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import android.util.Slog;
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import java.io.File;
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import java.io.IOException;
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/**
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* A specialized ExtconUEventObserver that on receiving a {@link UEvent} calls {@link
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* #updateState(ExtconInfo, String, S)} with the value of{@link #parseState(ExtconInfo, String)}.
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*
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* @param <S> the type of state to parse and update
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* @hide
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*/
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public abstract class ExtconStateObserver<S> extends ExtconUEventObserver {
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private static final String TAG = "ExtconStateObserver";
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private static final boolean LOG = false;
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/**
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* Parses the current state from the state file for {@code extconInfo}.
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*
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* @param extconInfo the extconInfo to parse state for
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* @see #parseState(ExtconInfo, String)
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* @see ExtconInfo#getStatePath()
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*/
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@Nullable
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public S parseStateFromFile(ExtconInfo extconInfo) throws IOException {
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String statePath = extconInfo.getStatePath();
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return parseState(
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extconInfo,
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FileUtils.readTextFile(new File(statePath), 0, null).trim());
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}
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@Override
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public void onUEvent(ExtconInfo extconInfo, UEvent event) {
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if (LOG) Slog.d(TAG, extconInfo.getName() + " UEVENT: " + event);
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String name = event.get("NAME");
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S state = parseState(extconInfo, event.get("STATE"));
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if (state != null) {
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updateState(extconInfo, name, state);
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}
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}
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/**
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* Subclasses of ExtconStateObserver should override this method update state for {@code
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* exconInfo} from an {@code UEvent}.
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*
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* @param extconInfo the external connection
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* @param eventName the {@code NAME} of the {@code UEvent}
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* @param state the{@code STATE} as parsed by {@link #parseState(ExtconInfo, String)}.
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*/
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public abstract void updateState(ExtconInfo extconInfo, String eventName, @NonNull S state);
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/**
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* Subclasses of ExtconStateObserver should override this method to parse the {@code STATE} from
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* an UEvent.
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*
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* @param extconInfo that matches the {@code DEVPATH} of {@code event}
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* @param state the {@code STATE} from a {@code UEvent}.
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* @return the parsed state. Return null if the state can not be parsed.
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*/
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@Nullable
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public abstract S parseState(ExtconInfo extconInfo, String state);
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}
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