/*
 * Copyright (C) 2008 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.server;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.os.PowerManager;
import android.os.PowerManager.WakeLock;
import android.os.UEventObserver;
import android.util.Slog;
import android.media.AudioManager;
import android.util.Log;

import java.io.File;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;

/**
 * <p>WiredAccessoryObserver monitors for a wired headset on the main board or dock.
 */
final class WiredAccessoryObserver extends UEventObserver {
    private static final String TAG = WiredAccessoryObserver.class.getSimpleName();
    private static final boolean LOG = true;
    private static final int BIT_HEADSET = (1 << 0);
    private static final int BIT_HEADSET_NO_MIC = (1 << 1);
    private static final int BIT_USB_HEADSET_ANLG = (1 << 2);
    private static final int BIT_USB_HEADSET_DGTL = (1 << 3);
    private static final int BIT_HDMI_AUDIO = (1 << 4);
    private static final int SUPPORTED_HEADSETS = (BIT_HEADSET|BIT_HEADSET_NO_MIC|
                                                   BIT_USB_HEADSET_ANLG|BIT_USB_HEADSET_DGTL|
                                                   BIT_HDMI_AUDIO);

    private final Object mLock = new Object();

    private final Context mContext;
    private final WakeLock mWakeLock;  // held while there is a pending route change
    private final AudioManager mAudioManager;
    private final List<UEventInfo> mUEventInfo;

    private int mHeadsetState;
    private int mPrevHeadsetState;
    private String mHeadsetName;

    public WiredAccessoryObserver(Context context) {
        mContext = context;

        PowerManager pm = (PowerManager)context.getSystemService(Context.POWER_SERVICE);
        mWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "WiredAccessoryObserver");
        mWakeLock.setReferenceCounted(false);
        mAudioManager = (AudioManager)context.getSystemService(Context.AUDIO_SERVICE);

        mUEventInfo = makeObservedUEventList();

        context.registerReceiver(new BootCompletedReceiver(),
            new IntentFilter(Intent.ACTION_BOOT_COMPLETED), null, null);
    }

    @Override
    public void onUEvent(UEventObserver.UEvent event) {
        if (LOG) Slog.v(TAG, "Headset UEVENT: " + event.toString());

        try {
            String devPath = event.get("DEVPATH");
            String name = event.get("SWITCH_NAME");
            int state = Integer.parseInt(event.get("SWITCH_STATE"));
            synchronized (mLock) {
                updateStateLocked(devPath, name, state);
            }
        } catch (NumberFormatException e) {
            Slog.e(TAG, "Could not parse switch state from event " + event);
        }
    }

    private void bootCompleted() {
        synchronized (mLock) {
            char[] buffer = new char[1024];
            mPrevHeadsetState = mHeadsetState;

            if (LOG) Slog.v(TAG, "init()");

            for (int i = 0; i < mUEventInfo.size(); ++i) {
                UEventInfo uei = mUEventInfo.get(i);
                try {
                    int curState;
                    FileReader file = new FileReader(uei.getSwitchStatePath());
                    int len = file.read(buffer, 0, 1024);
                    file.close();
                    curState = Integer.valueOf((new String(buffer, 0, len)).trim());

                    if (curState > 0) {
                        updateStateLocked(uei.getDevPath(), uei.getDevName(), curState);
                    }
                } catch (FileNotFoundException e) {
                    Slog.w(TAG, uei.getSwitchStatePath() +
                            " not found while attempting to determine initial switch state");
                } catch (Exception e) {
                    Slog.e(TAG, "" , e);
                }
            }
        }

        // At any given time accessories could be inserted
        // one on the board, one on the dock and one on HDMI:
        // observe three UEVENTs
        for (int i = 0; i < mUEventInfo.size(); ++i) {
            UEventInfo uei = mUEventInfo.get(i);
            startObserving("DEVPATH="+uei.getDevPath());
        }
    }

    private void updateStateLocked(String devPath, String name, int state) {
        for (int i = 0; i < mUEventInfo.size(); ++i) {
            UEventInfo uei = mUEventInfo.get(i);
            if (devPath.equals(uei.getDevPath())) {
                updateLocked(name, uei.computeNewHeadsetState(mHeadsetState, state));
                return;
            }
        }
    }

    private void updateLocked(String newName, int newState) {
        // Retain only relevant bits
        int headsetState = newState & SUPPORTED_HEADSETS;
        int usb_headset_anlg = headsetState & BIT_USB_HEADSET_ANLG;
        int usb_headset_dgtl = headsetState & BIT_USB_HEADSET_DGTL;
        int h2w_headset = headsetState & (BIT_HEADSET | BIT_HEADSET_NO_MIC);
        boolean h2wStateChange = true;
        boolean usbStateChange = true;
        // reject all suspect transitions: only accept state changes from:
        // - a: 0 heaset to 1 headset
        // - b: 1 headset to 0 headset
        if (LOG) Slog.v(TAG, "newState = "+newState+", headsetState = "+headsetState+","
            + "mHeadsetState = "+mHeadsetState);
        if (mHeadsetState == headsetState || ((h2w_headset & (h2w_headset - 1)) != 0)) {
            Log.e(TAG, "unsetting h2w flag");
            h2wStateChange = false;
        }
        // - c: 0 usb headset to 1 usb headset
        // - d: 1 usb headset to 0 usb headset
        if ((usb_headset_anlg >> 2) == 1 && (usb_headset_dgtl >> 3) == 1) {
            Log.e(TAG, "unsetting usb flag");
            usbStateChange = false;
        }
        if (!h2wStateChange && !usbStateChange) {
            Log.e(TAG, "invalid transition, returning ...");
            return;
        }

        mHeadsetName = newName;
        mPrevHeadsetState = mHeadsetState;
        mHeadsetState = headsetState;

        mWakeLock.acquire();

        Message msg = mHandler.obtainMessage(0, mHeadsetState, mPrevHeadsetState, mHeadsetName);
        mHandler.sendMessage(msg);
    }

    private void setDevicesState(
            int headsetState, int prevHeadsetState, String headsetName) {
        synchronized (mLock) {
            int allHeadsets = SUPPORTED_HEADSETS;
            for (int curHeadset = 1; allHeadsets != 0; curHeadset <<= 1) {
                if ((curHeadset & allHeadsets) != 0) {
                    setDeviceStateLocked(curHeadset, headsetState, prevHeadsetState, headsetName);
                    allHeadsets &= ~curHeadset;
                }
            }
        }
    }

    private void setDeviceStateLocked(int headset,
            int headsetState, int prevHeadsetState, String headsetName) {
        if ((headsetState & headset) != (prevHeadsetState & headset)) {
            int device;
            int state;

            if ((headsetState & headset) != 0) {
                state = 1;
            } else {
                state = 0;
            }

            if (headset == BIT_HEADSET) {
                device = AudioManager.DEVICE_OUT_WIRED_HEADSET;
            } else if (headset == BIT_HEADSET_NO_MIC){
                device = AudioManager.DEVICE_OUT_WIRED_HEADPHONE;
            } else if (headset == BIT_USB_HEADSET_ANLG) {
                device = AudioManager.DEVICE_OUT_ANLG_DOCK_HEADSET;
            } else if (headset == BIT_USB_HEADSET_DGTL) {
                device = AudioManager.DEVICE_OUT_DGTL_DOCK_HEADSET;
            } else if (headset == BIT_HDMI_AUDIO) {
                device = AudioManager.DEVICE_OUT_AUX_DIGITAL;
            } else {
                Slog.e(TAG, "setDeviceState() invalid headset type: "+headset);
                return;
            }

            if (LOG)
                Slog.v(TAG, "device "+headsetName+((state == 1) ? " connected" : " disconnected"));

            mAudioManager.setWiredDeviceConnectionState(device, state, headsetName);
        }
    }

    private static List<UEventInfo> makeObservedUEventList() {
        List<UEventInfo> retVal = new ArrayList<UEventInfo>();
        UEventInfo uei;

        // Monitor h2w
        uei = new UEventInfo("h2w", BIT_HEADSET, BIT_HEADSET_NO_MIC);
        if (uei.checkSwitchExists()) {
            retVal.add(uei);
        } else {
            Slog.w(TAG, "This kernel does not have wired headset support");
        }

        // Monitor USB
        uei = new UEventInfo("usb_audio", BIT_USB_HEADSET_ANLG, BIT_USB_HEADSET_DGTL);
        if (uei.checkSwitchExists()) {
            retVal.add(uei);
        } else {
            Slog.w(TAG, "This kernel does not have usb audio support");
        }

        // Monitor HDMI
        //
        // If the kernel has support for the "hdmi_audio" switch, use that.  It will be signalled
        // only when the HDMI driver has a video mode configured, and the downstream sink indicates
        // support for audio in its EDID.
        //
        // If the kernel does not have an "hdmi_audio" switch, just fall back on the older "hdmi"
        // switch instead.
        uei = new UEventInfo("hdmi_audio", BIT_HDMI_AUDIO, 0);
        if (uei.checkSwitchExists()) {
            retVal.add(uei);
        } else {
            uei = new UEventInfo("hdmi", BIT_HDMI_AUDIO, 0);
            if (uei.checkSwitchExists()) {
                retVal.add(uei);
            } else {
                Slog.w(TAG, "This kernel does not have HDMI audio support");
            }
        }

        return retVal;
    }

    private final Handler mHandler = new Handler(Looper.myLooper(), null, true) {
        @Override
        public void handleMessage(Message msg) {
            setDevicesState(msg.arg1, msg.arg2, (String)msg.obj);
            mWakeLock.release();
        }
    };

    private static final class UEventInfo {
        private final String mDevName;
        private final int mState1Bits;
        private final int mState2Bits;

        public UEventInfo(String devName, int state1Bits, int state2Bits) {
            mDevName = devName;
            mState1Bits = state1Bits;
            mState2Bits = state2Bits;
        }

        public String getDevName() { return mDevName; }

        public String getDevPath() {
            return String.format("/devices/virtual/switch/%s", mDevName);
        }

        public String getSwitchStatePath() {
            return String.format("/sys/class/switch/%s/state", mDevName);
        }

        public boolean checkSwitchExists() {
            File f = new File(getSwitchStatePath());
            return ((null != f) && f.exists());
        }

        public int computeNewHeadsetState(int headsetState, int switchState) {
            int preserveMask = ~(mState1Bits | mState2Bits);
            int setBits = ((switchState == 1) ? mState1Bits :
                          ((switchState == 2) ? mState2Bits : 0));

            return ((headsetState & preserveMask) | setBits);
        }
    }

    private final class BootCompletedReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            bootCompleted();
        }
    }
}