/*
 * Copyright (C) 2007 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 android.ddm;

import org.apache.harmony.dalvik.ddmc.Chunk;
import org.apache.harmony.dalvik.ddmc.ChunkHandler;
import org.apache.harmony.dalvik.ddmc.DdmServer;
import org.apache.harmony.dalvik.ddmc.DdmVmInternal;
import android.util.Log;
import java.nio.ByteBuffer;

/**
 * Handle thread-related traffic.
 */
public class DdmHandleThread extends ChunkHandler {

    public static final int CHUNK_THEN = type("THEN");
    public static final int CHUNK_THCR = type("THCR");
    public static final int CHUNK_THDE = type("THDE");
    public static final int CHUNK_THST = type("THST");
    public static final int CHUNK_STKL = type("STKL");

    private static DdmHandleThread mInstance = new DdmHandleThread();


    /* singleton, do not instantiate */
    private DdmHandleThread() {}

    /**
     * Register for the messages we're interested in.
     */
    public static void register() {
        DdmServer.registerHandler(CHUNK_THEN, mInstance);
        DdmServer.registerHandler(CHUNK_THST, mInstance);
        DdmServer.registerHandler(CHUNK_STKL, mInstance);
    }

    /**
     * Called when the DDM server connects.  The handler is allowed to
     * send messages to the server.
     */
    public void connected() {}

    /**
     * Called when the DDM server disconnects.  Can be used to disable
     * periodic transmissions or clean up saved state.
     */
    public void disconnected() {}

    /**
     * Handle a chunk of data.
     */
    public Chunk handleChunk(Chunk request) {
        if (false)
            Log.v("ddm-thread", "Handling " + name(request.type) + " chunk");
        int type = request.type;

        if (type == CHUNK_THEN) {
            return handleTHEN(request);
        } else if (type == CHUNK_THST) {
            return handleTHST(request);
        } else if (type == CHUNK_STKL) {
            return handleSTKL(request);
        } else {
            throw new RuntimeException("Unknown packet "
                + ChunkHandler.name(type));
        }
    }

    /*
     * Handle a "THread notification ENable" request.
     */
    private Chunk handleTHEN(Chunk request) {
        ByteBuffer in = wrapChunk(request);

        boolean enable = (in.get() != 0);
        //Log.i("ddm-thread", "Thread notify enable: " + enable);

        DdmVmInternal.threadNotify(enable);
        return null;        // empty response
    }

    /*
     * Handle a "THread STatus" request.  This is constructed by the VM.
     */
    private Chunk handleTHST(Chunk request) {
        ByteBuffer in = wrapChunk(request);
        // currently nothing to read from "in"

        //Log.d("ddm-thread", "Thread status request");

        byte[] status = DdmVmInternal.getThreadStats();
        if (status != null)
            return new Chunk(CHUNK_THST, status, 0, status.length);
        else
            return createFailChunk(1, "Can't build THST chunk");
    }

    /*
     * Handle a STacK List request.
     *
     * This is done by threadId, which isn't great since those are
     * recycled.  We need a thread serial ID.  The Linux tid is an okay
     * answer as it's unlikely to recycle at the exact wrong moment.
     * However, we're using the short threadId in THST messages, so we
     * use them here for consistency.  (One thought is to keep the current
     * thread ID in the low 16 bits and somehow serialize the top 16 bits.)
     */
    private Chunk handleSTKL(Chunk request) {
        ByteBuffer in = wrapChunk(request);
        int threadId;

        threadId = in.getInt();

        //Log.d("ddm-thread", "Stack list request " + threadId);

        StackTraceElement[] trace = DdmVmInternal.getStackTraceById(threadId);
        if (trace == null) {
            return createFailChunk(1, "Stack trace unavailable");
        } else {
            return createStackChunk(trace, threadId);
        }
    }

    /*
     * Serialize a StackTraceElement[] into an STKL chunk.
     *
     * We include the threadId in the response so the other side doesn't have
     * to match up requests and responses as carefully.
     */
    private Chunk createStackChunk(StackTraceElement[] trace, int threadId) {
        int bufferSize = 0;

        bufferSize += 4;            // version, flags, whatever
        bufferSize += 4;            // thread ID
        bufferSize += 4;            // frame count
        for (StackTraceElement elem : trace) {
            bufferSize += 4 + elem.getClassName().length() * 2;
            bufferSize += 4 + elem.getMethodName().length() * 2;
            bufferSize += 4;
            if (elem.getFileName() != null)
                bufferSize += elem.getFileName().length() * 2;
            bufferSize += 4;        // line number
        }

        ByteBuffer out = ByteBuffer.allocate(bufferSize);
        out.putInt(0);
        out.putInt(threadId);
        out.putInt(trace.length);
        for (StackTraceElement elem : trace) {
            out.putInt(elem.getClassName().length());
            putString(out, elem.getClassName());
            out.putInt(elem.getMethodName().length());
            putString(out, elem.getMethodName());
            if (elem.getFileName() != null) {
                out.putInt(elem.getFileName().length());
                putString(out, elem.getFileName());
            } else {
                out.putInt(0);
            }
            out.putInt(elem.getLineNumber());
        }

        return new Chunk(CHUNK_STKL, out);
    }
}