/*
 * Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer. 
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution. 
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "Logging.h"
#include "Page.h"
#include "Threading.h"
#include <errno.h>
#include <windows.h>
#include <wtf/HashMap.h>

namespace WebCore {

struct FunctionWithContext {
    MainThreadFunction* function;
    void* context;
    FunctionWithContext(MainThreadFunction* f = 0, void* c = 0) : function(f), context(c) { }
};

typedef Vector<FunctionWithContext> FunctionQueue;

static HWND threadingWindowHandle = 0;
static UINT threadingFiredMessage = 0;
const LPCWSTR kThreadingWindowClassName = L"ThreadingWindowClass";
static bool processingCustomThreadingMessage = false;

static Mutex& threadMapMutex()
{
    static Mutex mutex;
    return mutex;
}

static HashMap<DWORD, HANDLE>& threadMap()
{
    static HashMap<DWORD, HANDLE> map;
    return map;
}

static void storeThreadHandleByIdentifier(DWORD threadID, HANDLE threadHandle)
{
    MutexLocker locker(threadMapMutex());
    threadMap().add(threadID, threadHandle);
}

static HANDLE threadHandleForIdentifier(ThreadIdentifier id)
{
    MutexLocker locker(threadMapMutex());
    return threadMap().get(id);
}

static void clearThreadHandleForIdentifier(ThreadIdentifier id)
{
    MutexLocker locker(threadMapMutex());
    ASSERT(threadMap().contains(id));
    threadMap().remove(id);
}

ThreadIdentifier createThread(ThreadFunction entryPoint, void* data)
{
    DWORD threadIdentifier = 0;
    ThreadIdentifier threadID = 0;
    HANDLE hEvent = ::CreateEvent(0, FALSE, FALSE, 0);
    HANDLE threadHandle = ::CreateThread(0, 0, (LPTHREAD_START_ROUTINE)entryPoint, data, 0, &threadIdentifier);
    if (!threadHandle) {
        LOG_ERROR("Failed to create thread at entry point %p with data %p", entryPoint, data);
        return 0;
    }

    threadID = static_cast<ThreadIdentifier>(threadIdentifier);
    storeThreadHandleByIdentifier(threadIdentifier, threadHandle);

    LOG(Threading, "Created thread with thread id %u", threadID);
    return threadID;
}

int waitForThreadCompletion(ThreadIdentifier threadID, void** result)
{
    ASSERT(threadID);
    
    HANDLE threadHandle = threadHandleForIdentifier(threadID);
    if (!threadHandle)
        LOG_ERROR("ThreadIdentifier %u did not correspond to an active thread when trying to quit", threadID);
 
    DWORD joinResult = ::WaitForSingleObject(threadHandle, INFINITE);
    if (joinResult == WAIT_FAILED)
        LOG_ERROR("ThreadIdentifier %u was found to be deadlocked trying to quit", threadID);

    ::CloseHandle(threadHandle);
    clearThreadHandleForIdentifier(threadID);

    return joinResult;
}

void detachThread(ThreadIdentifier threadID)
{
    ASSERT(threadID);
    
    HANDLE threadHandle = threadHandleForIdentifier(threadID);
    if (threadHandle)
        ::CloseHandle(threadHandle);
    clearThreadHandleForIdentifier(threadID);
}

ThreadIdentifier currentThread()
{
    return static_cast<ThreadIdentifier>(::GetCurrentThreadId());
}

static Mutex& functionQueueMutex()
{
    static Mutex staticFunctionQueueMutex;
    return staticFunctionQueueMutex;
}

static FunctionQueue& functionQueue()
{
    static FunctionQueue staticFunctionQueue;
    return staticFunctionQueue;
}

static void callFunctionsOnMainThread()
{
    FunctionQueue queueCopy;
    {
        MutexLocker locker(functionQueueMutex());
        queueCopy.swap(functionQueue());
    }

    LOG(Threading, "Calling %u functions on the main thread", queueCopy.size());
    for (unsigned i = 0; i < queueCopy.size(); ++i)
        queueCopy[i].function(queueCopy[i].context);
}

LRESULT CALLBACK ThreadingWindowWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    if (message == threadingFiredMessage) {
        processingCustomThreadingMessage = true;
        callFunctionsOnMainThread();
        processingCustomThreadingMessage = false;
    } else
        return DefWindowProc(hWnd, message, wParam, lParam);
    return 0;
}

void initializeThreading()
{
    if (threadingWindowHandle)
        return;
    
    WNDCLASSEX wcex;
    memset(&wcex, 0, sizeof(WNDCLASSEX));
    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.lpfnWndProc    = ThreadingWindowWndProc;
    wcex.hInstance      = Page::instanceHandle();
    wcex.lpszClassName  = kThreadingWindowClassName;
    RegisterClassEx(&wcex);

    threadingWindowHandle = CreateWindow(kThreadingWindowClassName, 0, 0,
       CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, HWND_MESSAGE, 0, Page::instanceHandle(), 0);
    threadingFiredMessage = RegisterWindowMessage(L"com.apple.WebKit.MainThreadFired");
}
    
void callOnMainThread(MainThreadFunction* function, void* context)
{
    ASSERT(function);
    ASSERT(threadingWindowHandle);

    if (processingCustomThreadingMessage)
        LOG(Threading, "callOnMainThread() called recursively.  Beware of nested PostMessage()s");

    {
        MutexLocker locker(functionQueueMutex());
        functionQueue().append(FunctionWithContext(function, context));
    }

    PostMessage(threadingWindowHandle, threadingFiredMessage, 0, 0);
}

} // namespace WebCore