/*

 * Copyright (C) 2010 Google 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:

 *

 *     * Redistributions of source code must retain the above copyright

 * notice, this list of conditions and the following disclaimer.

 *     * 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.

 *     * Neither the name of Google Inc. 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 THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT

 * OWNER OR 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"

#if ENABLE(FILE_READER) || ENABLE(FILE_WRITER)

#include "FileStream.h"

#include "Blob.h"

#include "PlatformString.h"

namespace WebCore {

FileStream::FileStream(FileStreamClient* client)

    : m_client(client)

    , m_handle(invalidPlatformFileHandle)

    , m_bytesProcessed(0)

    , m_totalBytesToRead(0)

{

}

FileStream::~FileStream()

{

    ASSERT(!isHandleValid(m_handle));

}

void FileStream::start()

{

    ASSERT(!isMainThread());

    m_client->didStart();

}

void FileStream::stop()

{

    ASSERT(!isMainThread());

    close();

    m_client->didStop();

}

void FileStream::openForRead(Blob* blob)

{

    ASSERT(!isMainThread());

    if (isHandleValid(m_handle))

        return;

    // FIXME: Need to handle multiple items that may include non-file ones when BlobBuilder is introduced.

    ASSERT(blob->items().size() >= 1);

    const FileBlobItem* fileItem = blob->items().at(0)->toFileBlobItem();

    if (!fileItem) {

        ASSERT(false);

        m_client->didFail(NOT_READABLE_ERR);

        return;

    }

    // Check if the file exists by querying its modification time. We choose not to call fileExists() in order to save an

    // extra file system call when the modification time is needed to check the validity of the sliced file blob.

    // Per the spec, we need to return different error codes to differentiate between non-existent file and permission error.

    // openFile() could not tell use the failure reason.

    time_t currentModificationTime;

    if (!getFileModificationTime(fileItem->path(), currentModificationTime)) {

        m_client->didFail(NOT_FOUND_ERR);

        return;

    }

    // Open the file blob.

    m_handle = openFile(fileItem->path(), OpenForRead);

    if (!isHandleValid(m_handle)) {

        m_client->didFail(NOT_READABLE_ERR);

        return;

    }

#if ENABLE(BLOB_SLICE)

    const FileRangeBlobItem* fileRangeItem = fileItem->toFileRangeBlobItem();

    if (fileRangeItem) {

        // Check the modificationt time for the possible file change.

        if (static_cast<time_t>(fileRangeItem->snapshotModificationTime()) != currentModificationTime) {

            m_client->didFail(NOT_READABLE_ERR);

            return;

        }

        // Jump to the beginning position if the file has been sliced.

        if (fileRangeItem->start() > 0) {

            if (seekFile(m_handle, fileRangeItem->start(), SeekFromBeginning) < 0) {

                m_client->didFail(NOT_READABLE_ERR);

                return;

            }

        }

    }

#endif

    // Get the size.

    m_totalBytesToRead = blob->size();

    m_client->didGetSize(m_totalBytesToRead);

}

void FileStream::openForWrite(const String&)

{

    ASSERT(!isMainThread());

    // FIXME: to be implemented.

}

void FileStream::close()

{

    ASSERT(!isMainThread());

    if (isHandleValid(m_handle)) {

        closeFile(m_handle);

        m_handle = invalidPlatformFileHandle;

    }

}

void FileStream::read(char* buffer, int length)

{

    ASSERT(!isMainThread());

    if (!isHandleValid(m_handle)) {

        m_client->didFail(NOT_READABLE_ERR);

        return;

    }

    if (m_bytesProcessed >= m_totalBytesToRead) {

        m_client->didFinish();

        return;

    }

    long long remaining = m_totalBytesToRead - m_bytesProcessed;

    int bytesToRead = (remaining < length) ? static_cast<int>(remaining) : length;

    int bytesRead = readFromFile(m_handle, buffer, bytesToRead);

    if (bytesRead < 0) {

        m_client->didFail(NOT_READABLE_ERR);

        return;

    }

    if (!bytesRead) {

        m_client->didFinish();

        return;

    }

    m_bytesProcessed += bytesRead;

    m_client->didRead(buffer, bytesRead);

}

void FileStream::write(Blob*, long long, int)

{

    ASSERT(!isMainThread());

    // FIXME: to be implemented.

}

void FileStream::truncate(long long)

{

    ASSERT(!isMainThread());

    // FIXME: to be implemented.

}

} // namespace WebCore

#endif // ENABLE(FILE_READER) || ENABLE(FILE_WRITER)