/*
 * 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"
#include "FileReader.h"

#include "DOMException.h"
#include "EventLoop.h"
#include "EventNames.h"
#include "Exception.h"
#include "ExceptionCode.h"
#include "File.h"
#include "Logging.h"
#include "ProgressEvent.h"
#include "ScriptExecutionContext.h"
#include <JavaScriptCore/ArrayBuffer.h>
#include <wtf/IsoMallocInlines.h>
#include <wtf/text/CString.h>

namespace WebCore {

WTF_MAKE_ISO_ALLOCATED_IMPL(FileReader);

// Fire the progress event at least every 50ms.
static const auto progressNotificationInterval = 50_ms;

Ref<FileReader> FileReader::create(ScriptExecutionContext& context)
{
    auto fileReader = adoptRef(*new FileReader(context));
    fileReader->suspendIfNeeded();
    return fileReader;
}

FileReader::FileReader(ScriptExecutionContext& context)
    : ActiveDOMObject(&context)
{
}

FileReader::~FileReader()
{
    if (m_loader)
        m_loader->cancel();
}

const char* FileReader::activeDOMObjectName() const
{
    return "FileReader";
}

void FileReader::stop()
{
    m_pendingTasks.clear();
    if (m_loader) {
        m_loader->cancel();
        m_loader = nullptr;
    }
    m_state = DONE;
}

bool FileReader::virtualHasPendingActivity() const
{
    return m_state == LOADING;
}

ExceptionOr<void> FileReader::readAsArrayBuffer(Blob* blob)
{
    if (!blob)
        return { };

    LOG(FileAPI, "FileReader: reading as array buffer: %s %s\n", blob->url().string().utf8().data(), is<File>(*blob) ? downcast<File>(*blob).path().utf8().data() : "");

    return readInternal(*blob, FileReaderLoader::ReadAsArrayBuffer);
}

ExceptionOr<void> FileReader::readAsBinaryString(Blob* blob)
{
    if (!blob)
        return { };

    LOG(FileAPI, "FileReader: reading as binary: %s %s\n", blob->url().string().utf8().data(), is<File>(*blob) ? downcast<File>(*blob).path().utf8().data() : "");

    return readInternal(*blob, FileReaderLoader::ReadAsBinaryString);
}

ExceptionOr<void> FileReader::readAsText(Blob* blob, const String& encoding)
{
    if (!blob)
        return { };

    LOG(FileAPI, "FileReader: reading as text: %s %s\n", blob->url().string().utf8().data(), is<File>(*blob) ? downcast<File>(*blob).path().utf8().data() : "");

    m_encoding = encoding;
    return readInternal(*blob, FileReaderLoader::ReadAsText);
}

ExceptionOr<void> FileReader::readAsDataURL(Blob* blob)
{
    if (!blob)
        return { };

    LOG(FileAPI, "FileReader: reading as data URL: %s %s\n", blob->url().string().utf8().data(), is<File>(*blob) ? downcast<File>(*blob).path().utf8().data() : "");

    return readInternal(*blob, FileReaderLoader::ReadAsDataURL);
}

ExceptionOr<void> FileReader::readInternal(Blob& blob, FileReaderLoader::ReadType type)
{
    // If multiple concurrent read methods are called on the same FileReader, InvalidStateError should be thrown when the state is LOADING.
    if (m_state == LOADING)
        return Exception { InvalidStateError };

    m_blob = &blob;
    m_readType = type;
    m_state = LOADING;
    m_error = nullptr;

    m_loader = makeUnique<FileReaderLoader>(m_readType, static_cast<FileReaderLoaderClient*>(this));
    m_loader->setEncoding(m_encoding);
    m_loader->setDataType(m_blob->type());
    m_loader->start(scriptExecutionContext(), blob);

    return { };
}

void FileReader::abort()
{
    LOG(FileAPI, "FileReader: aborting\n");

    if (m_aborting || m_state != LOADING)
        return;
    m_aborting = true;

    // Schedule to have the abort done later since abort() might be called from the event handler and we do not want the resource loading code to be in the stack.
    m_pendingTasks.clear();
    enqueueTask([this] {
        ASSERT(m_state != DONE);

        stop();
        m_aborting = false;

        m_error = DOMException::create(Exception { AbortError });

        fireEvent(eventNames().errorEvent);
        fireEvent(eventNames().abortEvent);
        fireEvent(eventNames().loadendEvent);
    });
}

void FileReader::didStartLoading()
{
    enqueueTask([this] {
        fireEvent(eventNames().loadstartEvent);
    });
}

void FileReader::didReceiveData()
{
    enqueueTask([this] {
        auto now = MonotonicTime::now();
        if (std::isnan(m_lastProgressNotificationTime)) {
            m_lastProgressNotificationTime = now;
            return;
        }
        if (now - m_lastProgressNotificationTime > progressNotificationInterval) {
            fireEvent(eventNames().progressEvent);
            m_lastProgressNotificationTime = now;
        }
    });
}

void FileReader::didFinishLoading()
{
    if (m_aborting)
        return;

    enqueueTask([this] {
        ASSERT(m_state != DONE);
        m_state = DONE;

        fireEvent(eventNames().progressEvent);
        fireEvent(eventNames().loadEvent);
        fireEvent(eventNames().loadendEvent);
    });
}

void FileReader::didFail(ExceptionCode errorCode)
{
    // If we're aborting, do not proceed with normal error handling since it is covered in aborting code.
    if (m_aborting)
        return;

    enqueueTask([this, errorCode] {
        ASSERT(m_state != DONE);
        m_state = DONE;

        m_error = DOMException::create(Exception { errorCode });

        fireEvent(eventNames().errorEvent);
        fireEvent(eventNames().loadendEvent);
    });
}

void FileReader::fireEvent(const AtomString& type)
{
    RELEASE_ASSERT(isAllowedToRunScript());
    dispatchEvent(ProgressEvent::create(type, true, m_loader ? m_loader->bytesLoaded() : 0, m_loader ? m_loader->totalBytes() : 0));
}

Optional<Variant<String, RefPtr<JSC::ArrayBuffer>>> FileReader::result() const
{
    if (!m_loader || m_error)
        return WTF::nullopt;
    if (m_readType == FileReaderLoader::ReadAsArrayBuffer) {
        auto result = m_loader->arrayBufferResult();
        if (!result)
            return WTF::nullopt;
        return { result };
    }
    String result = m_loader->stringResult();
    if (result.isNull())
        return WTF::nullopt;
    return { WTFMove(result) };
}

void FileReader::enqueueTask(Function<void()>&& task)
{
    auto* context = scriptExecutionContext();
    if (!context)
        return;

    static uint64_t taskIdentifierSeed = 0;
    uint64_t taskIdentifier = ++taskIdentifierSeed;
    m_pendingTasks.add(taskIdentifier, WTFMove(task));
    context->eventLoop().queueTask(TaskSource::FileReading, [this, protectedThis = makeRef(*this), pendingActivity = makePendingActivity(*this), taskIdentifier] {
        auto task = m_pendingTasks.take(taskIdentifier);
        if (task)
            task();
    });
}

} // namespace WebCore