// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/url_request/url_request_job.h"

#include "base/message_loop.h"
#include "base/string_util.h"
#include "googleurl/src/gurl.h"
#include "net/base/auth.h"
#include "net/base/net_errors.h"
#include "net/url_request/url_request.h"
#include "net/url_request/url_request_job_metrics.h"
#include "net/url_request/url_request_job_tracker.h"

using base::Time;
using base::TimeTicks;

// Buffer size allocated when de-compressing data.
static const int kFilterBufSize = 32 * 1024;

URLRequestJob::URLRequestJob(URLRequest* request)
    : request_(request),
      done_(false),
      read_buffer_(NULL),
      read_buffer_len_(0),
      has_handled_response_(false),
      expected_content_size_(-1) {
  is_profiling_ = request->enable_profiling();
  if (is_profiling()) {
    metrics_.reset(new URLRequestJobMetrics());
    metrics_->start_time_ = TimeTicks::Now();
  }
  g_url_request_job_tracker.AddNewJob(this);
}

URLRequestJob::~URLRequestJob() {
  g_url_request_job_tracker.RemoveJob(this);
}

void URLRequestJob::Kill() {
  // Make sure the request is notified that we are done.  We assume that the
  // request took care of setting its error status before calling Kill.
  if (request_)
    NotifyCanceled();
}

void URLRequestJob::DetachRequest() {
  request_ = NULL;
}

void URLRequestJob::SetupFilter() {
  std::vector<Filter::FilterType> encoding_types;
  if (GetContentEncodings(&encoding_types)) {
    filter_.reset(Filter::Factory(encoding_types, kFilterBufSize));
    if (filter_.get()) {
      std::string mime_type;
      GetMimeType(&mime_type);
      filter_->SetURL(request_->url());
      filter_->SetMimeType(mime_type);
      // Approximate connect time with request_time. If it is not cached, then
      // this is a good approximation for when the first bytes went on the
      // wire.
      filter_->SetConnectTime(request_->response_info_.request_time);
    }
  }
}

void URLRequestJob::GetAuthChallengeInfo(
    scoped_refptr<net::AuthChallengeInfo>* auth_info) {
  // This will only be called if NeedsAuth() returns true, in which
  // case the derived class should implement this!
  NOTREACHED();
}

void URLRequestJob::SetAuth(const std::wstring& username,
                            const std::wstring& password) {
  // This will only be called if NeedsAuth() returns true, in which
  // case the derived class should implement this!
  NOTREACHED();
}

void URLRequestJob::CancelAuth() {
  // This will only be called if NeedsAuth() returns true, in which
  // case the derived class should implement this!
  NOTREACHED();
}

void URLRequestJob::ContinueDespiteLastError() {
  // Implementations should know how to recover from errors they generate.
  // If this code was reached, we are trying to recover from an error that
  // we don't know how to recover from.
  NOTREACHED();
}

// This function calls ReadData to get stream data. If a filter exists, passes
// the data to the attached filter. Then returns the output from filter back to
// the caller.
bool URLRequestJob::Read(char* buf, int buf_size, int *bytes_read) {
  bool rv = false;

  DCHECK_LT(buf_size, 1000000);  // sanity check
  DCHECK(buf);
  DCHECK(bytes_read);

  *bytes_read = 0;

  // Skip Filter if not present
  if (!filter_.get()) {
    rv = ReadRawData(buf, buf_size, bytes_read);
    if (rv && *bytes_read > 0)
      RecordBytesRead(*bytes_read);
  } else {
    // Save the caller's buffers while we do IO
    // in the filter's buffers.
    read_buffer_ = buf;
    read_buffer_len_ = buf_size;

    if (ReadFilteredData(bytes_read)) {
      rv = true;   // we have data to return
    } else {
      rv = false;  // error, or a new IO is pending
    }
  }
  if (rv && *bytes_read == 0)
    NotifyDone(URLRequestStatus());
  return rv;
}

bool URLRequestJob::ReadRawDataForFilter(int *bytes_read) {
  bool rv = false;

  DCHECK(bytes_read);
  DCHECK(filter_.get());

  *bytes_read = 0;

  // Get more pre-filtered data if needed.
  // TODO(mbelshe): is it possible that the filter needs *MORE* data
  //    when there is some data already in the buffer?
  if (!filter_->stream_data_len() && !is_done()) {
    char* stream_buffer = filter_->stream_buffer();
    int stream_buffer_size = filter_->stream_buffer_size();
    rv = ReadRawData(stream_buffer, stream_buffer_size, bytes_read);
    if (rv && *bytes_read > 0)
      RecordBytesRead(*bytes_read);
  }
  return rv;
}

void URLRequestJob::FilteredDataRead(int bytes_read) {
  DCHECK(filter_.get());  // don't add data if there is no filter
  filter_->FlushStreamBuffer(bytes_read);
}

bool URLRequestJob::ReadFilteredData(int *bytes_read) {
  DCHECK(filter_.get());  // don't add data if there is no filter
  DCHECK(read_buffer_ != NULL);  // we need to have a buffer to fill
  DCHECK(read_buffer_len_ > 0);  // sanity check
  DCHECK(read_buffer_len_ < 1000000);  // sanity check

  bool rv = false;
  *bytes_read = 0;

  if (is_done())
    return true;

  if (!filter_->stream_data_len()) {
    // We don't have any raw data to work with, so
    // read from the socket.

    int filtered_data_read;
    if (ReadRawDataForFilter(&filtered_data_read)) {
      if (filtered_data_read > 0) {
        filter_->FlushStreamBuffer(filtered_data_read);
      } else {
        return true;  // EOF
      }
    } else {
      return false;  // IO Pending (or error)
    }
  }

  if (filter_->stream_data_len() && !is_done()) {
    // Get filtered data
    int filtered_data_len = read_buffer_len_;
    Filter::FilterStatus status;
    status = filter_->ReadData(read_buffer_, &filtered_data_len);
    switch (status) {
      case Filter::FILTER_DONE: {
        *bytes_read = filtered_data_len;
        rv = true;
        break;
      }
      case Filter::FILTER_NEED_MORE_DATA: {
        // We have finished filtering all data currently in the buffer.
        // There might be some space left in the output buffer. One can
        // consider reading more data from the stream to feed the filter
        // and filling up the output buffer. This leads to more complicated
        // buffer management and data notification mechanisms.
        // We can revisit this issue if there is a real perf need.
        if (filtered_data_len > 0) {
          *bytes_read = filtered_data_len;
          rv = true;
        } else {
          // Read again since we haven't received enough data yet (e.g., we may
          // not have a complete gzip header yet)
          rv = ReadFilteredData(bytes_read);
        }
        break;
      }
      case Filter::FILTER_OK: {
        *bytes_read = filtered_data_len;
        rv = true;
        break;
      }
      case Filter::FILTER_ERROR: {
        // TODO: Figure out a better error code.
        NotifyDone(URLRequestStatus(URLRequestStatus::FAILED, net::ERR_FAILED));
        rv = false;
        break;
      }
      default: {
        NOTREACHED();
        rv = false;
        break;
      }
    }
  } else {
    // we are done, or there is no data left.
    rv = true;
  }

  if (rv) {
    // When we successfully finished a read, we no longer need to
    // save the caller's buffers.  For debugging purposes, we clear
    // them out.
    read_buffer_ = NULL;
    read_buffer_len_ = 0;
  }
  return rv;
}

bool URLRequestJob::ReadRawData(char* buf, int buf_size, int *bytes_read) {
  DCHECK(bytes_read);
  *bytes_read = 0;
  NotifyDone(URLRequestStatus());
  return false;
}

URLRequestJobMetrics* URLRequestJob::RetrieveMetrics() {
  if (is_profiling())
    return metrics_.release();
  else
    return NULL;
}

void URLRequestJob::NotifyHeadersComplete() {
  if (!request_ || !request_->delegate())
    return;  // The request was destroyed, so there is no more work to do.

  if (has_handled_response_)
    return;

  DCHECK(!request_->status().is_io_pending());

  // Initialize to the current time, and let the subclass optionally override
  // the time stamps if it has that information.  The default request_time is
  // set by URLRequest before it calls our Start method.
  request_->response_info_.response_time = Time::Now();
  GetResponseInfo(&request_->response_info_);

  // When notifying the delegate, the delegate can release the request
  // (and thus release 'this').  After calling to the delgate, we must
  // check the request pointer to see if it still exists, and return
  // immediately if it has been destroyed.  self_preservation ensures our
  // survival until we can get out of this method.
  scoped_refptr<URLRequestJob> self_preservation = this;

  int http_status_code;
  GURL new_location;
  if (IsRedirectResponse(&new_location, &http_status_code)) {
    const GURL& url = request_->url();

    // Move the reference fragment of the old location to the new one if the
    // new one has none. This duplicates mozilla's behavior.
    if (url.is_valid() && url.has_ref() && !new_location.has_ref()) {
      GURL::Replacements replacements;
      // Reference the |ref| directly out of the original URL to avoid a
      // malloc.
      replacements.SetRef(url.spec().data(),
                          url.parsed_for_possibly_invalid_spec().ref);
      new_location = new_location.ReplaceComponents(replacements);
    }

    // Toggle this flag to true so the consumer can access response headers.
    // Then toggle it back if we choose to follow the redirect.
    has_handled_response_ = true;
    request_->delegate()->OnReceivedRedirect(request_, new_location);

    // Ensure that the request wasn't destroyed in OnReceivedRedirect
    if (!request_ || !request_->delegate())
      return;

    // If we were not cancelled, then follow the redirect.
    if (request_->status().is_success()) {
      has_handled_response_ = false;
      FollowRedirect(new_location, http_status_code);
      return;
    }
  } else if (NeedsAuth()) {
    scoped_refptr<net::AuthChallengeInfo> auth_info;
    GetAuthChallengeInfo(&auth_info);
    // Need to check for a NULL auth_info because the server may have failed
    // to send a challenge with the 401 response.
    if (auth_info) {
      request_->delegate()->OnAuthRequired(request_, auth_info);
      // Wait for SetAuth or CancelAuth to be called.
      return;
    }
  }

  has_handled_response_ = true;
  if (request_->status().is_success())
    SetupFilter();

  if (!filter_.get()) {
    std::string content_length;
    request_->GetResponseHeaderByName("content-length", &content_length);
    if (!content_length.empty())
      expected_content_size_ = StringToInt64(content_length);
  }

  request_->delegate()->OnResponseStarted(request_);
}

void URLRequestJob::NotifyStartError(const URLRequestStatus &status) {
  DCHECK(!has_handled_response_);
  has_handled_response_ = true;
  if (request_) {
    request_->set_status(status);
    if (request_->delegate())
      request_->delegate()->OnResponseStarted(request_);
  }
}

void URLRequestJob::NotifyReadComplete(int bytes_read) {
  if (!request_ || !request_->delegate())
    return;  // The request was destroyed, so there is no more work to do.

  // TODO(darin): Bug 1004233. Re-enable this test once all of the chrome
  // unit_tests have been fixed to not trip this.
  //DCHECK(!request_->status().is_io_pending());

  // The headers should be complete before reads complete
  DCHECK(has_handled_response_);

  if (bytes_read > 0)
    RecordBytesRead(bytes_read);

  // Don't notify if we had an error.
  if (!request_->status().is_success())
    return;

  // When notifying the delegate, the delegate can release the request
  // (and thus release 'this').  After calling to the delgate, we must
  // check the request pointer to see if it still exists, and return
  // immediately if it has been destroyed.  self_preservation ensures our
  // survival until we can get out of this method.
  scoped_refptr<URLRequestJob> self_preservation = this;

  if (filter_.get()) {
    // Tell the filter that it has more data
    FilteredDataRead(bytes_read);

    // Filter the data.
    int filter_bytes_read = 0;
    if (ReadFilteredData(&filter_bytes_read))
      request_->delegate()->OnReadCompleted(request_, filter_bytes_read);
  } else {
    request_->delegate()->OnReadCompleted(request_, bytes_read);
  }
}

void URLRequestJob::NotifyDone(const URLRequestStatus &status) {
  DCHECK(!done_) << "Job sending done notification twice";
  if (done_)
    return;
  done_ = true;

  if (is_profiling() && metrics_->total_bytes_read_ > 0) {
    // There are valid IO statistics. Fill in other fields of metrics for
    // profiling consumers to retrieve information.
    metrics_->original_url_.reset(new GURL(request_->original_url()));
    metrics_->end_time_ = TimeTicks::Now();
    metrics_->success_ = status.is_success();

    if (!(request_->original_url() == request_->url())) {
      metrics_->url_.reset(new GURL(request_->url()));
    }
  } else {
    metrics_.reset();
  }


  // Unless there was an error, we should have at least tried to handle
  // the response before getting here.
  DCHECK(has_handled_response_ || !status.is_success());

  // In the success case, we cannot send the NotifyDone now.  It can only be
  // sent after the request is completed, because otherwise we can get the
  // NotifyDone() called while the delegate is still accessing the request.
  // In the case of an error, we are fre
  if (status.is_success()) {
    // If there is data left in the filter, then something is probably wrong.
    DCHECK(!FilterHasData());
  }

  // As with NotifyReadComplete, we need to take care to notice if we were
  // destroyed during a delegate callback.
  if (request_) {
    request_->set_is_pending(false);
    // With async IO, it's quite possible to have a few outstanding
    // requests.  We could receive a request to Cancel, followed shortly
    // by a successful IO.  For tracking the status(), once there is
    // an error, we do not change the status back to success.  To
    // enforce this, only set the status if the job is so far
    // successful.
    if (request_->status().is_success())
      request_->set_status(status);
  }

  g_url_request_job_tracker.OnJobDone(this, status);

  // Complete this notification later.  This prevents us from re-entering the
  // delegate if we're done because of a synchronous call.
  MessageLoop::current()->PostTask(FROM_HERE, NewRunnableMethod(
      this, &URLRequestJob::CompleteNotifyDone));
}

void URLRequestJob::CompleteNotifyDone() {
  // Check if we should notify the delegate that we're done because of an error.
  if (request_ &&
      !request_->status().is_success() &&
      request_->delegate()) {
    // We report the error differently depending on whether we've called
    // OnResponseStarted yet.
    if (has_handled_response_) {
      // We signal the error by calling OnReadComplete with a bytes_read of -1.
      request_->delegate()->OnReadCompleted(request_, -1);
    } else {
      has_handled_response_ = true;
      request_->delegate()->OnResponseStarted(request_);
    }
  }
}

void URLRequestJob::NotifyCanceled() {
  if (!done_) {
    NotifyDone(URLRequestStatus(URLRequestStatus::CANCELED,
                                net::ERR_ABORTED));
  }
}

bool URLRequestJob::FilterHasData() {
    return filter_.get() && filter_->stream_data_len();
}

void URLRequestJob::FollowRedirect(const GURL& location,
                                   int http_status_code) {
  g_url_request_job_tracker.OnJobRedirect(this, location, http_status_code);
  Kill();
  // Kill could have notified the Delegate and destroyed the request.
  if (!request_)
    return;

  int rv = request_->Redirect(location, http_status_code);
  if (rv != net::OK)
    NotifyStartError(URLRequestStatus(URLRequestStatus::FAILED, rv));
}

void URLRequestJob::RecordBytesRead(int bytes_read) {
  if (is_profiling()) {
    ++(metrics_->number_of_read_IO_);
    metrics_->total_bytes_read_ += bytes_read;
  }
  g_url_request_job_tracker.OnBytesRead(this, bytes_read);
}

const URLRequestStatus URLRequestJob::GetStatus() {
  if (request_)
    return request_->status();
  // If the request is gone, we must be cancelled.
  return URLRequestStatus(URLRequestStatus::CANCELED,
                          net::ERR_ABORTED);
}

void URLRequestJob::SetStatus(const URLRequestStatus &status) {
  if (request_)
    request_->set_status(status);
}