// Copyright 2015 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 "media/blink/resource_multibuffer_data_provider.h"

#include <stddef.h>
#include <utility>

#include "base/bind.h"
#include "base/bits.h"
#include "base/callback_helpers.h"
#include "base/message_loop/message_loop.h"
#include "base/metrics/histogram.h"
#include "base/strings/string_number_conversions.h"
#include "media/blink/active_loader.h"
#include "media/blink/cache_util.h"
#include "media/blink/media_blink_export.h"
#include "media/blink/url_index.h"
#include "net/http/http_byte_range.h"
#include "net/http/http_request_headers.h"
#include "third_party/WebKit/public/platform/WebURLError.h"
#include "third_party/WebKit/public/platform/WebURLResponse.h"

using blink::WebFrame;
using blink::WebString;
using blink::WebURLError;
using blink::WebURLLoader;
using blink::WebURLLoaderOptions;
using blink::WebURLRequest;
using blink::WebURLResponse;

namespace media {

// The number of milliseconds to wait before retrying a failed load.
const int kLoaderFailedRetryDelayMs = 250;

// The number of milliseconds to wait before retrying when the server
// decides to not give us all the data at once.
const int kLoaderPartialRetryDelayMs = 25;

const int kHttpOK = 200;
const int kHttpPartialContent = 206;
const int kHttpRangeNotSatisfiable = 416;
const int kMaxRetries = 3;

ResourceMultiBufferDataProvider::ResourceMultiBufferDataProvider(
    UrlData* url_data,
    MultiBufferBlockId pos)
    : pos_(pos),
      url_data_(url_data),
      retries_(0),
      cors_mode_(url_data->cors_mode()),
      origin_(url_data->url().GetOrigin()),
      weak_factory_(this) {
  DCHECK(url_data_) << " pos = " << pos;
  DCHECK_GE(pos, 0);
}

void ResourceMultiBufferDataProvider::Start() {
  // Prepare the request.
  WebURLRequest request(url_data_->url());
  // TODO(mkwst): Split this into video/audio.
  request.setRequestContext(WebURLRequest::RequestContextVideo);

  DVLOG(1) << __FUNCTION__ << " @ " << byte_pos();
  if (url_data_->length() > 0) {
    DCHECK_LT(byte_pos(), url_data_->length()) << " " << url_data_->url();
  }

  request.setHTTPHeaderField(
      WebString::fromUTF8(net::HttpRequestHeaders::kRange),
      WebString::fromUTF8(
          net::HttpByteRange::RightUnbounded(byte_pos()).GetHeaderValue()));

  url_data_->frame()->setReferrerForRequest(request, blink::WebURL());

  // Disable compression, compression for audio/video doesn't make sense...
  request.setHTTPHeaderField(
      WebString::fromUTF8(net::HttpRequestHeaders::kAcceptEncoding),
      WebString::fromUTF8("identity;q=1, *;q=0"));

  // Check for our test WebURLLoader.
  scoped_ptr<WebURLLoader> loader;
  if (test_loader_) {
    loader = std::move(test_loader_);
  } else {
    WebURLLoaderOptions options;
    if (url_data_->cors_mode() == UrlData::CORS_UNSPECIFIED) {
      options.allowCredentials = true;
      options.crossOriginRequestPolicy =
          WebURLLoaderOptions::CrossOriginRequestPolicyAllow;
    } else {
      options.exposeAllResponseHeaders = true;
      // The author header set is empty, no preflight should go ahead.
      options.preflightPolicy = WebURLLoaderOptions::PreventPreflight;
      options.crossOriginRequestPolicy =
          WebURLLoaderOptions::CrossOriginRequestPolicyUseAccessControl;
      if (url_data_->cors_mode() == UrlData::CORS_USE_CREDENTIALS)
        options.allowCredentials = true;
    }
    loader.reset(url_data_->frame()->createAssociatedURLLoader(options));
  }

  // Start the resource loading.
  loader->loadAsynchronously(request, this);
  active_loader_.reset(new ActiveLoader(std::move(loader)));
}

ResourceMultiBufferDataProvider::~ResourceMultiBufferDataProvider() {}

/////////////////////////////////////////////////////////////////////////////
// MultiBuffer::DataProvider implementation.
MultiBufferBlockId ResourceMultiBufferDataProvider::Tell() const {
  return pos_;
}

bool ResourceMultiBufferDataProvider::Available() const {
  if (fifo_.empty())
    return false;
  if (fifo_.back()->end_of_stream())
    return true;
  if (fifo_.front()->data_size() == block_size())
    return true;
  return false;
}

scoped_refptr<DataBuffer> ResourceMultiBufferDataProvider::Read() {
  DCHECK(Available());
  scoped_refptr<DataBuffer> ret = fifo_.front();
  fifo_.pop_front();
  ++pos_;
  return ret;
}

void ResourceMultiBufferDataProvider::SetDeferred(bool deferred) {
  if (!active_loader_ || active_loader_->deferred() == deferred)
    return;
  active_loader_->SetDeferred(deferred);
}

/////////////////////////////////////////////////////////////////////////////
// WebURLLoaderClient implementation.

void ResourceMultiBufferDataProvider::willFollowRedirect(
    WebURLLoader* loader,
    WebURLRequest& newRequest,
    const WebURLResponse& redirectResponse) {
  redirects_to_ = newRequest.url();
  url_data_->set_valid_until(base::Time::Now() +
                             GetCacheValidUntil(redirectResponse));

  // This test is vital for security!
  if (cors_mode_ == UrlData::CORS_UNSPECIFIED) {
    // We allow the redirect if the origin is the same.
    if (origin_ != redirects_to_.GetOrigin()) {
      // We also allow the redirect if we don't have any data in the
      // cache, as that means that no dangerous data mixing can occur.
      if (url_data_->multibuffer()->map().empty() && fifo_.empty())
        return;

      url_data_->Fail();
    }
  }
}

void ResourceMultiBufferDataProvider::didSendData(
    WebURLLoader* loader,
    unsigned long long bytes_sent,
    unsigned long long total_bytes_to_be_sent) {
  NOTIMPLEMENTED();
}

void ResourceMultiBufferDataProvider::didReceiveResponse(
    WebURLLoader* loader,
    const WebURLResponse& response) {
#if ENABLE_DLOG
  string version;
  switch (response.httpVersion()) {
    case WebURLResponse::HTTPVersion_0_9:
      version = "0.9";
      break;
    case WebURLResponse::HTTPVersion_1_0:
      version = "1.0";
      break;
    case WebURLResponse::HTTPVersion_1_1:
      version = "1.1";
      break;
    case WebURLResponse::HTTPVersion_2_0:
      version = "2.1";
      break;
  }
  DVLOG(1) << "didReceiveResponse: HTTP/" << version << " "
           << response.httpStatusCode();
#endif
  DCHECK(active_loader_);

  scoped_refptr<UrlData> destination_url_data(url_data_);

  UrlIndex* url_index = url_data_->url_index();

  if (!redirects_to_.is_empty()) {
    if (!url_index) {
      // We've been disconnected from the url index.
      // That means the url_index_ has been destroyed, which means we do not
      // need to do anything clever.
      return;
    }
    destination_url_data = url_index->GetByUrl(redirects_to_, cors_mode_);
    redirects_to_ = GURL();
  }

  base::Time last_modified;
  if (base::Time::FromString(
          response.httpHeaderField("Last-Modified").utf8().data(),
          &last_modified)) {
    destination_url_data->set_last_modified(last_modified);
  }

  destination_url_data->set_valid_until(base::Time::Now() +
                                        GetCacheValidUntil(response));

  uint32_t reasons = GetReasonsForUncacheability(response);
  destination_url_data->set_cacheable(reasons == 0);
  UMA_HISTOGRAM_BOOLEAN("Media.CacheUseful", reasons == 0);
  int shift = 0;
  int max_enum = base::bits::Log2Ceiling(kMaxReason);
  while (reasons) {
    DCHECK_LT(shift, max_enum);  // Sanity check.
    if (reasons & 0x1) {
      UMA_HISTOGRAM_ENUMERATION("Media.UncacheableReason", shift,
                                max_enum);  // PRESUBMIT_IGNORE_UMA_MAX
    }

    reasons >>= 1;
    ++shift;
  }

  // Expected content length can be |kPositionNotSpecified|, in that case
  // |content_length_| is not specified and this is a streaming response.
  int64_t content_length = response.expectedContentLength();

  // We make a strong assumption that when we reach here we have either
  // received a response from HTTP/HTTPS protocol or the request was
  // successful (in particular range request). So we only verify the partial
  // response for HTTP and HTTPS protocol.
  if (destination_url_data->url().SchemeIsHTTPOrHTTPS()) {
    bool partial_response = (response.httpStatusCode() == kHttpPartialContent);
    bool ok_response = (response.httpStatusCode() == kHttpOK);

    // Check to see whether the server supports byte ranges.
    std::string accept_ranges =
        response.httpHeaderField("Accept-Ranges").utf8();
    if (accept_ranges.find("bytes") != std::string::npos)
      destination_url_data->set_range_supported();

    // If we have verified the partial response and it is correct.
    // It's also possible for a server to support range requests
    // without advertising "Accept-Ranges: bytes".
    if (partial_response && VerifyPartialResponse(response)) {
      destination_url_data->set_range_supported();
    } else if (ok_response && pos_ == 0) {
      // We accept a 200 response for a Range:0- request, trusting the
      // Accept-Ranges header, because Apache thinks that's a reasonable thing
      // to return.
      destination_url_data->set_length(content_length);
    } else if (response.httpStatusCode() == kHttpRangeNotSatisfiable) {
      // Really, we should never request a range that doesn't exist, but
      // if we do, let's handle it in a sane way.
      // Unsatisfiable range
      fifo_.push_back(DataBuffer::CreateEOSBuffer());
      destination_url_data->multibuffer()->OnDataProviderEvent(this);
      return;
    } else {
      destination_url_data->Fail();
      return;
    }
  } else {
    destination_url_data->set_range_supported();
    if (content_length != kPositionNotSpecified) {
      destination_url_data->set_length(content_length + byte_pos());
    }
  }

  if (url_index) {
    destination_url_data = url_index->TryInsert(destination_url_data);
  }

  if (destination_url_data != url_data_) {
    // At this point, we've encountered a redirect, or found a better url data
    // instance for the data that we're about to download.

    // First, let's take a ref on the current url data.
    scoped_refptr<UrlData> old_url_data(url_data_);
    destination_url_data->Use();

    // Take ownership of ourselves. (From the multibuffer)
    scoped_ptr<DataProvider> self(
        url_data_->multibuffer()->RemoveProvider(this));
    url_data_ = destination_url_data.get();
    // Give the ownership to our new owner.
    url_data_->multibuffer()->AddProvider(std::move(self));

    // Call callback to let upstream users know about the transfer.
    // This will merge the data from the two multibuffers and
    // cause clients to start using the new UrlData.
    old_url_data->RedirectTo(destination_url_data);
  }
}

void ResourceMultiBufferDataProvider::didReceiveData(WebURLLoader* loader,
                                                     const char* data,
                                                     int data_length,
                                                     int encoded_data_length) {
  DVLOG(1) << "didReceiveData: " << data_length << " bytes";
  DCHECK(!Available());
  DCHECK(active_loader_);
  DCHECK_GT(data_length, 0);

  // When we receive data, we allow more retries.
  retries_ = 0;

  while (data_length) {
    if (fifo_.empty() || fifo_.back()->data_size() == block_size()) {
      fifo_.push_back(new DataBuffer(block_size()));
      fifo_.back()->set_data_size(0);
    }
    int last_block_size = fifo_.back()->data_size();
    int to_append = std::min<int>(data_length, block_size() - last_block_size);
    DCHECK_GT(to_append, 0);
    memcpy(fifo_.back()->writable_data() + last_block_size, data, to_append);
    data += to_append;
    fifo_.back()->set_data_size(last_block_size + to_append);
    data_length -= to_append;
  }

  if (Available())
    url_data_->multibuffer()->OnDataProviderEvent(this);

  // Beware, this object might be deleted here.
}

void ResourceMultiBufferDataProvider::didDownloadData(WebURLLoader* loader,
                                                      int dataLength,
                                                      int encoded_data_length) {
  NOTIMPLEMENTED();
}

void ResourceMultiBufferDataProvider::didReceiveCachedMetadata(
    WebURLLoader* loader,
    const char* data,
    int data_length) {
  NOTIMPLEMENTED();
}

void ResourceMultiBufferDataProvider::didFinishLoading(
    WebURLLoader* loader,
    double finishTime,
    int64_t total_encoded_data_length) {
  DVLOG(1) << "didFinishLoading";
  DCHECK(active_loader_.get());
  DCHECK(!Available());

  // We're done with the loader.
  active_loader_.reset();

  // If we didn't know the |instance_size_| we do now.
  int64_t size = byte_pos();
  if (!fifo_.empty())
    size += fifo_.back()->data_size();

  // This request reports something smaller than what we've seen in the past,
  // Maybe it's transient error?
  if (url_data_->length() != kPositionNotSpecified &&
      size < url_data_->length()) {
    if (retries_ < kMaxRetries) {
      DVLOG(1) << " Partial data received.... @ pos = " << size;
      retries_++;
      base::MessageLoop::current()->PostDelayedTask(
          FROM_HERE, base::Bind(&ResourceMultiBufferDataProvider::Start,
                                weak_factory_.GetWeakPtr()),
          base::TimeDelta::FromMilliseconds(kLoaderPartialRetryDelayMs));
      return;
    } else {
      scoped_ptr<ActiveLoader> active_loader = std::move(active_loader_);
      url_data_->Fail();
      return;
    }
  }

  url_data_->set_length(size);
  fifo_.push_back(DataBuffer::CreateEOSBuffer());

  DCHECK(Available());
  url_data_->multibuffer()->OnDataProviderEvent(this);

  // Beware, this object might be deleted here.
}

void ResourceMultiBufferDataProvider::didFail(WebURLLoader* loader,
                                              const WebURLError& error) {
  DVLOG(1) << "didFail: reason=" << error.reason
           << ", isCancellation=" << error.isCancellation
           << ", domain=" << error.domain.utf8().data()
           << ", localizedDescription="
           << error.localizedDescription.utf8().data();
  DCHECK(active_loader_.get());

  if (retries_ < kMaxRetries && pos_ != 0) {
    retries_++;
    base::MessageLoop::current()->PostDelayedTask(
        FROM_HERE, base::Bind(&ResourceMultiBufferDataProvider::Start,
                              weak_factory_.GetWeakPtr()),
        base::TimeDelta::FromMilliseconds(kLoaderFailedRetryDelayMs));
  } else {
    // We don't need to continue loading after failure.
    //
    // Keep it alive until we exit this method so that |error| remains valid.
    scoped_ptr<ActiveLoader> active_loader = std::move(active_loader_);
    url_data_->Fail();
  }
}

bool ResourceMultiBufferDataProvider::ParseContentRange(
    const std::string& content_range_str,
    int64_t* first_byte_position,
    int64_t* last_byte_position,
    int64_t* instance_size) {
  const std::string kUpThroughBytesUnit = "bytes ";
  if (content_range_str.find(kUpThroughBytesUnit) != 0)
    return false;
  std::string range_spec =
      content_range_str.substr(kUpThroughBytesUnit.length());
  size_t dash_offset = range_spec.find("-");
  size_t slash_offset = range_spec.find("/");

  if (dash_offset == std::string::npos || slash_offset == std::string::npos ||
      slash_offset < dash_offset || slash_offset + 1 == range_spec.length()) {
    return false;
  }
  if (!base::StringToInt64(range_spec.substr(0, dash_offset),
                           first_byte_position) ||
      !base::StringToInt64(
          range_spec.substr(dash_offset + 1, slash_offset - dash_offset - 1),
          last_byte_position)) {
    return false;
  }
  if (slash_offset == range_spec.length() - 2 &&
      range_spec[slash_offset + 1] == '*') {
    *instance_size = kPositionNotSpecified;
  } else {
    if (!base::StringToInt64(range_spec.substr(slash_offset + 1),
                             instance_size)) {
      return false;
    }
  }
  if (*last_byte_position < *first_byte_position ||
      (*instance_size != kPositionNotSpecified &&
       *last_byte_position >= *instance_size)) {
    return false;
  }

  return true;
}

int64_t ResourceMultiBufferDataProvider::byte_pos() const {
  int64_t ret = pos_;
  ret += fifo_.size();
  ret = ret << url_data_->multibuffer()->block_size_shift();
  if (!fifo_.empty()) {
    ret += fifo_.back()->data_size() - block_size();
  }
  return ret;
}

int64_t ResourceMultiBufferDataProvider::block_size() const {
  int64_t ret = 1;
  return ret << url_data_->multibuffer()->block_size_shift();
}

bool ResourceMultiBufferDataProvider::VerifyPartialResponse(
    const WebURLResponse& response) {
  int64_t first_byte_position, last_byte_position, instance_size;
  if (!ParseContentRange(response.httpHeaderField("Content-Range").utf8(),
                         &first_byte_position, &last_byte_position,
                         &instance_size)) {
    return false;
  }

  if (url_data_->length() == kPositionNotSpecified) {
    url_data_->set_length(instance_size);
  }

  if (byte_pos() != first_byte_position) {
    return false;
  }

  return true;
}

}  // namespace media