// Copyright 2014 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 "components/data_reduction_proxy/browser/data_reduction_proxy_protocol.h"

#include "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "components/data_reduction_proxy/browser/data_reduction_proxy_params.h"
#include "components/data_reduction_proxy/common/data_reduction_proxy_headers.h"
#include "net/base/load_flags.h"
#include "net/http/http_response_headers.h"
#include "net/proxy/proxy_info.h"
#include "net/proxy/proxy_list.h"
#include "net/proxy/proxy_server.h"
#include "net/proxy/proxy_service.h"
#include "net/url_request/url_request.h"
#include "net/url_request/url_request_context.h"
#include "url/gurl.h"

namespace {
bool SetProxyServerFromGURL(const GURL& gurl,
                            net::ProxyServer* proxy_server) {
  DCHECK(proxy_server);
  if (!gurl.SchemeIsHTTPOrHTTPS())
    return false;
  *proxy_server = net::ProxyServer(gurl.SchemeIs("http") ?
                                       net::ProxyServer::SCHEME_HTTP :
                                       net::ProxyServer::SCHEME_HTTPS,
                                   net::HostPortPair::FromURL(gurl));
  return true;
}
}  // namespace

namespace data_reduction_proxy {

bool MaybeBypassProxyAndPrepareToRetry(
    const DataReductionProxyParams* data_reduction_proxy_params,
    net::URLRequest* request,
    const net::HttpResponseHeaders* original_response_headers,
    scoped_refptr<net::HttpResponseHeaders>* override_response_headers) {
  if (!data_reduction_proxy_params)
    return false;
  std::pair<GURL, GURL> data_reduction_proxies;
  if (!data_reduction_proxy_params->WasDataReductionProxyUsed(
          request, &data_reduction_proxies)) {
    return false;
  }

  // Empty implies either that the request was served from cache or that
  // request was served directly from the origin.
  if (request->proxy_server().IsEmpty())
    return false;

  if (data_reduction_proxies.first.is_empty())
    return false;

  DataReductionProxyInfo data_reduction_proxy_info;
  net::ProxyService::DataReductionProxyBypassType bypass_type =
      GetDataReductionProxyBypassType(
          original_response_headers, &data_reduction_proxy_info);
  if (bypass_type == net::ProxyService::BYPASS_EVENT_TYPE_MAX) {
    return false;
  }

  DCHECK(request->context());
  DCHECK(request->context()->proxy_service());
  net::ProxyServer proxy_server;
  SetProxyServerFromGURL(data_reduction_proxies.first, &proxy_server);
  request->context()->proxy_service()->RecordDataReductionProxyBypassInfo(
      !data_reduction_proxies.second.is_empty(),
      data_reduction_proxy_info.bypass_all,
      proxy_server,
      bypass_type);

  MarkProxiesAsBadUntil(request,
                        data_reduction_proxy_info.bypass_duration,
                        data_reduction_proxy_info.bypass_all,
                        data_reduction_proxies);

  // Only retry idempotent methods.
  if (!IsRequestIdempotent(request))
    return false;

  OverrideResponseAsRedirect(request,
                             original_response_headers,
                             override_response_headers);
  return true;
}



bool IsRequestIdempotent(const net::URLRequest* request) {
  DCHECK(request);
  if (request->method() == "GET" ||
      request->method() == "OPTIONS" ||
      request->method() == "HEAD" ||
      request->method() == "PUT" ||
      request->method() == "DELETE" ||
      request->method() == "TRACE")
    return true;
  return false;
}

void OverrideResponseAsRedirect(
    net::URLRequest* request,
    const net::HttpResponseHeaders* original_response_headers,
    scoped_refptr<net::HttpResponseHeaders>* override_response_headers) {
  DCHECK(request);
  DCHECK(original_response_headers);
  DCHECK(override_response_headers->get() == NULL);

  request->SetLoadFlags(request->load_flags() |
                        net::LOAD_DISABLE_CACHE |
                        net::LOAD_BYPASS_PROXY);
  *override_response_headers = new net::HttpResponseHeaders(
      original_response_headers->raw_headers());
  (*override_response_headers)->ReplaceStatusLine("HTTP/1.1 302 Found");
  (*override_response_headers)->RemoveHeader("Location");
  (*override_response_headers)->AddHeader("Location: " +
                                          request->url().spec());
  // TODO(bengr): Should we pop_back the request->url_chain?
}

void MarkProxiesAsBadUntil(
    net::URLRequest* request,
    base::TimeDelta& bypass_duration,
    bool bypass_all,
    const std::pair<GURL, GURL>& data_reduction_proxies) {
  DCHECK(!data_reduction_proxies.first.is_empty());
  // Synthesize a suitable |ProxyInfo| to add the proxies to the
  // |ProxyRetryInfoMap| of the proxy service.
  net::ProxyList proxy_list;
  net::ProxyServer primary;
  SetProxyServerFromGURL(data_reduction_proxies.first, &primary);
  if (primary.is_valid())
    proxy_list.AddProxyServer(primary);
  net::ProxyServer fallback;
  if (bypass_all) {
    if (!data_reduction_proxies.second.is_empty())
      SetProxyServerFromGURL(data_reduction_proxies.second, &fallback);
    if (fallback.is_valid())
      proxy_list.AddProxyServer(fallback);
    proxy_list.AddProxyServer(net::ProxyServer::Direct());
  }
  net::ProxyInfo proxy_info;
  proxy_info.UseProxyList(proxy_list);
  DCHECK(request->context());
  net::ProxyService* proxy_service = request->context()->proxy_service();
  DCHECK(proxy_service);

  proxy_service->MarkProxiesAsBadUntil(proxy_info,
                                       bypass_duration,
                                       fallback,
                                       request->net_log());
}

}  // namespace data_reduction_proxy