Create an abstract flow class that abstracts the following logical steps of calling an OAuth2 enabl…

chrome/common/net/gaia/oauth2_api_call_flow.cc

+// Copyright (c) 2012 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 "chrome/common/net/gaia/oauth2_api_call_flow.h"
+
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "chrome/common/net/gaia/gaia_urls.h"
+#include "net/base/escape.h"
+#include "net/base/load_flags.h"
+#include "net/http/http_status_code.h"
+#include "net/url_request/url_request_context_getter.h"
+#include "net/url_request/url_request_status.h"
+
+using content::URLFetcher;
+using content::URLFetcherDelegate;
+using net::ResponseCookies;
+using net::URLRequestContextGetter;
+using net::URLRequestStatus;
+
+OAuth2ApiCallFlow::OAuth2ApiCallFlow(
+    net::URLRequestContextGetter* context,
+    const std::string& refresh_token,
+    const std::string& access_token,
+    const std::vector<std::string>& scopes)
+    : context_(context),
+      refresh_token_(refresh_token),
+      access_token_(access_token),
+      scopes_(scopes),
+      state_(INITIAL),
+      tried_mint_access_token_(false) {
+}
+
+OAuth2ApiCallFlow::~OAuth2ApiCallFlow() { }
+
+void OAuth2ApiCallFlow::Start() {
+  BeginApiCall();
+}
+
+void OAuth2ApiCallFlow::BeginApiCall() {
+  CHECK(state_ == INITIAL || state_ == MINT_ACCESS_TOKEN_DONE);
+
+  // If the access token is empty then directly try to mint one.
+  if (access_token_.empty()) {
+    BeginMintAccessToken();
+    return;
+  } else {
+    state_ = API_CALL_STARTED;
+
+    url_fetcher_.reset(CreateURLFetcher());
+    url_fetcher_->Start();  // OnURLFetchComplete will be called.
+  }
+}
+
+void OAuth2ApiCallFlow::EndApiCall(const URLFetcher* source) {
+  CHECK_EQ(API_CALL_STARTED, state_);
+  state_ = API_CALL_DONE;
+
+  URLRequestStatus status = source->GetStatus();
+  if (!status.is_success()) {
+    ProcessApiCallFailure(source);
+    return;
+  }
+
+  // If the response code is 401 Unauthorized then access token may have
+  // expired. So try generating a new access token.
+  if (source->GetResponseCode() == net::HTTP_UNAUTHORIZED) {
+    // If we already tried minting a new access token, don't do it again.
+    if (tried_mint_access_token_)
+      ProcessApiCallFailure(source);
+    else
+      BeginMintAccessToken();
+
+    return;
+  }
+
+  if (source->GetResponseCode() != net::HTTP_OK) {
+    ProcessApiCallFailure(source);
+    return;
+  }
+
+  ProcessApiCallSuccess(source);
+}
+
+void OAuth2ApiCallFlow::BeginMintAccessToken() {
+  CHECK(state_ == INITIAL || state_ == API_CALL_DONE);
+  CHECK(!tried_mint_access_token_);
+  state_ = MINT_ACCESS_TOKEN_STARTED;
+  tried_mint_access_token_ = true;
+
+  oauth2_access_token_fetcher_.reset(CreateAccessTokenFetcher());
+  oauth2_access_token_fetcher_->Start(
+      GaiaUrls::GetInstance()->oauth2_chrome_client_id(),
+      GaiaUrls::GetInstance()->oauth2_chrome_client_secret(),
+      refresh_token_,
+      scopes_);
+}
+
+void OAuth2ApiCallFlow::EndMintAccessToken(
+    const GoogleServiceAuthError* error) {
+  CHECK_EQ(MINT_ACCESS_TOKEN_STARTED, state_);
+
+  if (!error) {
+    state_ = MINT_ACCESS_TOKEN_DONE;
+    BeginApiCall();
+  } else {
+    state_ = ERROR_STATE;
+    ProcessMintAccessTokenFailure(*error);
+  }
+}
+
+OAuth2AccessTokenFetcher* OAuth2ApiCallFlow::CreateAccessTokenFetcher() {
+  return new OAuth2AccessTokenFetcher(this, context_);
+}
+
+void OAuth2ApiCallFlow::OnURLFetchComplete(const URLFetcher* source) {
+  CHECK(source);
+  CHECK_EQ(API_CALL_STARTED, state_);
+  EndApiCall(source);
+}
+
+void OAuth2ApiCallFlow::OnGetTokenSuccess(const std::string& access_token) {
+  access_token_ = access_token;
+  EndMintAccessToken(NULL);
+}
+
+void OAuth2ApiCallFlow::OnGetTokenFailure(
+    const GoogleServiceAuthError& error) {
+  EndMintAccessToken(&error);
+}
+
+URLFetcher* OAuth2ApiCallFlow::CreateURLFetcher() {
+  std::string body = CreateApiCallBody();
+  bool empty_body = body.empty();
+  URLFetcher* result = URLFetcher::Create(
+      0,
+      CreateApiCallUrl(),
+      empty_body ? URLFetcher::GET : URLFetcher::POST,
+      this);
+
+  result->SetRequestContext(context_);
+  result->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
+                       net::LOAD_DO_NOT_SAVE_COOKIES);
+
+  if (!empty_body)
+    result->SetUploadData("application/x-www-form-urlencoded", body);
+
+  return result;
+}