// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/trusted_vault/trusted_vault_access_token_fetcher_frontend.h"

#include <utility>

#include "base/types/expected.h"
#include "components/signin/public/identity_manager/access_token_info.h"
#include "components/signin/public/identity_manager/primary_account_access_token_fetcher.h"
#include "components/trusted_vault/trusted_vault_access_token_fetcher.h"

namespace trusted_vault {

namespace {

void FulfillPendingRequests(
    std::vector<TrustedVaultAccessTokenFetcher::TokenCallback> pending_requests,
    TrustedVaultAccessTokenFetcher::AccessTokenInfoOrError
        access_token_or_error) {
  for (TrustedVaultAccessTokenFetcher::TokenCallback& pending_request :
       pending_requests) {
    std::move(pending_request).Run(access_token_or_error);
  }
}

}  // namespace

TrustedVaultAccessTokenFetcherFrontend::TrustedVaultAccessTokenFetcherFrontend(
    signin::IdentityManager* identity_manager)
    : identity_manager_(identity_manager) {
  DCHECK(identity_manager_);
  identity_manager_observation_.Observe(identity_manager_);
  UpdatePrimaryAccountIfNeeded();
}

TrustedVaultAccessTokenFetcherFrontend::
    ~TrustedVaultAccessTokenFetcherFrontend() = default;

base::WeakPtr<TrustedVaultAccessTokenFetcherFrontend>
TrustedVaultAccessTokenFetcherFrontend::GetWeakPtr() {
  return weak_ptr_factory_.GetWeakPtr();
}

void TrustedVaultAccessTokenFetcherFrontend::FetchAccessToken(
    const CoreAccountId& account_id,
    TrustedVaultAccessTokenFetcher::TokenCallback callback) {
  if (account_id != primary_account_) {
    // The requester is likely not aware of a recent change to the primary
    // account yet (this is possible because requests come from another
    // sequence). Run |callback| immediately without access token.
    // Although |account_id| can be in persistent auth error state, it's not
    // relevant here since primary account change is the main reason for
    // returning nullopt, so passing false is fine.
    std::move(callback).Run(base::unexpected(
        TrustedVaultAccessTokenFetcher::FetchingError::kNotPrimaryAccount));
    return;
  }

  pending_requests_.emplace_back(std::move(callback));
  if (ongoing_access_token_fetch_ == nullptr) {
    StartAccessTokenFetch();
  }
}

void TrustedVaultAccessTokenFetcherFrontend::OnPrimaryAccountChanged(
    const signin::PrimaryAccountChangeEvent& event) {
  UpdatePrimaryAccountIfNeeded();
}

void TrustedVaultAccessTokenFetcherFrontend::OnIdentityManagerShutdown(
    signin::IdentityManager* identity_manager) {
  CHECK_EQ(identity_manager, identity_manager_);
  identity_manager_observation_.Reset();
}

void TrustedVaultAccessTokenFetcherFrontend::UpdatePrimaryAccountIfNeeded() {
  CoreAccountInfo primary_account_info =
      identity_manager_->GetPrimaryAccountInfo(signin::ConsentLevel::kSignin);
  if (primary_account_info.account_id == primary_account_) {
    return;
  }

  ongoing_access_token_fetch_ = nullptr;
  primary_account_ = primary_account_info.account_id;

  // Fulfill |pending_requests_| since they belong to the previous
  // |primary_account_|.
  FulfillPendingRequestsAndMaybeDestroySelf(base::unexpected(
      TrustedVaultAccessTokenFetcher::FetchingError::kNotPrimaryAccount));
}

void TrustedVaultAccessTokenFetcherFrontend::StartAccessTokenFetch() {
  DCHECK(!ongoing_access_token_fetch_);
  // Use kWaitUntilAvailable to avoid failed fetches while refresh tokens are
  // still loading. Note, that it doesn't cause infinite waits for persistent
  // auth errors.
  ongoing_access_token_fetch_ = std::make_unique<
      signin::PrimaryAccountAccessTokenFetcher>(
      signin::OAuthConsumerId::kTrustedVaultFrontend, identity_manager_,
      base::BindOnce(
          &TrustedVaultAccessTokenFetcherFrontend::OnAccessTokenFetchCompleted,
          base::Unretained(this)),
      signin::PrimaryAccountAccessTokenFetcher::Mode::kWaitUntilAvailable,
      signin::ConsentLevel::kSignin);
}

void TrustedVaultAccessTokenFetcherFrontend::OnAccessTokenFetchCompleted(
    GoogleServiceAuthError error,
    signin::AccessTokenInfo access_token_info) {
  ongoing_access_token_fetch_ = nullptr;
  if (error.state() == GoogleServiceAuthError::NONE) {
    FulfillPendingRequestsAndMaybeDestroySelf(access_token_info);
  } else if (error.IsPersistentError()) {
    FulfillPendingRequestsAndMaybeDestroySelf(base::unexpected(
        TrustedVaultAccessTokenFetcher::FetchingError::kPersistentAuthError));
  } else {
    FulfillPendingRequestsAndMaybeDestroySelf(base::unexpected(
        TrustedVaultAccessTokenFetcher::FetchingError::kTransientAuthError));
  }
}

void TrustedVaultAccessTokenFetcherFrontend::
    FulfillPendingRequestsAndMaybeDestroySelf(
        TrustedVaultAccessTokenFetcher::AccessTokenInfoOrError
            access_token_or_error) {
  // Move the pending requests to a local variable to avoid UAF in case
  // the callbacks synchronously destroy `this`.
  // TODO(crbug.com/427316421): The cleaner fix would be to make sure that all
  // callbacks run asynchronously (currently it is not the case with
  // EnclaveManager if error happens while fetching access token).
  std::vector<TrustedVaultAccessTokenFetcher::TokenCallback> pending_requests =
      std::move(pending_requests_);
  pending_requests_.clear();
  FulfillPendingRequests(std::move(pending_requests), access_token_or_error);
}

}  // namespace trusted_vault