// 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 "services/network/public/cpp/cross_origin_embedder_policy_parser.h"

#include <algorithm>
#include <optional>
#include <string_view>
#include <utility>

#include "net/http/http_response_headers.h"
#include "net/http/structured_headers.h"
#include "services/network/public/cpp/cross_origin_embedder_policy.h"

namespace network {

namespace {
constexpr char kHeaderName[] = "cross-origin-embedder-policy";
constexpr char kReportOnlyHeaderName[] =
    "cross-origin-embedder-policy-report-only";

// [spec]: https://html.spec.whatwg.org/C/#obtain-an-embedder-policy
std::pair<mojom::CrossOriginEmbedderPolicyValue, std::optional<std::string>>
Parse(std::string_view header_value) {
  auto item = net::structured_headers::ParseItem(header_value);
  const std::string* token = item ? item->item.GetIfToken() : nullptr;
  if (!token) {
    return {
        mojom::CrossOriginEmbedderPolicyValue::kNone,
        std::nullopt,
    };
  }

  std::optional<std::string> endpoint;
  for (auto& [key, value] : item->params) {
    if (std::string* str = value.GetIfString(); key == "report-to" && str) {
      endpoint = std::move(*str);
    }
  }

  if (*token == "require-corp") {
    return {
        mojom::CrossOriginEmbedderPolicyValue::kRequireCorp,
        std::move(endpoint),
    };
  }

  if (*token == "credentialless") {
    return {
        mojom::CrossOriginEmbedderPolicyValue::kCredentialless,
        std::move(endpoint),
    };
  }

  return {
      mojom::CrossOriginEmbedderPolicyValue::kNone,
      std::nullopt,
  };
}

}  // namespace

CrossOriginEmbedderPolicy ParseCrossOriginEmbedderPolicy(
    const net::HttpResponseHeaders& headers) {
  CrossOriginEmbedderPolicy coep;
  if (std::optional<std::string> header_value =
          headers.GetNormalizedHeader(kHeaderName)) {
    std::tie(coep.value, coep.reporting_endpoint) = Parse(*header_value);
  }
  if (std::optional<std::string> header_value =
          headers.GetNormalizedHeader(kReportOnlyHeaderName)) {
    std::tie(coep.report_only_value, coep.report_only_reporting_endpoint) =
        Parse(*header_value);
  }
  return coep;
}

}  // namespace network