// 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.

#ifndef GOOGLE_APIS_GAIA_GAIA_CONFIG_H_
#define GOOGLE_APIS_GAIA_GAIA_CONFIG_H_

#include <memory>
#include <string>
#include <string_view>

#include "base/component_export.h"
#include "base/functional/callback_helpers.h"
#include "base/values.h"
#include "google_apis/google_api_keys.h"

class GURL;

namespace base {
class CommandLine;
class FilePath;
}  // namespace base

// Class representing a configuration for Gaia URLs and Google API keys.
// Parses a JSON config file specified by |switches::kGaiaConfigPath| or
// |switches::kGaiaConfigContents| and provides convenient getters for reading
// this config.
//
// The config is represented by a JSON object with the following structure:
// {
//   "urls": {
//     "gaia_url": {
//       "url": "https://accounts.example.com"
//     },
//     ...
//   },
//   "api_keys": {
//     "GOOGLE_CLIENT_ID_MAIN": "example_key",
//     ...
//   },
//   "flags": {
//     "enable_issue_token_fetch": true,
//     ...
//   }
// }
class COMPONENT_EXPORT(GOOGLE_APIS) GaiaConfig {
 public:
  // Returns a global instance of GaiaConfig.
  // This may return nullptr if the config file was not specified by a command
  // line parameter.
  static GaiaConfig* GetInstance();

  // Constructs a new GaiaConfig from a parsed JSON dictionary.
  // Prefer GetInstance() over this constructor.
  explicit GaiaConfig(base::DictValue parsed_config);
  GaiaConfig(const GaiaConfig&) = delete;
  GaiaConfig& operator=(const GaiaConfig&) = delete;
  ~GaiaConfig();

  // Searches for a URL by |key|.
  // Returns true if |key| exists and contains a valid URL. |out_url| will be
  // set to that URL.
  // Otherwise, returns false. |out_url| will be unmodified.
  bool GetURLIfExists(std::string_view key, GURL* out_url);

  // Searches for an API key, OAuth2 client ID or secret by |key|.
  // Returns true if |key| exists and contains a valid string.
  // |out_api_key| will be set to that string.
  // Otherwise, returns false. |out_api_key| will be unmodified.
  bool GetAPIKeyIfExists(std::string_view key, std::string* out_api_key);

  // Searches for a boolean flag by `key`.
  // Returns the value of the flag if it exists and contains a boolean value.
  // Otherwise, returns std::nullopt.
  std::optional<bool> GetFlagIfExists(std::string_view key);

  // Serializes the state of |this| into |command_line|, in a way that
  // GaiaConfig::GetInstance() would honor. Internally, it uses switch
  // |kGaiaConfigContents| for this purpose, which is appended to
  // |*command_line|.
  void SerializeContentsToCommandLineSwitch(
      base::CommandLine* command_line) const;

  // Instantiates `GaiaConfig` with `base::CommandLine`. Used in tests.
  [[nodiscard]] static std::unique_ptr<GaiaConfig>
  CreateFromCommandLineForTesting(const base::CommandLine* command_line);

  // Overrides the global instance of GaiaConfig with `config` and returns a
  // scoped object that will restore the previous value once destroyed.
  [[nodiscard]] static base::ScopedClosureRunner SetScopedConfigForTesting(
      std::unique_ptr<GaiaConfig> config);

 private:
  static std::unique_ptr<GaiaConfig>* GetGlobalConfig();

  static std::unique_ptr<GaiaConfig> ReadConfigFromString(
      const std::string& config_contents);
  static std::unique_ptr<GaiaConfig> ReadConfigFromDisk(
      const base::FilePath& config_path);
  static std::unique_ptr<GaiaConfig> ReadConfigFromCommandLineSwitches(
      const base::CommandLine* command_line);

  base::DictValue parsed_config_;
};

#endif  // GOOGLE_APIS_GAIA_GAIA_CONFIG_H_