// 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.

#ifndef CHROME_COMMON_EXTENSIONS_PERMISSIONS_CHROME_PERMISSION_MESSAGE_RULES_H_
#define CHROME_COMMON_EXTENSIONS_PERMISSIONS_CHROME_PERMISSION_MESSAGE_RULES_H_

#include <initializer_list>
#include <set>
#include <vector>

#include "base/macros.h"
#include "extensions/common/permissions/api_permission.h"
#include "extensions/common/permissions/api_permission_set.h"
#include "extensions/common/permissions/permission_message.h"

namespace extensions {

// A formatter which generates a single permission message for all permissions
// that match a given rule. All remaining permissions that match the given rule
// are bucketed together, then GetPermissionMessage() is called with the
// resultant permission set.
//
// Note: since a ChromePermissionMessageFormatter can only produce a single
// PermissionMessage and applies to all permissions with a given ID, this
// maintains the property that one permission ID can still only produce one
// message (that is, multiple permissions with the same ID cannot appear in
// multiple messages).
class ChromePermissionMessageFormatter {
 public:
  ChromePermissionMessageFormatter() {}
  virtual ~ChromePermissionMessageFormatter() {}

  // Returns the permission message for the given set of |permissions|.
  // |permissions| is guaranteed to have the IDs specified by the
  // required/optional permissions for the rule. The set will never be empty.
  virtual PermissionMessage GetPermissionMessage(
      const PermissionIDSet& permissions) const = 0;

 private:
  DISALLOW_COPY_AND_ASSIGN(ChromePermissionMessageFormatter);
};

// A simple rule to generate a coalesced permission message that stores the
// corresponding message ID for a given set of permission IDs. This rule
// generates the message with the given |message_id| if all the |required|
// permissions are present. If any |optional| permissions are present, they are
// also 'absorbed' by the rule to generate the final coalesced message.
//
// An optional |formatter| can be provided, which decides how the final
// PermissionMessage appears. The default formatter simply displays the message
// with the ID |message_id|.
//
// Once a permission is used in a rule, it cannot apply to any future rules.
//
// TODO(sashab): Move all ChromePermissionMessageFormatters to their own
// provider class and remove ownership from ChromePermissionMessageRule.
class ChromePermissionMessageRule {
 public:
  ChromePermissionMessageRule(ChromePermissionMessageRule&& other);
  ChromePermissionMessageRule& operator=(ChromePermissionMessageRule&& other);
  virtual ~ChromePermissionMessageRule();

  // Returns all the rules used to generate permission messages for Chrome apps
  // and extensions.
  static std::vector<ChromePermissionMessageRule> GetAllRules();

  std::set<APIPermission::ID> required_permissions() const;
  std::set<APIPermission::ID> optional_permissions() const;
  std::set<APIPermission::ID> all_permissions() const;

  PermissionMessage GetPermissionMessage(
      const PermissionIDSet& permissions) const;

 private:
  // Create a rule using the default formatter (display the message with ID
  // |message_id|).
  ChromePermissionMessageRule(
      int message_id,
      const std::initializer_list<APIPermission::ID>& required,
      const std::initializer_list<APIPermission::ID>& optional);
  // Create a rule with a custom formatter.
  ChromePermissionMessageRule(
      std::unique_ptr<ChromePermissionMessageFormatter> formatter,
      const std::initializer_list<APIPermission::ID>& required,
      const std::initializer_list<APIPermission::ID>& optional);

  std::set<APIPermission::ID> required_permissions_;
  std::set<APIPermission::ID> optional_permissions_;

  // Owned by this class.
  std::unique_ptr<ChromePermissionMessageFormatter> formatter_;

 private:
  DISALLOW_COPY_AND_ASSIGN(ChromePermissionMessageRule);
};

}  // namespace extensions

#endif  // CHROME_COMMON_EXTENSIONS_PERMISSIONS_CHROME_PERMISSION_MESSAGE_RULES_H_