// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2019 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.

ircd::m::room::power::revoke::revoke(json::stack::object &out,
                                     const room::power &power,
                                     const pair<string_view> &prop_key)
:returns<bool>{false}
{
	bool &ret(*this);
	const auto replace{[&ret]
	(json::stack::object &out, const json::object &object, const string_view &sought)
	{
		for(const auto &[key, val] : object)
		{
			if(key == sought)
			{
				ret = true;
				continue;
			}

			json::stack::member
			{
				out, key, val
			};
		}
	}};

	power.view([&out, &prop_key, &replace]
	(const json::object &power)
	{
		const auto &[revoke_prop, revoke_key]
		{
			prop_key
		};

		if(!revoke_prop)
		{
			replace(out, power, revoke_key);
			return;
		}

		for(const auto &[key, val] : power)
		{
			if(key == revoke_prop)
			{
				json::stack::object prop
				{
					out, key
				};

				replace(prop, val, revoke_key);
				continue;
			}

			json::stack::member
			{
				out, key, val
			};
		}
	});
}

ircd::m::room::power::grant::grant(json::stack::object &out,
                                   const room::power &power,
                                   const pair<string_view> &prop_key,
                                   const int64_t &level)
:returns<bool>{false}
{
	bool &ret(*this);
	const auto replace{[&ret, &level]
	(json::stack::object &out, const json::object &object, const string_view &sought)
	{
		for(const auto &[key, val] : object)
		{
			if(key == sought)
			{
				json::stack::member
				{
					out, key, json::value{level}
				};

				ret = true;
				continue;
			}
			else if(key > sought && !ret) // maintains lexical sorting
			{
				json::stack::member
				{
					out, sought, json::value{level}
				};

				ret = true;
			}

			json::stack::member
			{
				out, key, val
			};
		}
	}};

	power.view([&out, &prop_key, &level, &replace]
	(const json::object &power)
	{
		const auto &[grant_prop, grant_key]
		{
			prop_key
		};

		if(!grant_prop)
		{
			replace(out, power, grant_key);
			return;
		}

		for(const auto &[key, val] : power)
		{
			if(key == grant_prop)
			{
				json::stack::object prop
				{
					out, key
				};

				replace(prop, val, grant_key);
				continue;
			}

			json::stack::member
			{
				out, key, val
			};
		}
	});
}

//
// room::power
//

decltype(ircd::m::room::power::default_creator_level)
ircd::m::room::power::default_creator_level
{
	{ "name",     "ircd.m.room.power.default.creator_level" },
	{ "default",  100L                                      },
};

decltype(ircd::m::room::power::default_power_level)
ircd::m::room::power::default_power_level
{
	{ "name",     "ircd.m.room.power.default.power_level" },
	{ "default",  50L                                     },
};

decltype(ircd::m::room::power::default_event_level)
ircd::m::room::power::default_event_level
{
	{ "name",     "ircd.m.room.power.default.event_level" },
	{ "default",  0L                                      },
};

decltype(ircd::m::room::power::default_user_level)
ircd::m::room::power::default_user_level
{
	{ "name",     "ircd.m.room.power.default.user_level" },
	{ "default",  0L                                     },
};

ircd::json::object
ircd::m::room::power::default_content(const mutable_buffer &buf,
                                      const m::user::id &creator)
{
	return compose_content(buf, [&creator]
	(const string_view &key, json::stack::object &object)
	{
		if(key != "users")
			return;

		assert(default_creator_level == 100);
		json::stack::member
		{
			object, creator, json::value(default_creator_level)
		};
	});
}

ircd::json::object
ircd::m::room::power::compose_content(const mutable_buffer &buf,
                                      const compose_closure &closure)
{
	json::stack out{buf};
	json::stack::object content{out};

	assert(default_power_level == 50);
	json::stack::member
	{
		content, "ban", json::value(default_power_level)
	};

	{
		json::stack::object events
		{
			content, "events"
		};

		json::stack::member
		{
			events, "m.room.encryption", json::value(default_creator_level)
		};

		json::stack::member
		{
			events, "m.room.server_acl", json::value(default_creator_level)
		};

		json::stack::member
		{
			events, "m.room.tombstone", json::value(default_creator_level)
		};

		closure("events", events);
	}

	assert(default_event_level == 0);
	json::stack::member
	{
		content, "events_default", json::value(default_event_level)
	};

	json::stack::member
	{
		content, "historical", json::value(default_creator_level)
	};

	json::stack::member
	{
		content, "invite", json::value(default_power_level)
	};

	json::stack::member
	{
		content, "kick", json::value(default_power_level)
	};

	{
		json::stack::object notifications
		{
			content, "notifications"
		};

		json::stack::member
		{
			notifications, "room", json::value(default_power_level)
		};

		closure("notifications", notifications);
	}

	json::stack::member
	{
		content, "redact", json::value(default_power_level)
	};

	json::stack::member
	{
		content, "state_default", json::value(default_power_level)
	};

	{
		json::stack::object users
		{
			content, "users"
		};

		closure("users", users);
	}

	assert(default_user_level == 0);
	json::stack::member
	{
		content, "users_default", json::value(default_user_level)
	};

	content.~object();
	return json::object{out.completed()};
}

//
// room::power::power
//

ircd::m::room::power::power(const m::room &room)
:power
{
	room, room.get(std::nothrow, "m.room.power_levels", "")
}
{
}

ircd::m::room::power::power(const m::room &room,
                            const event::idx &power_event_idx)
:room
{
	room
}
,power_event_idx
{
	power_event_idx
}
{
}

ircd::m::room::power::power(const m::event &power_event,
                            const m::event &create_event)
:power
{
	power_event, m::user::id(unquote(json::get<"content"_>(create_event).get("creator")))
}
{
}

ircd::m::room::power::power(const m::event &power_event,
                            const m::user::id &room_creator_id)
:power
{
	json::get<"content"_>(power_event), room_creator_id
}
{
}

ircd::m::room::power::power(const json::object &power_event_content,
                            const m::user::id &room_creator_id)
:power_event_content
{
	power_event_content
}
,room_creator_id
{
	room_creator_id
}
{
}

/// "all who attain great power and riches make use of either force or fraud"
///
/// Returns bool for "allow" or "deny"
///
/// Provide the user invoking the power. The return value indicates whether
/// they have the power.
///
/// Provide the property/event_type. There are two usages here: 1. This is a
/// string corresponding to one of the spec top-level properties like "ban"
/// and "redact". In this case, the type and state_key parameters to this
/// function are not used. 2. This string is empty or "events" in which case
/// the type parameter is used to fetch the power threshold for that type.
/// For state events of a type, the state_key must be provided for inspection
/// here as well.
bool
ircd::m::room::power::operator()(const m::user::id &user_id,
                                 const string_view &prop,
                                 const string_view &type,
                                 const string_view &state_key)
const
{
	const auto &user_level
	{
		level_user(user_id)
	};

	const auto &required_level
	{
		empty(prop) || prop == "events"?
			level_event(type, state_key):
			level(prop)
	};

	return user_level >= required_level;
}

int64_t
ircd::m::room::power::level_user(const m::user::id &user_id)
const try
{
	int64_t ret
	{
		default_user_level
	};

	const auto closure{[&user_id, &ret]
	(const json::object &content)
	{
		const json::string &users_default
		{
			content.get("users_default")
		};

		const json::object &users
		{
			content.get("users")
		};

		const json::string &value
		{
			users.get(user_id)
		};

		ret = as_level(value, as_level(users_default, default_user_level));
	}};

	const bool has_power_levels_event
	{
		view(closure)
	};

	if(!has_power_levels_event)
	{
		if(room_creator_id && user_id == room_creator_id)
			ret = default_creator_level;

		if(room.room_id && creator(room, user_id))
			ret = default_creator_level;
	}

	return ret;
}
catch(const json::error &e)
{
	log::derror
	{
		log, "power users :%s",
		e.what(),
	};

	return default_user_level;
}

int64_t
ircd::m::room::power::level_event(const string_view &type)
const try
{
	int64_t ret
	{
		default_event_level
	};

	const auto closure{[&type, &ret]
	(const json::object &content)
	{
		const json::string &events_default
		{
			content.get("events_default")
		};

		const json::object &events
		{
			content.get("events")
		};

		const json::string &value
		{
			events.get(type)
		};

		ret = as_level(value, as_level(events_default, default_event_level));
	}};

	const bool has_power_levels_event
	{
		view(closure)
	};

	return ret;
}
catch(const json::error &e)
{
	log::derror
	{
		log, "power events type=%s :%s",
		type,
		e.what(),
	};

	return default_event_level;
}

int64_t
ircd::m::room::power::level_event(const string_view &type,
                                  const string_view &state_key)
const try
{
	if(!defined(state_key))
		return level_event(type);

	int64_t ret
	{
		default_power_level
	};

	const auto closure{[&type, &ret]
	(const json::object &content)
	{
		const json::string &state_default
		{
			content.get("state_default")
		};

		const json::object &events
		{
			content.get("events")
		};

		const json::string &value
		{
			events.get(type)
		};

		ret = as_level(value, as_level(state_default, default_power_level));
	}};

	const bool has_power_levels_event
	{
		view(closure)
	};

	return ret;
}
catch(const json::error &e)
{
	log::derror
	{
		log, "power events type=%s state_key=%s :%s",
		type,
		state_key,
		e.what(),
	};

	return default_power_level;
}

int64_t
ircd::m::room::power::level(const string_view &prop)
const try
{
	int64_t ret
	{
		default_power_level
	};

	view([&prop, &ret]
	(const json::object &content)
	{
		const json::string &value
		{
			content.at(prop)
		};

		ret = as_level(value, ret);
	});

	return ret;
}
catch(const json::error &e)
{
	log::derror
	{
		log, "power level prop=%s :%s",
		prop,
		e.what(),
	};

	return prop == "invite"?
		default_event_level:
		default_power_level;
}

size_t
ircd::m::room::power::count_levels()
const
{
	size_t ret{0};
	for_each([&ret]
	(const string_view &, const int64_t &) noexcept
	{
		++ret;
		return true;
	});

	return ret;
}

size_t
ircd::m::room::power::count_collections()
const
{
	size_t ret{0};
	view([&ret]
	(const json::object &content)
	{
		for(const auto &[key, val] : content)
			ret += json::type(val, json::OBJECT);
	});

	return ret;
}

size_t
ircd::m::room::power::count(const string_view &prop)
const
{
	size_t ret{0};
	for_each(prop, [&ret]
	(const string_view &, const int64_t &) noexcept
	{
		++ret;
		return true;
	});

	return ret;
}

bool
ircd::m::room::power::has_event(const string_view &type)
const try
{
	bool ret{false};
	view([&type, &ret]
	(const json::object &content)
	{
		const json::object &events
		{
			content.at("events")
		};

		const json::string &value
		{
			events.at(type)
		};

		ret = is_level(value);
	});

	return ret;
}
catch(const json::error &)
{
	return false;
}

bool
ircd::m::room::power::has_user(const m::user::id &user_id)
const try
{
	bool ret{false};
	view([&user_id, &ret]
	(const json::object &content)
	{
		const json::object &users
		{
			content.at("users")
		};

		const json::string &value
		{
			users.at(user_id)
		};

		ret = is_level(value);
	});

	return ret;
}
catch(const json::error &)
{
	return false;
}

bool
ircd::m::room::power::has_collection(const string_view &prop)
const
{
	bool ret{false};
	view([&prop, &ret]
	(const json::object &content)
	{
		const string_view &value
		{
			content.get(prop)
		};

		ret = json::type(value, json::OBJECT);
	});

	return ret;
}

bool
ircd::m::room::power::has_level(const string_view &prop)
const
{
	bool ret{false};
	view([&prop, &ret]
	(const json::object &content)
	{
		const json::string &value
		{
			content.get(prop)
		};

		ret = is_level(value);
	});

	return ret;
}

bool
ircd::m::room::power::for_each_collection(const closure &closure)
const
{
	bool ret{true};
	view([&closure, &ret]
	(const json::object &content)
	{
		for(const auto &[key, val] : content)
		{
			if(!json::type(val, json::OBJECT))
				continue;

			if(!closure(key, std::numeric_limits<int64_t>::min()))
			{
				ret = false;
				break;
			}
		}
	});

	return ret;
}

bool
ircd::m::room::power::for_each(const closure &closure)
const
{
	return for_each(string_view{}, closure);
}

bool
ircd::m::room::power::for_each(const string_view &prop,
                               const closure &closure)
const
{
	bool ret{true};
	view([&prop, &closure, &ret]
	(const json::object &content)
	{
		const json::object &collection
		{
			// This little cmov gimmick sets collection to be the outer object
			// itself if no property was given, allowing us to reuse this func
			// for all iterations of key -> level mappings.
			prop? json::object{content.get(prop)} : content
		};

		const string_view _collection{collection};
		if(prop && (!_collection || !json::type(_collection, json::OBJECT)))
			return;

		for(auto it(begin(collection)); it != end(collection) && ret; ++it)
		{
			const auto &[key, val]
			{
				*it
			};

			if(!is_level(val))
				continue;

			ret = closure(key, as_level(val));
		}
	});

	return ret;
}

bool
ircd::m::room::power::view(const std::function<void (const json::object &)> &closure)
const
{
	if(power_event_idx)
		if(m::get(std::nothrow, power_event_idx, "content", closure))
			return true;

	closure(power_event_content);
	return !empty(power_event_content);
}

int64_t
ircd::m::room::power::as_level(const json::string &value,
                               const int64_t &default_)
noexcept
{
	return is_level(value)?
		as_level(value):
		default_;
}

int64_t
ircd::m::room::power::as_level(const json::string &value)
{
	return lex_cast<int64_t>(value);
}

bool
ircd::m::room::power::is_level(const json::string &value)
noexcept
{
	return lex_castable<int64_t>(value);
}