// 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.

using namespace ircd;

mapi::header
IRCD_MODULE
{
	"Federation 21 :End-to-End Encryption"
};

m::resource
user_keys_query_resource
{
	"/_matrix/federation/v1/user/keys/query",
	{
		"federation user keys query",
	}
};

static void
_query_user_device(client &,
                   const m::resource::request &,
                   const m::user::devices &,
                   const string_view &device_id,
                   json::stack::object &out);

static void
_query_user_keys(client &,
                 const m::resource::request &,
                 json::stack &);

static void
_query_self_keys(client &,
                 const m::resource::request &,
                 json::stack &);

static void
_query_master_keys(client &,
                   const m::resource::request &,
                   json::stack &);

static void
_query_device_keys(client &,
                   const m::resource::request &,
                   json::stack &);

static m::resource::response
post__user_keys_query(client &client,
                      const m::resource::request &request);

m::resource::method
user_keys_query__post
{
	user_keys_query_resource, "POST", post__user_keys_query,
	{
		user_keys_query__post.VERIFY_ORIGIN
	}
};

m::resource::response
post__user_keys_query(client &client,
                      const m::resource::request &request)
{
	m::resource::response::chunked::json response
	{
		client, http::OK
	};

	_query_device_keys(client, request, response);
	_query_master_keys(client, request, response);
	_query_self_keys(client, request, response);
	if(my_host(request.node_id))
		_query_user_keys(client, request, response);

	return response;
}

void
_query_device_keys(client &client,
                   const m::resource::request &request,
                   json::stack &out)
{
	json::stack::object response_keys
	{
		out, "device_keys"
	};

	const json::object request_keys
	{
		request.at("device_keys")
	};

	for(const auto &[user_id_, device_ids_] : request_keys)
	{
		const m::user::id &user_id
		{
			user_id_
		};

		const json::array &device_ids
		{
			device_ids_
		};

		const m::user::devices devices
		{
			user_id
		};

		json::stack::object response_keys_user
		{
			response_keys, user_id
		};

		if(empty(device_ids))
			devices.for_each([&client, &request, &devices, &response_keys_user]
			(const auto &event_idx, const string_view &device_id)
			{
				_query_user_device(client, request, devices, device_id, response_keys_user);
				return true;
			});
		else
			for(const json::string device_id : device_ids)
				_query_user_device(client, request, devices, device_id, response_keys_user);
	}
}

void
_query_master_keys(client &client,
                   const m::resource::request &request,
                   json::stack &out)
{
	const json::object request_keys
	{
		request.at("device_keys")
	};

	json::stack::object response_keys
	{
		out, "master_keys"
	};

	for(const auto &[user_id_, device_ids_] : request_keys)
	{
		const m::user::id &user_id
		{
			user_id_
		};

		const m::user::room room
		{
			user_id
		};

		const auto event_idx
		{
			room.get(std::nothrow, "ircd.cross_signing.master", "")
		};

		m::get(std::nothrow, event_idx, "content", [&response_keys, &user_id]
		(const json::object &content)
		{
			json::stack::member
			{
				response_keys, user_id, content
			};
		});
	}
}

void
_query_self_keys(client &client,
                 const m::resource::request &request,
                 json::stack &out)
{
	const json::object request_keys
	{
		request.at("device_keys")
	};

	json::stack::object response_keys
	{
		out, "self_signing_keys"
	};

	for(const auto &[user_id_, device_ids_] : request_keys)
	{
		const m::user::id &user_id
		{
			user_id_
		};

		const m::user::room room
		{
			user_id
		};

		const auto event_idx
		{
			room.get(std::nothrow, "ircd.cross_signing.self", "")
		};

		m::get(std::nothrow, event_idx, "content", [&response_keys, &user_id]
		(const json::object &content)
		{
			json::stack::member
			{
				response_keys, user_id, content
			};
		});
	}
}

void
_query_user_keys(client &client,
                 const m::resource::request &request,
                 json::stack &out)
{
	const json::object request_keys
	{
		request.at("device_keys")
	};

	json::stack::object response_keys
	{
		out, "user_signing_keys"
	};

	for(const auto &[user_id_, device_ids_] : request_keys)
	{
		const m::user::id &user_id
		{
			user_id_
		};

		const m::user::room room
		{
			user_id
		};

		const auto event_idx
		{
			room.get(std::nothrow, "ircd.cross_signing.user", "")
		};

		m::get(std::nothrow, event_idx, "content", [&response_keys, &user_id]
		(const json::object &content)
		{
			json::stack::member
			{
				response_keys, user_id, content
			};
		});
	}
}

void
_query_user_device(client &client,
                   const m::resource::request &request,
                   const m::user::devices &devices,
                   const string_view &device_id,
                   json::stack::object &out)
{
	if(!devices.has(device_id, "keys"))
		return;

	const m::user::room user_room
	{
		devices.user.user_id
	};

	json::stack::object object
	{
		out, device_id
	};

	devices.get(std::nothrow, device_id, "keys", [&user_room, &device_id, &object]
	(const auto &, const json::object &device_keys)
	{
		const auto &user_id
		{
			user_room.user.user_id
		};

		for(const auto &member : device_keys)
			if(member.first != "signatures")
				json::stack::member
				{
					object, member
				};

		json::stack::object sigs
		{
			object, "signatures"
		};

		json::stack::object user_sigs
		{
			sigs, user_id
		};

		const json::object device_keys_sigs
		{
			device_keys["signatures"]
		};

		const json::object device_keys_user_sigs
		{
			device_keys_sigs[user_id]
		};

		for(const auto &member : device_keys_user_sigs)
			json::stack::member
			{
				user_sigs, member
			};

		const m::room::state state
		{
			user_room
		};

		state.for_each("ircd.keys.signatures", [&user_id, &user_sigs, &device_id]
		(const string_view &, const string_view &state_key, const auto &event_idx)
		{
			const auto &[target, source]
			{
				rsplit(state_key, '%')
			};

			if(target && target != device_id)
				return true;

			m::get(std::nothrow, event_idx, "content", [&user_id, &user_sigs]
			(const json::object &device_sigs)
			{
				const json::object device_sigs_sigs
				{
					device_sigs["signatures"]
				};

				const json::object device_sigs_user_sigs
				{
					device_sigs_sigs[user_id]
				};

				for(const auto &member : device_sigs_user_sigs)
					json::stack::member
					{
						user_sigs, member
					};
			});

			return true;
		});
	});

	devices.get(std::nothrow, device_id, "display_name", [&device_id, &object]
	(const auto &event_idx, const string_view &display_name)
	{
		json::stack::object non_hancock
		{
			object, "unsigned"
		};

		json::stack::member
		{
			non_hancock, "device_display_name", display_name
		};
	});
}