// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 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::mapi::header
IRCD_MODULE
{
	"Client Sync :Room Unread Notifications"
};

namespace ircd::m::sync
{
	static long _notification_count(const room &, const event::idx &a, const event::idx &b);
	static long _highlight_count(const room &, const user &u, const event::idx &a, const event::idx &b);
	static bool room_unread_notifications_polylog(data &);
	static bool room_unread_notifications_linear(data &);

	extern conf::item<int64_t> exposure_depth;
	extern item room_unread_notifications;
}

decltype(ircd::m::sync::room_unread_notifications)
ircd::m::sync::room_unread_notifications
{
	"rooms.unread_notifications",
	room_unread_notifications_polylog,
	room_unread_notifications_linear,
	{
		{ "initial",  true },
	}
};

decltype(ircd::m::sync::exposure_depth)
ircd::m::sync::exposure_depth
{
	{ "name",         "ircd.client.sync.rooms.unread_notifications.exposure.depth" },
	{ "default",      20L                                                          },
};

bool
ircd::m::sync::room_unread_notifications_linear(data &data)
{
	if(!data.event_idx)
		return false;

	if(!data.membership)
		return false;

	if(!data.room)
		return false;

	// skips state events only until a non-state event is seen.
	assert(data.event);
	if(defined(json::get<"state_key"_>(*data.event)))
		return false;

	// skips old events the server has backfilled in the background.
	if(int64_t(exposure_depth) > -1)
		if(json::get<"depth"_>(*data.event) + int64_t(exposure_depth) < data.room_depth)
			return false;

	const auto &room{*data.room};
	m::event::id::buf last_read;
	if(!m::receipt::read(last_read, room.room_id, data.user))
		return false;

	const auto start_idx
	{
		index(last_read)
	};

	json::stack::object rooms
	{
		*data.out, "rooms"
	};

	json::stack::object membership_
	{
		*data.out, data.membership
	};

	json::stack::object room_
	{
		*data.out, data.room->room_id
	};

	json::stack::object unread_notifications
	{
		*data.out, "unread_notifications"
	};

	const event::idx upper_bound
	{
		std::max(data.range.second, data.event_idx + 1)
	};

	// highlight_count
	json::stack::member
	{
		*data.out, "highlight_count", json::value
		{
			_highlight_count(room, data.user, start_idx, upper_bound)
		}
	};

	// notification_count
	json::stack::member
	{
		*data.out, "notification_count", json::value
		{
			_notification_count(room, start_idx, upper_bound)
		}
	};

	return true;
}

bool
ircd::m::sync::room_unread_notifications_polylog(data &data)
{
	const auto &room{*data.room};
	m::event::id::buf last_read;
	if(!m::receipt::read(last_read, room.room_id, data.user))
		return false;

	const auto start_idx
	{
		index(last_read)
	};

	if(!apropos(data, start_idx))
		return false;

	// notification_count
	json::stack::member
	{
		*data.out, "notification_count", json::value
		{
			_notification_count(room, start_idx, data.range.second)
		}
	};

	// highlight_count
	if(m::user::highlight::enable_count)
		json::stack::member
		{
			*data.out, "highlight_count", json::value
			{
				_highlight_count(room, data.user, start_idx, data.range.second)
			}
		};

	return true;
}

long
ircd::m::sync::_notification_count(const room &room,
                                   const event::idx &a,
                                   const event::idx &b)
{
	return m::count_since(room, a, a < b? b : a);
}

long
ircd::m::sync::_highlight_count(const room &room,
                                const user &user,
                                const event::idx &a,
                                const event::idx &b)
{
	const m::user::highlight highlight
	{
		user
	};

	const m::event::idx_range range
	{
		a, a < b? b : a
	};

	return highlight.count_between(room, range);
}