// 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.

namespace ircd::m::rooms
{
	static string_view make_state_key(const mutable_buffer &out, const m::room::id &);
	static m::room::id::buf unmake_state_key(const string_view &);

	static void remote_summary_chunk(const m::room &room, json::stack::object &obj);
	static void local_summary_chunk(const m::room &room, json::stack::object &obj);
	static bool for_each_public(const string_view &room_id_lb, const room::id::closure_bool &);

	extern conf::item<size_t> fetch_limit;
	extern conf::item<seconds> fetch_timeout;
	extern m::hookfn<vm::eval &> create_public_room;
	extern const room::id::buf public_room_id;
}

ircd::mapi::header
IRCD_MODULE
{
	"Matrix rooms interface; modular components"
};

decltype(ircd::m::rooms::public_room_id)
ircd::m::rooms::public_room_id
{
    "public", ircd::my_host()
};

/// Create the public rooms room during initial database bootstrap.
/// This hooks the creation of the !ircd room which is a fundamental
/// event indicating the database has just been created.
decltype(ircd::m::rooms::create_public_room)
ircd::m::rooms::create_public_room
{
	{
		{ "_site",       "vm.effect"      },
		{ "room_id",     "!ircd"          },
		{ "type",        "m.room.create"  },
	},

	[](const m::event &, m::vm::eval &)
	{
		m::create(public_room_id, m::me.user_id);
	}
};

bool
IRCD_MODULE_EXPORT
ircd::m::rooms::for_each(const each_opts &opts)
{
	if(opts.public_rooms)
		return for_each_public(opts.key, opts.closure);

	const room::state state
	{
		my_room
	};

	const room::state::keys_bool keys{[&opts]
	(const string_view &room_id) -> bool
	{
		return opts.closure(room_id);
	}};

	return state.for_each("ircd.room", opts.key, keys);
}

bool
IRCD_MODULE_EXPORT
ircd::m::rooms::is_public(const room::id &room_id)
{
	const m::room room{public_room_id};
	const m::room::state state{room};
	return state.has("ircd.room", room_id);
}

size_t
IRCD_MODULE_EXPORT
ircd::m::rooms::count_public(const string_view &server)
{
	size_t ret{0};
	const auto count{[&ret]
	(const m::room::id &room_id)
	{
		++ret;
		return true;
	}};

	for_each_public(server, count);
	return ret;
}

bool
ircd::m::rooms::for_each_public(const string_view &key,
                                const room::id::closure_bool &closure)
{
	const room::state state
	{
		public_room_id
	};

	const bool is_room_id
	{
		m::valid(m::id::ROOM, key)
	};

	char state_key_buf[256];
	const auto state_key
	{
		is_room_id?
			make_state_key(state_key_buf, key):
			key
	};

	const string_view &server
	{
		is_room_id?
			room::id(key).host():
			key
	};

	const room::state::keys_bool keys{[&closure, &server]
	(const string_view &state_key) -> bool
	{
		const auto room_id
		{
			unmake_state_key(state_key)
		};

		if(server && room_id.host() != server)
			return false;

		return closure(room_id);
	}};

	return state.for_each("ircd.rooms", state_key, keys);
}

void
IRCD_MODULE_EXPORT
ircd::m::rooms::summary_chunk(const m::room &room,
                              json::stack::object &obj)
{
	return exists(room)?
		local_summary_chunk(room, obj):
		remote_summary_chunk(room, obj);
}

void
ircd::m::rooms::remote_summary_chunk(const m::room &room,
                                     json::stack::object &obj)
{
	const m::room publix
	{
		public_room_id
	};

	char state_key_buf[256];
	const auto state_key
	{
		make_state_key(state_key_buf, room.room_id)
	};

	publix.get("ircd.rooms", state_key, [&obj]
	(const m::event &event)
	{
		const json::object &summary
		{
			json::at<"content"_>(event)
		};

		for(const auto &member : summary)
			json::stack::member m{obj, member.first, member.second};
	});
}

void
ircd::m::rooms::local_summary_chunk(const m::room &room,
                                    json::stack::object &obj)
{
	static const event::keys::include keys
	{
		"content",
	};

	const m::event::fetch::opts fopts
	{
		keys, room.fopts? room.fopts->gopts : db::gopts{}
	};

	const m::room::state state
	{
		room, &fopts
	};

	// Closure over boilerplate primary room state queries; i.e matrix
	// m.room.$type events with state key "" where the content is directly
	// presented to the closure.
	const auto query{[&state]
	(const string_view &type, const string_view &content_key, const auto &closure)
	{
		state.get(std::nothrow, type, "", [&content_key, &closure]
		(const m::event &event)
		{
			const auto &content(json::get<"content"_>(event));
			const auto &value(unquote(content.get(content_key)));
			closure(value);
		});
	}};

	// Aliases array
	{
		json::stack::member aliases_m{obj, "aliases"};
		json::stack::array array{aliases_m};
		state.for_each("m.room.aliases", [&array]
		(const m::event &event)
		{
			const json::array aliases
			{
				json::get<"content"_>(event).get("aliases")
			};

			for(const string_view &alias : aliases)
				array.append(unquote(alias));
		});
	}

	query("m.room.avatar_url", "url", [&obj]
	(const string_view &value)
	{
		json::stack::member
		{
			obj, "avatar_url", value
		};
	});

	query("m.room.canonical_alias", "alias", [&obj]
	(const string_view &value)
	{
		json::stack::member
		{
			obj, "canonical_alias", value
		};
	});

	query("m.room.guest_access", "guest_access", [&obj]
	(const string_view &value)
	{
		json::stack::member
		{
			obj, "guest_can_join", json::value
			{
				value == "can_join"
			}
		};
	});

	query("m.room.name", "name", [&obj]
	(const string_view &value)
	{
		json::stack::member
		{
			obj, "name", value
		};
	});

	// num_join_members
	{
		const m::room::members members{room};
		json::stack::member
		{
			obj, "num_joined_members", json::value
			{
				long(members.count("join"))
			}
		};
	}

	// room_id
	{
		json::stack::member
		{
			obj, "room_id", room.room_id
		};
	}

	query("m.room.topic", "topic", [&obj]
	(const string_view &value)
	{
		json::stack::member
		{
			obj, "topic", value
		};
	});

	query("m.room.history_visibility", "history_visibility", [&obj]
	(const string_view &value)
	{
		json::stack::member
		{
			obj, "world_readable", json::value
			{
				value == "world_readable"
			}
		};
	});
}

decltype(ircd::m::rooms::fetch_timeout)
ircd::m::rooms::fetch_timeout
{
	{ "name",     "ircd.m.rooms.fetch.timeout" },
	{ "default",  45L /*  matrix.org :-/    */ },
};

decltype(ircd::m::rooms::fetch_limit)
ircd::m::rooms::fetch_limit
{
	{ "name",     "ircd.m.rooms.fetch.limit" },
	{ "default",  64L                        },
};

std::pair<size_t, std::string>
IRCD_MODULE_EXPORT
ircd::m::rooms::fetch_update(const net::hostport &hp,
                             const string_view &since,
                             const size_t &limit)
{
	m::v1::public_rooms::opts opts;
	opts.limit = limit;
	opts.since = since;
	opts.include_all_networks = true;
	opts.dynamic = true;

	// Buffer for headers and send content only; received content is dynamic
	const unique_buffer<mutable_buffer> buf
	{
		16_KiB
	};

	m::v1::public_rooms request
	{
		hp, buf, std::move(opts)
	};

	request.wait(seconds(fetch_timeout));

	const auto code
	{
		request.get()
	};

	const json::object response
	{
		request
	};

	const json::array &chunk
	{
		response.get("chunk")
	};

	for(const json::object &summary : chunk)
	{
		const m::room::id &room_id
		{
			unquote(summary.at("room_id"))
		};

		summary_set(room_id, summary);
	}

	return
	{
		response.get("total_room_count_estimate", 0UL),
		unquote(response.get("next_batch", string_view{}))
	};
}

ircd::m::event::id::buf
IRCD_MODULE_EXPORT
ircd::m::rooms::summary_del(const m::room &room)
{
	char state_key_buf[m::event::STATE_KEY_MAX_SIZE];
	const m::room::state state{public_room_id};
	const m::event::idx &event_idx
	{
		state.get(std::nothrow, "ircd.rooms", make_state_key(state_key_buf, room.room_id))
	};

	if(!event_idx)
		return {};

	const m::event::id::buf event_id
	{
		m::event_id(event_idx)
	};

	return redact(public_room_id, m::me, event_id, "delisted");
}

ircd::m::event::id::buf
IRCD_MODULE_EXPORT
ircd::m::rooms::summary_set(const m::room::id &room_id,
                            const json::object &summary)
{
	char state_key_buf[256];
	const auto state_key
	{
		make_state_key(state_key_buf, room_id)
	};

	return send(public_room_id, m::me, "ircd.rooms", state_key, summary);
}

ircd::m::room::id::buf
ircd::m::rooms::unmake_state_key(const string_view &key)
{
	const auto s
	{
		split(key, '!')
	};

	return m::room::id::buf
	{
		s.second, s.first
	};
}

ircd::string_view
ircd::m::rooms::make_state_key(const mutable_buffer &buf,
                               const m::room::id &room_id)
{
	mutable_buffer out{buf};
	consume(out, copy(out, room_id.host()));
	consume(out, copy(out, room_id.local()));
	return string_view
	{
		data(buf), data(out)
	};
}