// 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.

namespace ircd::m::rooms::summary
{
	static string_view make_state_key(const mutable_buffer &out, const m::room::id &);
	static room::id::buf unmake_state_key(const string_view &);
	static void chunk_remote(const room &, json::stack::object &o);
	static void chunk_local(const room &, json::stack::object &o);

	extern const room::id::buf public_room_id;
	extern hookfn<vm::eval &> create_public_room;
}

ircd::mapi::header
IRCD_MODULE
{
	"Matrix rooms summary"
};

decltype(ircd::m::rooms::summary::public_room_id)
ircd::m::rooms::summary::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::summary::create_public_room)
ircd::m::rooms::summary::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);
	}
};

//
// rooms::summary::fetch
//

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

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

//
// fetch::fetch
//

IRCD_MODULE_EXPORT
ircd::m::rooms::summary::fetch::fetch(const string_view &origin,
                                      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;
	const unique_buffer<mutable_buffer> buf
	{
		// Buffer for headers and send content; received content is dynamic
		16_KiB
	};

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

	const auto code
	{
		request.get(seconds(timeout))
	};

	const json::object response
	{
		request
	};

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

	for(const json::object &summary : chunk)
	{
		const json::string &room_id
		{
			summary.at("room_id")
		};

		summary::set(room_id, summary);
	}

	this->total_room_count_estimate =
	{
		response.get("total_room_count_estimate", 0UL)
	};

	this->next_batch = json::string
	{
		response.get("next_batch", string_view{})
	};
}

//
// rooms::summary
//

ircd::m::event::id::buf
IRCD_MODULE_EXPORT
ircd::m::rooms::summary::del(const m::room &room)
{
	const m::room::state state
	{
		public_room_id
	};

	char state_key_buf[m::event::STATE_KEY_MAX_SIZE];
	const auto state_key
	{
		make_state_key(state_key_buf, room.room_id)
	};

	const m::event::idx &event_idx
	{
		state.get(std::nothrow, "ircd.rooms", state_key)
	};

	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 &room)
{
	if(!exists(room))
		throw m::NOT_FOUND
		{
			"Cannot set a summary for room '%s' which I have no state for",
			string_view{room.room_id}
		};

	const unique_buffer<mutable_buffer> buf
	{
		48_KiB
	};

	const json::object summary
	{
		chunk(room, buf)
	};

	return set(room.room_id, summary);
}

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[event::STATE_KEY_MAX_SIZE];
	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::json::object
IRCD_MODULE_EXPORT
ircd::m::rooms::summary::chunk(const m::room &room,
                               const mutable_buffer &buf)
{
	json::stack out{buf};
	{
		json::stack::object obj{out};
		chunk(room, obj);
	}

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

void
IRCD_MODULE_EXPORT
ircd::m::rooms::summary::chunk(const m::room &room,
                               json::stack::object &obj)
{
	return exists(room)?
		chunk_local(room, obj):
		chunk_remote(room, obj);
}

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

	char state_key_buf[event::STATE_KEY_MAX_SIZE];
	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::summary::chunk_local(const m::room &room,
                                     json::stack::object &obj)
{
	const m::room::state state
	{
		room
	};

	// 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 auto &type, const auto &content_key, const auto &closure)
	{
		const auto event_idx
		{
			state.get(std::nothrow, type, "")
		};

		m::get(std::nothrow, event_idx, "content", [&content_key, &closure]
		(const json::object &content)
		{
			const json::string &value
			{
				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"
			}
		};
	});
}

bool
IRCD_MODULE_EXPORT
ircd::m::rooms::summary::has(const room::id &room_id)
{
	const m::room::state state
	{
		public_room_id
	};

	char state_key_buf[m::event::STATE_KEY_MAX_SIZE];
	const auto state_key
	{
		make_state_key(state_key_buf, room_id)
	};

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

ircd::m::room::id::buf
ircd::m::rooms::summary::unmake_state_key(const string_view &key)
{
	m::room::id::buf ret;
	return m::room::id::unswap(key, ret);
}

ircd::string_view
ircd::m::rooms::summary::make_state_key(const mutable_buffer &buf,
                                        const m::room::id &room_id)
{
	return room_id.swap(buf);
}