tildefriends/core/ssb.js

"use strict";
var g_wants_requests = {};
var g_database = new Database('core');
const k_use_create_history_stream = false;

function get_latest_sequence_for_author(author) {
	var sequence = 0;
	ssb.sqlStream(
		'SELECT MAX(sequence) AS sequence FROM messages WHERE author = ?1',
		[author],
		function(row) {
			if (row.sequence) {
				sequence = row.sequence;
			}
		});
	return sequence;
}

function storeMessage(message) {
	var payload = message.message.value ? message.message.value : message.message;
	if (typeof(payload) == 'object') {
		ssb.storeMessage(payload);
	}
}

ssb.addEventListener('connections', function on_connections_changed(change, connection) {
	if (change == 'add') {
		var sequence = get_latest_sequence_for_author(connection.id);
		if (k_use_create_history_stream) {
			connection.send_json({'name': ['createHistoryStream'], 'type': 'source', 'args': [{'id': connection.id, 'seq': sequence, 'live': true, 'keys': false}]}, storeMessage);
			var identities = ssb.getAllIdentities();
			ssb.followingDeep(identities, 2).then(function(ids) {
				for (let id of ids) {
					if (identities.indexOf(id) != -1) {
						continue;
					}
					var sequence = get_latest_sequence_for_author(id);
					connection.send_json({'name': ['createHistoryStream'], 'type': 'source', 'args': [{'id': id, 'seq': sequence, 'live': true, 'keys': false}]}, storeMessage);
				}
			});
		} else {
			if (connection.is_client) {
				connection.send_json({"name": ["ebt", "replicate"], "args": [{"version": 3, "format": "classic"}], "type": "duplex"}, ebtReplicateClient);
			}
		}
	} else if (change == 'remove') {
		print('REMOVE', connection.id);
		delete g_wants_requests[connection.id];
	} else {
		print('CHANGE', change);
	}
});

function ebtReplicateSendClock(request, have) {
	var identities = ssb.getAllIdentities();
	var message = {};
	var last_sent = request.connection.sent_clock || {};
	var ids = ssb.followingDeep(identities, 2).concat([request.connection.id]);
	if (!Object.keys(last_sent).length) {
		for (let id of ids) {
			message[id] = get_latest_sequence_for_author(id);
		}
	}
	for (let id of Object.keys(have)) {
		if (message[id] === undefined) {
			var sequence = get_latest_sequence_for_author(id);
			message[id] = sequence ? sequence : -1;
		}
	}

	var to_send = {}
	var offset = Math.floor(Math.random() * ids.length);
	for (var i = 0; i < ids.length; i++) {
		var id = ids[(i + offset) % ids.length];
		if (last_sent[id] === undefined || message[id] > last_sent[id]) {
			last_sent[id] = to_send[id] = message[id] === -1 ? -1 : message[id] << 1;
		}
		if (Object.keys(to_send).length >= 32) {
			request.send_json(to_send);
			to_send = {};
		}
	}
	request.connection.sent_clock = last_sent;

	if (Object.keys(to_send).length) {
		request.send_json(to_send);
	}
}

function formatMessage(row) {
	if (row.sequence_before_author) {
		return {
			previous: row.previous,
			sequence: row.sequence,
			author: row.author,
			timestamp: row.timestamp,
			hash: row.hash,
			content: JSON.parse(row.content),
			signature: row.signature,
		};
	} else {
		return {
			previous: row.previous,
			author: row.author,
			sequence: row.sequence,
			timestamp: row.timestamp,
			hash: row.hash,
			content: JSON.parse(row.content),
			signature: row.signature,
		};
	}
}

function ebtReplicateRegisterMessageCallback(request) {
	ssb.addEventListener('message', function(message_id) {
		if (request.connection.send_clock) {
			ssb.sqlStream(
				'SELECT previous, author, id, sequence, timestamp, hash, content, signature FROM messages WHERE id = ?1',
				[message_id],
				function (row) {
					if (request.connection.send_clock[row.author] < row.sequence) {
						request.send_json(formatMessage(row));
					}
				});
		}
	});
}

function ebtReplicateCommon(request) {
	if (request.message.author) {
		storeMessage(request);
	} else {
		ebtReplicateSendClock(request, request.message);

		if (!request.connection.send_clock) {
			request.connection.send_clock = {};
		}
		for (let id of Object.keys(request.message)) {
			if (request.message[id] >= 0 && (request.message[id] & 1) == 0) {
				request.connection.send_clock[id] = request.message[id] >> 1;
				ssb.sqlStream(
					'SELECT previous, author, id, sequence, timestamp, hash, content, signature FROM messages WHERE author = ?1 AND sequence >= ?2 ORDER BY sequence',
					[id, request.message[id] >> 1],
					function (row) {
						request.send_json(formatMessage(row));
						request.connection.send_clock[id] = row.sequence;
					});
			} else {
				delete request.connection.send_clock[id];
			}
		}
	}
}

function ebtReplicateClient(request) {
	if (request.message?.name !== 'Error') {
		if (!request.connection.message_registered) {
			ebtReplicateRegisterMessageCallback(request);
			request.connection.message_registered = true;
		}
		ebtReplicateCommon(request);
	}
}

function ebtReplicateServer(request) {
	ebtReplicateRegisterMessageCallback(request);
	ebtReplicateSendClock(request, {});
	request.more(ebtReplicateCommon);
}

ssb.addRpc(['ebt', 'replicate'], ebtReplicateServer);

ssb.addRpc(['createHistoryStream'], function(request) {
	if (!request?.args) {
		print('missing request.args in createHistoryStream');
	}
	var id = request.args[0].id;
	var seq = request.args[0].seq;
	var keys = request.args[0].keys || request.args[0].keys === undefined;
	function sendMessage(row) {
		if (keys) {
			var message = {
				key: row.id,
				value: formatMessage(row),
				timestamp: row.timestamp,
			};
		} else {
			var message = formatMessage(row);
		}
		request.send_json(message);
	}
	ssb.sqlStream(
		'SELECT previous, author, id, sequence, timestamp, hash, content, signature, sequence_before_author FROM messages WHERE author = ?1 AND sequence >= ?2 ORDER BY sequence',
		[id, seq ?? 0],
		sendMessage);
	ssb.addEventListener('message', function(message_id) {
		ssb.sqlStream(
			'SELECT previous, author, id, sequence, timestamp, hash, content, signature, sequence_before_author FROM messages WHERE id = ?1 AND author = ?2',
			[message_id, id],
			function (row) {
				sendMessage(row);
			});
	});
});