pzp-dict/lib/index.js

282 lines
8.1 KiB
JavaScript

const MsgV3 = require('ppppp-db/msg-v3')
const PREFIX = 'record_v1__'
/**
* @typedef {string} Subdomain
* @typedef {string} MsgID
* @typedef {`${Subdomain}.${string}`} SubdomainField
*/
/**
* @param {string} domain
* @returns {Subdomain}
*/
function toSubdomain(domain) {
return domain.slice(PREFIX.length)
}
/**
* @param {Subdomain} subdomain
* @returns {string}
*/
function fromSubdomain(subdomain) {
return PREFIX + subdomain
}
module.exports = {
name: 'record',
manifest: {},
init(peer, config) {
//#region state
let accountID = /** @type {string | null} */ (null)
let cancelListeningToRecordAdded = null
let loadPromise = /** @type {Promise<void> | null} */ (null)
const tangles = /** @type {Map<Subdomain, unknown>} */ (new Map())
const fieldRoots = {
/** @type {Map<SubdomainField, Set<MsgID>} */
_map: new Map(),
_getKey(subdomain, field) {
return subdomain + '.' + field
},
get(subdomain, field = null) {
if (field) {
const key = this._getKey(subdomain, field)
return this._map.get(key)
} else {
const out = {}
for (const [key, value] of this._map.entries()) {
if (key.startsWith(subdomain + '.')) {
const field = key.slice(subdomain.length + 1)
out[field] = [...value]
}
}
return out
}
},
add(subdomain, field, msgID) {
const key = this._getKey(subdomain, field)
const set = this._map.get(key) ?? new Set()
set.add(msgID)
return this._map.set(key, set)
},
del(subdomain, field, msgID) {
const key = this._getKey(subdomain, field)
const set = this._map.get(key)
if (!set) return false
set.delete(msgID)
if (set.size === 0) this._map.delete(key)
return true
},
toString() {
return this._map
},
}
//#endregion
//#region active processes
peer.close.hook(function (fn, args) {
cancelListeningToRecordAdded()
fn.apply(this, args)
})
//#endregion
//#region internal methods
function isValidRecordRootMsg(msg) {
if (!msg) return false
if (msg.metadata.account !== accountID) return false
const domain = msg.metadata.domain
if (!domain.startsWith(PREFIX)) return false
return MsgV3.isMoot(msg, accountID, domain)
}
function isValidRecordMsg(msg) {
if (!msg) return false
if (!msg.data) return false
if (msg.metadata.account !== accountID) return false
if (!msg.metadata.domain.startsWith(PREFIX)) return false
if (!msg.data.update) return false
if (typeof msg.data.update !== 'object') return false
if (Array.isArray(msg.data.update)) return false
if (!Array.isArray(msg.data.supersedes)) return false
return true
}
function learnRecordRoot(rootID, root) {
const subdomain = toSubdomain(root.metadata.domain)
const tangle = tangles.get(subdomain) ?? new MsgV3.Tangle(rootID)
tangle.add(rootID, root)
tangles.set(subdomain, tangle)
}
function learnRecordUpdate(msgID, msg) {
const { account, domain } = msg.metadata
const rootID = MsgV3.getMootID(account, domain)
const subdomain = toSubdomain(domain)
const tangle = tangles.get(subdomain) ?? new MsgV3.Tangle(rootID)
tangle.add(msgID, msg)
tangles.set(subdomain, tangle)
for (const field in msg.data.update) {
const existing = fieldRoots.get(subdomain, field)
if (!existing) {
fieldRoots.add(subdomain, field, msgID)
} else {
for (const existingID of existing) {
if (tangle.precedes(existingID, msgID)) {
fieldRoots.del(subdomain, field, existingID)
fieldRoots.add(subdomain, field, msgID)
} else {
fieldRoots.add(subdomain, field, msgID)
}
}
}
}
}
function maybeLearnAboutRecord(msgID, msg) {
if (msg.metadata.account !== accountID) return
if (isValidRecordRootMsg(msg)) {
learnRecordRoot(msgID, msg)
return
}
if (isValidRecordMsg(msg)) {
learnRecordUpdate(msgID, msg)
return
}
}
function loaded(cb) {
if (cb === void 0) return loadPromise
else loadPromise.then(() => cb(null), cb)
}
function _squeezePotential(subdomain) {
// TODO: improve this so that the squeezePotential is the size of the
// tangle suffix built as a slice from the fieldRoots
const mootID = MsgV3.getMootID(accountID, fromSubdomain(subdomain))
const tangle = peer.db.getTangle(mootID)
const maxDepth = tangle.maxDepth
const fieldRoots = getFieldRoots(accountID, subdomain)
let minDepth = Infinity
for (const field in fieldRoots) {
for (const msgID of fieldRoots[field]) {
const depth = tangle.getDepth(msgID)
if (depth < minDepth) minDepth = depth
}
}
return maxDepth - minDepth
}
function forceUpdate(subdomain, update, cb) {
const domain = fromSubdomain(subdomain)
// Populate supersedes
const supersedes = []
for (const field in update) {
const existing = fieldRoots.get(subdomain, field)
if (existing) supersedes.push(...existing)
}
peer.db.feed.publish(
{ account: accountID, domain, data: { update, supersedes } },
(err, rec) => {
// prettier-ignore
if (err) return cb(new Error('Failed to create msg when force updating Record', { cause: err }))
cb(null, true)
}
)
}
//#endregion
//#region public methods
/**
* @param {string} id
*/
function load(id, cb) {
accountID = id
loadPromise = new Promise((resolve, reject) => {
for (const { id, msg } of peer.db.records()) {
maybeLearnAboutRecord(id, msg)
}
cancelListeningToRecordAdded = peer.db.onRecordAdded(({ id, msg }) => {
maybeLearnAboutRecord(id, msg)
})
resolve()
cb()
})
}
function getFieldRoots(id, subdomain) {
// prettier-ignore
if (id !== accountID) return cb(new Error(`Cannot getFieldRoots for another user's record. Given ID was "${id}"`))
return fieldRoots.get(subdomain)
}
function get(id, subdomain) {
const domain = fromSubdomain(subdomain)
const mootID = MsgV3.getMootID(id, domain)
const tangle = peer.db.getTangle(mootID)
if (!tangle || tangle.size === 0) return {}
const msgIDs = tangle.topoSort()
const record = {}
for (const msgID of msgIDs) {
const msg = peer.db.get(msgID)
if (isValidRecordMsg(msg)) {
const { update } = msg.data
Object.assign(record, update)
}
}
return record
}
function update(id, subdomain, update, cb) {
// prettier-ignore
if (id !== accountID) return cb(new Error(`Cannot update another user's record. Given ID was "${id}"`))
loaded(() => {
const record = get(id, subdomain)
let hasChanges = false
for (const [field, value] of Object.entries(update)) {
if (value !== record[field]) {
hasChanges = true
break
}
}
if (!hasChanges) return cb(null, false)
forceUpdate(subdomain, update, cb)
})
}
function squeeze(id, subdomain, cb) {
// prettier-ignore
if (id !== accountID) return cb(new Error(`Cannot squeeze another user's record. Given ID was "${id}"`))
const potential = _squeezePotential(subdomain)
if (potential < 1) return cb(null, false)
loaded(() => {
const record = get(id, subdomain)
forceUpdate(subdomain, record, (err) => {
// prettier-ignore
if (err) return cb(new Error('Failed to force update when squeezing Record', { cause: err }))
cb(null, true)
})
})
}
//#endregion
return {
load,
update,
get,
getFieldRoots,
squeeze,
_squeezePotential,
}
},
}