@vaadin/hilla-react-signals/FullStackSignal.js

Signals for Hilla React

import { nanoid } from 'nanoid';
import { computed, signal, Signal } from './core.js';
import { createSetStateEvent } from './events.js';
const ENDPOINT = 'SignalsHandler';
export class DependencyTrackingSignal extends Signal {
    #onFirstSubscribe;
    #onLastUnsubscribe;
    #subscribeCount = -1;
    constructor(value, onFirstSubscribe, onLastUnsubscribe) {
        super(value);
        this.#onFirstSubscribe = onFirstSubscribe;
        this.#onLastUnsubscribe = onLastUnsubscribe;
    }
    S(node) {
        super.S(node);
        if (this.#subscribeCount === 0) {
            this.#onFirstSubscribe();
        }
        this.#subscribeCount += 1;
    }
    U(node) {
        super.U(node);
        this.#subscribeCount -= 1;
        if (this.#subscribeCount === 0) {
            this.#onLastUnsubscribe();
        }
    }
}
class ServerConnection {
    #id;
    config;
    #subscription;
    constructor(id, config) {
        this.config = config;
        this.#id = id;
    }
    get subscription() {
        return this.#subscription;
    }
    connect() {
        const { client, endpoint, method, params, parentClientSignalId } = this.config;
        this.#subscription ??= client.subscribe(ENDPOINT, 'subscribe', {
            providerEndpoint: endpoint,
            providerMethod: method,
            clientSignalId: this.#id,
            params,
            parentClientSignalId,
        });
        return this.#subscription;
    }
    async update(event) {
        const onTheFly = !this.#subscription;
        if (onTheFly) {
            this.connect();
        }
        await this.config.client.call(ENDPOINT, 'update', {
            clientSignalId: this.#id,
            event,
        });
        if (onTheFly) {
            this.disconnect();
        }
    }
    disconnect() {
        this.#subscription?.cancel();
        this.#subscription = undefined;
    }
}
export const $update = Symbol('update');
export const $processServerResponse = Symbol('processServerResponse');
export const $setValueQuietly = Symbol('setValueQuietly');
export const $resolveOperation = Symbol('resolveOperation');
export const $createOperation = Symbol('createOperation');
export class FullStackSignal extends DependencyTrackingSignal {
    id;
    server;
    pending = computed(() => this.#pending.value);
    error = computed(() => this.#error.value);
    #pending = signal(false);
    #error = signal(undefined);
    #paused = true;
    constructor(value, config, id) {
        super(value, () => this.#connect(), () => this.#disconnect());
        this.id = id ?? nanoid();
        this.server = new ServerConnection(this.id, config);
        this.subscribe((v) => {
            if (!this.#paused) {
                this.#pending.value = true;
                this.#error.value = undefined;
                const signalId = config.parentClientSignalId !== undefined ? this.id : undefined;
                this[$update](createSetStateEvent(v, signalId, config.parentClientSignalId));
            }
        });
        this.#paused = false;
    }
    #operationPromises = new Map();
    [$createOperation]({ id, promise }) {
        const thens = this.#operationPromises;
        const promises = [];
        if (promise) {
            promises.push(promise);
        }
        if (id) {
            promises.push(new Promise((resolve, reject) => {
                thens.set(id, { resolve, reject });
            }));
        }
        if (promises.length === 0) {
            promises.push(Promise.resolve());
        }
        return {
            result: Promise.allSettled(promises).then((results) => {
                const lastResult = results[results.length - 1];
                if (lastResult.status === 'fulfilled') {
                    return undefined;
                }
                throw lastResult.reason;
            }),
        };
    }
    [$setValueQuietly](value) {
        this.#paused = true;
        super.value = value;
        this.#paused = false;
    }
    async [$update](event) {
        return this.server
            .update(event)
            .catch((error) => {
            this.#error.value = error instanceof Error ? error : new Error(String(error));
        })
            .finally(() => {
            this.#pending.value = false;
        });
    }
    [$resolveOperation](eventId, reason) {
        const operationPromise = this.#operationPromises.get(eventId);
        if (operationPromise) {
            this.#operationPromises.delete(eventId);
            if (reason) {
                operationPromise.reject(reason);
            }
            else {
                operationPromise.resolve();
            }
        }
    }
    #connect() {
        this.server
            .connect()
            .onSubscriptionLost(() => 'resubscribe')
            .onNext((event) => {
            this.#paused = true;
            this[$processServerResponse](event);
            this.#paused = false;
        });
    }
    #disconnect() {
        if (this.server.subscription === undefined) {
            return;
        }
        this.server.disconnect();
    }
}
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