@alexknips/nestjs-kafka-events/dist/kafka-event-functions.service.js

Lightweight, tested, straight-forward wrapper around KafkaJS and Confluent's Schema Registry.

"use strict";
var __decorate = (this && this.__decorate) || function (decorators, target, key, desc) {
    var c = arguments.length, r = c < 3 ? target : desc === null ? desc = Object.getOwnPropertyDescriptor(target, key) : desc, d;
    if (typeof Reflect === "object" && typeof Reflect.decorate === "function") r = Reflect.decorate(decorators, target, key, desc);
    else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
    return c > 3 && r && Object.defineProperty(target, key, r), r;
};
var __metadata = (this && this.__metadata) || function (k, v) {
    if (typeof Reflect === "object" && typeof Reflect.metadata === "function") return Reflect.metadata(k, v);
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.KafkaEventFunctionsService = void 0;
const common_1 = require("@nestjs/common");
const core_1 = require("@nestjs/core");
const decorators_1 = require("./decorators");
const loggers_1 = require("./loggers");
let KafkaEventFunctionsService = class KafkaEventFunctionsService {
    constructor(modulesContainer, metadataScanner, kafkaLogger) {
        this.modulesContainer = modulesContainer;
        this.metadataScanner = metadataScanner;
        this.kafkaLogger = kafkaLogger;
        this.eventHandlerMap = new Map();
        this.eventEmitterTopics = new Set();
    }
    explore() {
        const modules = [...this.modulesContainer.values()];
        const providersMap = modules
            .filter(({ providers }) => providers.size > 0)
            .map(({ providers }) => providers)
            .concat(modules
            .filter(({ controllers }) => controllers.size > 0)
            .map(({ controllers }) => controllers));
        const instanceWrappers = [];
        providersMap.forEach((map) => {
            const mapKeys = [...map.keys()];
            const r = mapKeys.map((key) => {
                return map.get(key);
            });
            instanceWrappers.push(...r.filter((i) => !!i.instance));
        });
        const eventHandlers = instanceWrappers
            .map(({ instance }) => {
            const instancePrototype = Object.getPrototypeOf(instance);
            return this.metadataScanner.scanFromPrototype(instance, instancePrototype, (method) => this.exploreMethodMetadata(instance, instancePrototype, method, decorators_1.KAFKA_EVENT_HANDLER));
        })
            .reduce((prev, curr) => {
            return prev.concat(curr);
        });
        const eventEmitters = instanceWrappers
            .map(({ instance }) => {
            const instancePrototype = Object.getPrototypeOf(instance);
            const r = this.metadataScanner.scanFromPrototype(instance, instancePrototype, (method) => this.exploreMethodMetadata(instance, instancePrototype, method, decorators_1.KAFKA_EVENT_EMITTER));
            return r;
        })
            .reduce((prev, curr) => {
            return prev.concat(curr);
        });
        for (const eventHandler of eventHandlers) {
            this.eventHandlerMap.set(eventHandler.topic, {
                target: eventHandler.target,
                methodName: eventHandler.methodName,
            });
        }
        for (const eventEmitter of eventEmitters) {
            this.eventEmitterTopics = new Set([
                ...Array.from(this.eventEmitterTopics),
                ...(Array.isArray(eventEmitter.topics)
                    ? eventEmitter.topics
                    : [eventEmitter.topics]),
            ]);
        }
        this.kafkaLogger.debug(`Registered ${this.eventHandlerMap.size} event handlers`);
        this.kafkaLogger.debug(`Registered ${eventEmitters.length} event emitters with ${this.eventEmitterTopics.size} topics`);
    }
    getEventHandlerTopics() {
        return Array.from(this.eventHandlerMap.keys());
    }
    getEventEmitterTopics() {
        return Array.from(this.eventEmitterTopics);
    }
    async callEventHandler(topic, event) {
        const handler = this.eventHandlerMap.get(topic);
        if (!handler) {
            this.kafkaLogger.warn(`Unable to find handler for topic ${topic}`);
            return;
        }
        return await handler.target[handler.methodName].apply(handler.target, [
            event,
        ]);
    }
    exploreMethodMetadata(instance, instancePrototype, methodKey, metadataKey) {
        const targetCallback = instancePrototype[methodKey];
        const handler = Reflect.getMetadata(metadataKey, targetCallback);
        if (handler == null) {
            return null;
        }
        return Object.assign(Object.assign({}, handler), { target: instance });
    }
};
KafkaEventFunctionsService = __decorate([
    (0, common_1.Injectable)(),
    __metadata("design:paramtypes", [core_1.ModulesContainer,
        core_1.MetadataScanner,
        loggers_1.KafkaLogger])
], KafkaEventFunctionsService);
exports.KafkaEventFunctionsService = KafkaEventFunctionsService;
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