alpha-command-bus/compiled/CommandBus.js

Very simple command bus implementation

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.CommandBus = void 0;
const CommandHandlerDescriptor_1 = require("./CommandHandlerDescriptor");
class CommandBus {
    constructor() {
        this.middlewares = [];
        this.commandHandlers = [];
    }
    /**
     * Registers middleware that wraps process of handling a command
     */
    use(middleware) {
        this.middlewares.push(middleware);
        return this;
    }
    registerCommandHandler(filterOrDescriptor, handler) {
        if (filterOrDescriptor instanceof CommandHandlerDescriptor_1.CommandHandlerDescriptor) {
            this.commandHandlers.push(filterOrDescriptor);
        }
        else {
            this.commandHandlers.push(CommandHandlerDescriptor_1.CommandHandlerDescriptor.fromFilter(filterOrDescriptor, handler));
        }
        return this;
    }
    registerCommandHandlers(descriptors) {
        for (const descriptor of descriptors) {
            this.registerCommandHandler(descriptor);
        }
        return this;
    }
    /**
     * Dispatches command to the bus.
     */
    async handle(command) {
        let currentMiddleware = 0;
        const next = (command) => {
            const middleware = this.middlewares[currentMiddleware++];
            if (middleware) {
                return middleware(command, next);
            }
            return this.runCommandHandler(command);
        };
        return next(command);
    }
    asCommandRunner() {
        return this.handle.bind(this);
    }
    hasCommandHandler(command) {
        return !!this.getCommandHandlerForCommand(command);
    }
    runCommandHandler(command) {
        const commandHandler = this.getCommandHandlerForCommand(command);
        if (!commandHandler) {
            throw new Error(`No command handler registered for command: ${command.command}`);
        }
        return commandHandler.func(command);
    }
    getCommandHandlerForCommand(command) {
        return this.commandHandlers.find(({ predicate }) => predicate(command));
    }
}
exports.CommandBus = CommandBus;