code-api-web/src/packages/fastify-service-session/index.ts

import fp from 'fastify-plugin'
import { FastifyInstance, FastifyRequest } from 'fastify'

export interface FastifySessionOpts<SessionType = unknown, SessionId = string, RequestType extends FastifyRequest = FastifyRequest> {
	sessionRequestKey?: string,
	extractSessionId: (request: RequestType) => SessionId | null | undefined,
	isSessionValid: (sessionId: SessionId) => Promise<boolean>,
	getSession: (sessionId: SessionId) => Promise<SessionType>
}

const fastifySession = async (app: FastifyInstance, opts: FastifySessionOpts) => {
	const { sessionRequestKey = 'session' } = opts
	app.decorateRequest(sessionRequestKey, null)
	app.addHook('onRequest', async (request: FastifyRequest) => {
		const sessionId = opts.extractSessionId(request)
		if (typeof sessionId === 'string') {
			const isSessionValid = await opts.isSessionValid(sessionId)
			if (isSessionValid) {
				const mutableRequest = (request as unknown) as Record<string, unknown>
				mutableRequest[sessionRequestKey] = await opts.getSession(sessionId)
			}
		}
	})
}

export default fp(fastifySession)