lib/src/support/cache/CacheFactory.ts

import {
    AbstractFactory,
    Container,
    DependencyRequirement,
    PropertyDependency,
    isInstantiable,
    DEPENDENCY_KEYS_METADATA_KEY,
    StaticClass, Instantiable, getPropertyInjectionMetadata,
} from '../../di'
import {Collection, ErrorWithContext} from '../../util'
import {Logging} from '../../service/Logging'
import {Config} from '../../service/Config'
import {Cache} from '../../util'
import {MemoryCache} from './MemoryCache'

/**
 * Dependency container factory that matches the abstract Cache token, but
 * produces an instance of whatever Cache driver is configured in the `server.cache.driver` config.
 */
export class CacheFactory extends AbstractFactory<Cache> {
    protected readonly logging: Logging

    protected readonly config: Config

    /** true if we have printed the memory-based cache driver warning once. */
    private static loggedMemoryCacheWarningOnce = false

    constructor() {
        super({})
        this.logging = Container.getContainer().make<Logging>(Logging)
        this.config = Container.getContainer().make<Config>(Config)
    }

    produce(): Cache {
        return new (this.getCacheClass())()
    }

    match(something: unknown): boolean {
        return something === Cache
    }

    getDependencyKeys(): Collection<DependencyRequirement> {
        const meta = Reflect.getMetadata(DEPENDENCY_KEYS_METADATA_KEY, this.getCacheClass())
        if ( meta ) {
            return meta
        }
        return new Collection<DependencyRequirement>()
    }

    getInjectedProperties(): Collection<PropertyDependency> {
        const meta = new Collection<PropertyDependency>()
        let currentToken = this.getCacheClass()

        do {
            const loadedMeta = getPropertyInjectionMetadata(currentToken)
            if ( loadedMeta ) {
                meta.concat(loadedMeta)
            }
            currentToken = Object.getPrototypeOf(currentToken)
        } while (Object.getPrototypeOf(currentToken) !== Function.prototype && Object.getPrototypeOf(currentToken) !== Object.prototype)

        return meta
    }

    /**
     * Get the configured cache driver and return some Instantiable<Cache>.
     * @protected
     */
    protected getCacheClass(): StaticClass<Cache, Instantiable<Cache>> {
        const CacheClass = this.config.get('server.cache.driver', MemoryCache)
        if ( CacheClass === MemoryCache && !CacheFactory.loggedMemoryCacheWarningOnce ) {
            this.logging.warn(`You are using the default memory-based cache driver. It is recommended you configure a persistent cache driver instead.`)
            CacheFactory.loggedMemoryCacheWarningOnce = true
        }

        if ( !isInstantiable(CacheClass) || !(CacheClass.prototype instanceof Cache) ) {
            const e = new ErrorWithContext('Provided session class does not extend from @extollo/lib.Cache')
            e.context = {
                configKey: 'server.cache.driver',
                class: CacheClass.toString(),
            }
        }

        return CacheClass
    }
}