import {Collection, ErrorWithContext} from '../../util'
import {AppClass} from '../../lifecycle/AppClass'
import {RouteHandler} from './Route'
import {Container} from '../../di'
import {Logging} from '../../service/Logging'

/**
 * Class that defines a group of Routes in the application, with a prefix.
 */
export class RouteGroup extends AppClass {
    /**
     * The current set of nested groups. This is used when compiling route groups.
     * @private
     */
    private static currentGroupNesting: RouteGroup[] = []

    /**
     * Mapping of group names to group registration functions.
     * @protected
     */
    protected static namedGroups: {[key: string]: () => void } = {}

    /**
     * Array of middlewares that should apply to all routes in this group.
     * @protected
     */
    protected middlewares: Collection<{ stage: 'pre' | 'post', handler: RouteHandler }> = new Collection<{stage: 'pre' | 'post'; handler: RouteHandler}>()

    /**
     * Get the current group nesting.
     */
    public static getCurrentGroupHierarchy(): RouteGroup[] {
        return [...this.currentGroupNesting]
    }

    /**
     * Create a new named group that can be registered at a later time, by name.
     *
     * @example
     * ```typescript
     * RouteGroup.named('auth', () => {
     *     Route.group('/auth', () => {
     *         Route.get('/login', 'auth:Forms.getLogin')
     *     })
     * })
     * ```
     *
     * @param name
     * @param define
     */
    public static named(name: string, define: () => void): void {
        if ( this.namedGroups[name] ) {
            Container.getContainer()
                .make<Logging>(Logging)
                .warn(`Replacing named route group: ${name}`)
        }

        this.namedGroups[name] = define
    }

    /**
     * Register the routes from a named group by calling its registration function.
     *
     * @example
     * From the example above, we can register the auth `/auth/*` routes, like so:
     * ```typescript
     * RouteGroup.include('auth')
     * ```
     *
     * @param name
     */
    public static include(name: string): void {
        if (!this.namedGroups[name]) {
            throw new ErrorWithContext(`No route group exists with name: ${name}`, {name})
        }

        this.namedGroups[name]()
    }


    constructor(
        /** Function to register routes for this group. */
        public readonly group: () => void | Promise<void>,

        /** The route prefix of this group. */
        public readonly prefix: string,
    ) {
        super()
    }

    /** Register the given middleware to be applied before all routes in this group. */
    pre(middleware: RouteHandler): this {
        this.middlewares.push({
            stage: 'pre',
            handler: middleware,
        })

        return this
    }

    /** Register the given middleware to be applied after all routes in this group. */
    post(middleware: RouteHandler): this {
        this.middlewares.push({
            stage: 'post',
            handler: middleware,
        })

        return this
    }

    /** Return the middlewares that apply to this group. */
    getGroupMiddlewareDefinitions(): Collection<{ stage: 'pre' | 'post', handler: RouteHandler }> {
        return this.middlewares
    }
}