daton/lib/src/unit/Routing.ts

import LifecycleUnit from '../lifecycle/Unit.ts'
import {Unit} from '../lifecycle/decorators.ts'
import Routes from './Routes.ts'
import {RouterDefinition} from '../http/type/RouterDefinition.ts'
import {Collection} from '../collection/Collection.ts'
import {Route} from '../http/routing/Route.ts'
import {SimpleRoute} from '../http/routing/SimpleRoute.ts'
import {ComplexRoute} from '../http/routing/ComplexRoute.ts'
import ActivatedRoute from '../http/routing/ActivatedRoute.ts'
import {Request} from '../http/Request.ts'
import ResponseFactory from '../http/response/ResponseFactory.ts'
import {Canonical} from './Canonical.ts'
import {Logging} from '../service/logging/Logging.ts'
import {Canon} from './Canon.ts'
import {isBindable} from '../lifecycle/AppClass.ts'
import {DeepmatchRoute} from "../http/routing/DeepmatchRoute.ts";
import {RegExRoute} from "../http/routing/RegExRoute.ts";

/**
 * Base type defining a single route handler.
 */
export type RouteHandler = (request: Request) => Request | Promise<Request> | ResponseFactory | Promise<ResponseFactory> | void | Promise<void>

/**
 * Base type for a collection of route handlers.
 */
export type RouteHandlers = RouteHandler[]

/**
 * Base type for a router definition.
 */
export interface RouteDefinition {
    get?: RouteHandlers,
    post?: RouteHandlers,
    patch?: RouteHandlers,
    delete?: RouteHandlers,
    head?: RouteHandlers,
    put?: RouteHandlers,
    connect?: RouteHandlers,
    options?: RouteHandlers,
    trace?: RouteHandlers,
}

/**
 * Returns true if the given object is a valid route handler.
 * @param what
 * @return boolean
 */
export function isRouteHandler(what: any): what is RouteHandler {
    return (
        typeof what === 'function'
        || typeof what.handleRequest === 'function'
    )
}

const verbs = ['get', 'post', 'patch', 'delete', 'head', 'put', 'connect', 'options', 'trace']

/**
 * Lifecycle unit which processes the loaded routes and builds Route instances from them.
 * @extends LifecycleUnit
 */
@Unit()
export default class Routing extends LifecycleUnit {
    /**
     * Mapping of route definition strings to route definitions.
     * @type object
     */
    protected definitions: { [key: string]: RouteDefinition } = {}

    /**
     * Collection of Route instances
     * @type Collection<Route>
     */
    protected instances: Collection<Route> = new Collection<Route>()

    constructor(
        protected readonly routes: Routes,
        protected readonly logger: Logging,
        protected readonly canon: Canon,
    ) {
        super()
    }

    public async up() {
        const route_groups = this.routes.all()
        for ( const route_group_name of route_groups ) {
            const route_group: RouterDefinition | undefined = this.routes.get(route_group_name)
            if ( !route_group ) continue

            const prefix = route_group.prefix || '/'
            for ( const verb of verbs ) {
                // @ts-ignore
                if ( route_group[verb] ) {
                    // @ts-ignore
                    const group = route_group[verb]
                    for ( const key in group ) {
                        if ( !group.hasOwnProperty(key) ) continue
                        const handlers = Array.isArray(group[key]) ? group[key] : [group[key]]
                        const base = this.resolve([prefix, key])

                        if ( !this.definitions[base] ) {
                            this.definitions[base] = {}
                        }

                        // @ts-ignore
                        this.definitions[base][verb] = this.build_handler(handlers)
                        this.instances.push(this.build_route(base, key))
                    }
                }
            }
        }
    }

    /**
     * Given a group of canonical-string handlers, build an array of route handlers.
     * @param {Array<string>} group
     * @return RouteHandlers
     */
    public build_handler(group: string[]): RouteHandlers {
        const handlers: RouteHandlers = []
        for ( const item of group ) {
            const ref = Canonical.resolve(item)
            
            if ( !ref.resource ) {
                this.logger.error(`Invalid canonical reference for route: ${item}. Reference must include resource (e.g. controller::)!`)
                continue
            }

            const resource = this.canon.resource(ref.resource)
            const resolved = resource.get(ref.item)

            if ( !ref.particular ) {
                if ( isRouteHandler(resolved) ) {
                    handlers.push(resolved)
                } else {
                    throw new TypeError(`Invalid canonical reference for route: ${item}. Reference is not a valid route handler.`)
                }
            } else {
                if ( isBindable(resolved) ) {
                    let handler
                    try {
                        handler = resolved.get_bound_method(ref.particular)
                    } catch (e) {
                        this.logger.error(e)
                        throw new Error(`Invalid canonical reference for route: ${item}. Reference particular could not be bound.`)
                    }

                    if ( isRouteHandler(handler) ) {
                        handlers.push(handler)
                    } else {
                        throw new TypeError(`Invalid canonical reference for route: ${item}. Reference is not a valid route handler.`)
                    }
                } else {
                    throw new TypeError(`Invalid canonical reference for route: ${item}. Reference specifies particular, but resolved resource is not bindable.`)
                }
            }
        }
        return handlers
    }

    /**
     * Given a set of route parts, resolve them to a string.
     * @param {Array<string>} parts
     * @return string
     */
    public resolve(parts: string[]): string {
        const cleaned = parts.map(part => {
            if ( part.startsWith('/') ) part = part.substr(1)
            if ( part.endsWith('/') ) part = part.slice(0, -1)
            return part
        })

        let joined = cleaned.join('/')
        if ( joined.startsWith('/') ) joined = joined.substr(1)
        if ( joined.endsWith('/') ) joined = joined.slice(0, -1)
        return `/${joined}`.toLowerCase()
    }

    /**
     * Given a base and a key, return a new Route instance.
     * @param {string} base
     * @param {string} key
     * @return Route
     */
    public build_route(base: string, key: string): Route {
        if ( key.startsWith('rex ') ) {
            return new RegExRoute(base.split(key)[0], key)
        } else if ( !base.includes(':') && !base.includes('*') ) {
            return new SimpleRoute(base)
        } else if ( base.includes('**') ) {
            return new DeepmatchRoute(base)
        } else {
            return new ComplexRoute(base)
        }
    }

    /**
     * Find the route instance given an incoming route string, if one exists.
     * @param {string} incoming
     * @return Route | undefined
     */
    public match(incoming: string): Route | undefined {
        return this.instances.firstWhere((route: Route) => route.match(incoming))
    }

    /**
     * Given an incoming route and HTTP method, build an activated route if a matching route is found.
     * @param {string} incoming
     * @param {string} method
     * @return ActivatedRoute | undefined
     */
    public build(incoming: string, method: string): ActivatedRoute | undefined {
        const route: Route | undefined = this.match(incoming)

        if ( route ) {
            // @ts-ignore
            const handlers: RouteHandlers | undefined = this.definitions[route.route][method]
            return new ActivatedRoute(incoming, route, handlers)
        }
    }
}