import {AppClass} from "../../lifecycle/AppClass";
import {HTTPMethod, Request} from "../lifecycle/Request";
import {Application} from "../../lifecycle/Application";
import {RouteGroup} from "./RouteGroup";
import {ResponseFactory} from "../response/ResponseFactory";
import {Response} from "../lifecycle/Response";
import {Controllers} from "../../service/Controllers";
import {ErrorWithContext, Collection} from "@extollo/util";
import {Controller} from "../Controller";
import {Middlewares} from "../../service/Middlewares";
import {Middleware} from "./Middleware";

export type ResponseObject = ResponseFactory | string | number | void | any | Promise<ResponseObject>
export type RouteHandler = ((request: Request, response: Response) => ResponseObject) | ((request: Request) => ResponseObject) | (() => ResponseObject) | string
export type ResolvedRouteHandler = (request: Request) => ResponseObject


// TODO domains, named routes - support this on groups as well

export class Route extends AppClass {
    private static registeredRoutes: Route[] = []
    private static registeredGroups: RouteGroup[] = []

    private static compiledGroupStack: RouteGroup[] = []

    public static registerGroup(group: RouteGroup) {
        this.registeredGroups.push(group)
    }

    public static async compile(): Promise<Route[]> {
        let registeredRoutes = this.registeredRoutes
        const registeredGroups = this.registeredGroups

        this.registeredRoutes = []
        this.registeredGroups = []

        const stack = [...this.compiledGroupStack].reverse()
        for ( const route of registeredRoutes ) {
            for ( const group of stack ) {
                route.prepend(group.prefix)
                group.getGroupMiddlewareDefinitions()
                    .each(def => route.prependMiddleware(def))
            }

            for ( const group of this.compiledGroupStack ) {
                group.getGroupMiddlewareDefinitions()
                    .each(def => route.appendMiddleware(def))
            }

            route.resolvePreflight()  // Try to resolve here to catch any errors at boot-time and pre-compile
            route.resolveHandler()
            route.resolvePostflight()
        }

        for ( const group of registeredGroups ) {
            this.compiledGroupStack.push(group)
            await group.group()

            const childCompilation = await this.compile()
            registeredRoutes = registeredRoutes.concat(childCompilation)

            this.compiledGroupStack.pop()
        }

        return registeredRoutes
    }

    public static endpoint(method: HTTPMethod | HTTPMethod[], definition: string, handler: RouteHandler) {
        const route = new Route(method, handler, definition)
        this.registeredRoutes.push(route)
        return route
    }

    public static get(definition: string, handler: RouteHandler) {
        return this.endpoint('get', definition, handler)
    }

    public static post(definition: string, handler: RouteHandler) {
        return this.endpoint('post', definition, handler)
    }

    public static put(definition: string, handler: RouteHandler) {
        return this.endpoint('put', definition, handler)
    }

    public static patch(definition: string, handler: RouteHandler) {
        return this.endpoint('patch', definition, handler)
    }

    public static delete(definition: string, handler: RouteHandler) {
        return this.endpoint('delete', definition, handler)
    }

    public static any(definition: string, handler: RouteHandler) {
        return this.endpoint(['get', 'put', 'patch', 'post', 'delete'], definition, handler)
    }

    public static group(prefix: string, group: () => void | Promise<void>) {
        const grp = <RouteGroup> Application.getApplication().make(RouteGroup, group, prefix)
        this.registeredGroups.push(grp)
        return grp
    }

    protected middlewares: Collection<{ stage: 'pre' | 'post', handler: RouteHandler }> = new Collection<{stage: "pre" | "post"; handler: RouteHandler}>()
    protected _compiledPreflight?: ResolvedRouteHandler[]
    protected _compiledHandler?: ResolvedRouteHandler
    protected _compiledPostflight?: ResolvedRouteHandler[]

    constructor(
        protected method: HTTPMethod | HTTPMethod[],
        protected readonly handler: RouteHandler,
        protected route: string
    ) { super() }

    public match(method: HTTPMethod, potential: string): boolean {
        if ( Array.isArray(this.method) && !this.method.includes(method) ) return false
        else if ( !Array.isArray(this.method) && this.method !== method ) return false

        return !!this.extract(potential)
    }

    public extract(potential: string): {[key: string]: string} | undefined {
        const routeParts = (this.route.startsWith('/') ? this.route.substr(1) : this.route).split('/')
        const potentialParts = (potential.startsWith('/') ? potential.substr(1) : potential).split('/')

        const params: any = {}
        let wildcardIdx = 0

        for ( let i = 0; i < routeParts.length; i += 1 ) {
            const part = routeParts[i]

            if ( part === '**' ) {
                params[wildcardIdx] = potentialParts.slice(i).join('/')
                return params
            }

            if ( (potentialParts.length - 1) < i ) {
                return
            }

            if ( part === '*' ) {
                params[wildcardIdx] = potentialParts[i]
                wildcardIdx += 1
            } else if ( part.startsWith(':') ) {
                params[part.substr(1)] = potentialParts[i]
            } else if ( potentialParts[i] !== part ) {
                return
            }
        }

        // If we got here, we didn't find a **
        // So, if the lengths are different, fail
        if ( routeParts.length !== potentialParts.length ) return
        return params
    }

    public resolvePreflight(): ResolvedRouteHandler[] {
        if ( !this._compiledPreflight ) {
            this._compiledPreflight = this.resolveMiddlewareHandlersForStage('pre')
        }

        return this._compiledPreflight
    }

    public resolvePostflight(): ResolvedRouteHandler[] {
        if ( !this._compiledPostflight ) {
            this._compiledPostflight = this.resolveMiddlewareHandlersForStage('post')
        }

        return this._compiledPostflight
    }

    public resolveHandler(): ResolvedRouteHandler {
        if ( !this._compiledHandler ) {
            this._compiledHandler = this._resolveHandler()
        }

        return this._compiledHandler
    }

    pre(middleware: RouteHandler) {
        this.middlewares.push({
            stage: 'pre',
            handler: middleware
        })

        return this
    }

    post(middleware: RouteHandler) {
        this.middlewares.push({
            stage: 'post',
            handler: middleware,
        })

        return this
    }

    private prepend(prefix: string) {
        if ( !prefix.endsWith('/') ) prefix = `${prefix}/`
        if ( this.route.startsWith('/') ) this.route = this.route.substring(1)
        this.route = `${prefix}${this.route}`
    }

    private prependMiddleware(def: { stage: 'pre' | 'post', handler: RouteHandler }) {
        this.middlewares.prepend(def)
    }

    private appendMiddleware(def: { stage: 'pre' | 'post', handler: RouteHandler }) {
        this.middlewares.push(def)
    }

    private _resolveHandler(): ResolvedRouteHandler {
        if ( typeof this.handler !== 'string' ) {
            return (request: Request) => {
                // @ts-ignore
                return this.handler(request, request.response)
            }
        } else {
            const parts = this.handler.split('.')
            if ( parts.length < 2 ) {
                const e = new ErrorWithContext('Route handler does not specify a method name.')
                e.context = {
                    handler: this.handler
                }
                throw e
            }

            const [controllerName, methodName] = parts

            const controllersService = <Controllers> this.make(Controllers)
            const controllerClass = controllersService.get(controllerName)
            if ( !controllerClass ) {
                const e = new ErrorWithContext('Controller not found for route handler.')
                e.context = {
                    handler: this.handler,
                    controllerName,
                    methodName,
                }
                throw e
            }

            return (request: Request) => {
                // If not a function, then we got a string reference to a controller method
                // So, we need to use the request container to instantiate the controller
                // and bind the method
                const controller = <Controller> request.make(controllerClass, request)
                const method = controller.getBoundMethod(methodName)
                return method()
            }
        }
    }

    private resolveMiddlewareHandlersForStage(stage: 'pre' | 'post'): ResolvedRouteHandler[] {
        return this.middlewares.where('stage', '=', stage)
            .map<ResolvedRouteHandler>(def => {
                if ( typeof def.handler !== 'string' ) {
                    return (request: Request) => {
                        // @ts-ignore
                        return def.handler(request, request.response)
                    }
                } else {
                    const parts = def.handler.split('.')
                    if ( parts.length < 2 ) {
                        parts.push('apply')  // default middleware method name, if none provided
                    }

                    const [middlewareName, methodName] = parts

                    const middlewaresService = <Middlewares> this.make(Middlewares)
                    const middlewareClass = middlewaresService.get(middlewareName)
                    if ( !middlewareClass ) {
                        const e = new ErrorWithContext('Middleware not found for route handler.')
                        e.context = {
                            handler: def.handler,
                            middlewareName,
                            methodName,
                        }
                        throw e
                    }

                    return (request: Request) => {
                        // If not a function, then we got a string reference to a middleware method
                        // So, we need to use the request container to instantiate the middleware
                        // and bind the method
                        const middleware = <Middleware> request.make(middlewareClass, request)
                        const method = middleware.getBoundMethod(methodName)
                        return method()
                    }
                }
            })
            .toArray()
    }

    toString() {
        const method = Array.isArray(this.method) ? this.method : [this.method]
        return `${method.join('|')} -> ${this.route}`
    }
}