import {Request} from '../lifecycle/Request'
import {ActivatedRoute} from '../routing/ActivatedRoute'
import {Config} from '../../service/Config'
import {Collection, HTTPStatus, UniversalPath, universalPath} from '../../util'
import {Application} from '../../lifecycle/Application'
import {HTTPError} from '../HTTPError'
import {view, ViewResponseFactory} from '../response/ViewResponseFactory'
import {redirect} from '../response/RedirectResponseFactory'
import {file} from '../response/FileResponseFactory'
import {ResponseObject} from '../routing/Route'
import {Logging} from '../../service/Logging'

/**
 * Defines the behavior of the static server.
 */
export interface StaticServerOptions {
    /** If true, browsing to a directory route will show the directory listing page. */
    directoryListing?: boolean

    /** The path to the directory whose files should be served. */
    basePath?: string | string[] | UniversalPath

    /** If specified, only files with these extensions will be served. */
    allowedExtensions?: string[]

    /** If specified, files with these extensions will not be served. */
    excludedExtensions?: string[]

    /** If a file with this name exists in a directory, it will be served. */
    indexFile?: string
}

/**
 * HTTPError class thrown by the static server.
 */
export class StaticServerHTTPError extends HTTPError {

}

/**
 * Build the response factory that shows the directory listing.
 * @param dirname
 * @param dirPath
 */
async function getDirectoryListingResponse(dirname: string, dirPath: UniversalPath): Promise<ViewResponseFactory> {
    return view('@extollo:static:dirlist', {
        dirname,
        contents: (await (await dirPath.list())
            .promiseMap(async path => {
                const isDirectory = await path.isDirectory()
                return {
                    isDirectory,
                    name: path.toBase,
                    size: isDirectory ? '-' : await path.sizeForHumans(),
                }
            }))
            .sortBy(row => {
                return `${row.isDirectory ? 0 : 1}${row.name}`
            })
            .all(),
    })
}

/**
 * Returns true if the given file path has an extension that is allowed by
 * the static server options.
 * @param filePath
 * @param options
 */
function isValidFileExtension(filePath: UniversalPath, options: StaticServerOptions): boolean {
    return (
        (
            !options.allowedExtensions
            || options.allowedExtensions.includes(filePath.ext)
        )
        && (
            !options.excludedExtensions
            || !options.excludedExtensions.includes(filePath.ext)
        )
    )
}

/**
 * Resolve the configured base path into a universal path.
 * Defaults to `{app path}/resources/static` if none provided.
 * @param appPath
 * @param basePath
 */
function getBasePath(appPath: UniversalPath, basePath?: string | string[] | UniversalPath): UniversalPath {
    if ( basePath instanceof UniversalPath ) {
        return basePath
    }

    if ( !basePath ) {
        return appPath.concat('resources', 'static')
    }

    if ( Array.isArray(basePath) ) {
        return appPath.concat(...basePath)
    }

    if ( basePath.startsWith('/') ) {
        return universalPath(basePath)
    }

    return appPath.concat(basePath)
}

/**
 * Get a route handler that serves a directory as static files.
 * @param options
 */
export function staticServer(options: StaticServerOptions = {}): (request: Request) => Promise<ResponseObject> {
    return async (request: Request) => {
        const config = <Config> request.make(Config)
        const route = <ActivatedRoute<unknown, unknown[]>> request.make(ActivatedRoute)
        const app = <Application> request.make(Application)
        const logging = <Logging> request.make(Logging)

        const staticConfig = config.get('server.builtIns.static', {})
        const mergedOptions = {
            ...staticConfig,
            ...options,
        }

        // Resolve the path to the resource on the filesystem
        const basePath = getBasePath(app.appPath(), mergedOptions.basePath)
        const filePath = basePath.concat(...Collection.normalize<string>(route.params[0]))

        // If the resolved path is outside of the base path, fail out
        if ( !filePath.isChildOf(basePath) && !filePath.is(basePath) ) {
            throw new StaticServerHTTPError(HTTPStatus.NOT_FOUND, 'File not found', {
                basePath: basePath.toString(),
                filePath: filePath.toString(),
                route: route.path,
                reason: 'Resolved file is not a child of the base path.',
            })
        }

        // If the resolved file is an invalid file extension, fail out
        if ( !isValidFileExtension(filePath, mergedOptions) ) {
            throw new StaticServerHTTPError(HTTPStatus.NOT_FOUND, 'File not found', {
                basePath: basePath.toString(),
                filePath: filePath.toString(),
                route: route.path,
                allowedExtensions: mergedOptions.allowedExtensions,
                excludedExtensions: mergedOptions.excludedExtensions,
                reason: 'Resolved file is not an allowed extension type',
            })
        }

        // If the resolved file does not exist on the filesystem, fail out
        if ( !(await filePath.exists()) ) {
            throw new StaticServerHTTPError(HTTPStatus.NOT_FOUND, `File not found: ${route.path}`, {
                basePath: basePath.toString(),
                filePath: filePath.toString(),
                route: route.path,
                reason: 'Resolved file does not exist on the filesystem',
            })
        }

        // If the resolved path is a directory, send the directory listing response
        if ( await filePath.isDirectory() ) {
            if ( options.indexFile ) {
                const indexFile = filePath.concat(options.indexFile)
                if ( await indexFile.exists() ) {
                    return file(indexFile)
                }
            }

            if ( !options.directoryListing ) {
                throw new StaticServerHTTPError(HTTPStatus.NOT_FOUND, 'File not found', {
                    basePath: basePath.toString(),
                    filePath: filePath.toString(),
                    route: route.path,
                    reason: 'Path is a directory, and directory listing is disabled',
                })
            }

            if ( !route.path.endsWith('/') ) {
                return redirect(`${route.path}/`)
            }

            return getDirectoryListingResponse(route.path, filePath)
        }

        // Otherwise, just send the file as the response body
        logging.verbose(`Sending file: ${filePath}`)
        return file(filePath)
    }
}