import {ResponseFactory} from './ResponseFactory'
import {Request} from '../lifecycle/Request'
import {ErrorWithContext, UniversalPath} from '../../util'
import {Logging} from '../../service/Logging'

/**
 * Helper function that creates a FileResponseFactory for the given path.
 * @param path
 */
export function file(path: UniversalPath): FileResponseFactory {
    return new FileResponseFactory(path)
}

/**
 * HTTP response factory that sends a file referenced by a given UniversalPath.
 */
export class FileResponseFactory extends ResponseFactory {
    constructor(
        /** The file to be sent. */
        public readonly path: UniversalPath,
    ) {
        super()
    }

    public async write(request: Request): Promise<Request> {
        if ( !(await this.path.isFile()) ) {
            throw new ErrorWithContext(`Cannot write non-file resource as response: ${this.path}`, {
                path: this.path,
            })
        }

        request.make<Logging>(Logging).debug(`Setting Content-Type of ${this.path} to ${this.path.contentType}...`)
        request.response.setHeader('Content-Type', this.path.contentType || 'application/octet-stream')
        request.response.setHeader('Content-Length', String(await this.path.sizeInBytes()))
        request.response.body = await this.path.readStream()
        return request
    }
}