daton/lib/src/http/response/ErrorResponseFactory.ts

import ResponseFactory from './ResponseFactory.ts'
import {Request} from '../Request.ts'
import * as api from '../../support/api.ts'

export default class ErrorResponseFactory extends ResponseFactory {
    protected target_mode: 'json' | 'html' = 'html'

    constructor(
        public readonly error: Error,
        status: number = 500,
        output: 'json' | 'html' = 'html',
    ) {
        super()
        this.status(status)
        this.mode(output)
    }

    public mode(output: 'json' | 'html'): ErrorResponseFactory {
        this.target_mode = output
        return this
    }

    public async write(request: Request): Promise<Request> {
        request = await super.write(request)

        if ( this.target_mode === 'json' ) {
            request.response.headers.set('Content-Type', 'application/json')
            request.response.body = this.build_json(this.error)
        } else if ( this.target_mode === 'html' ) {
            request.response.headers.set('Content-Type', 'text/html')
            request.response.body = this.build_html(this.error)
        }

        return request
    }

    protected build_html(error: Error) {
        return `
            <b>Sorry, an unexpected error occurred while processing your request.</b>
            <br>
            <pre><code>
Name: ${error.name}
Message: ${error.message}
Stack trace:
    - ${error.stack ? error.stack.split(/\s+at\s+/).slice(1).join('<br>    - ') : 'none'}
            </code></pre>
        `
    }

    protected build_json(error: Error) {
        return JSON.stringify(api.error(error))
    }
}