import { APIGatewayEvent } from 'aws-lambda';

import { log } from '../system';
import { BadRequest } from './errors';

/**
 * An HTTP request object.
 *
 * @export
 * @class Request
 */
export class Request {

    /**
     * The request identifier.
     *
     * @type {string}
     * @memberof Request
     */
    id: string;

    /**
     * The decoded authorization JWT information.
     *
     * @type {*}
     * @memberof Request
     */
    auth: any;

    /**
     * The Javascript representation of the request body.
     *
     * @type {*}
     * @memberof Request
     */
    data: any;

    /**
     * The path requested.
     *
     * @type {string}
     * @memberof Request
     */
    path: string;

    /**
     * The method or verb requested.
     *
     * @type {string}
     * @memberof Request
     */
    method: string;

    /**
     * The body of the request.
     *
     * @type {(string | null)}
     * @memberof Request
     */
    body: string | null;

    /**
     * The underlying serverless event object.
     *
     * @type {APIGatewayEvent}
     * @memberof Request
     */
    event: APIGatewayEvent;

    /**
     * The request headers.
     *
     * @type {{ [name: string]: string }}
     * @memberof Request
     */
    headers: { [name: string]: string };

    /**
     * The query parameters.
     *
     * @type {({ [name: string]: string } | null)}
     * @memberof Request
     */
    query: { [name: string]: string } | null;

    /**
     * The path parameters.
     *
     * @type {({ [name: string]: string } | null)}
     * @memberof Request
     */
    params: { [name: string]: string } | null;

    /**
     * Creates an instance of Request.
     * @param {APIGatewayEvent} event
     * @memberof Request
     */
    constructor(event: APIGatewayEvent) {
        this.auth = null;
        this.headers = {};
        this.event = event;
        this.body = event.body;
        this.path = event.path;
        this.method = event.httpMethod;
        this.params = event.pathParameters;
        this.query = event.queryStringParameters;
        this.id = event.requestContext.requestId;
        // Normalize all header keys with capitalization.
        for (let key in event.headers) {
            let value = event.headers[key];
            key = key.replace(/(^[a-zA-Z]|-[a-zA-Z])/g, (str, char) => {
                return str.replace(char, char.toUpperCase());
            });
            this.headers[key] = value;
        }
        this.parseBody();
    }

    /**
     * Parses the body of a request if the Content-Type header is
     * application/json. If parsing fails, a Bad Request is thrown.
     *
     * @private
     * @throws {BadRequest}
     * @memberof Request
     */
    private parseBody() {
        let content = this.headers['Content-Type'];
        if (content && content.includes('application/json')) {
            try {
                this.data = JSON.parse(this.body);
            } catch (err) {
                log.error(err);
                throw new BadRequest('Parsing the request body failed.');
            }
        }
    }
}