import { Request, Response } from 'express';
import { DatabaseCrudOptions, Authorization } from './DatabaseCrudOptions';

type AuthRunner = {
  (req: Request, res: Response): Promise<boolean>;
}

export class DatabaseCrudOptionsReader {
  private _options: DatabaseCrudOptions;

  public constructor (options: DatabaseCrudOptions) {
    this._options = options;
  }

  private get_auth_runner (
    auth?: Authorization
  ): AuthRunner {
    if (typeof auth === 'undefined')
      return (): Promise<boolean> => new Promise ((r) => r (true));
    return (req, res): Promise<boolean> => new Promise (
      (resolve: (value: boolean) => void) => {
        (async (): Promise<void> => {
          let resolved = false;
          const result = await auth (req, res, (cb: unknown) => {
            resolved = true;
            resolve (typeof cb === 'undefined' || cb === true);
          });
          if (!resolved)
            resolve (result === true);
        }) ();
      }
    );
  }

  public get optional_columns (): Array<string> | undefined {
    return this._options.optional_columns;
  }

  public get create_authorization (): Authorization {
    const general = this.get_auth_runner (this._options.general_authorization);
    const specific = this.get_auth_runner (this._options.create_authorization);
    return async (req: Request, res: Response): Promise<boolean> => {
      const result = (await general (req, res)) && (await specific (req, res));
      return result;
    };
  }

  public get read_authorization (): Authorization {
    const general = this.get_auth_runner (this._options.general_authorization);
    const specific = this.get_auth_runner (this._options.read_authorization);
    return async (req: Request, res: Response): Promise<boolean> => {
      const result = (await general (req, res)) && (await specific (req, res));
      return result;
    };
  }

  public get update_authorization (): Authorization {
    const general = this.get_auth_runner (this._options.general_authorization);
    const specific = this.get_auth_runner (this._options.update_authorization);
    return async (req: Request, res: Response): Promise<boolean> => {
      const result = (await general (req, res)) && (await specific (req, res));
      return result;
    };
  }

  public get delete_authorization (): Authorization {
    const general = this.get_auth_runner (this._options.general_authorization);
    const specific = this.get_auth_runner (this._options.delete_authorization);
    return async (req: Request, res: Response): Promise<boolean> => {
      const result = (await general (req, res)) && (await specific (req, res));
      return result;
    };
  }
}