import { ansi } from './ansi';
import type { ISize } from './callback';

/**
 * Collection of environment variables that are known to a shell and are passed in and out of
 * commands.
 */
export class Environment extends Map<string, string> {
  constructor(color: boolean, shellId: string, browsingContextId: string | undefined) {
    super();
    if (shellId) {
      this.set('COCKLE_SHELL_ID', shellId);
    }
    if (browsingContextId) {
      this.set('COCKLE_BROWSING_CONTEXT_ID', browsingContextId);
    }
    if (color) {
      this.set('PS1', ansi.styleGreen + 'js-shell:' + ansi.styleReset + ' ');
      this.set('TERM', 'xterm-256color');
      this.set('TERMINFO', '/usr/local/share/terminfo'); // Needed for nano
    } else {
      this.set('PS1', 'js-shell: ');
    }
  }

  /**
   * Copy environment variables into a command before it is run.
   */
  copyIntoCommand(target: { [key: string]: string }) {
    for (const [key, value] of this.entries()) {
      target[key] = value;
    }
  }

  getNumber(key: string): number | null {
    const str = this.get(key);
    if (str === null) {
      return null;
    }
    const number = Number(str);
    return isNaN(number) ? null : number;
  }

  getPrompt(): string {
    return this.get('PS1') ?? '$ ';
  }

  get color(): boolean {
    return this.has('TERM');
  }

  names(): string[] {
    const re = /^[A-Za-z_]/;
    return Array.from(this.keys()).filter(name => re.test(name));
  }

  setSize(size: ISize): void {
    const { rows, columns } = size;
    if (rows >= 1) {
      const rowsString = rows.toString();
      this.set('LINES', rowsString);
    } else {
      this.delete('LINES');
    }

    if (columns >= 1) {
      const columnsString = columns.toString();
      this.set('COLUMNS', columnsString);
    } else {
      this.delete('COLUMNS');
    }
  }
}