// Copyright (c) Jupyter Development Team.
// Distributed under the terms of the Modified BSD License.

import {
  MimeData
} from '@phosphor/coreutils';


/**
 * The clipboard interface.
 */
export
namespace Clipboard {
  /**
   * Get the application clipboard instance.
   */
  export
  function getInstance(): MimeData {
    return Private.instance;
  }

  /**
   * Set the application clipboard instance.
   */
  export
  function setInstance(value: MimeData): void {
    Private.instance = value;
  }

  /**
   * Copy text to the system clipboard.
   *
   * #### Notes
   * This can only be called in response to a user input event.
   */
  export
  function copyToSystem(text: string): void {
    let node = document.body;
    let handler = (event: ClipboardEvent) => {
      let data = event.clipboardData || (window as any).clipboardData;
      data.setData('text', text);
      event.preventDefault();
      node.removeEventListener('copy', handler);
    };
    node.addEventListener('copy', handler);
    generateEvent(node);
  }

  /**
   * Generate a clipboard event on a node.
   *
   * @param node - The element on which to generate the event.
   *
   * @param type - The type of event to generate.
   *   `'paste'` events cannot be programmatically generated.
   *
   * #### Notes
   * This can only be called in response to a user input event.
   */
  export
  function generateEvent(node: HTMLElement, type: 'copy' | 'cut' = 'copy'): void {
    // http://stackoverflow.com/a/5210367

    // Identify selected text.
    let sel = window.getSelection();

    // Save the current selection.
    let savedRanges: any[] = [];
    for (let i = 0, len = sel.rangeCount; i < len; ++i) {
      savedRanges[i] = sel.getRangeAt(i).cloneRange();
    }

    // Select the node content.
    let range = document.createRange();
    range.selectNodeContents(node);
    sel.removeAllRanges();
    sel.addRange(range);

    // Execute the command.
    document.execCommand(type);

    // Restore the previous selection.
    sel = window.getSelection();
    sel.removeAllRanges();
    for (let i = 0, len = savedRanges.length; i < len; ++i) {
      sel.addRange(savedRanges[i]);
    }
  }
}


/**
 * The namespace for module private data.
 */
namespace Private {
  /**
   * The application clipboard instance.
   */
  export
  let instance = new MimeData();
}