/**
 * This class is based on the code in the following projects:
 *
 * - https://github.com/zenorocha/select
 * - https://github.com/zenorocha/clipboard.js/
 *- https://github.com/formly-js/ngx-formly/
 *
 * All released under MIT license
 *
 */
import { Injectable } from '@angular/core'

@Injectable()
export class CopierService {

  private textarea: HTMLTextAreaElement

  /** Copy the text value to the clipboard. */
  copyText(text: string): boolean {
    this.createTextareaAndSelect(text)

    const copySuccessful = document.execCommand('copy')
    this.removeFake()

    return copySuccessful
  }

  /**
   * Creates a hidden textarea element, sets its value from `text` property,
   * and makes a selection on it.
   */
  private createTextareaAndSelect(text: string) {
    // Create a fake element to hold the contents to copy
    this.textarea = document.createElement('textarea')

    // Prevent zooming on iOS
    this.textarea.style.fontSize = '12pt'

    // Hide the element
    this.textarea.classList.add('cdk-visually-hidden')

    // Move element to the same position vertically
    const yPosition = window.pageYOffset || document.documentElement.scrollTop
    this.textarea.style.top = yPosition + 'px'

    this.textarea.setAttribute('readonly', '')
    this.textarea.value = text

    document.body.appendChild(this.textarea)

    this.textarea.select()
    this.textarea.setSelectionRange(0, this.textarea.value.length)
  }

  /** Remove the text area from the DOM. */
  private removeFake() {
    if (this.textarea) {
      document.body.removeChild(this.textarea)
      this.textarea = null
    }
  }
}