/**
 * Utility Service
 */
class Utilities {
  /**
   * Creates an instance of the Utility service
   */
  constructor({ getOptions, getCaretPosition, dispatch }) {
    this.getOptions = getOptions;
    this.getCaretPosition = getCaretPosition;
    this.dispatch = dispatch;

    /**
     * Bindings
     */
    Utilities.bindMethods(Utilities, this);
  }

  /**
   * Adds default classes to a given button
   *
   * @param  {string} button The button's layout name
   * @return {string} The classes to be added to the button
   */
  getButtonClass(button) {
    let buttonTypeClass =
      button.includes("{") && button.includes("}") && button !== "{//}"
        ? "functionBtn"
        : "standardBtn";
    let buttonWithoutBraces = button.replace("{", "").replace("}", "");
    let buttonNormalized = "";

    if (buttonTypeClass !== "standardBtn")
      buttonNormalized = ` hg-button-${buttonWithoutBraces}`;

    return `hg-${buttonTypeClass}${buttonNormalized}`;
  }

  /**
   * Default button display labels
   */
  getDefaultDiplay() {
    return {
      "{bksp}": "backspace",
      "{backspace}": "backspace",
      "{enter}": "< enter",
      "{shift}": "shift",
      "{shiftleft}": "shift",
      "{shiftright}": "shift",
      "{alt}": "alt",
      "{s}": "shift",
      "{tab}": "tab",
      "{lock}": "caps",
      "{capslock}": "caps",
      "{accept}": "Submit",
      "{space}": " ",
      "{//}": " ",
      "{esc}": "esc",
      "{escape}": "esc",
      "{f1}": "f1",
      "{f2}": "f2",
      "{f3}": "f3",
      "{f4}": "f4",
      "{f5}": "f5",
      "{f6}": "f6",
      "{f7}": "f7",
      "{f8}": "f8",
      "{f9}": "f9",
      "{f10}": "f10",
      "{f11}": "f11",
      "{f12}": "f12",
      "{numpaddivide}": "/",
      "{numlock}": "lock",
      "{arrowup}": "↑",
      "{arrowleft}": "←",
      "{arrowdown}": "↓",
      "{arrowright}": "→",
      "{prtscr}": "print",
      "{scrolllock}": "scroll",
      "{pause}": "pause",
      "{insert}": "ins",
      "{home}": "home",
      "{pageup}": "up",
      "{delete}": "del",
      "{end}": "end",
      "{pagedown}": "down",
      "{numpadmultiply}": "*",
      "{numpadsubtract}": "-",
      "{numpadadd}": "+",
      "{numpadenter}": "enter",
      "{period}": ".",
      "{numpaddecimal}": ".",
      "{numpad0}": "0",
      "{numpad1}": "1",
      "{numpad2}": "2",
      "{numpad3}": "3",
      "{numpad4}": "4",
      "{numpad5}": "5",
      "{numpad6}": "6",
      "{numpad7}": "7",
      "{numpad8}": "8",
      "{numpad9}": "9"
    };
  }
  /**
   * Returns the display (label) name for a given button
   *
   * @param  {string} button The button's layout name
   * @param  {object} display The provided display option
   * @param  {boolean} mergeDisplay Whether the provided param value should be merged with the default one.
   */
  getButtonDisplayName(button, display, mergeDisplay) {
    if (mergeDisplay) {
      display = Object.assign({}, this.getDefaultDiplay(), display);
    } else {
      display = display || this.getDefaultDiplay();
    }

    return display[button] || button;
  }

  /**
   * Returns the updated input resulting from clicking a given button
   *
   * @param  {string} button The button's layout name
   * @param  {string} input The input string
   * @param  {number} caretPos The cursor's current position
   * @param  {boolean} moveCaret Whether to update simple-keyboard's cursor
   */
  getUpdatedInput(button, input, caretPos, moveCaret) {
    let options = this.getOptions();
    let output = input;

    if (
      (button === "{bksp}" || button === "{backspace}") &&
      output.length > 0
    ) {
      output = this.removeAt(output, caretPos, moveCaret);
    } else if (button === "{space}")
      output = this.addStringAt(output, " ", caretPos, moveCaret);
    else if (
      button === "{tab}" &&
      !(
        typeof options.tabCharOnTab === "boolean" &&
        options.tabCharOnTab === false
      )
    ) {
      output = this.addStringAt(output, "\t", caretPos, moveCaret);
    } else if (
      (button === "{enter}" || button === "{numpadenter}") &&
      options.newLineOnEnter
    )
      output = this.addStringAt(output, "\n", caretPos, moveCaret);
    else if (
      button.includes("numpad") &&
      Number.isInteger(Number(button[button.length - 2]))
    ) {
      output = this.addStringAt(
        output,
        button[button.length - 2],
        caretPos,
        moveCaret
      );
    } else if (button === "{numpaddivide}")
      output = this.addStringAt(output, "/", caretPos, moveCaret);
    else if (button === "{numpadmultiply}")
      output = this.addStringAt(output, "*", caretPos, moveCaret);
    else if (button === "{numpadsubtract}")
      output = this.addStringAt(output, "-", caretPos, moveCaret);
    else if (button === "{numpadadd}")
      output = this.addStringAt(output, "+", caretPos, moveCaret);
    else if (button === "{numpaddecimal}")
      output = this.addStringAt(output, ".", caretPos, moveCaret);
    else if (button === "{" || button === "}")
      output = this.addStringAt(output, button, caretPos, moveCaret);
    else if (!button.includes("{") && !button.includes("}"))
      output = this.addStringAt(output, button, caretPos, moveCaret);

    return output;
  }

  /**
   * Moves the cursor position by a given amount
   *
   * @param  {number} length Represents by how many characters the input should be moved
   * @param  {boolean} minus Whether the cursor should be moved to the left or not.
   */
  updateCaretPos(length, minus) {
    let newCaretPos = this.updateCaretPosAction(length, minus);

    this.dispatch(instance => {
      instance.caretPosition = newCaretPos;
    });
  }

  /**
   * Action method of updateCaretPos
   *
   * @param  {number} length Represents by how many characters the input should be moved
   * @param  {boolean} minus Whether the cursor should be moved to the left or not.
   */
  updateCaretPosAction(length, minus) {
    let options = this.getOptions();
    let caretPosition = this.getCaretPosition();

    if (minus) {
      if (caretPosition > 0) caretPosition = caretPosition - length;
    } else {
      caretPosition = caretPosition + length;
    }

    if (options.debug) {
      console.log("Caret at:", caretPosition, `(${this.keyboardDOMClass})`);
    }

    return caretPosition;
  }

  /**
   * Adds a string to the input at a given position
   *
   * @param  {string} source The source input
   * @param  {string} string The string to add
   * @param  {number} position The (cursor) position where the string should be added
   * @param  {boolean} moveCaret Whether to update simple-keyboard's cursor
   */
  addStringAt(source, string, position, moveCaret) {
    let output;

    if (!position && position !== 0) {
      output = source + string;
    } else {
      output = [source.slice(0, position), string, source.slice(position)].join(
        ""
      );

      /**
       * Avoid caret position change when maxLength is set
       */
      if (!this.isMaxLengthReached()) {
        if (moveCaret) this.updateCaretPos(string.length);
      }
    }

    return output;
  }

  /**
   * Removes an amount of characters at a given position
   *
   * @param  {string} source The source input
   * @param  {number} position The (cursor) position from where the characters should be removed
   * @param  {boolean} moveCaret Whether to update simple-keyboard's cursor
   */
  removeAt(source, position, moveCaret) {
    let caretPosition = this.getCaretPosition();

    if (caretPosition === 0) {
      return source;
    }

    let output;
    let prevTwoChars;
    let emojiMatched;
    let emojiMatchedReg = /([\uD800-\uDBFF][\uDC00-\uDFFF])/g;

    /**
     * Emojis are made out of two characters, so we must take a custom approach to trim them.
     * For more info: https://mathiasbynens.be/notes/javascript-unicode
     */
    if (position && position >= 0) {
      prevTwoChars = source.substring(position - 2, position);
      emojiMatched = prevTwoChars.match(emojiMatchedReg);

      if (emojiMatched) {
        output = source.substr(0, position - 2) + source.substr(position);
        if (moveCaret) this.updateCaretPos(2, true);
      } else {
        output = source.substr(0, position - 1) + source.substr(position);
        if (moveCaret) this.updateCaretPos(1, true);
      }
    } else {
      prevTwoChars = source.slice(-2);
      emojiMatched = prevTwoChars.match(emojiMatchedReg);

      if (emojiMatched) {
        output = source.slice(0, -2);
        if (moveCaret) this.updateCaretPos(2, true);
      } else {
        output = source.slice(0, -1);
        if (moveCaret) this.updateCaretPos(1, true);
      }
    }

    return output;
  }
  /**
   * Determines whether the maxLength has been reached. This function is called when the maxLength option it set.
   *
   * @param  {object} inputObj
   * @param  {string} updatedInput
   */
  handleMaxLength(inputObj, updatedInput) {
    let options = this.getOptions();
    let maxLength = options.maxLength;
    let currentInput = inputObj[options.inputName];
    let condition = updatedInput.length - 1 >= maxLength;

    if (
      /**
       * If pressing this button won't add more characters
       * We exit out of this limiter function
       */
      updatedInput.length <= currentInput.length
    ) {
      return false;
    }

    if (Number.isInteger(maxLength)) {
      if (options.debug) {
        console.log("maxLength (num) reached:", condition);
      }

      if (condition) {
        /**
         * @type {boolean} Boolean value that shows whether maxLength has been reached
         */
        this.maxLengthReached = true;
        return true;
      } else {
        this.maxLengthReached = false;
        return false;
      }
    }

    if (typeof maxLength === "object") {
      let condition = currentInput.length === maxLength[options.inputName];

      if (options.debug) {
        console.log("maxLength (obj) reached:", condition);
      }

      if (condition) {
        this.maxLengthReached = true;
        return true;
      } else {
        this.maxLengthReached = false;
        return false;
      }
    }
  }

  /**
   * Gets the current value of maxLengthReached
   */
  isMaxLengthReached() {
    return Boolean(this.maxLengthReached);
  }

  /**
   * Determines whether a touch device is being used
   */
  isTouchDevice() {
    return "ontouchstart" in window || navigator.maxTouchPoints;
  }

  /**
   * Determines whether pointer events are supported
   */
  pointerEventsSupported() {
    return window.PointerEvent;
  }

  /**
   * Bind all methods in a given class
   */

  static bindMethods(myClass, instance) {
    // eslint-disable-next-line no-unused-vars
    for (let myMethod of Object.getOwnPropertyNames(myClass.prototype)) {
      let excludeMethod =
        myMethod === "constructor" || myMethod === "bindMethods";
      if (!excludeMethod) {
        instance[myMethod] = instance[myMethod].bind(instance);
      }
    }
  }

  /**
   * Transforms an arbitrary string to camelCase
   *
   * @param  {string} string The string to transform.
   */
  camelCase(string) {
    if (!string) return false;

    return string
      .toLowerCase()
      .trim()
      .split(/[.\-_\s]/g)
      .reduce((string, word) =>
        word.length ? string + word[0].toUpperCase() + word.slice(1) : string
      );
  }
}

export default Utilities;