/**
 * Extended Ink Key type with additional properties
 *
 * Ink's standard Key type doesn't include backspace and delete,
 * but these are available at runtime. This extends the type
 * to include them for better type safety.
 */

/**
 * Extended Key type that includes backspace and delete
 * These properties are present at runtime but not in Ink's type definitions
 */
export interface ExtendedKey {
  upArrow: boolean;
  downArrow: boolean;
  leftArrow: boolean;
  rightArrow: boolean;
  pageDown: boolean;
  pageUp: boolean;
  return: boolean;
  escape: boolean;
  tab: boolean;
  backspace: boolean;
  delete: boolean;
  meta: boolean;
  ctrl: boolean;
  shift: boolean;
}

/**
 * Type guard to check if a key object has the extended properties
 */
export function isExtendedKey(key: unknown): key is ExtendedKey {
  return (
    typeof key === "object" &&
    key !== null &&
    "upArrow" in key &&
    "downArrow" in key
  );
}

/**
 * Check if the key press represents a backspace or delete action
 */
export function isBackspaceOrDelete(key: ExtendedKey): boolean {
  return key.backspace || key.delete;
}

/**
 * Handle text input with backspace/delete support
 * Returns the new string value after processing the input
 *
 * @param currentValue - The current text value
 * @param input - The input character (if any)
 * @param key - The key object with backspace/delete flags
 * @param maxLength - Optional maximum length for the input
 * @returns The new text value, or null if no change
 */
export function handleTextInput(
  currentValue: string,
  input: string,
  key: ExtendedKey,
  maxLength?: number
): string | null {
  // Handle backspace/delete
  if (key.backspace || key.delete) {
    if (currentValue.length > 0) {
      return currentValue.slice(0, -1);
    }
    return null;
  }

  // Handle regular character input
  if (input.length === 1) {
    if (maxLength !== undefined && currentValue.length >= maxLength) {
      return null;
    }
    return currentValue + input;
  }

  return null;
}

/**
 * Handle numeric-only input with backspace/delete support
 *
 * @param currentValue - The current numeric string value
 * @param input - The input character (if any)
 * @param key - The key object with backspace/delete flags
 * @param maxLength - Optional maximum length for the input
 * @returns The new numeric string value, or null if no change
 */
export function handleNumericInput(
  currentValue: string,
  input: string,
  key: ExtendedKey,
  maxLength?: number
): string | null {
  // Handle backspace/delete
  if (key.backspace || key.delete) {
    if (currentValue.length > 0) {
      return currentValue.slice(0, -1);
    }
    return null;
  }

  // Only accept numeric characters
  if (/^[0-9]$/.test(input)) {
    if (maxLength !== undefined && currentValue.length >= maxLength) {
      return null;
    }
    return currentValue + input;
  }

  return null;
}