@use 'sass:list';
@use 'sass:string';
@use 'sass:meta';

/// Checks if a value is a valid hex color code. The value must start with
/// '#' and be followed by 3, 4, 6, or 8 hexadecimal characters.
///
/// @param {*} $value - The value to check.
///
/// @return {Bool} - True if the value is a valid hex color code, false if not.
///
/// @access public
/// @group Utilities
@function is-valid-hex($value) {
  @if meta.type-of($value) != 'color' and meta.type-of($value) != 'string' {
    @return false;
  }

  @if meta.type-of($value) == 'color' {
    $value: '#{$color}';
  }

  @if meta.type-of($value) == 'string' {
    $value: string.to-lower-case($value);
  } @else {
    @return false;
  }

  // Check if the string starts with '#' and has a length of 4, 5, 7, or 9.
  @if string.slice($value, 1, 1) != '#' or not list.index((4 5 7 9), string.length($value)) {
    @return false;
  }

  // Iterate over each character after '#' to check if it's a valid hex character.
  @for $i from 2 through string.length($value) {
    $char: string.to-lower-case(string.slice($value, $i, $i));

    // Check if character is not a valid hexadecimal character.
    @if not index('0' '1' '2' '3' '4' '5' '6' '7' '8' '9' 'a' 'b' 'c' 'd' 'e' 'f', $char) {
      @return false;
    }
  }

  // If all characters are valid, return true.
  @return true;
}