class Primer::Classify::Utilities

def classes_to_args(classes)
  hash_to_args(classes_to_hash(classes))
end

def classes_to_hash(classes)
  obj = {}
  classes = classes.split
  # Loop through all classes supplied and reject ones we find a match for
  # So when we're at the end of the loop we have classes left with any non-system classes.
  classes.reject! do |classname|
    key, value, index = find_selector(classname)
    next false if key.nil?
    # Create array if nil
    obj[key] = Array.new(5, nil) if obj[key].nil?
    # Place the arguments in the responsive array based on index mr: [nil, 2]
    obj[key][index] = value
    next true
  end
  # Transform responsive arrays into arrays without trailing nil, so `mr: [1, nil, nil, nil, nil]` becomes `mr: 1`
  obj.transform_values! do |value|
    value = value.reverse.drop_while(&:nil?).reverse
    if value.count == 1
      value.first
    else
      value
    end
  end
  # Add back the non-system classes
  obj[:classes] = classes.join(" ") if classes.any?
  obj
end

def classname(key, val, breakpoint = "")
  # For cases when `argument: false` is passed in, treat like we would nil
  return nil unless val
  if (valid = validate(key, val, breakpoint))
    valid
  else
    # Get selector
    UTILITIES[key][val][BREAKPOINT_INDEX_CACHE[breakpoint]]
  end
end

def find_selector(selector)
  key = infer_selector_key(selector)
  value_hash = UTILITIES[key]
  return nil if value_hash.blank?
  # Each value hash will also contain an array of classnames for breakpoints
  # Key argument `0`, classes `[ "mr-0", "mr-sm-0", "mr-md-0", "mr-lg-0", "mr-xl-0" ]`
  value_hash.each do |key_argument, classnames|
    # Skip each value hash until we get one with the selector
    next unless classnames.include?(selector)
    # Return [:mr, 0, 1]
    # has index of classname, so we can match it up with responsive array `mr: [nil, 0]`
    return [key, key_argument, classnames.index(selector)]
  end
  nil
end

def hash_to_args(hash)
  hash.map do |key, value|
    val = case value
          when Symbol
            ":#{value}"
          when String
            value.to_json
          else
            value
          end
    "#{key}: #{val}"
  end.join(", ")
end

def infer_selector_key(selector)
  REPLACEMENT_KEYS.each do |k, v|
    return v.to_sym if selector.start_with?(k)
  end
  selector.split("-").first.to_sym
end

def mappings(key)
  return unless supported_key?(key)
  UTILITIES[key].keys
end

def responsive?(key, val)
  supported_value?(key, val) && UTILITIES[key][val].count > 1
end

def supported_key?(key)
  SUPPORTED_KEY_CACHE[key]
end

def supported_selector?(selector)
  # This method is too slow to run in production
  return false unless validate_class_names?
  find_selector(selector).present?
end

def supported_value?(key, val)
  supported_key?(key) && !UTILITIES[key][val].nil?
end

def validate(key, val, breakpoint)
  unless supported_key?(key)
    raise ArgumentError, "#{key} is not a valid Primer utility key" if validate_class_names?
    return ""
  end
  unless breakpoint.empty? || responsive?(key, val)
    raise ArgumentError, "#{key} does not support responsive values" if validate_class_names?
    return ""
  end
  unless supported_value?(key, val)
    raise ArgumentError, "#{val} is not a valid value for :#{key}. Use one of #{mappings(key)}" if validate_class_names?
    return nil if [true, false].include?(val)
    return "#{key.to_s.dasherize}-#{val.to_s.dasherize}"
  end
  nil
end