module Faraday::DecodeMethods

def add_to_context(is_array, context, value, subkey)
  is_array ? context << value : context[subkey] = value
end

def decode(query)
  return nil if query.nil?
  params = {}
  query.split('&').each do |pair|
    next if pair.empty?
    key, value = pair.split('=', 2)
    key = unescape(key)
    value = unescape(value.tr('+', ' ')) if value
    decode_pair(key, value, params)
  end
  dehash(params, 0)
end

def decode_pair(key, value, context)
  subkeys = key.scan(SUBKEYS_REGEX)
  subkeys.each_with_index do |subkey, i|
    is_array = subkey =~ /[\[\]]+\Z/
    subkey = Regexp.last_match.pre_match if is_array
    last_subkey = i == subkeys.length - 1
    context = prepare_context(context, subkey, is_array, last_subkey)
    add_to_context(is_array, context, value, subkey) if last_subkey
  end
end

def dehash(hash, depth)
  hash.each do |key, value|
    hash[key] = dehash(value, depth + 1) if value.is_a?(Hash)
  end
  if depth.positive? && !hash.empty? && hash.keys.all? { |k| k =~ /^\d+$/ }
    hash.sort.map(&:last)
  else
    hash
  end
end

def match_context(context, subkey)
  context << {} if !context.last.is_a?(Hash) || context.last.key?(subkey)
  context.last
end

def new_context(subkey, is_array, context)
  value_type = is_array ? Array : Hash
  if context[subkey] && !context[subkey].is_a?(value_type)
    raise TypeError, "expected #{value_type.name} " \
                     "(got #{context[subkey].class.name}) for param `#{subkey}'"
  end
  context[subkey] ||= value_type.new
end

def prepare_context(context, subkey, is_array, last_subkey)
  if !last_subkey || is_array
    context = new_context(subkey, is_array, context)
  end
  if context.is_a?(Array) && !is_array
    context = match_context(context, subkey)
  end
  context
end