class Github::PageIterator

def count
  parse_query(URI(last_page_uri).query)['page'] if last_page_uri
end

def first
  perform_request(first_page_uri) if first_page_uri
end

def get_page(page_number)
  # Find URI that we can work with, if we cannot get the first or the
  # last page URI then there is only one page.
  page_uri = first_page_uri || last_page_uri
  return nil unless page_uri
  perform_request(page_uri, page_number)
end

def initialize(links, current_api)
  @links       = links
  @current_api = current_api
  update_page_links(@links)
end

def last
  perform_request(last_page_uri) if last_page_uri
end

def next
  perform_request(next_page_uri) if next?
end

def next?
  next_page == 0 || !next_page_uri.nil?
end

def parse_page_number(uri) # :nodoc:
  parse_page_params(uri, PARAM_PAGE)
end

def parse_page_params(uri, attr) # :nodoc:
  return -1 if uri.nil? || uri.empty?
  parsed = nil
  begin
    parsed = URI.parse(uri)
  rescue URI::Error
    return -1
  end
  param = parse_query_for_param(parsed.query, attr)
  return -1 if param.nil? || param.empty?
  begin
    return param.to_i
  rescue ArgumentError
    return -1
  end
end

def parse_per_page_number(uri) # :nodoc:
  parse_page_params(uri, PARAM_PER_PAGE)
end

def perform_request(page_uri_path, page_number = nil)
  page_uri = URI(page_uri_path)
  params = parse_query(page_uri.query)
  if page_number
    params['page'] = page_number
  elsif next_page < 1
    sha = sha(params)
    params['sha'] = sha if sha
  else
    params['page'] = parse_page_number(page_uri_path)
  end
  params['per_page'] = parse_per_page_number(page_uri_path)
  response = page_request(page_uri.path, params)
  update_page_links response.links
  response
end

def prev
  perform_request(prev_page_uri) if prev_page_uri
end

def sha(params)
  return params['last_sha'] if params.keys.include?('last_sha')
  return DEFAULT_SHA if params.keys.include?('sha')
end

def update_page_links(links) # :nodoc:
  ATTRIBUTES.each do |attr|
    send(:"#{attr}_page_uri=", links.send(:"#{attr}"))
    send(:"#{attr}_page=", parse_page_number(links.send(:"#{attr}")))
  end
end