module Solargraph::YardMap::CoreDocs

def available
  uri = URI.parse("#{SOURCE}/versions.json")
  response = Net::HTTP.get_response(uri)
  obj = JSON.parse(response.body)
  raise SourceNotAvailableError.new("Error connecting to #{SOURCE}") unless obj['status'] == 'ok'
  obj['cores']
end

def best_download
  rv = Gem::Version.new(RUBY_VERSION)
  available.each do |ver|
    return ver if Gem::Version.new(ver) <= rv
  end
  obj['cores'].last
end

def best_match
  available = versions
  available.each do |v|
    return v if Gem::Version.new(v) <= Gem::Version.new(RUBY_VERSION)
  end
  return available.last
end

def cache_dir
  @cache_dir ||= File.join(Dir.home, '.solargraph', 'cache')
end

def clear
  FileUtils.rm_rf cache_dir, secure: true
  require_minimum
end

def download version
  FileUtils.mkdir_p cache_dir
  uri = URI.parse("#{SOURCE}/#{version}.tar.gz")
  response = Net::HTTP.get_response(uri)
  zipfile = File.join(cache_dir, "#{version}.tar.gz")
  File.binwrite zipfile, response.body
  install_archive zipfile
end

def install_archive filename
  tar_extract = Gem::Package::TarReader.new(Zlib::GzipReader.open(filename))
  tar_extract.rewind
  tar_extract.each do |entry|
    if entry.directory?
      FileUtils.mkdir_p File.join(cache_dir, entry.full_name)
    else
      FileUtils.mkdir_p File.join(cache_dir, File.dirname(entry.full_name))
      File.open(File.join(cache_dir, entry.full_name), 'wb') do |f|
        f << entry.read
      end
    end
  end
  tar_extract.close
end

def require_minimum
  return unless best_match.nil?
  FileUtils.mkdir_p cache_dir
  version_dir = File.join(cache_dir, '2.2.2')
  unless File.exist?(version_dir)
    FileUtils.cp File.join(Solargraph::YARDOC_PATH, '2.2.2.tar.gz'), cache_dir
    install_archive File.join(cache_dir, '2.2.2.tar.gz')
  end
end

def valid?(ver)
  dir = File.join(cache_dir, ver)
  return false unless File.directory?(dir)
  return false unless File.directory?(File.join(dir, 'yardoc'))
  return false unless File.directory?(File.join(dir, 'yardoc-stdlib'))
  true
end

def versions
  dirs = Dir[File.join(cache_dir, '*')].map{|d| File.basename(d)}
  dirs.keep_if{|d| valid?(d)}
  dirs.sort!{|a, b| Gem::Version.new(b) <=> Gem::Version.new(a)}
  dirs
end

def yard_stdlib_file(ver = best_match)
  raise ArgumentError.new("Invalid core yardoc version #{ver}") unless valid?(ver)
  File.join(cache_dir, ver, 'yardoc-stdlib')
end

def yardoc_file(ver = best_match)
  raise ArgumentError.new("Invalid core yardoc version #{ver}") unless valid?(ver)
  File.join(cache_dir, ver, 'yardoc')
end