class Bundler::CompactIndexClient

def self.debug
  return unless ENV["DEBUG_COMPACT_INDEX"]
  DEBUG_MUTEX.synchronize { warn("[#{self}] #{yield}") }
end

def dependencies(names)
  Bundler::CompactIndexClient.debug { "dependencies(#{names})" }
  execution_mode.call(names) do |name|
    update_info(name)
    @cache.dependencies(name).map {|d| d.unshift(name) }
  end.flatten(1)
end

def execution_mode
  @execution_mode || sequentially
end

def execution_mode=(block)
  Bundler::CompactIndexClient.debug { "execution_mode=" }
  @endpoints = Set.new
  @execution_mode = block
end

def initialize(directory, fetcher)
  @directory = Pathname.new(directory)
  @updater = Updater.new(fetcher)
  @cache = Cache.new(@directory)
  @endpoints = Set.new
  @info_checksums_by_name = {}
  @parsed_checksums = false
  @mutex = Thread::Mutex.new
end

def names
  Bundler::CompactIndexClient.debug { "/names" }
  update(@cache.names_path, "names")
  @cache.names
end

def sequential_execution_mode!
  self.execution_mode = sequentially
end

def sequentially
  @sequentially ||= lambda do |inputs, &blk|
    inputs.map(&blk)
  end
end

def synchronize
  @mutex.synchronize { yield }
end

def update(local_path, remote_path)
  Bundler::CompactIndexClient.debug { "update(#{local_path}, #{remote_path})" }
  unless synchronize { @endpoints.add?(remote_path) }
    Bundler::CompactIndexClient.debug { "already fetched #{remote_path}" }
    return
  end
  @updater.update(local_path, url(remote_path))
end

def update_and_parse_checksums!
  Bundler::CompactIndexClient.debug { "update_and_parse_checksums!" }
  return @info_checksums_by_name if @parsed_checksums
  update(@cache.versions_path, "versions")
  @info_checksums_by_name = @cache.checksums
  @parsed_checksums = true
end

def update_info(name)
  Bundler::CompactIndexClient.debug { "update_info(#{name})" }
  path = @cache.info_path(name)
  checksum = @updater.checksum_for_file(path)
  unless existing = @info_checksums_by_name[name]
    Bundler::CompactIndexClient.debug { "skipping updating info for #{name} since it is missing from versions" }
    return
  end
  if checksum == existing
    Bundler::CompactIndexClient.debug { "skipping updating info for #{name} since the versions checksum matches the local checksum" }
    return
  end
  Bundler::CompactIndexClient.debug { "updating info for #{name} since the versions checksum #{existing} != the local checksum #{checksum}" }
  update(path, "info/#{name}")
end

def url(path)
  path
end

def versions
  Bundler::CompactIndexClient.debug { "/versions" }
  update(@cache.versions_path, "versions")
  versions, @info_checksums_by_name = @cache.versions
  versions
end