# frozen_string_literal: true

module Picopackage
  module Scanner
    Found = Struct.new(:path, :package)

    # Scanning walks whole trees, so it has to survive binaries, unreadable
    # files and anything large enough that reading it to look for a comment
    # would be silly.
    MAX_SCAN_SIZE = 1024 * 1024

    def self.scan(directory, pattern: "**/*")
      Dir.glob(File.join(directory, pattern)).sort.filter_map do |path|
        content = readable_text(path)
        next unless content&.match?(METADATA_PATTERN)

        Found.new(path, Package.new(content: content))
      end
    end

    def self.readable_text(path)
      return nil unless File.file?(path)
      return nil if File.size(path) > MAX_SCAN_SIZE

      content = File.read(path, encoding: "UTF-8")
      content.valid_encoding? ? content : nil
    rescue SystemCallError, ArgumentError
      nil
    end
  end
end