require_relative './version'
require_relative './gem'
require 'shellwords'

module TinyTds
  class Bin

    attr_reader :name

    class << self
      def exe(name, *args)
        bin = new(name)
        puts bin.info unless args.any? { |x| x == '-q' }
        bin.run(*args)
      end
    end

    def initialize(name)
      @root = Gem.root_path
      @exts = (ENV['PATHEXT'] ? ENV['PATHEXT'].split(';') : ['']) | ['.exe']

      @name = name
      @binstub = find_bin
      @exefile = find_exe
    end

    def run(*args)
      with_ports_paths do
        return nil unless path
        Kernel.system Shellwords.join(args.unshift(path))
        $CHILD_STATUS.to_i
      end
    end

    def path
      @path ||= @exefile && File.exist?(@exefile) ? @exefile : which
    end

    def info
      "[TinyTds][v#{TinyTds::VERSION}][#{name}]: #{path}"
    end

    private

    def search_paths
      ENV['PATH'].split File::PATH_SEPARATOR
    end

    def with_ports_paths
      old_path = ENV['PATH']

      begin
        ENV['PATH'] = [
          Gem.ports_bin_paths,
          old_path
        ].flatten.join File::PATH_SEPARATOR

        yield if block_given?
      ensure
        ENV['PATH'] = old_path
      end
    end

    def find_bin
      File.join @root, 'bin', name
    end

    def find_exe
      Gem.ports_bin_paths.each do |bin|
        @exts.each do |ext|
          f = File.join bin, "#{name}#{ext}"
          return f if File.exist?(f)
        end
      end
      nil
    end

    def which
      search_paths.each do |path|
        @exts.each do |ext|
          exe = File.expand_path File.join(path, "#{name}#{ext}"), @root
          next if exe == @binstub
          next unless File.executable?(exe)
          next unless binary?(exe)
          return exe
        end
      end
      nil
    end

    # Implementation directly copied from ptools.
    # https://github.com/djberg96/ptools
    # https://opensource.org/licenses/Artistic-2.0
    #
    def binary?(file)
      bytes = File.stat(file).blksize
      return false unless bytes
      bytes = 4096 if bytes > 4096
      s = (File.read(file, bytes) || '')
      s = s.encode('US-ASCII', undef: :replace).split(//)
      ((s.size - s.grep(' '..'~').size) / s.size.to_f) > 0.30
    end
  end
end