require 'repertoire/exceptions/program_not_found'
require 'repertoire/exceptions/command_failed'

module Repertoire
  module Compat
    #
    # @return [String]
    #   The native platform.
    #
    # @example
    #   Compat.arch  #=> "linux"
    #
    def self.platform
      RUBY_PLATFORM.split('-').last
    end

    #
    # @return [Array]
    #   +PATH+ environment variable.
    #
    # @example
    #   Compat.paths
    #   #=> ["/bin", "/usr/bin"]
    #
    def self.paths
      # return an empty array in case
      # the PATH variable does not exist
      return [] unless ENV['PATH']

      if self.platform =~ /mswin32/
        return ENV['PATH'].split(';')
      else
        return ENV['PATH'].split(':')
      end
    end

    #
    # Finds the program matching name.
    #
    # @return [String, nil]
    #   The full path of the program, or +nil+ if the program could not be
    #   found.
    #
    # @example
    #   Compat.find_program('as')
    #   #=> "/usr/bin/as"
    #
    def self.find_program(name)
      self.paths.each do |dir|
        full_path = File.expand_path(File.join(dir,name))

        return full_path if File.file?(full_path)
      end

      return nil
    end

    #
    # Runs the command.
    #
    # @param [String] program
    #   The name of the program to run.
    #
    # @param [Array] args
    #   Optional arguments to run the program with.
    #
    # @raise [ProgramNotFound]
    #   The specified _program_ could not be found.
    #
    # @raise [CommandFailed]
    #   The command failed to run.
    #
    # @example
    #   Compat.sh('ls','-la','/')
    #
    def Compat.sh(program,*args)
      program = program.to_s

      program_path = Compat.find_program(program)
      unless program_path
        raise(ProgramNotFound,"the program #{program.dump} was not found",caller)
      end

      # stringify the args
      args = args.map { |arg| arg.to_s }

      unless system(program_path,*args)
        command = program_path
        command += ' ' + args.join(' ') unless args.empty?

        raise(CommandFailed,"the command #{command.dump} failed",caller)
      end
    end
  end
end