require 'json'
require 'yaml'

module KGrader
  class Filesystem

    def initialize(root)
      @root = root
    end

    def course(name)
      File.join spec_dir, name
    end

    def course_config(name)
      File.join course(name), '_config.yml'
    end

    def assignment(courseid, name)
      File.join course(courseid), name
    end

    def assignment_config(courseid, name)
      File.join assignment(courseid, name), '_config.yml'
    end

    def roster(courseid, semester)
      File.join desk_dir, courseid, semester, '_roster.csv'
    end

    def submission(courseid, semester, assignment, student)
      File.join desk_dir, courseid, semester, assignment, student
    end

    # -------------------------------------------------------------------------

    def courses
      Dir[File.join spec_dir, '*', '_config.yml'].map! do |fn|
        File.basename File.dirname fn
      end
    end

    def assignments(courseid)
      Dir[File.join course(courseid), '*', ''].map! { |fn| File.basename fn }
    end

    def semesters(courseid)
      Dir[roster courseid, '*'].map! { |fn| File.basename File.dirname fn }
    end

    # -------------------------------------------------------------------------

    def load(path)
      case File.extname path
      when '.txt'
        File.read path
      when '.json'
        JSON.parse File.read(path)
      when '.yml', '.yaml'
        YAML.load File.read(path)
      when '.csv'
        File.read(path).split("\n").map! { |line| line.split "," }
      else
        raise FilesystemError, "unknown file type: #{path}"
      end
    rescue SystemCallError  # Errno::ENOENT, etc.
      raise FilesystemError, "can't read file: #{path}"
    end

    def jail
      @jail ||= Jail.new jail_dir
    end

    def reset_desk
      FileUtils.rm_rf Dir[File.join desk_dir, '*', '']
    end

    def clean_desk
      Dir[File.join desk_dir, '*', '*', '*', '*', 'status.txt'].each do |fn|
        File.write fn, "ungraded" if File.read(fn) == "graded"
      end
      FileUtils.rm_f Dir[File.join desk_dir, '*', '*', '*', '*', 'pending']
      FileUtils.rm_f Dir[File.join desk_dir, '*', '*', '*', '*', '*.log*']
    end

    # -------------------------------------------------------------------------

    private
    def desk_dir
      File.join @root, 'desk'
    end

    def jail_dir
      File.join @root, 'jail'
    end

    def spec_dir
      File.join @root, 'spec'
    end
  end
end