require 'pry'
require 'pastel'

module Exa
  class ShellConfig
    attr_accessor :prompt
  end

  class ShellCommand
    def initialize(title:,args:)
      @title = title
      @args = args
    end

    def evaluate(shell)
      case @title
      when "ls" then
        if shell.pwd.children.any?
          shell.print_collection shell.pwd.children.map(&:name)
        else
          shell.print_warning "(no children of #{shell.pwd.path})"
        end
      when "cd" then
        target = Exa.expand(@args.first)
        if target && !target.empty?
          shell.change_directory target.first
        else
          shell.print_warning "Invalid path for cd: #{@args.first}"
        end
      when "mkdir" then
        target = Exa.recall(@args.first)
      when "pwd" then
        shell.print_info shell.pwd.path
      else
        shell.print_warning "Unknown command: '#@title'"
      end
    end

    def self.extract(string)
      tokens = string.split(' ')
      # p [ :extract, tokens: tokens ]
      cmd,*args = *tokens
      # p [ :extract, cmd: cmd, args: args ]
      new(title: cmd, args: args)
    end
  end

  class Shell
    attr_reader :pwd

    def initialize(pwd)
      @pwd = pwd
    end

    def configuration
      @config ||= ShellConfig.new
    end

    def kickstart!
      loop do
        print configuration.prompt.call(self)
        inp = gets.chomp
        outp = shell_eval(inp)
        p outp unless outp.nil? || (outp.respond_to?(:empty?) && outp.empty?)
      end
    end

    def shell_eval(cmd_str)
      cmd = ShellCommand.extract(cmd_str)
      cmd.evaluate(self)
    end

    def change_directory(target)
      @pwd = target
    end

    def print_collection(elements)
      puts
      elements.each do |element|
        puts " - " + pastel.blue("  #{element}")
      end
      puts
    end

    def print_warning(message)
      puts
      puts pastel.red(message)
      puts
    end

    def print_info(message)
      puts
      puts pastel.green(message)
      puts
    end

    def pastel
      @pastel ||= Pastel.new
    end

    def self.repl!
      shell = new(Exa['/'])
      yield shell.configuration
      shell.kickstart!
    end
  end
end