require 'optparse'
require 'stringio'
require 'rubygems'
require 'twitter'

module Twsh
  class Logout < StandardError; end
  class TwshError < StandardError; end

  class Shell
    class << self
      def login(argv, env)
        new argv, env
      end
    end

    def initialize(argv, env)
      username = nil
      password = nil

      OptionParser.new do |opt|
        opt.on('-u VAL') {|v| username = v}
        opt.on('-p VAL') {|v| password = v}
        opt.parse! argv
      end

      fail if username.nil? || password.nil?

      @client = Twitter::Base.new Twitter::HTTPAuth.new username, password
      input = Input.new self
      logged_in = true

      while logged_in
        begin
          output = execute input.read
          puts output if output
        rescue Logout
          logged_in = false
        rescue Interrupt
          puts
          logged_in = false
        rescue TwshError => e
          puts e.message
        end
      end
    end

    attr_reader :client

    def execute(argv)
      return if argv.empty?
      command = argv.shift
      Command.new(self).execute command, argv
    end
  end

  class Command
    @@commands = {}

    class << self
      def setup
        fail unless block_given?
        yield new
      end
    end

    def initialize(twsh = nil)
      @twsh = twsh
    end

    def on(*commands, &process)
      fail unless block_given?
      commands.each {|command| @@commands[command] = process}
    end

    def execute(command, argv)
      process = @@commands[command]

      if process
        args = []
        args << @twsh if process.arity >= 1
        args << argv if process.arity >= 2
        output = nil

        StringIO.open '', 'w' do |io|
          orig = $stdout
          $stdout = io
          process.call *args
          $stdout = orig
          output = io.string unless io.string.empty?
        end

        output
      else
        `#{command} #{argv.join ' '}`.chomp
      end
    end
  end

  class Input
    def initialize(twsh)
      @twsh = twsh
    end

    def read
      read_with_context
    end

    private

    def read_with_context(context = nil, argv = [])
      print context ? "#{context}> " : argv.empty? ? 'twsh% ' : '> '
      context, argv, continue = parse gets, context, argv
      continue ? read_with_context(context, argv) : argv
    end

    def parse(input, context = nil, argv = [])
      escape = false
      continue = false
      v = !argv.empty? ? argv.pop : ''

      new = lambda do
        argv << v unless v.empty?
        v = ''
      end

      input.each_byte do |c|
        if escape
          escape = false
          case c
          when LINE_FEED
            continue = true
            v << c if context
          when ?n
            v << "\n" if quoted? context
          when ?t
            v << "\t" if quoted? context
          when ?f
            v << "\f" if quoted? context
          when ?v
            v << "\v" if quoted? context
          else
            v << c
          end
        else
          case c
          when ?\n
            v << c if context
          when ?\s
            if context
              v << c
            else
              new.call
            end
          when ?'
            if context == :quote
              new.call
              context = nil
            elsif context
              v << c
            else
              context = :quote
            end
          when ?"
            if context == :dquote
              new.call
              context = nil
            elsif context
              v << c
            else
              context = :dquote
            end
          when ?`
            if context == :bquote
              v = @twsh.execute(parse(v)[1])
              context = nil
            elsif context
              v << c
            else
              context = :bquote
            end
          when ?\\
            escape = true
          else
            v << c
          end
        end
      end

      new.call
      [context, argv, continue || !context.nil?]
    end

    def quoted?(context)
      context == :quote || context == :dquote
    end
  end
end

Twsh::Command.setup do |c|
  c.on('exit', 'quit', 'logout') { fail Twsh::Logout }

  c.on 'echo' do |twsh, argv|
    twsh.client.update argv.join ' '
    nil
  end

  c.on 'head' do |twsh, argv|
    n = 5

    OptionParser.new do |opt|
      opt.on('-n VAL', Integer) {|v| n = v}
      opt.parse! argv
    end

    screen_name = argv.shift
    iterator = lambda {|status| puts "#{status.user.screen_name}: #{status.text}"}

    if screen_name
      twsh.client.user_timeline(:screen_name => screen_name, :count => n).each &iterator
    else
      twsh.client.home_timeline(:count => n).each &iterator
    end

    nil
  end
end

Twsh::Shell.login ARGV, ENV