#
#--
# Sketches - A Ruby library for live programming and code reloading.
#
# Copyright (c) 2009 Hal Brodigan (postmodern.mod3 at gmail.com)
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
#Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#++
#

require 'sketches/exceptions/editor_not_defined'
require 'sketches/config'
require 'sketches/temp_sketch'

require 'thread'
require 'fileutils'

module Sketches
  class Sketch

    # ID of the sketch
    attr_reader :id

    # Optional name of the sketch
    attr_accessor :name

    # Last modification time of the sketch
    attr_reader :mtime

    #
    # Creates a new sketch object with the specified _id_ and the given
    # _options_.
    #
    # _options_ may contain the following keys:
    # <tt>:name</tt>:: The name of the sketch.
    # <tt>:path</tt>:: The path to an existing sketch.
    #
    def initialize(id,options={})
      @id = id
      @name = options[:name]

      @mtime = Time.now
      @checksum = 0
      @mutex = Mutex.new

      if options[:path]
        @path = options[:path]
        @name ||= File.basename(@path)
      else
        TempSketch.open { |file| @path = file.path }
      end

      reload!
    end

    #
    # Provides thread-safe access to the sketch.
    #
    def synchronize(&block)
      @mutex.synchronize(&block)
      return nil
    end

    #
    # Spawns the Sketches.editor with the path of the sketch.
    #
    def edit
      if Config.editor.nil?
        raise(EditorNotDefined,"no editor has defined via ENV['EDITOR'] or Sketches.config",caller)
      elsif Config.editor.kind_of?(Proc)
        cmd = Config.editor.call(@path)
      else
        cmd = "#{Config.editor} #{@path}"
      end

      system(cmd)
    end

    #
    # Returns +true+ if the sketch has become stale and needs reloading,
    # returns +false+ otherwise.
    #
    def stale?
      if File.file?(@path)
        if File.mtime(@path) > @mtime
          return crc32 != @checksum
        end
      end

      return false
    end

    #
    # Reloads the sketch.
    #
    def reload!
      if File.file?(@path)
        @mtime = File.mtime(@path)
        @checksum = crc32

        begin
          return load(@path)
        rescue LoadError => e
          STDERR.puts "#{e.class}: #{e.message}"
        end
      end

      return false
    end

    #
    # Saves the sketch to the specified _path_.
    #
    def save(path)
      if (File.file?(@path) && @path != path)
        FileUtils.cp(@path,path)
        return true
      end

      return false
    end

    #
    # Returns the String representation of the sketch.
    #
    def to_s(verbose=false)
      str = "##{@id}"
      str << ": #{@name}" if @name
      str << "\n\n"

      if File.file?(@path)
        File.open(@path) do |file|
          unless verbose
            4.times do
              if file.eof?
                str << "\n" unless str[-1..-1] == "\n"
                str << "  ..."
                break
              end

              str << "  #{file.readline}"
            end
          else
            file.each_line { |line| str << "  #{line}" }
          end

          str << "\n"
        end
      end

      return str
    end

    protected

    #
    # Returns the CRC32 checksum of the sketch file.
    #
    def crc32
      r = 0xffffffff

      File.open(@path) do |file|
        file.each_byte do |b|
          r ^= b
          8.times { r = ((r >> 1) ^ (0xEDB88320 * (r & 1))) }
        end
      end

      return r ^ 0xffffffff
    end

  end
end