#! /usr/bin/ruby

# :Title: exifDirs.rb: Exif based image sorting.
# exifDirs.rb: Exif based image sorting.
# Author:: Matt Foster (mailto:mattfoster@clara.co.uk)
# Copyright:: Copyright (c) Matt Foster (mailto:mattfoster@clara.co.uk)
# Process jpeg images by looking at exif information, 
# and linking them to directories depending on what we find.
# currently only know what to do with dates and orientations, but is easy to
# extend.
# * Uses a few bits and pieces I haven't used before, like ostruct and optparse.
# * Uses a config file to specify what to look at, but currently, operations
#   functions are hard-coded.
#
# Changelog:
#   20050924: Replaced transform with to_a. Following changes to yaml.rb
#   20051022: Fixed the YAML, and changed the default config file.

require 'exif'
require 'time'
require 'fileutils'
require 'yaml'
require 'ostruct'
require 'optparse' 

# The exifDirs class... all of the operations live here.
class ExifDirs
 
  def initialize(verbose = false, config = '~/.exifDirs.rc')
	@config = File.expand_path(config)
	loadConfig
	@opts = parseOpts
	@opts.verbose ||= verbose
	
	if @opts.verbose
	  puts "Verbose mode on."
	  puts "Source dir: #{@opts.source}"
	  puts "Destination dir: #{@opts.dest}"
	end
	setup
	
	process @opts.source
  end
 
  # Create the necessary dirs.
  def setup
	@types.each_key do | key |
	  puts "Creating dir: #{@opts.dest}/#{@types[key]}" if @opts.verbose
	  FileUtils.mkdir_p "#{@opts.dest}/#{@types[key]}" 
	end

	if @types.has_key? 'Orientation'
	  @orientationDirs.each_value do |entry|
		puts "Creating dir: #{entry}" if @opts.verbose
		FileUtils.mkdir_p "#{@opts.dest}/#{entry}" 
	  end
	end
  end

  # process a given directory
  def process(dir)
	puts "Processing: #{dir}."
	# Give us access to the array outside of the iterator.
	dest = Array.new
	Dir.chdir dir 
	# Iterate over JPEGS.
	Dir["**/*.jpg"].each do |file|
	  unless Dir.pwd =~ /#{@opts.dest}(\/)*.*/
		exif = Exif.new file 
		unless exif.list_tags(Exif::IFD::EXIF) == nil
		  dest = []
		  puts "Processing: #{file}" if @opts.verbose 
		  # Get the destination dir.
		  @types.each_key do |key|
			op = "self.#{@types[key]}Op(\"#{exif[key]}\")"
			dest.push(eval(op))
		  end # types
		  # Now, process what we've learned.
		  makeLinks Dir.pwd, file, dest
		end
	  end
	end
	puts "Examined #{Dir['**/*.jpg'].length} files."
	exit 0
  end

  def undef_method?
	return nil
  end
 
  # Turn orientation into a path name.
  def orientationOp(exifKey)
	return "#{@opts.dest}/#{@orientationDirs[exifKey]}"
  end

  # Decodes dates, and returns a corresponding path
  def dateOp(exifKey)
	unless exifKey == nil
	  date = Time.parse exifKey.gsub(':', '')
	  dir = date.strftime "#{@opts.dest}/date/%Y%m%d/" 
	else
	  puts "Error parsing date." if @opts.verbose
	  return nil
	end
	return dir
  end

  # Create a filename with and inbuilt suffix.. I.e convert from 
  # foo.jpg to foo-1.jpg using the first available integer.
  def addSuffix(path)
    dir, base = File.split(path)
    name      = File.basename base, '.jpg'
    num       = 1
    nPath = "#{dir}/#{name}-#{num}.jpg"
   
    if File.exist? nPath
      num += 1
      nPath = "#{dir}/#{name}-#{num}.jpg"
    end 

    nPath
  end
    
  # Create symlinks
  def makeLinks(dir, source, dest)
	dest.each do |dst|
	  unless dst == nil
		if ! File.exist? dst
		  FileUtils.mkdir_p dst
		end
	  end
	  sourcePath = "#{dir}/#{source}".gsub("//", "/")
	  destPath = "#{dst}/#{File.basename(source)}".gsub("//", "/")
	  begin
        if File.exist? destPath
          # Assume it's because the cameras number was reset.
          destPath = addDestSuffix(destPath)
        end
		if File.exist? sourcePath
		  puts "Linking:\n\t#{sourcePath} to\n\t#{destPath}" if @opts.verbose
		  FileUtils.ln_s sourcePath, destPath
		else
		  puts "Link not created."
		end
	  rescue
		puts "Error, couldn't link #{sourcePath} to #{destPath}."
	  end
	end
  end

  # Load the YAML config, creating a default one if it doesn't exist.
  def loadConfig
    if File.exist? @config 
      yaml_tree = YAML::parse_file @config 
	  @types = yaml_tree.select('/types')[0].transform
	  @orientationDirs = yaml_tree.select('/orientations')[0].transform
    else
      puts "Config file #{@config} doesn't exist. Creating default config."
	  config = File.new(@config, "w")
	  config.write <<EOF
# exifDirs config file.
---
types:
  { Date and Time: date,
  Orientation: orientation }
orientations:
  { 'right - top': orientation/portrait/right,
  'left - bottom': orientation/portrait/left,
  'top - left': orientation/landscape } 
EOF
	  config.close
	  loadConfig
    end
  end # function

  # Parse the command line arguments. Users OptionParser.
  def parseOpts
	opt = OpenStruct.new
	# Default values.
	opt.verbose = false
	opt.source  = false
	opt.dest    = false
	# Nice simple way of parsing opts.
	p = OptionParser.new {|p|
	  p.on('-s source_dir', '--source', 'Source Directory', String) {|o| 
		opt.source = checkLen(File.expand_path(o))
	  }
	  p.on('-d dest_dir', '--dest', 'Dest. Directory', String) {|o| 
		opt.dest = checkLen(File.expand_path(o))
	  }
	  p.on('-v', '--[no-]verbose', 'Run verbosely') {|o|
		opt.verbose = o
	  }
	  p.on_tail("-h", "--help", "Show this message") {
		puts p
		puts "Processes JPEG images according to embedded EXIF information."
		exit(1)
	  }
	}

	p.parse!

	if opt.source == false or opt.dest == false
	  puts "#{$0}: No directories specified."
	  puts p
	  exit(1)
	end

	return opt
  end
 
  # Check for zero length strings.
  def checkLen(s)
	unless s.length == 0
	  return s
	else
	  return false
	end
  end
  
end

# Set up the class.
exDir = ExifDirs.new