Add names_to_numbers script

Add names_to_numbers script. I mainly use it for renumbering directories
full of audio book mp3s.

diff --git a/names_to_numbers.rb b/names_to_numbers.rb
new file mode 100755 (executable)
index 0000000..689e6de
--- /dev/null
+++ b/names_to_numbers.rb
@@ -0,0 +1,100 @@
+#!/usr/bin/ruby -w
+
+#
+# names_to_numbers.rb
+#
+# Renames all the files in a directory with the given file extension.
+# The renamed files will just have numbers.
+#
+# Colin Mccabe
+#
+
+require 'fileutils'
+require 'optparse'
+require 'ostruct'
+
+class MyOptions
+  def self.parse(args)
+    opts = OpenStruct.new
+    opts.dry_run = false
+    opts.num_digits = 2
+    opts.extension = nil
+    $fu_args = { :verbose => true }
+
+    # Fill in $opts values
+    parser = OptionParser.new do |myparser|
+      myparser.banner = "Usage: #{ File.basename($0) } [opts]"
+      myparser.separator("Specific options:")
+      myparser.on("--num-digits DIGITS", "-D",
+              "Set the number of digits in the numbering scheme.") do |d|
+        opts.num_digits = d.to_i
+      end
+      myparser.on("--dry-run", "-d",
+              "Show what would be done, without doing it.") do |d|
+        $fu_args = { :verbose => true, :noop => true }
+        opts.dry_run = true
+      end
+      myparser.on("--file-extension EXTENSION", "-e",
+              "The file extension for the files to rename.") do |e|
+        opts.extension = e
+      end
+    end
+
+    parser.parse!(args)
+    raise "invalid num_digits: #{opts.num_digits}" unless
+      opts.num_digits > 0
+    raise "must give an extension" unless opts.extension != nil
+    return opts
+  end
+end
+
+def pow(x, y)
+  ret = 1
+  (0...y).each do |z|
+    ret = ret * x
+  end
+  return ret
+end
+#.#{$opts.extension}").sort.each do |f|
+def file_iter
+  Dir.glob("*.#{$opts.extension}").sort.each do |f| 
+    yield f
+  end
+end
+
+def count_files(file)
+  $total_files = $total_files + 1
+end
+
+def get_file_name(num)
+  return sprintf("%0#{$opts.num_digits}d.#{$opts.extension}", num)
+end
+
+def rename_files(file)
+  FileUtils.mv(file, get_file_name(1 + $total_files), $fu_args)
+  $total_files = $total_files + 1
+end
+
+# MAIN
+begin
+  $opts = MyOptions.parse(ARGV)
+rescue Exception => msg
+  $stderr.print("#{msg}.\nType --help to see usage information.\n")
+  exit 1
+end
+
+# make sure there aren't too many files
+$total_files = 0
+max_total_files = pow(10, $opts.num_digits) - 1
+file_iter { |f| count_files(f) }
+if ($total_files > max_total_files) then
+  raise "With #{$opts.num_digits} digit(s), we can only have at most \
+#{max_total_files} files-- but there are #{$total_files} files in the \
+#directory. Try setting a higher value for num_digits, using -D."
+end
+
+# rename files
+$total_files = 0
+file_iter { |f| rename_files(f) }
+
+exit 0