gembr

#!/usr/bin/env ruby
#
# A little shortcut for browsing source for gems.
# !sequitur : 2006.12.15

require 'rubygems'

GEMS_ROOT = File.join Gem.dir, 'gems'
GEMS_DIR  = Dir.new GEMS_ROOT

GEM_NOT_FOUND = "Gem not found in #{GEMS_ROOT}"

# Verifies that the given gem name exists.
# If a version is not specified, grabs the most recent.
def find(gem)
  GEMS_DIR.entries.select { |name| name.include? gem }.last
end

# If a valid name with a bad version is passed,
# return a list of known versions.
def find_similar(gem)
  gem_name = /^([^-]+)/.match(gem)[1] # everything before the first '-'
  GEMS_DIR.entries.select { |g| g =~ /^#{gem_name}/ }
end

# Puts a numbered list of gems.
def list(similar)
  similar.each_with_index { |gem,i| puts "#{i + 1}) #{gem}" }
end

# Prompts the user to select from a list of similar
# gem names, and returns the selected name.
def get(similar)
  valid = 1..similar.size
  puts "Invalid selection. Enter #{valid.first} - #{valid.last}" while ! valid.include?(selection = gets.to_i)
  similar[selection-1]
end

# Launches the default text editor, passing the path
# to the gem as the only argument.
def browse!(gem)
  system "#{ENV['EDITOR']} #{File.join GEMS_ROOT, gem}"
end

###

if ARGV.empty?
  puts 'USAGE: gembr gemname'
  exit
end

gem = if gem_arg = ARGV.shift
  find gem_arg
else
  puts GEM_NOT_FOUND

  unless (similar = find_similar GEM_ARG).empty?
    list similar
    get similar
  end  
end

if gem
  browse! gem
else
  puts GEM_NOT_FOUND
end