hda-install-gem

#! /usr/bin/env ruby

def do_system_multiple(args)
	res = false
	(1..4).each {
		res = system("#{args} 2>&1")
		break if res
	}
	res
end

def run_gem_install(gem, version = nil)
	ver = version ? " --version #{version} " : ""
	#puts "system(\"gem install #{gem} #{ver} --no-rdoc --no-ri\")"
	do_system_multiple "gem install #{gem} #{ver} --no-rdoc --no-ri"
end

def gem_list
	res = {}
	raw_list = open("|gem list") { |f| f.readlines }.map do |g|
		if g =~ /\s*([^\s]+)\s*\(([^\)]+)\)/
			gem = $1
			versions = $2.split /[, ]+/
			res[gem] = versions
			# puts "DEBUG gem: \"#{gem}\" -> #{versions.inspect}"
		end
	end
	res
end

# return true if there are no errors - pass thru false for errors
def install_gem(gem, version = nil)
	# puts gem.inspect
	# puts version.inspect
	usage if version && ! (version =~ /[0-9.]+/)
	gems = gem_list
	if gems[gem]
		# puts "installed"
		if version && ! gems[gem].include?(version)
			# puts "DEBUG: gem versions available: #{gems[gem].inspect}"
			puts "gem \"#{gem}\" is already installed, but not the version requested. installing #{version} ..."
			run_gem_install(gem, version)
			puts "done."
		else
			puts "gem \"#{gem}\" is already installed. skipped."
		end
	else
		# puts "NOT installed at all - installing ..."
		puts "gem \"#{gem}\" is not installed. installing ..."
		run_gem_install(gem, version)
		puts "done."
	end
	# return true for no errors
	true
end

def usage
	puts "usage: hda-install-gem gem [version]"
	exit -1
end


unless ARGV.size > 0
	usage
end

unless install_gem(ARGV[0], ARGV[1])
	# could not install - exit with an error
	exit -1
end