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module Fission
class CommandLineParser
# Internal: Creates a new Fission::CommandLineParser object.
#
# args - The command line arguments to parse. This is expected to be in the
# same format of ARGV (Array) (default: ARGV).
#
# Examples:
#
# CommandLineParser.new ['foo', 'bar']
#
# CommandLineParser.new
#
# Returns a Fission::CommandLineParser object.
def initialize(args=ARGV)
@args = args
gather_commands_and_summaries
setup_options_parser
end
# Internal: Parses the command line arguments. If the arguments are
# invalid, the appropriate help will be output and then will exit. If the
# arguments are valid, then the @command variable will be set to a new
# instance of the determined command class.
#
# Examples:
#
# @command_line_parser.parse
#
# Returns nothing.
def parse
@options_parser.order! @args
determine_command_provided
self
rescue OptionParser::InvalidOption => e
ui.output e
show_all_help
exit 1
end
# Internal: Accessor for an instance of the determined command. This is set
# by running the parse method.
#
# Examples:
#
# @command_line_parser.command
#
# Returns an instance of the determined command if the arguments are valid.
# Returns nil if the parse command has not yet been run.
def command
@command
end
private
# Internal: Sets up the base option parser.
#
# Examples:
#
# @cli.setup_option_parser
#
# Returns nothing. This will set the @option_parser instance variable.
def setup_options_parser
@options_parser = OptionParser.new do |opts|
opts.banner = "\nUsage: fission [options] COMMAND [arguments]"
opts.on_head('-v', '--version', 'Output the version of fission') do
ui.output VERSION
exit 0
end
opts.on_head('-h', '--help', 'Displays this message') do
show_all_help
exit 0
end
end
end
# Internal: Provides the help of all of the known commands.
#
# Examples
#
# @cli.commands_help
#
# Outputs the summary text for all known commands.
def commands_help
longest_cmd = @commands.inject do |longest, cmd_name|
longest.length > cmd_name.length ? longest : cmd_name
end
ui.output "\nCommands:"
Hash[@command_names_and_summaries.sort].each_pair do |name, summary|
ui.output_printf "%-#{longest_cmd.length}s %s\n", name, summary
end
end
# Internal: Determines all of the available commands and their summaries.
#
# Examples
#
# @cli.command_names_and_summaries
# # => { 'clone' => 'Clones a VM', 'stop' => 'Stops a VM' }
#
# Returns nothing. This will set the @command_names_and_summaries instance
# variable with the result.
def gather_commands_and_summaries
@command_names_and_summaries = Command.descendants.inject({}) do |result, klass|
cmd = klass.new
result[cmd.command_name] = cmd.summary
result
end
@commands = @command_names_and_summaries.keys.sort
end
# Internal: Determines the command that has been provided. If it is
# determined that an invalid command is provided, then the help/usage will
# be displayed and it will exit.
#
# Examples:
#
# @cli.determine_command_to_execute
#
# Returns nothing. This will set the @command instance variable to an instance
# of the appropriate command class (assuming it is valid).
def determine_command_provided
if @commands.include? @args.first
@command = Command.const_get(@args.first.capitalize).new @args.drop 1
elsif is_snapshot_command?
klass = @args.take(2).map {|c| c.capitalize}.join('')
@command = Command.const_get(klass).new @args.drop 2
else
show_all_help
exit 1
end
end
# Internal: Determines if the provided command is a snapshot related
# command. This will use the @args instance variable to make the
# determination.
#
# Examples
#
# @cli.is_snapshot_command? ['foo', 'bar']
# # => false
#
# @cli.is_snapshot_command? ['snapshot', 'list']
# # => true
#
# Returns a Boolean of whether a snapshot command was given or not.
def is_snapshot_command?
@args.first == 'snapshot' &&
@args.count > 1 &&
@commands.include?(@args.take(2).join(' '))
end
# Internal: Outputs the usage as well as the known commands and their
# summaries.
#
# Examples
#
# @cli.show_all_help
# # => 'fission options command arguments ....'
#
# Returns nothing.
def show_all_help
ui.output @options_parser
commands_help
end
# Internal: Helper method for outputting text to the ui
#
# Examples
#
# @cli.ui.output 'foo'
#
# Returns a UI instance.
def ui
@ui ||= UI.new
end
end
end
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