/stdhome

# program.py
#
# Copyright (C) 2013 Tim Marston <tim@edm.am>
#
# This file is part of stdhome (hereafter referred to as "this program").
# See http://ed.am/dev/stdhome for more information.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


import os, sys, getopt
from . import the
from .config import Config
from .vcs.vcs import Vcs


class Program:


	def __init__( self, version ):
		self.name = os.path.basename( sys.argv[ 0 ] )
		self.version = version


	def die( self, error_message ):
		prefix = self.name + ( ' ' + the.command if the.command else '' )
		print('%s: %s' % ( prefix, error_message ), file=sys.stderr)
		exit( 1 )


	def print_usage( self, error_message ):
		command = ' ' + the.command if the.command else ''
		self.die( error_message + \
				  "\nTry '%s%s --help' for more information." % \
				  ( self.name, command ) )


	def print_help( self ):
		print("Usage: " + self.name + " COMMAND [OPTION]...")
		print()
		#      01234567890123456789012345678901234567890123456789012345678901234567890123456789
		print("Tool to manage a set of files in your home directory and distribute them across")
		print("multiple computers, merging local changes (in the same way as you would manage")
		print("source code under version control).")
		print()
		print("Global options (for all commands):")
		print("     --help     display help and exit")
		print("     --version  output version information and exit")
		print()
		print("Commands:")
		print("  init          initialise a local copy of your repository")
		print("  update        merge remote changes in to your home directory")
		print("  resolve       try to finish an update (that had conflicts)")
		print("  add           add local files/changes to the repository")
#		print("  remove        remove a local file from the repository")
		print("  status        list files that have changed locally")
		print("  diff          shows changes made to local files")
		print("  revert        undo changes made to local files")
		print()
		print("Manual staging commands:")
		print("  stage-add     add (but don't commit) files/changes to local repository")
#		print("  stage-remove  delete *but don't comit) files from the local repository")
		print("  stage-revert  revert changes in the local repository")
		print("  stage-status  show status of local repository")
#		print("  stage-diff    shows changes in local repository")
		print("  stage-commit  commit changes in the local repository")
		print()
		print("For help about a particular command (including the additional options that the")
		print("command accepts) try typing:")
		print("  $ " + self.name + " COMMAND --help")
		exit( 0 )


	def print_version( self ):
		print("stdhome " + self.version)
		print()
		print("Copyright (C) 2013 to 2014 Tim Marston")
		print()
		#      01234567890123456789012345678901234567890123456789012345678901234567890123456789
		print("This program is free software, and you may use, modify and redistribute it")
		print("under the terms of the GNU General Public License version 3 or later.  This")
		print("program comes with ABSOLUTELY NO WARRANTY, to the extent permitted by law.")
		print()
		print("For more information, including documentation, please see the project website")
		print("at http://ed.am/dev/stdhome.")
		print()
		print("Please report bugs to <tim@ed.am>.")
		exit( 0 )


	def check_command( self, command ):
		"""Check that the given command is valid and return the full name of the
		command.

		@param command the given command
		"""

		# commands
		if [ 'init', 'update', 'resolve', 'add', 'remove', 'revert', 'status',
			 'diff', 'stage-add', 'stage-remove', 'stage-revert',
			 'stage-status', 'stage-diff', 'stage-commit'
		].count( command ) == 1:
			return command

		# resolve aliases
		alias = {
			'up': 'update',
			'rm': 'remove',
			'st': 'status',
			'co': 'init',
			'ci': 'add',
			'stst': 'stage-status',
			'stadd': 'stage-add',
			'strm': 'stage-remove',
			'stci': 'stage-commit',
		}.get( command, False )
		if alias: return alias

		# invalid
		return None


	def get_command_argument( self, args ):
		"""Find the first program argument what isn't an option argument.

		@param args the program arguments
		"""

		while args:
			if args[ 0 ] == '--':
				return args[ 1 ] if len( args ) > 1 else None
			if args[ 0 ][ 0 : 1 ] != '-':
				return args[ 0 ]
			args = args[ 1 : ]
		return None


	def run( self ):
		# make an initial attempt to parse the command line, looking only for
		# --help and --version so that they have the chance to run without a
		# command being specified
		try:
			opts, args = getopt.gnu_getopt(
				sys.argv[ 1: ], "",
				[ "help", "version" ] )

			for opt, optarg in opts:
				# we only show help if there are no non-option arguments (e.g.,
				# a command) specified.  If a command has been specified it will
				# have to be parsed and --help will be handled by it, instead)
				if opt == "--help" and len( args ) == 0:
					self.print_help()
				elif opt == "--version":
					self.print_version()

		except getopt.GetoptError as e:
			# ignore errors -- we aren't parsing the command line properly yet
			pass

		# read program configuration
		the.config = Config()

		# find the command by grabbing the first program argument that doesn't
		# look like an option (note: the first argument that doesn't look like
		# an option may actually be an argument to an option, so this is far
		# from perfect, but, provided the user is mindful, this is preferable to
		# forcing the user to always specify options after the command)
		the.command = self.get_command_argument( sys.argv[ 1: ] )
		if the.command == None:
			self.print_usage( "missing command" )

		# check command is valid
		the.command = self.check_command( the.command )
		if the.command == None:
			self.print_usage( "bad command" )

		# calculate module and class name
		class_name = module_name = ''
		bits = the.command.split( '-' )
		for bit in bits:
			class_name += bit[ 0 ].upper() + bit[ 1 : ]
			if module_name: module_name += '_'
			module_name += bit
		class_name += 'Command'

		# import module and instantiate the class
		module = __import__( 'stdhome.command.' + module_name,
							 fromlist = [ class_name ] )
		instance = getattr( module, class_name )()

		# fully parse the command line, as per the command
		try:
			instance.parse_command_line()
		except( getopt.GetoptError, self.UsageError ) as e:
			self.print_usage( e.msg )
		except self.FatalError as e:
			self.die( e.msg )

		# do late initialisation
		the.late_init()

		# run the command
		try:
			instance.run()
		except Vcs.VcsError as e:
			message = e.msg.rstrip() + '\n\nVCS OUTPUT:\n' + e.output.rstrip()
			self.die( message )
		except self.FatalError as e:
			self.die( e.msg )


	class UsageError( Exception ):

		def __init__( self, error_message ):
			self.msg = error_message


	class FatalError( Exception ):

		def __init__( self, message ):
			self.msg = message