#!/usr/bin/env python3
# KLL Compiler
# Keyboard Layout Langauge
#
# Copyright (C) 2014-2015 by Jacob Alexander
#
# This file 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 file 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 file.  If not, see <http://www.gnu.org/licenses/>.

### Imports ###

import argparse
import importlib
import io
import os
import re
import sys
import token

from pprint   import pformat
from re       import VERBOSE
from tokenize import generate_tokens

from kll_lib.containers import *
from kll_lib.hid_dict   import *

from funcparserlib.lexer  import make_tokenizer, Token, LexerError
from funcparserlib.parser import (some, a, many, oneplus, skip, finished, maybe, skip, forward_decl, NoParseError)



### Decorators ###

 ## Print Decorator Variables
ERROR = '\033[5;1;31mERROR\033[0m:'


 ## Python Text Formatting Fixer...
 ##  Because the creators of Python are averse to proper capitalization.
textFormatter_lookup = {
	"usage: "            : "Usage: ",
	"optional arguments" : "Optional Arguments",
}

def textFormatter_gettext( s ):
	return textFormatter_lookup.get( s, s )

argparse._ = textFormatter_gettext



### Argument Parsing ###

def checkFileExists( filename ):
	if not os.path.isfile( filename ):
		print ( "{0} {1} does not exist...".format( ERROR, filename ) )
		sys.exit( 1 )

def processCommandLineArgs():
	# Setup argument processor
	pArgs = argparse.ArgumentParser(
	        usage="%(prog)s [options] <file1>...",
	        description="Generates .h file state tables and pointer indices from KLL .kll files.",
	        epilog="Example: {0} mykeyboard.kll -d colemak.kll -p hhkbpro2.kll -p symbols.kll".format( os.path.basename( sys.argv[0] ) ),
	        formatter_class=argparse.RawTextHelpFormatter,
	        add_help=False,
)

	# Positional Arguments
	pArgs.add_argument( 'files', type=str, nargs='+',
		help=argparse.SUPPRESS ) # Suppressed help output, because Python output is verbosely ugly

	# Optional Arguments
	pArgs.add_argument( '-b', '--backend', type=str, default="kiibohd",
		help="Specify target backend for the KLL compiler.\n"
		"Default: kiibohd\n"
		"Options: kiibohd, json" )
	pArgs.add_argument( '-d', '--default', type=str, nargs='+',
		help="Specify .kll files to layer on top of the default map to create a combined map." )
	pArgs.add_argument( '-p', '--partial', type=str, nargs='+', action='append',
		help="Specify .kll files to generate partial map, multiple files per flag.\n"
		"Each -p defines another partial map.\n"
		"Base .kll files (that define the scan code maps) must be defined for each partial map." )
	pArgs.add_argument( '-t', '--templates', type=str, nargs='+',
		help="Specify template used to generate the keymap.\n"
		"Default: <backend specific>" )
	pArgs.add_argument( '-o', '--outputs', type=str, nargs='+',
		help="Specify output file. Writes to current working directory by default.\n"
		"Default: <backend specific>" )
	pArgs.add_argument( '-h', '--help', action="help",
		help="This message." )

	# Process Arguments
	args = pArgs.parse_args()

	# Parameters
	baseFiles = args.files
	defaultFiles = args.default
	partialFileSets = args.partial
	if defaultFiles is None:
		defaultFiles = []
	if partialFileSets is None:
		partialFileSets = [[]]

	# Check file existance
	for filename in baseFiles:
		checkFileExists( filename )

	for filename in defaultFiles:
		checkFileExists( filename )

	for partial in partialFileSets:
		for filename in partial:
			checkFileExists( filename )

	return (baseFiles, defaultFiles, partialFileSets, args.backend, args.templates, args.outputs)



### Tokenizer ###

def tokenize( string ):
	"""str -> Sequence(Token)"""

	# Basic Tokens Spec
	specs = [
		( 'Comment',          ( r' *#.*', ) ),
		( 'Space',            ( r'[ \t\r\n]+', ) ),
		( 'USBCode',          ( r'U(("[^"]+")|(0x[0-9a-fA-F]+)|([0-9]+))', ) ),
		( 'USBCodeStart',     ( r'U\[', ) ),
		( 'ConsCode',         ( r'CONS(("[^"]+")|(0x[0-9a-fA-F]+)|([0-9]+))', ) ),
		( 'ConsCodeStart',    ( r'CONS\[', ) ),
		( 'SysCode',          ( r'SYS(("[^"]+")|(0x[0-9a-fA-F]+)|([0-9]+))', ) ),
		( 'SysCodeStart',     ( r'SYS\[', ) ),
		( 'LedCode',          ( r'LED(("[^"]+")|(0x[0-9a-fA-F]+)|([0-9]+))', ) ),
		( 'LedCodeStart',     ( r'LED\[', ) ),
		( 'ScanCode',         ( r'S((0x[0-9a-fA-F]+)|([0-9]+))', ) ),
		( 'ScanCodeStart',    ( r'S\[', ) ),
		( 'CodeEnd',          ( r'\]', ) ),
		( 'String',           ( r'"[^"]*"', VERBOSE ) ),
		( 'SequenceString',   ( r"'[^']*'", ) ),
		( 'Operator',         ( r'=>|:\+|:-|:|=', ) ),
		( 'Comma',            ( r',', ) ),
		( 'Dash',             ( r'-', ) ),
		( 'Plus',             ( r'\+', ) ),
		( 'Parenthesis',      ( r'\(|\)', ) ),
		( 'None',             ( r'None', ) ),
		( 'Number',           ( r'-?(0x[0-9a-fA-F]+)|(0|([1-9][0-9]*))', VERBOSE ) ),
		( 'Name',             ( r'[A-Za-z_][A-Za-z_0-9]*', ) ),
		( 'VariableContents', ( r'''[^"' ;:=>()]+''', ) ),
		( 'EndOfLine',        ( r';', ) ),
	]

	# Tokens to filter out of the token stream
	useless = ['Space', 'Comment']

	tokens = make_tokenizer( specs )
	return [x for x in tokens( string ) if x.type not in useless]



### Parsing ###

 ## Map Arrays
macros_map        = Macros()
variables_dict    = Variables()
capabilities_dict = Capabilities()


 ## Parsing Functions

def make_scanCode( token ):
	scanCode = int( token[1:], 0 )
	# Check size, to make sure it's valid
	if scanCode > 0xFF:
		print ( "{0} ScanCode value {1} is larger than 255".format( ERROR, scanCode ) )
		raise
	return scanCode

def make_hidCode( type, token ):
	# If first character is a U, strip
	if token[0] == "U":
		token = token[1:]
	# CONS specifier
	elif 'CONS' in token:
		token = token[4:]
	# SYS specifier
	elif 'SYS' in token:
		token = token[3:]

	# If using string representation of USB Code, do lookup, case-insensitive
	if '"' in token:
		try:
			hidCode = kll_hid_lookup_dictionary[ type ][ token[1:-1].upper() ][1]
		except LookupError as err:
			print ( "{0} {1} is an invalid USB HID Code Lookup...".format( ERROR, err ) )
			raise
	else:
		# Already tokenized
		if type == 'USBCode' and token[0] == 'USB' or type == 'SysCode' and token[0] == 'SYS' or type == 'ConsCode' and token[0] == 'CONS':
			hidCode = token[1]
		# Convert
		else:
			hidCode = int( token, 0 )

	# Check size if a USB Code, to make sure it's valid
	if type == 'USBCode' and hidCode > 0xFF:
		print ( "{0} USBCode value {1} is larger than 255".format( ERROR, hidCode ) )
		raise

	# Return a tuple, identifying which type it is
	if type == 'USBCode':
		return make_usbCode_number( hidCode )
	elif type == 'ConsCode':
		return make_consCode_number( hidCode )
	elif type == 'SysCode':
		return make_sysCode_number( hidCode )

	print ( "{0} Unknown HID Specifier '{1}'".format( ERROR, type ) )
	raise

def make_usbCode( token ):
	return make_hidCode( 'USBCode', token )

def make_consCode( token ):
	return make_hidCode( 'ConsCode', token )

def make_sysCode( token ):
	return make_hidCode( 'SysCode', token )

def make_hidCode_number( type, token ):
	lookup = {
		'ConsCode' : 'CONS',
		'SysCode'  : 'SYS',
		'USBCode'  : 'USB',
	}
	return ( lookup[ type ], token )

def make_usbCode_number( token ):
	return make_hidCode_number( 'USBCode', token )

def make_consCode_number( token ):
	return make_hidCode_number( 'ConsCode', token )

def make_sysCode_number( token ):
	return make_hidCode_number( 'SysCode', token )

   # Replace key-word with None specifier (which indicates a noneOut capability)
def make_none( token ):
	return [[[('NONE', 0)]]]

def make_seqString( token ):
	# Shifted Characters, and amount to move by to get non-shifted version
	# US ANSI
	shiftCharacters = (
		( "ABCDEFGHIJKLMNOPQRSTUVWXYZ", 0x20 ),
		( "+",       0x12 ),
		( "&(",      0x11 ),
		( "!#$%<>",  0x10 ),
		( "*",       0x0E ),
		( ")",       0x07 ),
		( '"',       0x05 ),
		( ":",       0x01 ),
		( "^",      -0x10 ),
		( "_",      -0x18 ),
		( "{}|",    -0x1E ),
		( "~",      -0x20 ),
		( "@",      -0x32 ),
		( "?",      -0x38 ),
	)

	listOfLists = []
	shiftKey = kll_hid_lookup_dictionary['USBCode']["SHIFT"]

	# Creates a list of USB codes from the string: sequence (list) of combos (lists)
	for char in token[1:-1]:
		processedChar = char

		# Whether or not to create a combo for this sequence with a shift
		shiftCombo = False

		# Depending on the ASCII character, convert to single character or Shift + character
		for pair in shiftCharacters:
			if char in pair[0]:
				shiftCombo = True
				processedChar = chr( ord( char ) + pair[1] )
				break

		# Do KLL HID Lookup on non-shifted character
		# NOTE: Case-insensitive, which is why the shift must be pre-computed
		usbCode = kll_hid_lookup_dictionary['USBCode'][ processedChar.upper() ]

		# Create Combo for this character, add shift key if shifted
		charCombo = []
		if shiftCombo:
			charCombo = [ [ shiftKey ] ]
		charCombo.append( [ usbCode ] )

		# Add to list of lists
		listOfLists.append( charCombo )

	return listOfLists

def make_string( token ):
	return token[1:-1]

def make_unseqString( token ):
	return token[1:-1]

def make_number( token ):
	return int( token, 0 )

  # Range can go from high to low or low to high
def make_scanCode_range( rangeVals ):
	start = rangeVals[0]
	end   = rangeVals[1]

	# Swap start, end if start is greater than end
	if start > end:
		start, end = end, start

	# Iterate from start to end, and generate the range
	return list( range( start, end + 1 ) )

  # Range can go from high to low or low to high
  # Warn on 0-9 for USBCodes (as this does not do what one would expect) TODO
  # Lookup USB HID tags and convert to a number
def make_hidCode_range( type, rangeVals ):
	# Check if already integers
	if isinstance( rangeVals[0], int ):
		start = rangeVals[0]
	else:
		start = make_hidCode( type, rangeVals[0] )[1]

	if isinstance( rangeVals[1], int ):
		end = rangeVals[1]
	else:
		end = make_hidCode( type, rangeVals[1] )[1]

	# Swap start, end if start is greater than end
	if start > end:
		start, end = end, start

	# Iterate from start to end, and generate the range
	listRange = list( range( start, end + 1 ) )

	# Convert each item in the list to a tuple
	for item in range( len( listRange ) ):
		listRange[ item ] = make_hidCode_number( type, listRange[ item ] )
	return listRange

def make_usbCode_range( rangeVals ):
	return make_hidCode_range( 'USBCode', rangeVals )

def make_sysCode_range( rangeVals ):
	return make_hidCode_range( 'SysCode', rangeVals )

def make_consCode_range( rangeVals ):
	return make_hidCode_range( 'ConsCode', rangeVals )


 ## Base Rules

const       = lambda x: lambda _: x
unarg       = lambda f: lambda x: f(*x)
flatten     = lambda list: sum( list, [] )

tokenValue  = lambda x: x.value
tokenType   = lambda t: some( lambda x: x.type == t ) >> tokenValue
operator    = lambda s: a( Token( 'Operator', s ) ) >> tokenValue
parenthesis = lambda s: a( Token( 'Parenthesis', s ) ) >> tokenValue
eol         = a( Token( 'EndOfLine', ';' ) )

def listElem( item ):
	return [ item ]

def listToTuple( items ):
	return tuple( items )

  # Flatten only the top layer (list of lists of ...)
def oneLayerFlatten( items ):
	mainList = []
	for sublist in items:
		for item in sublist:
			mainList.append( item )

	return mainList

  # Capability arguments may need to be expanded (e.g. 1 16 bit argument needs to be 2 8 bit arguments for the state machine)
def capArgExpander( items ):
	newArgs = []
	# For each defined argument in the capability definition
	for arg in range( 0, len( capabilities_dict[ items[0] ][1] ) ):
		argLen = capabilities_dict[ items[0] ][1][ arg ][1]
		num = items[1][ arg ]
		byteForm = num.to_bytes( argLen, byteorder='little' ) # XXX Yes, little endian from how the uC structs work

		# For each sub-argument, split into byte-sized chunks
		for byte in range( 0, argLen ):
			newArgs.append( byteForm[ byte ] )

	return tuple( [ items[0], tuple( newArgs ) ] )

  # Expand ranges of values in the 3rd dimension of the list, to a list of 2nd lists
  # i.e. [ sequence, [ combo, [ range ] ] ] --> [ [ sequence, [ combo ] ], <option 2>, <option 3> ]
def optionExpansion( sequences ):
	expandedSequences = []

	# Total number of combinations of the sequence of combos that needs to be generated
	totalCombinations = 1

	# List of leaf lists, with number of leaves
	maxLeafList = []

	# Traverse to the leaf nodes, and count the items in each leaf list
	for sequence in sequences:
		for combo in sequence:
			rangeLen = len( combo )
			totalCombinations *= rangeLen
			maxLeafList.append( rangeLen )

	# Counter list to keep track of which combination is being generated
	curLeafList = [0] * len( maxLeafList )

	# Generate a list of permuations of the sequence of combos
	for count in range( 0, totalCombinations ):
		expandedSequences.append( [] ) # Prepare list for adding the new combination
		position = 0

		# Traverse sequence of combos to generate permuation
		for sequence in sequences:
			expandedSequences[ -1 ].append( [] )
			for combo in sequence:
				expandedSequences[ -1 ][ -1 ].append( combo[ curLeafList[ position ] ] )
				position += 1

		# Increment combination tracker
		for leaf in range( 0, len( curLeafList ) ):
			curLeafList[ leaf ] += 1

			# Reset this position, increment next position (if it exists), then stop
			if curLeafList[ leaf ] >= maxLeafList[ leaf ]:
				curLeafList[ leaf ] = 0
				if leaf + 1 < len( curLeafList ):
					curLeafList[ leaf + 1 ] += 1

	return expandedSequences


# Converts USB Codes into Capabilities
# These are tuples (<type>, <integer>)
def hidCodeToCapability( items ):
	# Items already converted to variants using optionExpansion
	for variant in range( 0, len( items ) ):
		# Sequence of Combos
		for sequence in range( 0, len( items[ variant ] ) ):
			for combo in range( 0, len( items[ variant ][ sequence ] ) ):
				if items[ variant ][ sequence ][ combo ][0] in backend.requiredCapabilities.keys():
					# Use backend capability name and a single argument
					items[ variant ][ sequence ][ combo ] = tuple(
						[ backend.capabilityLookup( items[ variant ][ sequence ][ combo ][0] ),
						tuple( [ hid_lookup_dictionary[ items[ variant ][ sequence ][ combo ] ] ] ) ]
					)
	return items


 ## Evaluation Rules

def eval_scanCode( triggers, operator, results ):
	# Convert to lists of lists of lists to tuples of tuples of tuples
	# Tuples are non-mutable, and can be used has index items
	triggers = tuple( tuple( tuple( sequence ) for sequence in variant ) for variant in triggers )
	results  = tuple( tuple( tuple( sequence ) for sequence in variant ) for variant in results )

	# Iterate over all combinations of triggers and results
	for trigger in triggers:
		for result in results:
			# Append Case
			if operator == ":+":
				macros_map.appendScanCode( trigger, result )

			# Remove Case
			elif operator == ":-":
				macros_map.removeScanCode( trigger, result )

			# Replace Case
			elif operator == ":":
				macros_map.replaceScanCode( trigger, result )

def eval_usbCode( triggers, operator, results ):
	# Convert to lists of lists of lists to tuples of tuples of tuples
	# Tuples are non-mutable, and can be used has index items
	triggers = tuple( tuple( tuple( sequence ) for sequence in variant ) for variant in triggers )
	results  = tuple( tuple( tuple( sequence ) for sequence in variant ) for variant in results )

	# Iterate over all combinations of triggers and results
	for trigger in triggers:
		scanCodes = macros_map.lookupUSBCodes( trigger )
		for scanCode in scanCodes:
			for result in results:
				# Cache assignment until file finishes processing
				macros_map.cacheAssignment( operator, scanCode, result )

def eval_variable( name, content ):
	# Content might be a concatenation of multiple data types, convert everything into a single string
	assigned_content = ""
	for item in content:
		assigned_content += str( item )

	variables_dict.assignVariable( name, assigned_content )

def eval_capability( name, function, args ):
	capabilities_dict[ name ] = [ function, args ]

def eval_define( name, cdefine_name ):
	variables_dict.defines[ name ] = cdefine_name

map_scanCode   = unarg( eval_scanCode )
map_usbCode    = unarg( eval_usbCode )

set_variable   = unarg( eval_variable )
set_capability = unarg( eval_capability )
set_define     = unarg( eval_define )


 ## Sub Rules

usbCode     = tokenType('USBCode') >> make_usbCode
scanCode    = tokenType('ScanCode') >> make_scanCode
consCode    = tokenType('ConsCode') >> make_consCode
sysCode     = tokenType('SysCode') >> make_sysCode
none        = tokenType('None') >> make_none
name        = tokenType('Name')
number      = tokenType('Number') >> make_number
comma       = tokenType('Comma')
dash        = tokenType('Dash')
plus        = tokenType('Plus')
content     = tokenType('VariableContents')
string      = tokenType('String') >> make_string
unString    = tokenType('String') # When the double quotes are still needed for internal processing
seqString   = tokenType('SequenceString') >> make_seqString
unseqString = tokenType('SequenceString') >> make_unseqString # For use with variables

  # Code variants
code_end = tokenType('CodeEnd')

  # Scan Codes
scanCode_start     = tokenType('ScanCodeStart')
scanCode_range     = number + skip( dash ) + number >> make_scanCode_range
scanCode_listElem  = number >> listElem
scanCode_innerList = oneplus( ( scanCode_range | scanCode_listElem ) + skip( maybe( comma ) ) ) >> flatten
scanCode_expanded  = skip( scanCode_start ) + scanCode_innerList + skip( code_end )
scanCode_elem      = scanCode >> listElem
scanCode_combo     = oneplus( ( scanCode_expanded | scanCode_elem ) + skip( maybe( plus ) ) )
scanCode_sequence  = oneplus( scanCode_combo + skip( maybe( comma ) ) )

  # USB Codes
usbCode_start       = tokenType('USBCodeStart')
usbCode_number      = number >> make_usbCode_number
usbCode_range       = ( usbCode_number | unString ) + skip( dash ) + ( number | unString ) >> make_usbCode_range
usbCode_listElemTag = unString >> make_usbCode
usbCode_listElem    = ( usbCode_number | usbCode_listElemTag ) >> listElem
usbCode_innerList   = oneplus( ( usbCode_range | usbCode_listElem ) + skip( maybe( comma ) ) ) >> flatten
usbCode_expanded    = skip( usbCode_start ) + usbCode_innerList + skip( code_end )
usbCode_elem        = usbCode >> listElem
usbCode_combo       = oneplus( ( usbCode_expanded | usbCode_elem ) + skip( maybe( plus ) ) ) >> listElem
usbCode_sequence    = oneplus( ( usbCode_combo | seqString ) + skip( maybe( comma ) ) ) >> oneLayerFlatten

  # Cons Codes
consCode_start       = tokenType('ConsCodeStart')
consCode_number      = number >> make_consCode_number
consCode_range       = ( consCode_number | unString ) + skip( dash ) + ( number | unString ) >> make_consCode_range
consCode_listElemTag = unString >> make_consCode
consCode_listElem    = ( consCode_number | consCode_listElemTag ) >> listElem
consCode_innerList   = oneplus( ( consCode_range | consCode_listElem ) + skip( maybe( comma ) ) ) >> flatten
consCode_expanded    = skip( consCode_start ) + consCode_innerList + skip( code_end )
consCode_elem        = consCode >> listElem

  # Sys Codes
sysCode_start       = tokenType('SysCodeStart')
sysCode_number      = number >> make_sysCode_number
sysCode_range       = ( sysCode_number | unString ) + skip( dash ) + ( number | unString ) >> make_sysCode_range
sysCode_listElemTag = unString >> make_sysCode
sysCode_listElem    = ( sysCode_number | sysCode_listElemTag ) >> listElem
sysCode_innerList   = oneplus( ( sysCode_range | sysCode_listElem ) + skip( maybe( comma ) ) ) >> flatten
sysCode_expanded    = skip( sysCode_start ) + sysCode_innerList + skip( code_end )
sysCode_elem        = sysCode >> listElem

  # HID Codes
hidCode_elem        = usbCode_expanded | usbCode_elem | sysCode_expanded | sysCode_elem | consCode_expanded | consCode_elem

  # Capabilities
capFunc_arguments = many( number + skip( maybe( comma ) ) ) >> listToTuple
capFunc_elem      = name + skip( parenthesis('(') ) + capFunc_arguments + skip( parenthesis(')') ) >> capArgExpander >> listElem
capFunc_combo     = oneplus( ( hidCode_elem | capFunc_elem ) + skip( maybe( plus ) ) ) >> listElem
capFunc_sequence  = oneplus( ( capFunc_combo | seqString ) + skip( maybe( comma ) ) ) >> oneLayerFlatten

  # Trigger / Result Codes
triggerCode_outerList    = scanCode_sequence >> optionExpansion
triggerUSBCode_outerList = usbCode_sequence >> optionExpansion >> hidCodeToCapability
resultCode_outerList     = ( ( capFunc_sequence >> optionExpansion ) | none ) >> hidCodeToCapability


 ## Main Rules

#| <variable> = <variable contents>;
variable_contents   = name | content | string | number | comma | dash | unseqString
variable_expression = name + skip( operator('=') ) + oneplus( variable_contents ) + skip( eol ) >> set_variable

#| <capability name> => <c function>;
capability_arguments  = name + skip( operator(':') ) + number + skip( maybe( comma ) )
capability_expression = name + skip( operator('=>') ) + name + skip( parenthesis('(') ) + many( capability_arguments ) + skip( parenthesis(')') ) + skip( eol ) >> set_capability

#| <define name> => <c define>;
define_expression = name + skip( operator('=>') ) + name + skip( eol ) >> set_define

#| <trigger> : <result>;
operatorTriggerResult = operator(':') | operator(':+') | operator(':-')
scanCode_expression   = triggerCode_outerList + operatorTriggerResult + resultCode_outerList + skip( eol ) >> map_scanCode
usbCode_expression    = triggerUSBCode_outerList + operatorTriggerResult + resultCode_outerList + skip( eol ) >> map_usbCode

def parse( tokenSequence ):
	"""Sequence(Token) -> object"""

	# Top-level Parser
	expression = scanCode_expression | usbCode_expression | variable_expression | capability_expression | define_expression

	kll_text = many( expression )
	kll_file = maybe( kll_text ) + skip( finished )

	return kll_file.parse( tokenSequence )



def processKLLFile( filename ):
	with open( filename ) as file:
		data = file.read()
		tokenSequence = tokenize( data )
		#print ( pformat( tokenSequence ) ) # Display tokenization
		try:
			tree = parse( tokenSequence )
		except NoParseError as e:
			print("Error parsing %s. %s" % (filename, e.msg), file=sys.stderr)
			sys.exit(1)


### Misc Utility Functions ###

def gitRevision( kllPath ):
	import subprocess

	# Change the path to where kll.py is
	origPath = os.getcwd()
	os.chdir( kllPath )

	# Just in case git can't be found
	try:
		# Get hash of the latest git commit
		revision = subprocess.check_output( ['git', 'rev-parse', 'HEAD'] ).decode()[:-1]

		# Get list of files that have changed since the commit
		changed = subprocess.check_output( ['git', 'diff-index', '--name-only', 'HEAD', '--'] ).decode().splitlines()
	except:
		revision = "<no git>"
		changed = []

	# Change back to the old working directory
	os.chdir( origPath )

	return revision, changed


### Main Entry Point ###

if __name__ == '__main__':
	(baseFiles, defaultFiles, partialFileSets, backend_name, templates, outputs) = processCommandLineArgs()

	# Look up git information on the compiler
	gitRev, gitChanges = gitRevision( os.path.dirname( os.path.realpath( __file__ ) ) )

	# Load backend module
	global backend
	backend_import = importlib.import_module( "backends.{0}".format( backend_name ) )
	backend = backend_import.Backend( templates )

	# Process base layout files
	for filename in baseFiles:
		variables_dict.setCurrentFile( filename )
		processKLLFile( filename )
	macros_map.completeBaseLayout() # Indicates to macros_map that the base layout is complete
	variables_dict.baseLayoutFinished()

	# Default combined layer
	for filename in defaultFiles:
		variables_dict.setCurrentFile( filename )
		processKLLFile( filename )
		# Apply assignment cache, see 5.1.2 USB Codes for why this is necessary
		macros_map.replayCachedAssignments()

	# Iterate through additional layers
	for partial in partialFileSets:
		# Increment layer for each -p option
		macros_map.addLayer()
		variables_dict.incrementLayer() # DefaultLayer is layer 0

		# Iterate and process each of the file in the layer
		for filename in partial:
			variables_dict.setCurrentFile( filename )
			processKLLFile( filename )

		# Apply assignment cache, see 5.1.2 USB Codes for why this is necessary
		macros_map.replayCachedAssignments()
		# Remove un-marked keys to complete the partial layer
		macros_map.removeUnmarked()

	# Do macro correlation and transformation
	macros_map.generate()

	# Process needed templating variables using backend
	backend.process(
		capabilities_dict,
		macros_map,
		variables_dict,
		gitRev,
		gitChanges
	)

	# Generate output file using template and backend
	backend.generate( outputs )

	# Successful Execution
	sys.exit( 0 )