#!/usr/bin/env python3

#--------------------------------------------------------------------------------------------------------------------------------------------------------------
#
# SingleHeader/MakeSingleHeader.py
#
# Copyright 2020-2023 Apple Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
#--------------------------------------------------------------------------------------------------------------------------------------------------------------

import argparse
import datetime
import logging
import os
import re
import subprocess
import sys

#--------------------------------------------------------------------------------------------------------------------------------------------------------------

class HeaderPrefix( object ):
	__template 			= ( '//\n'
							'// {file}\n'
							'//\n'
							'// {meta_data}\n'
							'//\n'
							'// Copyright 2020-2023 Apple Inc.\n'
							'//\n'
							'// Licensed under the Apache License, Version 2.0 (the "License");\n'
							'// you may not use this file except in compliance with the License.\n'
							'// You may obtain a copy of the License at\n'
							'//\n'
							'//     http://www.apache.org/licenses/LICENSE-2.0\n'
							'//\n'
							'// Unless required by applicable law or agreed to in writing, software\n'
							'// distributed under the License is distributed on an "AS IS" BASIS,\n'
							'// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n'
							'// See the License for the specific language governing permissions and\n'
							'// limitations under the License.\n'
							'//\n'
							'\n' )

	__template_commit	=	'Autogenerated from commit {commit}.'
	__template_date		=	'Autogenerated on %B %d, %Y.'

	def __init__( self, file ):
		self.__file = file

	def __str__( self ):
		return self.__template.format( file = self.__file, meta_data = self.__meta_data_string() )

	def __get_commit_hash( self ):
		git_commit_hash = None

		try:
			git_dir			= os.path.dirname( os.path.realpath( __file__ ) )
			proc 			= subprocess.Popen( [ 'git', 'rev-parse', 'HEAD' ], cwd = git_dir, stdout = subprocess.PIPE, stderr = subprocess.PIPE )
			git_commit_hash = proc.stdout.read().decode( 'utf-8', 'replace' ).strip()
		except:
			logging.error( 'Failed to determine git commit hash!' )
			pass

		return git_commit_hash

	def __get_commit_string( self ):
		meta_data		= None
		git_commit_hash	= self.__get_commit_hash()

		if git_commit_hash:
			meta_data = self.__template_commit.format( commit = git_commit_hash )

		return meta_data

	def __get_date_string( self ):
		today = datetime.date.today()
 
		return today.strftime( self.__template_date )

	def __meta_data_string( self ):
		meta_data = self.__get_commit_string()

		if not meta_data:
			meta_data = self.__get_date_string()

		return meta_data

#--------------------------------------------------------------------------------------------------------------------------------------------------------------

class SingleHeader( object ):
	__pragma_once = '#pragma once\n\n'

	def __init__( self ):
		self.__header_paths = list()

	def __str__( self ):
		return self.process()

	def append( self, header_path ):
		self.__header_paths.append( header_path )

	def process( self ):
		out_header 				= self.__pragma_once

		self.__included_headers	= set()
		self.__base_path 		= list()

		for header_path in self.__header_paths:
			out_header += self.__process_header( header_path )

		return self.__strip_empty_lines( out_header )

	def __read_header( self, path ):
		path = os.path.realpath( path )

		try:
			f = open( path, 'r' )
		except:
			raise RuntimeError( 'Failed to open file \"' + path + '\" for read!' )

		return f.read()

	def __strip_pragma_once( self, header ):
		return re.sub( '\\s*#pragma once\s*\\/\\/-*\\n', '', header )

	def __strip_comments( self, header ):
		return re.sub( '^//.*\\n', '', header, flags = re.MULTILINE )

	def __strip_empty_lines( self, header ):
		return re.sub( '\\n\\n+', '\\n\\n', header, flags = re.MULTILINE )

	def __substitute_include_directive( self, match ):
		header_path = match.group( 'HEADER_PATH' )

		logging.info( '\tSubstituting \"' + header_path + '\"...' )

		return self.__process_header( os.path.join( self.__base_path[-1], header_path ) )

	def __process_include_directives( self, header ):
		return re.sub( '^\\s*#include\\s\\"(?P<HEADER_PATH>\\S*)\\"', self.__substitute_include_directive, header, flags = re.MULTILINE )

	def __process_foundation_directives( self, header ):
		if header.find("#include <Foundation/Foundation.hpp>") != -1:
			logging.info( '\tSubstituting <Foundation/Foundation.hpp>...' )
			return header.replace("#include <Foundation/Foundation.hpp>", self.__process_header( os.path.join( self.__base_path[-1], "../Foundation/Foundation.hpp" ) ) )
		return header


	def __process_header( self, header_path ):
		out_header = ''		

		header_path = os.path.realpath( header_path )

		if not header_path in self.__included_headers:
			logging.info( 'Processing \"' + header_path + '\"...' )

			self.__base_path.append( os.path.dirname( header_path ) )
			self.__included_headers.add( header_path )
			
			out_header = self.__read_header( header_path )
			out_header = self.__strip_pragma_once( out_header )
			out_header = self.__strip_comments( out_header )
			out_header = self.__process_include_directives( out_header )
			out_header = self.__process_foundation_directives( out_header )

			self.__base_path.pop()
		else:
			logging.info( '\tSkipping \"' + header_path + '\"...' )

		return out_header

#--------------------------------------------------------------------------------------------------------------------------------------------------------------

def create_argument_parser():
	parser 			= argparse.ArgumentParser()
	base_path 		= os.path.dirname( os.path.realpath( __file__ ) )
	output_path		= os.path.join( base_path, 'Metal.hpp' )

	parser.add_argument( '-o', '--output',  dest = 'output_path', metavar = 'PATH', default = output_path, help = 'Output path for the single header file.' )
	parser.add_argument( '-v', '--verbose', action = 'store_true',  help = 'Show verbose output.' )
	parser.add_argument( dest = 'header_paths', metavar = 'HEADER_FILE', nargs='+', help = 'Input header file.' )

	return parser

#--------------------------------------------------------------------------------------------------------------------------------------------------------------

def parse_arguments():
	parser	= create_argument_parser()
	args	= parser.parse_args()

	if args.verbose:
		logging.getLogger().setLevel( logging.INFO )
	else:
		logging.getLogger().setLevel( logging.ERROR )

	return args

#--------------------------------------------------------------------------------------------------------------------------------------------------------------

def make_header( args ):
	prefix = HeaderPrefix( os.path.basename( args.output_path ) )
	header = SingleHeader()
	
	for header_path in args.header_paths:
		header.append( header_path )

	return str( prefix ) + str( header )

#--------------------------------------------------------------------------------------------------------------------------------------------------------------

def make_dir( path ):
	try:
		if not os.path.exists( path ):
			os.makedirs( path )
	except os.error:
		pass
	except:
		raise

#--------------------------------------------------------------------------------------------------------------------------------------------------------------

def write_header( args, content ):
	path = os.path.realpath( args.output_path )

	logging.info( 'Writing \"' + path + '\"...' )

	make_dir( os.path.dirname( path ) )

	try:
		f = open( path, 'w' )
	except:
		raise RuntimeError( 'Failed to open file \"' + path + '\" for write!' )

	f.write( content )

#--------------------------------------------------------------------------------------------------------------------------------------------------------------

if __name__ == '__main__':
	result = -1
	
	try:
		if sys.getdefaultencoding().lower() == 'ascii':
			reload( sys )
			sys.setdefaultencoding( 'utf-8' )

		args 	= parse_arguments()
		header 	= make_header( args )

		write_header( args, header )

		result = 0

	except ( KeyboardInterrupt, SystemExit ):
	 	pass
	except:
	 	raise

	sys.exit( result )

#--------------------------------------------------------------------------------------------------------------------------------------------------------------
