#!/usr/bin/env python3

# fix_header_guards.py
# Copyright 2024 Andreas Nicolai <andreas.nicolai -[at]- gmx.net>
#
# Script to automatically replace the file headers of .h and .cpp files and adjust include guards.
# Also checks for correct naming of files. 
#
# Syntax: fix_header_guards.py <directory> [--license-file /path/to/LICENSE]
#
#         <directory> is the directory with the .h and .cpp files
#         LICENSE is a file with the license text to insert.

import sys
import os
import argparse
import glob
import pathlib

def baseName(className, namespaceName):
	if namespaceName == None:
		return className
	else:
		return namespaceName + "_" + className

def headerGuard(className, namespaceName):
	return baseName(className, namespaceName) + "H"


def process_header(hdr, LICENSE):
	hdr_basename = os.path.basename(hdr)
	# open file and read all lines
	try:
		hdr_file = open(hdr, 'r')
		hdr = hdr.replace('\\', '/')
		# print '  ' + hdr
		lines = hdr_file.readlines()
		
		# now process all lines and check if there is a class declaration in the file
		className = None
		namespaceName = None
		for line in lines:
			if len(line.strip()) == 0:
				continue
			# class declaration found if line is ended with a {
			trimmedLine = line.strip()
			pos = trimmedLine.find("class")
			if pos != -1:
				pos2 = trimmedLine.find(':', pos)
				if pos2 == -1:
					pos2 = trimmedLine.find('{', pos)
				if pos2 != -1:
					if className == None:
						className = trimmedLine[pos+6:pos2].strip()
					else:
						print('WARNING: multiple class declarations in file are not supported.')
						return

			pos = trimmedLine.find("namespace")
			if pos != -1:
				pos2 = trimmedLine.find('{', pos)
				if pos2 != -1:
					if namespaceName == None:
						namespaceName = trimmedLine[pos+9:pos2].strip()
					else:
						print('WARNING: multiple namespace declarations in file are not supported.')
						return
		
		if className == None:
			print('WARNING: Files without class declaration are not supported.')
			return
		# compose header guard
		hdr_guard = headerGuard(className, namespaceName)
		basename = baseName(className, namespaceName)
		# check if filename matches naming convention
		hdr_filename = basename + ".h"
		if hdr_filename != hdr_basename:
			print('WARNING: mismatch of generated file name "'+hdr_filename+'" and file name for file: "'+ hdr_basename+'"')

		# now create new file content
		new_content = ""
		have_header = False
		skip_next_define = False
		for line in lines:
			if line[-1] == '\n':
				line = line[0:-1]
			if not have_header:
				if line.find('#ifndef') == -1: 
					continue
				have_header = True
				# now insert license
				if LICENSE != None:
					new_content = LICENSE + '\n'
				# insert header guards
				new_content = new_content + '#ifndef ' + hdr_guard + '\n'
				new_content = new_content + '#define ' + hdr_guard + '\n'
				skip_next_define = True
			else:
				if skip_next_define and line.find('#define') != -1:
					skip_next_define = False
					continue
				new_content = new_content + line + '\n'
		# now substitute closing hdr_guard
		pos = new_content.rfind('#endif')
		new_content = new_content[0:pos] + '#endif // ' + hdr_guard + '\n'
		# write content
		hdr_file.close()
		hdr_file = open(hdr, 'w')
		hdr_file.write(new_content)
	except IOError as err:
		print('Cannot open file (check permissions)', hdr)
		print("I/O error({0}): {1}".format(err))

def process_cpp(cpp, LICENSE):
	# open file and read all lines
	try:
		cpp_file = open(cpp, 'r')
		cpp = cpp.replace('\\', '/')
		# print '  ' + cpp
		lines = cpp_file.readlines()

		# now create new file content
		new_content = ""
		have_header = False
		for line in lines:
			if line[-1] == '\n':
				line = line[0:-1]
			if not have_header:
				if line.find('#include') == -1:
					continue
				have_header = True
				# now insert license
				if LICENSE != None:
					new_content = LICENSE + '\n'
				# insert header guards
				new_content = new_content + line + '\n'
			else:
				new_content = new_content + line + '\n'
		# write content
		cpp_file.close()
		cpp_file = open(cpp, 'w')
		cpp_file.write(new_content)
	except IOError as err:
		print('Cannot open file (check permissions)', hdr)
		print("I/O error({0}): {1}".format(err))



# *** MAIN PROGRAM ***

parser = argparse.ArgumentParser(prog='fix_header_guards', description='Replaces header guards and inserts license header')
parser.add_argument('-l', '--license-file', type=pathlib.Path, dest='license', help='Path to license file')
parser.add_argument('srcdir', type=pathlib.Path, help='Path to sources')
args = parser.parse_args()

LICENSE = None
if args.license != None:
	if not args.license.exists:
		print("License file '{}' doesn't exist.".format(args.license))
		exit(1)
	print("Reading license file: {}".format(args.license))
	fobj = open(args.license, 'r')
	LICENSE = fobj.readlines()
	fobj.close()
	del fobj
	LICENSE = "".join(LICENSE)

# glob all header files in the directory
print('Processing files in directory: {}'.format(args.srcdir))
headers = glob.glob(str(args.srcdir) + "/*.h");
# process all files
for hdr in headers:
	process_header(hdr, LICENSE)

cpps = glob.glob(str(args.srcdir) + "/*.cpp");
# process all files
for cpp in cpps:
	process_cpp(cpp, LICENSE)