"""

    Copyright 2018-2022 Emil Dotchevski and Reverge Studios, Inc.
    Copyright (c) Sorin Fetche

    Distributed under the Boost Software License, Version 1.0. (See accompanying
    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

    This program generates a single header file from a file including multiple C/C++ headers.

    Usage:

        python3 generate_single_header.py  --help

        e.g. python3 generate_single_header.py -i include/boost/leaf/detail/all.hpp -p include  -o test/leaf.hpp boost/leaf

"""

import argparse
import os
import re
from datetime import date
import subprocess

included = {}
total_line_count = 11

def append(input_file_name, input_file, output_file, regex_includes, include_folder):
    global total_line_count
    line_count = 1
    for line in input_file:
        line_count += 1
        result = regex_includes.search(line)
        if result:
            next_input_file_name = result.group("include")
            if next_input_file_name in included:
                output_file.write("// Expanded at line %d: %s" % (included[next_input_file_name], line))
                total_line_count += 1
            else:
                included[next_input_file_name] = total_line_count
                print("%s (%d)" % (next_input_file_name, total_line_count))
                with open(os.path.join(include_folder, next_input_file_name), "r") as next_input_file:
                    output_file.write('// >>> %s#line 1 "%s"\n' % (line, next_input_file_name))
                    total_line_count += 2
                    append(next_input_file_name, next_input_file, output_file, regex_includes, include_folder)
                    if not ('include/boost/leaf/detail/all.hpp' in input_file_name):
                        output_file.write('// <<< %s#line %d "%s"\n' % (line, line_count, input_file_name))
                        total_line_count += 2
        else:
            output_file.write(line)
            total_line_count += 1

def _main():
    parser = argparse.ArgumentParser(
        description="Generates a single include file from a file including multiple C/C++ headers")
    parser.add_argument("-i", "--input", action="store", type=str, default="in.cpp",
        help="Input file including the headers to be merged")
    parser.add_argument("-o", "--output", action="store", type=str, default="out.cpp",
        help="Output file. NOTE: It will be overwritten!")
    parser.add_argument("-p", "--path", action="store", type=str, default=".",
        help="Include path")
    parser.add_argument("--hash", action="store", type=str,
        help="The git hash to print in the output file, e.g. the output of \"git rev-parse HEAD\"")
    parser.add_argument("prefix", action="store", type=str,
        help="Non-empty include file prefix (e.g. a/b)")
    args = parser.parse_args()

    regex_includes = re.compile(r"""^\s*#[\t\s]*include[\t\s]*("|\<)(?P<include>%s.*)("|\>)""" % args.prefix)
    print("Rebuilding %s:" % args.input)
    with open(args.output, 'w') as output_file, open(args.input, 'r') as input_file:
        output_file.write(
            '#ifndef BOOST_LEAF_HPP_INCLUDED\n'
            '#define BOOST_LEAF_HPP_INCLUDED\n'
            '\n'
            '// LEAF single header distribution. Do not edit.\n'
            '\n'
            '// Generated on ' + date.today().strftime("%m/%d/%Y"))
        if args.hash:
            output_file.write(
                ' from https://github.com/boostorg/leaf/tree/' + args.hash[0:7])
        output_file.write(
            '.\n'
            '// Latest version of this file: https://raw.githubusercontent.com/boostorg/leaf/gh-pages/leaf.hpp.\n'
            '\n')
        append(args.input, input_file, output_file, regex_includes, args.path)
        output_file.write(
            '\n'
            '#endif\n' )
#       print("%d" % total_line_count)

if __name__ == "__main__":
    _main()