#!/usr/bin/env python3

import os, sys
from argparse import ArgumentParser
from difflib import unified_diff
from json import load

def dprint(msg):
    print('[DEBUG]: %s' % str(msg))

class HeaderChecker:
    def __init__(self, header, padding=1000):
        self.padding = padding
        self.header = header

    def normalizeHeader():
        assert False, 'Unimplemented'

    def checkJSONList(self, path_json):
        '''
        This is particularly useful when ingesting output from other programs, like git actions
        '''
        assert os.path.exists(path_json), 'No such file: ' + path_json

        # Get list of files to check from JSON file
        with open(path_json) as file_json:
            file_checklist = load(file_json)
            assert isinstance(file_checklist, list), 'Expected list for singular JSON List entry'

        # Accrue how how files fail the check
        n_failed = 0
        for path_file in file_checklist:
            assert isinstance(path_file, str), 'Unexpected JSON format for ' + path_json
            n_failed += not self.isValidFile(path_file)

        return n_failed

    def isValidFile(self, path):
        assert os.path.exists(path), 'No such file: ' + path

        # Don't need entire file. Read sufficienly large chunk of file that should contain the header
        with open(path, encoding='utf-8', errors='ignore') as file:
            chunk = file.read(len(''.join(self.header)) + self.padding)
            lines = [('%s\n' % l) for l in chunk.strip().splitlines()][:len(self.header)]
            if self.header == lines:
                return True
            else:
                print('File Delta: %s' % path)
                print(*unified_diff(lines[:len(self.header)], self.header))
                return False


def configArgParser():
    parser = ArgumentParser(description='FreeRTOS file header checker. We expect a consistent header across all '
                                        'first party files. The header includes current version number, copyright, '
                                        'and FreeRTOS license.')

    parser.add_argument('files_checked',
                        nargs   = '+',
                        metavar = 'FILE_LIST',
                        help    = 'Space separated list of files to check.')

    parser.add_argument('-k', '--kernel',
                        default = False,
                        action  = 'store_true',
                        help    = 'Compare with kernel file header. It has different versioning.')

    parser.add_argument('-j', '--json',
                        default = False,
                        action  = 'store_true',
                        help    = 'Treat arguments json files that store a list of files to check.')
    return parser

def main():
    parser = configArgParser()
    args = parser.parse_args()

    freertos_header = [
        '/*\n',
        ' * FreeRTOS V202011.00\n',
        ' * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.\n',
        ' *\n',
        ' * Permission is hereby granted, free of charge, to any person obtaining a copy of\n',
        ' * this software and associated documentation files (the "Software"), to deal in\n',
        ' * the Software without restriction, including without limitation the rights to\n',
        ' * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of\n',
        ' * the Software, and to permit persons to whom the Software is furnished to do so,\n',
        ' * subject to the following conditions:\n',
        ' *\n',
        ' * The above copyright notice and this permission notice shall be included in all\n',
        ' * copies or substantial portions of the Software.\n',
        ' *\n',
        ' * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR\n',
        ' * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS\n',
        ' * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR\n',
        ' * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER\n',
        ' * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN\n',
        ' * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.\n',
        ' *\n',
        ' * https://www.FreeRTOS.org\n',
        ' * https://github.com/FreeRTOS\n',
        ' *\n',
        ' * 1 tab == 4 spaces!\n',
        ' */\n',
    ]

    kernel_header = [
        '/*\n',
        ' * FreeRTOS Kernel V10.4.2\n',
        ' * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.\n',
        ' *\n',
        ' * Permission is hereby granted, free of charge, to any person obtaining a copy of\n',
        ' * this software and associated documentation files (the "Software"), to deal in\n',
        ' * the Software without restriction, including without limitation the rights to\n',
        ' * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of\n',
        ' * the Software, and to permit persons to whom the Software is furnished to do so,\n',
        ' * subject to the following conditions:\n',
        ' *\n',
        ' * The above copyright notice and this permission notice shall be included in all\n',
        ' * copies or substantial portions of the Software.\n',
        ' *\n',
        ' * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR\n',
        ' * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS\n',
        ' * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR\n',
        ' * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER\n',
        ' * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN\n',
        ' * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.\n',
        ' *\n',
        ' * https://www.FreeRTOS.org\n',
        ' * https://github.com/FreeRTOS\n',
        ' *\n',
        ' */\n',
    ]

    checker = HeaderChecker(kernel_header if args.kernel else freertos_header)

    print()
    n_failed = 0
    for path in args.files_checked:
        if args.json:
            n_failed += checker.checkJSONList(path)
        else:
            n_failed += not checker.isValidFile(path)

    return n_failed

if __name__ == '__main__':
    exit(main())