# -*- coding: utf-8 -*-

#-------------------------------------------------------------------------
# drawElements Quality Program utilities
# --------------------------------------
#
# Copyright (c) 2017 The Khronos Group 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 os
import sys
import codecs
from optparse import OptionParser

FILE_PATTERNS = ["*.hpp", "*.h", "*.cpp", "*.py"]
IGNORE_FILES = set()
CHECK_END_COMMENT = True

def hasBOM (file):
    with open(file, 'rb') as f:
        line0 = f.readline()
        if line0.startswith(codecs.BOM_UTF8):
            return True
    return False

def removeBOM (file):
    with open(file, 'r+b') as f:
        chunk = f.read(1024)
        if chunk.startswith(codecs.BOM_UTF8):
            chunk = chunk[3:]
        else:
            return
        readpos = 1024;
        writepos = 0;
        while chunk:
            f.seek(writepos, os.SEEK_SET)
            f.write(chunk)
            writepos += len(chunk)
            f.seek(readpos, os.SEEK_SET)
            chunk = f.read(1024)
            readpos += len(chunk)
        f.truncate(readpos-3)

def getFileList (path):
    if os.path.isfile(path):
        yield path
    elif os.path.isdir(path):
        for root, dirs, files in os.walk(path):
            for file in files:
                yield os.path.join(root, file)

def checkBOMs (files, fix):
    correct = True
    for file in files:
        if hasBOM(file):
            if fix:
                removeBOM(file)
                print("File %s contained BOM and was fixed" % file)
            else:
                correct = False
                print("File %s contains BOM" % file)
    return correct

if __name__ == "__main__":
    parser = OptionParser()
    parser.add_option("-x", "--fix", action="store_true", dest="fix", default=False, help="attempt to fix BOMs")

    (options, args) = parser.parse_args()
    fix = options.fix

    print("Checking BOMs...")
    for dir in args:
        checkBOMs(getFileList(os.path.normpath(dir)), fix)