#!/usr/bin/env python3

# Copyright 2016 Google Inc. All Rights Reserved.
#
# 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.

from __future__ import print_function

import argparse
import glob
import json
import mmap
import os
import re
import sys

parser = argparse.ArgumentParser()
parser.add_argument("filenames", help="list of files to check, all files if unspecified", nargs='*')
args = parser.parse_args()

rootdir = os.path.dirname(__file__) + "/../../"
rootdir = os.path.abspath(rootdir)

def get_refs():
    refs = {}
    for path in glob.glob(os.path.join(rootdir, "build/boilerplate/boilerplate.*.txt")):
        extension = os.path.basename(path).split(".")[1]

        ref_file = open(path, 'r')
        ref = ref_file.read().splitlines()
        ref_file.close()
        refs[extension] = ref

    return refs

def file_passes(filename, refs, regexs):
    try:
        f = open(filename, 'r')
    except:
        return False

    data = f.read()
    f.close()

    extension = file_extension(filename)
    ref = refs[extension]

    # remove build tags from the top of Go files
    if extension == "go":
        p = regexs["go_build_constraints"]
        (data, found) = p.subn("", data, 1)

    # remove shebang from the top of shell files
    if extension == "sh":
        p = regexs["shebang"]
        (data, found) = p.subn("", data, 1)

    data = data.splitlines()

    # if our test file is smaller than the reference it surely fails!
    if len(ref) > len(data):
        return False

    # trim our file to the same number of lines as the reference file
    data = data[:len(ref)]

    p = regexs["year"]
    for d in data:
        if p.search(d):
            return False

    # Replace all occurrences of the regex "2016|2015|2014" with "YEAR"
    p = regexs["date"]
    for i, d in enumerate(data):
        (data[i], found) = p.subn('YEAR', d)
        if found != 0:
            break

    # if we don't match the reference at this point, fail
    if ref != data:
        return False

    return True

def file_extension(filename):
    return os.path.splitext(filename)[1].split(".")[-1].lower()

skipped_dirs = ['Godeps', 'vendor', 'third_party', '_gopath', '_output', '.git']
def normalize_files(files):
    newfiles = []
    for pathname in files:
        if any(x in pathname for x in skipped_dirs):
            continue
        newfiles.append(pathname)
    for i, pathname in enumerate(newfiles):
        if not os.path.isabs(pathname):
            newfiles[i] = os.path.join(rootdir, pathname)
    return newfiles

def get_files(extensions):
    files = []
    if len(args.filenames) > 0:
        files = args.filenames
    else:
        for root, dirs, walkfiles in os.walk(rootdir):
            # don't visit certain dirs. This is just a performance improvement
            # as we would prune these later in normalize_files(). But doing it
            # cuts down the amount of filesystem walking we do and cuts down
            # the size of the file list
            for d in skipped_dirs:
                if d in dirs:
                    dirs.remove(d)

            for name in walkfiles:
                pathname = os.path.join(root, name)
                files.append(pathname)

    files = normalize_files(files)
    outfiles = []
    for pathname in files:
        extension = file_extension(pathname)
        if extension in extensions:
            outfiles.append(pathname)
    return outfiles

def get_regexs():
    regexs = {}
    # Search for "YEAR" which exists in the boilerplate, but shouldn't in the real thing
    regexs["year"] = re.compile( 'YEAR' )
    # dates can be something in the 21st century
    regexs["date"] = re.compile( '20[0-9][0-9]' )
    # strip // +build \n\n build and //go:build constraints
    regexs["go_build_constraints"] = re.compile(r"^(//\s*(\+build|go:build).*\n)+\n", re.MULTILINE)
    # strip #!.* from shell scripts
    regexs["shebang"] = re.compile(r"^(#!.*\n)\n*", re.MULTILINE)
    return regexs

def main():
    regexs = get_regexs()
    refs = get_refs()
    filenames = get_files(refs.keys())

    for filename in filenames:
        if not file_passes(filename, refs, regexs):
            print(filename, file=sys.stdout)

if __name__ == "__main__":
  sys.exit(main())
