#!/usr/bin/env python
# Copyright (c) 2016 Red Hat, 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.
from __future__ import print_function

import email
import getopt
import re
import sys

__errors = 0
__warnings = 0
print_file_name = None
checking_file = False


def print_file():
    global print_file_name
    if print_file_name:
        print("In file %s" % print_file_name)
        print_file_name = None


def print_error(message, lineno=None):
    global __errors
    print_file()
    if lineno is not None:
        print("E(%d): %s" % (lineno, message))
    else:
        print("E: %s" % (message))

    __errors = __errors + 1


def print_warning(message, lineno=None):
    global __warnings
    print_file()
    if lineno:
        print("W(%d): %s" % (lineno, message))
    else:
        print("W: %s" % (message))

    __warnings = __warnings + 1


__regex_added_line = re.compile(r'^\+{1,2}[^\+][\w\W]*')
__regex_subtracted_line = re.compile(r'^\-{1,2}[^\-][\w\W]*')
__regex_leading_with_whitespace_at_all = re.compile(r'^\s+')
__regex_leading_with_spaces = re.compile(r'^ +[\S]+')
__regex_trailing_whitespace = re.compile(r'[^\S]+$')
__regex_single_line_feed = re.compile(r'^\f$')
__regex_for_if_missing_whitespace = re.compile(r' +(if|for|while)[\(]')
__regex_for_if_too_much_whitespace = re.compile(r' +(if|for|while)  +[\(]')
__regex_for_if_parens_whitespace = \
    re.compile(r' +(if|for|while) \( +[\s\S]+\)')
__regex_is_for_if_single_line_bracket = \
    re.compile(r'^ +(if|for|while) \(.*\)')
__regex_ends_with_bracket = \
    re.compile(r'[^\s]\) {(\s+/\*[\s\Sa-zA-Z0-9\.,\?\*/+-]*)?$')
__regex_ptr_declaration_missing_whitespace = re.compile(r'[a-zA-Z0-9]\*')

skip_leading_whitespace_check = False
skip_trailing_whitespace_check = False
skip_block_whitespace_check = False
skip_signoff_check = False

# Don't enforce character limit on files that include these characters in their
# name, as they may have legitimate reasons to have longer lines.
#
# Python isn't checked as flake8 performs these checks during build.
line_length_blacklist = ['.am', '.at', 'etc', '.in', '.m4', '.mk', '.patch',
                         '.py']


def is_subtracted_line(line):
    """Returns TRUE if the line in question has been removed."""
    return __regex_subtracted_line.search(line) is not None


def is_added_line(line):
    """Returns TRUE if the line in question is an added line.
    """
    global checking_file
    return __regex_added_line.search(line) is not None or checking_file


def added_line(line):
    """Returns the line formatted properly by removing diff syntax"""
    global checking_file
    if not checking_file:
        return line[1:]
    return line


def leading_whitespace_is_spaces(line):
    """Returns TRUE if the leading whitespace in added lines is spaces
    """
    if skip_leading_whitespace_check:
        return True
    if (__regex_leading_with_whitespace_at_all.search(line) is not None and
            __regex_single_line_feed.search(line) is None):
        return __regex_leading_with_spaces.search(line) is not None

    return True


def trailing_whitespace_or_crlf(line):
    """Returns TRUE if the trailing characters is whitespace
    """
    if skip_trailing_whitespace_check:
        return False
    return (__regex_trailing_whitespace.search(line) is not None and
            __regex_single_line_feed.search(line) is None)


def if_and_for_whitespace_checks(line):
    """Return TRUE if there is appropriate whitespace after if, for, while
    """
    if skip_block_whitespace_check:
        return True
    if (__regex_for_if_missing_whitespace.search(line) is not None or
            __regex_for_if_too_much_whitespace.search(line) is not None or
            __regex_for_if_parens_whitespace.search(line)):
        return False
    return True


def if_and_for_end_with_bracket_check(line):
    """Return TRUE if there is not a bracket at the end of an if, for, while
       block which fits on a single line ie: 'if (foo)'"""

    def balanced_parens(line):
        """This is a rather naive counter - it won't deal with quotes"""
        balance = 0
        for letter in line:
            if letter == '(':
                balance += 1
            elif letter == ')':
                balance -= 1
        return balance == 0

    if __regex_is_for_if_single_line_bracket.search(line) is not None:
        if not balanced_parens(line):
            return True
        if __regex_ends_with_bracket.search(line) is None:
            return False
    return True


def pointer_whitespace_check(line):
    """Return TRUE if there is no space between a pointer name and the
       asterisk that denotes this is a apionter type, ie: 'struct foo*'"""
    return __regex_ptr_declaration_missing_whitespace.search(line) is not None


def line_length_check(line):
    """Return TRUE if the line length is too long"""
    if len(line) > 79:
        return True
    return False


checks = [
    {'regex': None,
     'match_name':
     lambda x: not any([fmt in x for fmt in line_length_blacklist]),
     'check': lambda x: line_length_check(x),
     'print':
     lambda x: print_warning("Line is greater than 79-characters long", x)},

    {'regex': '$(?<!\.mk)',
     'match_name': None,
     'check': lambda x: not leading_whitespace_is_spaces(x),
     'print':
     lambda x: print_warning("Line has non-spaces leading whitespace", x)},

    {'regex': None, 'match_name': None,
     'check': lambda x: trailing_whitespace_or_crlf(x),
     'print': lambda x: print_warning("Line has trailing whitespace", x)},

    {'regex': '(.c|.h)(.in)?$', 'match_name': None,
     'check': lambda x: not if_and_for_whitespace_checks(x),
     'print': lambda x: print_error("Improper whitespace around control block",
                                    x)},

    {'regex': '(.c|.h)(.in)?$', 'match_name': None,
     'check': lambda x: not if_and_for_end_with_bracket_check(x),
     'print': lambda x: print_error("Inappropriate bracing around statement",
                                    x)},

    {'regex': '(.c|.h)(.in)?$', 'match_name': None,
     'check': lambda x: pointer_whitespace_check(x),
     'print':
     lambda x: print_error("Inappropriate spacing in pointer declaration", x)}
]


def get_file_type_checks(filename):
    """Returns the list of checks for a file based on matching the filename
       against regex."""
    global checks
    checkList = []
    for check in checks:
        if check['regex'] is None and check['match_name'] is None:
            checkList.append(check)
        if check['regex'] is not None and \
           re.compile(check['regex']).search(filename) is not None:
            checkList.append(check)
        elif check['match_name'] is not None and check['match_name'](filename):
            checkList.append(check)
    return checkList


def run_checks(current_file, line, lineno):
    """Runs the various checks for the particular line.  This will take
       filename into account."""
    print_line = False
    for check in get_file_type_checks(current_file):
        if check['check'](line):
            check['print'](lineno)
            print_line = True

    if print_line:
        print("\n%s\n" % line)


def ovs_checkpatch_parse(text):
    global print_file_name
    lineno = 0
    signatures = []
    co_authors = []
    parse = 0
    current_file = ''
    previous_file = ''
    scissors = re.compile(r'^[\w]*---[\w]*')
    hunks = re.compile('^(---|\+\+\+) (\S+)')
    hunk_differences = re.compile(
        r'^@@ ([0-9-+]+),([0-9-+]+) ([0-9-+]+),([0-9-+]+) @@')
    is_signature = re.compile(r'((\s*Signed-off-by: )(.*))$',
                              re.I | re.M | re.S)
    is_co_author = re.compile(r'(\s*(Co-authored-by: )(.*))$',
                              re.I | re.M | re.S)

    for line in text.decode(errors='ignore').split('\n'):
        if current_file != previous_file:
            previous_file = current_file

        lineno = lineno + 1
        if len(line) <= 0:
            continue

        if checking_file:
            parse = 2

        if parse == 1:
            match = hunks.match(line)
            if match:
                parse = parse + 1
                current_file = match.group(2)
                print_file_name = current_file
            continue
        elif parse == 0:
            if scissors.match(line):
                parse = parse + 1
                if not skip_signoff_check:
                    if len(signatures) == 0:
                        print_error("No signatures found.")
                    elif len(signatures) != 1 + len(co_authors):
                        print_error("Too many signoffs; "
                                    "are you missing Co-authored-by lines?")
                    if not set(co_authors) <= set(signatures):
                        print_error("Co-authored-by/Signed-off-by corruption")
            elif is_signature.match(line):
                m = is_signature.match(line)
                signatures.append(m.group(3))
            elif is_co_author.match(line):
                m = is_co_author.match(line)
                co_authors.append(m.group(3))
        elif parse == 2:
            newfile = hunks.match(line)
            if newfile:
                current_file = newfile.group(2)
                print_file_name = current_file
                continue
            reset_line_number = hunk_differences.match(line)
            if reset_line_number:
                lineno = int(reset_line_number.group(3))
                if lineno < 0:
                    lineno = -1 * lineno
                lineno -= 1
            if is_subtracted_line(line):
                lineno -= 1
            if not is_added_line(line):
                continue

            cmp_line = added_line(line)

            # Skip files which have /datapath in them, since they are
            # linux or windows coding standards
            if '/datapath' in current_file:
                continue
            run_checks(current_file, cmp_line, lineno)
    if __errors or __warnings:
        return -1
    return 0


def usage():
    print("Open vSwitch checkpatch.py")
    print("Checks a patch for trivial mistakes.")
    print("usage:")
    print("%s [options] [patch file]" % sys.argv[0])
    print("options:")
    print("-h|--help\t\t\t\tThis help message")
    print("-b|--skip-block-whitespace\t"
          "Skips the if/while/for whitespace tests")
    print("-f|--check-file\t\t\tCheck a file instead of a patchfile.")
    print("-l|--skip-leading-whitespace\t"
          "Skips the leading whitespace test")
    print("-s|--skip-signoff-lines\t"
          "Do not emit an error if no Signed-off-by line is present")
    print("-t|--skip-trailing-whitespace\t"
          "Skips the trailing whitespace test")


def ovs_checkpatch_file(filename):
    global __warnings, __errors, checking_file
    try:
        mail = email.message_from_file(open(filename, 'r'))
    except:
        print_error("Unable to parse file '%s'. Is it a patch?" % filename)
        return -1

    for part in mail.walk():
        if part.get_content_maintype() == 'multipart':
            continue
    result = ovs_checkpatch_parse(part.get_payload(decode=True))
    if result < 0:
        print("Warnings: %d, Errors: %d" % (__warnings, __errors))
    return result


if __name__ == '__main__':
    try:
        optlist, args = getopt.getopt(sys.argv[1:], 'bhlstf',
                                      ["check-file",
                                       "help",
                                       "skip-block-whitespace",
                                       "skip-leading-whitespace",
                                       "skip-signoff-lines",
                                       "skip-trailing-whitespace"])
    except:
        print("Unknown option encountered. Please rerun with -h for help.")
        sys.exit(-1)

    for o, a in optlist:
        if o in ("-h", "--help"):
            usage()
            sys.exit(0)
        elif o in ("-b", "--skip-block-whitespace"):
            skip_block_whitespace_check = True
        elif o in ("-l", "--skip-leading-whitespace"):
            skip_leading_whitespace_check = True
        elif o in ("-s", "--skip-signoff-lines"):
            skip_signoff_check = True
        elif o in ("-t", "--skip-trailing-whitespace"):
            skip_trailing_whitespace_check = True
        elif o in ("-f", "--check-file"):
            checking_file = True
        else:
            print("Unknown option '%s'" % o)
            sys.exit(-1)
    try:
        filename = args[0]
    except:
        if sys.stdin.isatty():
            usage()
            sys.exit(-1)
        sys.exit(ovs_checkpatch_parse(sys.stdin.read()))
    sys.exit(ovs_checkpatch_file(filename))