#!/usr/bin/env python
# Copyright (c) 2013, AT&T Labs, Yun Mao <yunmao@gmail.com>
# 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.

"""pylint error checking."""

from __future__ import print_function

import json
import re
import sys

from pylint import lint
from pylint.reporters import text
from six.moves import cStringIO as StringIO

# Note(maoy): E1103 is error code related to partial type inference
ignore_codes = ["E1103"]
# Note(maoy): the error message is the pattern of E0202. It should be ignored
# for cinder.tests modules
# Note(fengqian): the second error message is the pattern of [E0611].
# It should be ignored because use six module to keep py3.X compatibility.
# Note(e0ne): the third error message is for SQLAlchemy update() calls
# in DB schema migrations.
# Note(xyang): the fourth and fifth error messages are for the code [E1101].
# They should be ignored because 'sha256' and 'sha224' are functions in
# 'hashlib'.
ignore_messages = ["An attribute affected in cinder.tests",
                   "No name 'urllib' in module '_MovedItems'",
                   "No value passed for parameter 'dml'",
                   "Module 'hashlib' has no 'sha256' member",
                   "Module 'hashlib' has no 'sha224' member"]
# Note(maoy): we ignore all errors in openstack.common because it should be
# checked elsewhere. We also ignore cinder.tests for now due to high false
# positive rate.
ignore_modules = ["cinder/openstack/common/", "cinder/tests/"]

# Note(thangp): E0213, E1101, and E1102 should be ignored for only
# cinder.object modules. E0213 and E1102 are error codes related to
# the first argument of a method, but should be ignored because the method
# is a remotable class method. E1101 is error code related to accessing a
# non-existent member of an object, but should be ignored because the object
# member is created dynamically.
objects_ignore_codes = ["E0213", "E1101", "E1102"]
# Note(thangp): The error messages are for codes [E1120, E1101] appearing in
# the cinder code base using objects. E1120 is an error code related no value
# passed for a parameter in function call, but should be ignored because it is
# reporting false positives. E1101 is error code related to accessing a
# non-existent member of an object, but should be ignored because the object
# member is created dynamically.
objects_ignore_messages = [
    "No value passed for parameter 'id' in function call",
    "Module 'cinder.objects' has no 'Snapshot' member",
    "Module 'cinder.objects' has no 'SnapshotList' member",
    "Module 'cinder.objects' has no 'Backup' member",
    "Module 'cinder.objects' has no 'BackupList' member",
]
objects_ignore_modules = ["cinder/objects/"]

KNOWN_PYLINT_EXCEPTIONS_FILE = "tools/pylint_exceptions"


class LintOutput(object):

    _cached_filename = None
    _cached_content = None

    def __init__(self, filename, lineno, line_content, code, message,
                 lintoutput):
        self.filename = filename
        self.lineno = lineno
        self.line_content = line_content
        self.code = code
        self.message = message
        self.lintoutput = lintoutput

    @classmethod
    def from_line(cls, line):
        m = re.search(r"(\S+):(\d+): \[(\S+)(, \S+)?] (.*)", line)
        matched = m.groups()
        filename, lineno, code, message = (matched[0], int(matched[1]),
                                           matched[2], matched[-1])
        if cls._cached_filename != filename:
            with open(filename) as f:
                cls._cached_content = list(f.readlines())
                cls._cached_filename = filename
        line_content = cls._cached_content[lineno - 1].rstrip()
        return cls(filename, lineno, line_content, code, message,
                   line.rstrip())

    @classmethod
    def from_msg_to_dict(cls, msg):
        """From the output of pylint msg, to a dict, where each key
        is a unique error identifier, value is a list of LintOutput
        """
        result = {}
        for line in msg.splitlines():
            obj = cls.from_line(line)
            if obj.is_ignored():
                continue
            key = obj.key()
            if key not in result:
                result[key] = []
            result[key].append(obj)
        return result

    def is_ignored(self):
        if self.code in ignore_codes:
            return True
        if any(self.filename.startswith(name) for name in ignore_modules):
            return True
        if any(msg in self.message for msg in
               (ignore_messages + objects_ignore_messages)):
            return True
        if (self.code in objects_ignore_codes and
            any(self.filename.startswith(name)
                for name in objects_ignore_modules)):
            return True
        if (self.code in objects_ignore_codes and
            any(self.filename.startswith(name)
                for name in objects_ignore_modules)):
            return True
        return False

    def key(self):
        if self.code in ["E1101", "E1103"]:
            # These two types of errors are like Foo class has no member bar.
            # We discard the source code so that the error will be ignored
            # next time another Foo.bar is encountered.
            return self.message, ""
        return self.message, self.line_content.strip()

    def json(self):
        return json.dumps(self.__dict__)

    def review_str(self):
        return ("File %(filename)s\nLine %(lineno)d:%(line_content)s\n"
                "%(code)s: %(message)s" % self.__dict__)


class ErrorKeys(object):

    @classmethod
    def print_json(cls, errors, output=sys.stdout):
        print("# automatically generated by tools/lintstack.py", file=output)
        for i in sorted(errors.keys()):
            print(json.dumps(i), file=output)

    @classmethod
    def from_file(cls, filename):
        keys = set()
        for line in open(filename):
            if line and line[0] != "#":
                d = json.loads(line)
                keys.add(tuple(d))
        return keys


def run_pylint():
    buff = StringIO()
    reporter = text.ParseableTextReporter(output=buff)
    args = ["--include-ids=y", "-E", "cinder"]
    lint.Run(args, reporter=reporter, exit=False)
    val = buff.getvalue()
    buff.close()
    return val


def generate_error_keys(msg=None):
    print("Generating", KNOWN_PYLINT_EXCEPTIONS_FILE)
    if msg is None:
        msg = run_pylint()
    errors = LintOutput.from_msg_to_dict(msg)
    with open(KNOWN_PYLINT_EXCEPTIONS_FILE, "w") as f:
        ErrorKeys.print_json(errors, output=f)


def validate(newmsg=None):
    print("Loading", KNOWN_PYLINT_EXCEPTIONS_FILE)
    known = ErrorKeys.from_file(KNOWN_PYLINT_EXCEPTIONS_FILE)
    if newmsg is None:
        print("Running pylint. Be patient...")
        newmsg = run_pylint()
    errors = LintOutput.from_msg_to_dict(newmsg)

    print("Unique errors reported by pylint: was %d, now %d."
          % (len(known), len(errors)))
    passed = True
    for err_key, err_list in errors.items():
        for err in err_list:
            if err_key not in known:
                print(err.lintoutput)
                print()
                passed = False
    if passed:
        print("Congrats! pylint check passed.")
        redundant = known - set(errors.keys())
        if redundant:
            print("Extra credit: some known pylint exceptions disappeared.")
            for i in sorted(redundant):
                print(json.dumps(i))
            print("Consider regenerating the exception file if you will.")
    else:
        print("Please fix the errors above. If you believe they are false "
              "positives, run 'tools/lintstack.py generate' to overwrite.")
        sys.exit(1)


def usage():
    print("""Usage: tools/lintstack.py [generate|validate]
    To generate pylint_exceptions file: tools/lintstack.py generate
    To validate the current commit: tools/lintstack.py
    """)


def main():
    option = "validate"
    if len(sys.argv) > 1:
        option = sys.argv[1]
    if option == "generate":
        generate_error_keys()
    elif option == "validate":
        validate()
    else:
        usage()


if __name__ == "__main__":
    main()