# -*- coding:utf-8 -*-
#
# Copyright 2014 Hewlett-Packard Development Company, L.P.
#
# 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 ast
import sys

import bandit
from bandit.core import test_properties as test


CANDIDATES = set(["password", "pass", "passwd", "pwd", "secret", "token",
                  "secrete"])


def _report(value):
    return bandit.Issue(
        severity=bandit.LOW,
        confidence=bandit.MEDIUM,
        text=("Possible hardcoded password: '%s'" % value))


@test.checks('Str')
@test.test_id('B105')
def hardcoded_password_string(context):
    """**B105: Test for use of hard-coded password strings**

    The use of hard-coded passwords increases the possibility of password
    guessing tremendously. This plugin test looks for all string literals and
    checks the following conditions:

    - assigned to a variable that looks like a password
    - assigned to a dict key that looks like a password
    - used in a comparison with a variable that looks like a password

    Variables are considered to look like a password if they have match any one
    of:

    - "password"
    - "pass"
    - "passwd"
    - "pwd"
    - "secret"
    - "token"
    - "secrete"

    Note: this can be noisy and may generate false positives.

    **Config Options:**

    None

    :Example:

    .. code-block:: none

        >> Issue: Possible hardcoded password '(root)'
           Severity: Low   Confidence: Low
           Location: ./examples/hardcoded-passwords.py:5
        4 def someFunction2(password):
        5     if password == "root":
        6         print("OK, logged in")

    .. seealso::

        - https://www.owasp.org/index.php/Use_of_hard-coded_password

    .. versionadded:: 0.9.0

    """
    node = context.node
    if isinstance(node.parent, ast.Assign):
        # looks for "candidate='some_string'"
        for targ in node.parent.targets:
            if isinstance(targ, ast.Name) and targ.id in CANDIDATES:
                return _report(node.s)

    elif isinstance(node.parent, ast.Index) and node.s in CANDIDATES:
        # looks for "dict[candidate]='some_string'"
        # assign -> subscript -> index -> string
        assign = node.parent.parent.parent
        if isinstance(assign, ast.Assign) and isinstance(assign.value,
                                                         ast.Str):
            return _report(assign.value.s)

    elif isinstance(node.parent, ast.Compare):
        # looks for "candidate == 'some_string'"
        comp = node.parent
        if isinstance(comp.left, ast.Name) and comp.left.id in CANDIDATES:
            if isinstance(comp.comparators[0], ast.Str):
                return _report(comp.comparators[0].s)


@test.checks('Call')
@test.test_id('B106')
def hardcoded_password_funcarg(context):
    """**B106: Test for use of hard-coded password function arguments**

    The use of hard-coded passwords increases the possibility of password
    guessing tremendously. This plugin test looks for all function calls being
    passed a keyword argument that is a string literal. It checks that the
    assigned local variable does not look like a password.

    Variables are considered to look like a password if they have match any one
    of:

    - "password"
    - "pass"
    - "passwd"
    - "pwd"
    - "secret"
    - "token"
    - "secrete"

    Note: this can be noisy and may generate false positives.

    **Config Options:**

    None

    :Example:

    .. code-block:: none

        >> Issue: [B106:hardcoded_password_funcarg] Possible hardcoded
        password: 'blerg'
           Severity: Low   Confidence: Medium
           Location: ./examples/hardcoded-passwords.py:16
        15
        16    doLogin(password="blerg")

    .. seealso::

        - https://www.owasp.org/index.php/Use_of_hard-coded_password

    .. versionadded:: 0.9.0

    """
    # looks for "function(candidate='some_string')"
    for kw in context.node.keywords:
        if isinstance(kw.value, ast.Str) and kw.arg in CANDIDATES:
            return _report(kw.value.s)


@test.checks('FunctionDef')
@test.test_id('B107')
def hardcoded_password_default(context):
    """**B107: Test for use of hard-coded password argument defaults**

    The use of hard-coded passwords increases the possibility of password
    guessing tremendously. This plugin test looks for all function definitions
    that specify a default string literal for some argument. It checks that
    the argument does not look like a password.

    Variables are considered to look like a password if they have match any one
    of:

    - "password"
    - "pass"
    - "passwd"
    - "pwd"
    - "secret"
    - "token"
    - "secrete"

    Note: this can be noisy and may generate false positives.

    **Config Options:**

    None

    :Example:

    .. code-block:: none

        >> Issue: [B107:hardcoded_password_default] Possible hardcoded
        password: 'Admin'
           Severity: Low   Confidence: Medium
           Location: ./examples/hardcoded-passwords.py:1

        1    def someFunction(user, password="Admin"):
        2      print("Hi " + user)

    .. seealso::

        - https://www.owasp.org/index.php/Use_of_hard-coded_password

    .. versionadded:: 0.9.0

    """
    # looks for "def function(candidate='some_string')"

    # this pads the list of default values with "None" if nothing is given
    defs = [None] * (len(context.node.args.args) -
                     len(context.node.args.defaults))
    defs.extend(context.node.args.defaults)

    # go through all (param, value)s and look for candidates
    for key, val in zip(context.node.args.args, defs):
        if isinstance(key, ast.Name):
            check = key.arg if sys.version_info.major > 2 else key.id  # Py3
            if isinstance(val, ast.Str) and check in CANDIDATES:
                return _report(val.s)
