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

# Copyright (c) 2020 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing checks for potential SQL injections risks.
"""

#
# This is a modified version of the one found in the bandit package.
#
# Original Copyright (C) 2018 [Victor Torre](https://github.com/ehooo)
#
# SPDX-License-Identifier: Apache-2.0
#

import ast

import AstUtilities


def getChecks():
    """
    Public method to get a dictionary with checks handled by this module.
    
    @return dictionary containing checker lists containing checker function and
        list of codes
    @rtype dict
    """
    return {
        "Call": [
            (checkDjangoExtraUsed, ("S610",)),
            (checkDjangoRawSqlUsed, ("S611",)),
        ],
    }


def keywords2dict(keywords):
    """
    Function to extract keywords arguments into a dictionary.
    
    @param keywords list of keyword nodes
    @type list of ast.keyword
    @return dictionary with keyword name and value
    @rtype dict
    """
    kwargs = {}
    for node in keywords:
        if isinstance(node, ast.keyword):
            kwargs[node.arg] = node.value
    return kwargs


def checkDjangoExtraUsed(reportError, context, config):
    """
    Function to check for potential SQL injection on extra function.
    
    @param reportError function to be used to report errors
    @type func
    @param context security context object
    @type SecurityContext
    @param config dictionary with configuration data
    @type dict
    """
    if context.callFunctionName == 'extra':
        kwargs = keywords2dict(context.node.keywords)
        args = context.node.args
        if args:
            if len(args) >= 1:
                kwargs['select'] = args[0]
            if len(args) >= 2:
                kwargs['where'] = args[1]
            if len(args) >= 3:
                kwargs['params'] = args[2]
            if len(args) >= 4:
                kwargs['tables'] = args[3]
            if len(args) >= 5:
                kwargs['order_by'] = args[4]
            if len(args) >= 6:
                kwargs['select_params'] = args[5]
        insecure = False
        for key in ['where', 'tables']:
            if key in kwargs:
                if isinstance(kwargs[key], ast.List):
                    for val in kwargs[key].elts:
                        if not AstUtilities.isString(val):
                            insecure = True
                            break
                else:
                    insecure = True
                    break
        if not insecure and 'select' in kwargs:
            if isinstance(kwargs['select'], ast.Dict):
                for k in kwargs['select'].keys:
                    if not AstUtilities.isString(k):
                        insecure = True
                        break
                if not insecure:
                    for v in kwargs['select'].values:
                        if not AstUtilities.isString(v):
                            insecure = True
                            break
            else:
                insecure = True
        
        if insecure:
            reportError(
                context.node.lineno - 1,
                context.node.col_offset,
                "S610",
                "M",
                "M"
            )


def checkDjangoRawSqlUsed(reportError, context, config):
    """
    Function to check for potential SQL injection on RawSQL function.
    
    @param reportError function to be used to report errors
    @type func
    @param context security context object
    @type SecurityContext
    @param config dictionary with configuration data
    @type dict
    """
    if context.isModuleImportedLike('django.db.models'):
        if context.callFunctionName == 'RawSQL':
            sql = context.node.args[0]
            if not AstUtilities.isString(sql):
                reportError(
                    context.node.lineno - 1,
                    context.node.col_offset,
                    "S611",
                    "M",
                    "M"
                )
