If-Elif

import ast
from collections.abc import Callable
from functools import partial, reduce

import demistomock as demisto
from CommonServerPython import *


def return_none_on_error(func: Callable) -> Callable:
    """Makes a function return None if an error is raised."""

    def new_func(*args):
        try:
            return func(*args)
        except Exception:
            return None

    return new_func


class ConditionParser:
    known_constants: dict[str, Any] = {"true": True, "false": False, "null": None}

    comparison_operators: dict[type, Callable] = {
        ast.Eq: lambda x, y: x == y,
        ast.NotEq: lambda x, y: x != y,
        ast.Lt: return_none_on_error(lambda x, y: x < y),
        ast.LtE: return_none_on_error(lambda x, y: x <= y),
        ast.Gt: return_none_on_error(lambda x, y: x > y),
        ast.GtE: return_none_on_error(lambda x, y: x >= y),
        ast.In: return_none_on_error(lambda x, y: x in y),
        ast.NotIn: return_none_on_error(lambda x, y: x not in y),
    }

    boolean_operators: dict[type, Callable] = {
        ast.And: lambda x, y: x and y,
        ast.Or: lambda x, y: x or y,
    }

    unary_operators: dict[type, Callable] = {
        ast.Not: lambda x: not x,
        ast.USub: lambda x: -x,
    }

    binary_operators: dict[type, Callable] = {
        ast.Add: return_none_on_error(lambda x, y: x + y),
    }

    def __init__(self, context, conditions, flags=None, **_):
        self.conditions: list
        self.functions: dict[str, Callable] = {"from_context": partial(demisto.dt, context)}
        self.modify_functions_with_flags(argToList(flags))
        self.load_conditions(conditions)
        self.default = self.conditions.pop()["default"] if "default" in self.conditions[-1] else ""
        self.validate_conditions()

    def modify_functions_with_flags(self, flags: list):
        self.regex_flags = (
            re.DOTALL * ("regex_dot_all" in flags)
            | re.MULTILINE * ("regex_multiline" in flags)
            | re.IGNORECASE * ("case_insensitive" in flags)
        )
        self.functions["regex_match"] = partial(
            re.fullmatch if "regex_full_match" in flags else re.search, flags=self.regex_flags
        )
        if "case_insensitive" in flags:

            def to_case_insensitive(func):
                return lambda x, y: func(repr(x).lower(), repr(y).lower())

            self.comparison_operators |= {
                ast.Eq: to_case_insensitive(self.comparison_operators[ast.Eq]),
                ast.NotEq: to_case_insensitive(self.comparison_operators[ast.NotEq]),
            }
        if "list_compare" in flags:

            def to_deep_search(func):
                return lambda x, y: (func(x, y) or (any(func(x, i) for i in y) if isinstance(y, list) else False))

            self.comparison_operators = {k: to_deep_search(v) for k, v in self.comparison_operators.items()}

    def load_conditions(self, conditions):
        conditions = re.sub(r"#{([\s\S]+?)}", r" from_context('\1')", conditions)
        try:
            self.conditions = self.evaluate(conditions)
        except SyntaxError as e:
            raise SyntaxError(f"Cannot load JSON. Invalid syntax at line: {e.args[1][1]}; position: {e.args[1][2]}") from e

    def validate_conditions(self):
        for i, d in enumerate(self.conditions, 1):
            if "condition" not in d:
                raise ValueError(f'Condition {i} has no key "condition".')
            elif "return" not in d:
                raise ValueError(f'Condition {i} has no key "return".')
            elif not isinstance(d, dict):
                raise ValueError(f"Condition {i} is not a dictionary.")

    def get_value(self, node):
        match type(node):
            case ast.Name:
                return self.known_constants[node.id]
            case ast.Constant:
                return node.value
            case ast.List:
                return [self.get_value(item) for item in node.elts]
            case ast.Dict:
                return {self.get_value(key): self.get_value(value) for key, value in zip(node.keys, node.values)}
            case ast.Call:
                return self.functions[node.func.id](*map(self.get_value, node.args))
            case ast.Compare:
                left = self.get_value(node.left)
                return all(
                    self.comparison_operators[type(op)](
                        left,
                        left := self.get_value(right),  # noqa: F841
                    )
                    for op, right in zip(node.ops, node.comparators)
                )
            case ast.BoolOp:
                return reduce(self.boolean_operators[type(node.op)], map(self.get_value, node.values))
            case ast.BinOp:
                return self.binary_operators[type(node.op)](self.get_value(node.left), self.get_value(node.right))
            case ast.UnaryOp:
                return self.unary_operators[type(node.op)](self.get_value(node.operand))
            case _:
                raise KeyError(node.__class__.__name__)

    def evaluate(self, expression: str):
        try:
            parsed = ast.parse(expression.strip(), mode="eval")
            return self.get_value(parsed.body)
        except KeyError as e:
            raise NameError(f"Unknown variable/operator: {e.args[0]!r}") from e

    def parse_conditions(self):
        try:
            return next(
                (condition["return"] for condition in self.conditions if self.evaluate(condition["condition"])), self.default
            )
        except SyntaxError as e:
            raise SyntaxError(f"Invalid expression: {e.args[1][3]!r}") from e


def main():
    try:
        args: dict = demisto.args()
        if_elif = ConditionParser(args.pop("value"), **args)
        return_results(if_elif.parse_conditions())
    except Exception as e:
        return_error(f"Error in If-Elif Transformer: {e}")


if __name__ in ("__main__", "builtin", "builtins"):
    main()