"""AST-level logical operator misuse injection for Python."""

import ast
from typing import Optional

from app.dataset.rules.base import Mutation, MutationRule


class LogicOperatorRule(MutationRule):
    """Swap `and` with `or` in a boolean expression.

    Uses `ast` to locate a BoolOp using `And` and replaces it with `Or`,
    preserving exact source position via line replacement.
    """

    name = "logic_operator"
    language = "python"
    defect_type = "logic_operator_misuse"

    def detect_and_mutate(self, source: str, filename: str = "") -> Optional[Mutation]:
        try:
            tree = ast.parse(source)
        except SyntaxError:
            return None

        for node in ast.walk(tree):
            if isinstance(node, ast.BoolOp) and isinstance(node.op, ast.And):
                line_no = node.lineno
                lines = source.splitlines(keepends=True)
                line = lines[line_no - 1]
                mutated_line = line.replace(" and ", " or ", 1)
                if mutated_line == line:
                    continue
                mutated = "".join(lines[:line_no - 1] + [mutated_line] + lines[line_no:])
                return Mutation(
                    defect_type=self.defect_type,
                    language=self.language,
                    line_start=line_no,
                    line_end=getattr(node, "end_lineno", line_no) or line_no,
                    mutated_source=mutated,
                    reference_fix="Restore the original `and` operator for correct short-circuit logic.",
                    description="Replaced boolean `and` with `or`.",
                )
        return None