"""
ctstruct/renderers/json_renderer.py
CTTree → JSON 렌더러
"""

from __future__ import annotations

import json
from typing import Any
from ..tree import CTTree
from .base import BaseRenderer


class JSONRenderer(BaseRenderer):
    """
    CTTree 를 JSON 문자열로 직렬화.

    Args:
        indent:       들여쓰기 공백 수 (기본 2)
        ensure_ascii: ASCII 강제 인코딩 여부 (기본 False)
        slim:         True 이면 null·기본값 필드를 제거해 출력을 간소화
    """

    def __init__(
        self,
        indent: int = 2,
        ensure_ascii: bool = False,
        slim: bool = False,
    ) -> None:
        self.indent = indent
        self.ensure_ascii = ensure_ascii
        self.slim = slim

    def render(self, tree: CTTree) -> str:
        data = tree.to_dict()
        if self.slim:
            data = self._strip(data)
        return json.dumps(data, indent=self.indent, ensure_ascii=self.ensure_ascii)

    # ── slim 헬퍼 ─────────────────────────────────────────────

    @staticmethod
    def _strip(obj: Any) -> Any:
        """None·기본값 필드를 재귀적으로 제거."""
        if isinstance(obj, list):
            return [JSONRenderer._strip(v) for v in obj]
        if isinstance(obj, dict):
            result: dict[str, Any] = {}
            for k, v in obj.items():
                if v is None:
                    continue
                if k == "data_type" and v == "unset":
                    continue
                if k == "attributes" and v == {}:
                    continue
                result[k] = JSONRenderer._strip(v)
            return result
        return obj