"""Antigravity CLI headless backend. `agy -p` subprocess + 드라이버 스키마 검증·재시도."""
import asyncio
import json
import re
import tempfile
from pydantic import BaseModel, ValidationError
from deep_research.backends.base import AgentBackend

_FENCE = re.compile(r"```(?:json)?\s*(\{.*?\})\s*```", re.DOTALL)


def extract_json_block(text: str) -> dict | None:
    """출력 텍스트에서 JSON 객체 추출: 펜스 우선, 없으면 최외곽 중괄호."""
    m = _FENCE.search(text)
    candidates = [m.group(1)] if m else []
    if not candidates:
        start, depth = -1, 0
        for i, ch in enumerate(text):
            if ch == "{":
                if depth == 0:
                    start = i
                depth += 1
            elif ch == "}" and depth > 0:
                depth -= 1
                if depth == 0 and start >= 0:
                    candidates.append(text[start:i + 1])
                    break
    for c in candidates:
        try:
            return json.loads(c)
        except json.JSONDecodeError:
            continue
    return None


class AntigravityBackend(AgentBackend):
    def __init__(self, *, retries: int = 2, neutral_cwd: str | None = None, model: str | None = None):
        self.retries = retries
        self.neutral_cwd = neutral_cwd or tempfile.gettempdir()
        self.model = model

    async def _invoke(self, prompt: str) -> str | None:
        # 실 CLI 스모크 (2026-06-10): agy 에 `--cd`/`-m` 플래그 없음 ("flags provided but
        # not defined" 즉사) — cwd 는 subprocess 인자로, 모델은 `--model`. stdin 차단(비-tty 안전).
        cmd = ["agy", "-p", prompt]
        if self.model:
            cmd += ["--model", self.model]
        proc = await asyncio.create_subprocess_exec(
            *cmd, cwd=self.neutral_cwd, stdin=asyncio.subprocess.DEVNULL,
            stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.PIPE)
        out, _ = await proc.communicate()
        if proc.returncode != 0:
            return None
        return out.decode("utf-8", "replace")

    async def run_agent(self, prompt: str, schema: type[BaseModel], *, label: str):
        schema_json = json.dumps(schema.model_json_schema())
        full = (prompt + "\n\n## Output format\nReturn ONLY a JSON object conforming to this "
                "JSON Schema (no prose, no markdown fences):\n" + schema_json)
        for attempt in range(self.retries + 1):
            text = await self._invoke(full if attempt == 0 else
                                      full + "\n\nYour previous output was invalid. Return ONLY the JSON object.")
            if text is None:
                continue
            obj = extract_json_block(text)
            if obj is None:
                continue
            try:
                return schema.model_validate(obj)
            except ValidationError:
                continue
        return None