"""Codex CLI headless backend. `codex exec --json --output-schema` subprocess."""
import asyncio
import json
import os
import tempfile
from pydantic import BaseModel, ValidationError
from deep_research.backends.base import AgentBackend


def extract_final_json(jsonl_stdout: str) -> dict | None:
    """JSONL 이벤트 스트림에서 마지막 agent_message 의 text(JSON) 파싱."""
    final = None
    for line in jsonl_stdout.splitlines():
        line = line.strip()
        if not line:
            continue
        try:
            evt = json.loads(line)
        except json.JSONDecodeError:
            continue
        if evt.get("type") in ("agent_message", "message") and "text" in evt:
            final = evt["text"]
        # 실 CLI 포맷 (2026-06-10 스모크 확인): item.completed 에 중첩된 agent_message
        item = evt.get("item")
        if (evt.get("type") == "item.completed" and isinstance(item, dict)
                and item.get("type") == "agent_message" and "text" in item):
            final = item["text"]
    if final is None:
        return None
    try:
        return json.loads(final)
    except json.JSONDecodeError:
        return None


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

    @staticmethod
    def _strict_schema(schema: dict) -> dict:
        """OpenAI structured-output strict 요구사항 적용 (실 스모크 2026-06-10 발견):
        모든 object 에 additionalProperties:false + 전 property required."""
        def walk(node):
            if isinstance(node, dict):
                if node.get("type") == "object" or "properties" in node:
                    node["additionalProperties"] = False
                    if "properties" in node:
                        node["required"] = list(node["properties"].keys())
                for v in node.values():
                    walk(v)
            elif isinstance(node, list):
                for v in node:
                    walk(v)
        walk(schema)
        return schema

    async def run_agent(self, prompt: str, schema: type[BaseModel], *, label: str):
        with tempfile.NamedTemporaryFile("w", suffix=".json", delete=False) as fh:
            json.dump(self._strict_schema(schema.model_json_schema()), fh)
            schema_path = fh.name
        # --skip-git-repo-check: neutral_cwd(/tmp)는 비신뢰 디렉터리 — 플래그 없으면 즉시 종료.
        # stdin=DEVNULL: 비-tty 환경에서 codex 가 "Reading additional input from stdin" 으로
        # 블록되는 것 방지 (실 CLI 스모크 2026-06-10 에서 발견).
        cmd = ["codex", "exec", "--json", "--output-schema", schema_path,
               "--cd", self.neutral_cwd, "-s", "read-only", "--skip-git-repo-check"]
        if self.model:
            cmd += ["-m", self.model]
        cmd.append(prompt)
        try:
            proc = await asyncio.create_subprocess_exec(
                *cmd, stdin=asyncio.subprocess.DEVNULL,
                stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.PIPE)
            out, _ = await proc.communicate()
        finally:
            try:
                os.unlink(schema_path)
            except OSError:
                pass
        if proc.returncode != 0:
            return None
        obj = extract_final_json(out.decode("utf-8", "replace"))
        if obj is None:
            return None
        try:
            return schema.model_validate(obj)
        except ValidationError:
            return None