"""Helpers for reading agent instructions from AGENTS.md."""

from __future__ import annotations

import asyncio
import logging
import shlex

from deepagents.backends.protocol import SandboxBackendProtocol

logger = logging.getLogger(__name__)


async def read_agents_md_in_sandbox(
    sandbox_backend: SandboxBackendProtocol,
    repo_dir: str | None,
) -> str | None:
    """Read AGENTS.md from the repo root if it exists."""
    if not repo_dir:
        return None

    safe_agents_path = shlex.quote(f"{repo_dir}/AGENTS.md")
    loop = asyncio.get_event_loop()
    result = await loop.run_in_executor(
        None,
        sandbox_backend.execute,
        f"test -f {safe_agents_path} && cat {safe_agents_path}",
    )
    if result.exit_code != 0:
        logger.debug("AGENTS.md not found at %s", safe_agents_path)
        return None
    content = result.output or ""
    content = content.strip()
    return content or None


async def read_repo_instructions(
    sandbox_backend: SandboxBackendProtocol,
    repo_dir: str,
) -> str:
    """AGENTS.md와 CLAUDE.md를 모두 읽어서 프롬프트에 주입할 문자열을 반환한다."""
    sections = []

    agents_md = await _read_file_if_exists(sandbox_backend, f"{repo_dir}/AGENTS.md")
    if agents_md:
        sections.append(f"## Repository Agent Rules\n{agents_md}")

    claude_md = await _read_file_if_exists(sandbox_backend, f"{repo_dir}/CLAUDE.md")
    if claude_md:
        sections.append(f"## Project Conventions\n{claude_md}")

    return "\n\n".join(sections)


async def _read_file_if_exists(
    sandbox_backend: SandboxBackendProtocol,
    file_path: str,
) -> str | None:
    """파일이 존재하면 내용을 읽고, 없으면 None을 반환한다."""
    safe_path = shlex.quote(file_path)
    try:
        loop = asyncio.get_event_loop()
        result = await loop.run_in_executor(
            None,
            sandbox_backend.execute,
            f"test -f {safe_path} && cat {safe_path}",
        )
        if result.exit_code == 0 and result.output.strip():
            return result.output.strip()
    except Exception:
        logger.debug("Failed to read %s", file_path)
    return None