"""
Chat Session Constants
======================

Shared constants for all chat session types (assistant, spec, expand).

The canonical ``API_ENV_VARS`` list lives in ``env_constants.py`` at the
project root and is re-exported here for convenience so that existing
imports (``from .chat_constants import API_ENV_VARS``) continue to work.
"""

import logging
import sys
from pathlib import Path
from typing import AsyncGenerator

# -------------------------------------------------------------------
# Root directory of the autoforge project (repository root).
# Used throughout the server package whenever the repo root is needed.
# -------------------------------------------------------------------
ROOT_DIR = Path(__file__).parent.parent.parent

# Ensure the project root is on sys.path so we can import env_constants
# from the root-level module without requiring a package install.
_root_str = str(ROOT_DIR)
if _root_str not in sys.path:
    sys.path.insert(0, _root_str)

# -------------------------------------------------------------------
# Environment variables forwarded to Claude CLI subprocesses.
# Single source of truth lives in env_constants.py at the project root.
# Re-exported here so existing ``from .chat_constants import API_ENV_VARS``
# imports continue to work unchanged.
# -------------------------------------------------------------------
from env_constants import API_ENV_VARS  # noqa: E402, F401
from rate_limit_utils import calculate_rate_limit_backoff, is_rate_limit_error, parse_retry_after  # noqa: E402, F401

logger = logging.getLogger(__name__)

# -------------------------------------------------------------------
# Rate-limit handling for chat sessions
# -------------------------------------------------------------------
MAX_CHAT_RATE_LIMIT_RETRIES = 3


def check_rate_limit_error(exc: Exception) -> tuple[bool, int | None]:
    """Inspect an exception and determine if it represents a rate-limit.

    Returns ``(is_rate_limit, retry_seconds)``.  ``retry_seconds`` is the
    parsed Retry-After value when available, otherwise ``None`` (caller
    should use exponential backoff).

    Handles:
    - ``MessageParseError`` whose raw *data* dict has
      ``type == "rate_limit_event"`` (Claude CLI sends this).
    - Any exception whose string representation matches known rate-limit
      patterns (via ``rate_limit_utils.is_rate_limit_error``).
    """
    exc_str = str(exc)

    # Check for MessageParseError with a rate_limit_event payload
    cls_name = type(exc).__name__
    if cls_name == "MessageParseError":
        raw_data = getattr(exc, "data", None)
        if isinstance(raw_data, dict) and raw_data.get("type") == "rate_limit_event":
            retry = parse_retry_after(str(raw_data)) if raw_data else None
            return True, retry

    # Fallback: match error text against known rate-limit patterns
    if is_rate_limit_error(exc_str):
        retry = parse_retry_after(exc_str)
        return True, retry

    return False, None


async def make_multimodal_message(content_blocks: list[dict]) -> AsyncGenerator[dict, None]:
    """Yield a single multimodal user message in Claude Agent SDK format.

    The Claude Agent SDK's ``query()`` method accepts either a plain string
    or an ``AsyncIterable[dict]`` for custom message formats.  This helper
    wraps a list of content blocks (text and/or images) in the expected
    envelope.

    Args:
        content_blocks: List of content-block dicts, e.g.
            ``[{"type": "text", "text": "..."}, {"type": "image", ...}]``.

    Yields:
        A single dict representing the user message.
    """
    yield {
        "type": "user",
        "message": {"role": "user", "content": content_blocks},
        "parent_tool_use_id": None,
        "session_id": "default",
    }