from collections import defaultdict
from typing import Dict, List
from app.config import config


# In-memory store: { uid: { "stt": [...], "text": [...] } }
_store: Dict[str, Dict[str, List[dict]]] = defaultdict(
    lambda: {"stt": [], "text": []}
)


def get_history(uid: str, channel: str) -> List[dict]:
    """Return conversation history for a user on a given channel (stt | text)."""
    return _store[uid][channel]


def append_turn(uid: str, channel: str, role: str, content: str) -> None:
    """Append a single turn and enforce the history cap."""
    history = _store[uid][channel]
    history.append({"role": role, "content": content})

    # Keep only the last N turns (each turn = 1 message, cap covers both roles)
    max_messages = config.MAX_HISTORY_TURNS * 2
    if len(history) > max_messages:
        _store[uid][channel] = history[-max_messages:]


def clear_session(uid: str) -> None:
    """Clear all history for a user across both channels."""
    _store.pop(uid, None)