"""Chat API routes — user-facing conversation endpoint.

POST /chat
    Accepts a user message, generates a CJK-safe Russian reply via Ollama.
    This is the ONLY path through which LLM text reaches a user.
    All output is hardened by chat.guard before being returned.
"""
from __future__ import annotations

import uuid

from fastapi import APIRouter

from chat.responder import generate_reply
from models.schemas import ChatRequest, ChatResponse

router = APIRouter(prefix="/chat", tags=["chat"])


@router.post("", response_model=ChatResponse, status_code=200)
def chat(body: ChatRequest) -> ChatResponse:
    """Generate a CJK-safe reply for the given user message.

    - LLM output is scanned for CJK before being returned.
    - On detection: one retry with strict Russian-only instruction.
    - On second failure: safe Russian fallback returned.
    - Diagnostic artifact saved to data/diagnostics/chat_cjk_<trace_id>.json on any CJK incident.
    """
    trace_id = body.trace_id or f"chat-{str(uuid.uuid4())[:8]}"
    reply, meta = generate_reply(user_message=body.message, trace_id=trace_id)
    return ChatResponse(
        reply=reply,
        cjk_detected=meta["cjk_detected"],
        fallback_used=meta["fallback_used"],
        model=meta["model"],
        trace_id=trace_id,
    )