"""
AlgoPharma — Chat API router.

POST /api/chat
  - Receives {message, state} from frontend.
  - Calls Nemotron slot-filler to update state.
  - If state is READY (medicine + source filled):
      * Creates a Project row in SQLite DB.
      * Launches llm_agent as a FastAPI BackgroundTask.
      * Returns {ready: true, project_id, bot_message}.
  - Otherwise returns {ready: false, bot_message, state}.

No session storage — the frontend owns and persists the state dict.
"""

import logging
from fastapi import APIRouter, BackgroundTasks, HTTPException
from pydantic import BaseModel

logger = logging.getLogger(__name__)

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


# ── Request / Response models ─────────────────────────────
class ChatRequest(BaseModel):
    message: str
    state: dict = {"medicine": None, "source": None, "symptom": None}


class ChatResponse(BaseModel):
    ready: bool
    bot_message: str
    state: dict
    project_id: int | None = None


# ── Helpers ───────────────────────────────────────────────
def _build_query(state: dict) -> str:
    """Convert the gathered state dict into an llm_agent query string."""
    med    = state["medicine"]
    source = state["source"]
    symp   = state.get("symptom")

    q = f"Find side effects of {med} on {source}"
    if symp:
        q += f" focusing on {symp}"
    return q


def _create_project(name: str) -> int:
    """Insert a new Project row and return its integer ID."""
    from database import SessionLocal
    from models import Project

    with SessionLocal() as session:
        # Avoid unique-constraint errors by appending a timestamp if needed
        from datetime import datetime
        ts = datetime.utcnow().strftime("%Y%m%d_%H%M%S")
        unique_name = f"{name[:120]}_{ts}"
        project = Project(name=unique_name, description=f"Auto-created by chat pipeline: {name}")
        session.add(project)
        session.commit()
        session.refresh(project)
        return project.id


# ── Endpoint ──────────────────────────────────────────────
@router.post("/chat", response_model=ChatResponse)
async def chat(request: ChatRequest, background_tasks: BackgroundTasks):
    """
    Main chat endpoint.  Frontend calls this every time the user sends a message.
    The frontend owns the `state` dict — it persists it in memory and sends it
    back each turn.
    """
    from agentic.chat_manager import get_nemotron_response, READY_SIGNAL

    # 1. Update state via Nemotron
    try:
        new_state, bot_message = get_nemotron_response(request.message, request.state)
    except Exception as e:
        logger.error(f"[/api/chat] chat_manager failed: {e}")
        raise HTTPException(status_code=500, detail=f"LLM error: {e}")

    # 2. Not ready yet — return next question
    if bot_message != READY_SIGNAL:
        return ChatResponse(
            ready=False,
            bot_message=bot_message,
            state=new_state,
        )

    # 3. READY — create project + fire background pipeline
    try:
        med    = new_state.get("medicine", "unknown")
        source = new_state.get("source",   "unknown")
        symp   = new_state.get("symptom")

        project_name = f"{med}_{source}" + (f"_{symp}" if symp else "")
        project_id   = _create_project(project_name)
        query        = _build_query(new_state)

        logger.info(f"[/api/chat] Pipeline triggered | project_id={project_id} | query={query!r}")

        # Fire-and-forget: runs llm_agent in the background so we respond immediately
        from llm_module import llm_agent
        background_tasks.add_task(llm_agent, query, project_id)

        return ChatResponse(
            ready=True,
            bot_message="Analysis started! Redirecting to your dashboard...",
            state=new_state,
            project_id=project_id,
        )

    except Exception as e:
        logger.error(f"[/api/chat] Pipeline launch failed: {e}")
        raise HTTPException(status_code=500, detail=f"Pipeline error: {e}")