# modules/nlp/api.py
from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy.orm import Session
from typing import List

from core.database import get_db

from modules.auth.dependencies import get_current_user
from modules.auth.models import User
# Import the new service functions and Enum
from modules.nlp.service import process_request, ask_ai, save_chat_message, get_chat_history, MessageSender
# Import the response schema and the new ChatMessage model for response type hinting
from modules.nlp.schemas import ProcessCommandRequest, ProcessCommandResponse
from modules.nlp.models import ChatMessage # Import ChatMessage model
from modules.calendar.service import create_calendar_event, get_calendar_events, update_calendar_event, delete_calendar_event
from modules.calendar.models import CalendarEvent
from modules.calendar.schemas import CalendarEventCreate, CalendarEventUpdate

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

# Helper to format calendar events (expects list of CalendarEvent models)
def format_calendar_events(events: List[CalendarEvent]) -> List[str]:
    if not events:
        return ["You have no events matching that criteria."]
    formatted = ["Here are the events:"]
    for event in events:
        # Access attributes directly from the model instance
        start_str = event.start.strftime("%Y-%m-%d %H:%M") if event.start else "No start time"
        end_str = event.end.strftime("%H:%M") if event.end else ""
        title = event.title or "Untitled Event"
        formatted.append(f"- {title} ({start_str}{' - ' + end_str if end_str else ''})")
    return formatted

# Update the response model for the endpoint
@router.post("/process-command", response_model=ProcessCommandResponse)
def process_command(request_data: ProcessCommandRequest, current_user: User = Depends(get_current_user), db: Session = Depends(get_db)):
    """
    Process the user command, save messages, execute action, save response, and return user-friendly responses.
    """
    user_input = request_data.user_input

    # --- Save User Message ---
    save_chat_message(db, user_id=current_user.id, sender=MessageSender.USER, text=user_input)
    # ------------------------

    command_data = process_request(user_input)
    intent = command_data["intent"]
    params = command_data["params"]
    response_text = command_data["response_text"]

    responses = [response_text] # Start with the initial response

    # --- Save Initial AI Response ---
    # Save the first response generated by process_request
    save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=response_text)
    # -----------------------------

    if intent == "error":
        # Don't raise HTTPException here if we want to save the error message
        # Instead, return the error response directly
        # save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=response_text) # Already saved above
        return ProcessCommandResponse(responses=responses)

    if intent == "clarification_needed" or intent == "unknown":
        # save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=response_text) # Already saved above
        return ProcessCommandResponse(responses=responses)

    try:
        match intent:
            case "ask_ai":
                ai_answer = ask_ai(**params)
                responses.append(ai_answer)
                # --- Save Additional AI Response ---
                save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=ai_answer)
                # ---------------------------------
                return ProcessCommandResponse(responses=responses)

            case "get_calendar_events":
                events: List[CalendarEvent] = get_calendar_events(db, current_user.id, **params)
                formatted_responses = format_calendar_events(events)
                responses.extend(formatted_responses)
                # --- Save Additional AI Responses ---
                for resp in formatted_responses:
                    save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=resp)
                # ----------------------------------
                return ProcessCommandResponse(responses=responses)

            case "add_calendar_event":
                event_data = CalendarEventCreate(**params)
                created_event = create_calendar_event(db, current_user.id, event_data)
                start_str = created_event.start.strftime("%Y-%m-%d %H:%M") if created_event.start else "No start time"
                title = created_event.title or "Untitled Event"
                add_response = f"Added: {title} starting at {start_str}."
                responses.append(add_response)
                # --- Save Additional AI Response ---
                save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=add_response)
                # ---------------------------------
                return ProcessCommandResponse(responses=responses)

            case "update_calendar_event":
                event_id = params.pop('event_id', None)
                if event_id is None:
                    # Save the error message before raising
                    error_msg = "Event ID is required for update."
                    save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=error_msg)
                    raise HTTPException(status_code=400, detail=error_msg)
                event_data = CalendarEventUpdate(**params)
                updated_event = update_calendar_event(db, current_user.id, event_id, event_data=event_data)
                title = updated_event.title or "Untitled Event"
                update_response = f"Updated event ID {updated_event.id}: {title}."
                responses.append(update_response)
                # --- Save Additional AI Response ---
                save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=update_response)
                # ---------------------------------
                return ProcessCommandResponse(responses=responses)

            case "delete_calendar_event":
                event_id = params.get('event_id')
                if event_id is None:
                    # Save the error message before raising
                    error_msg = "Event ID is required for delete."
                    save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=error_msg)
                    raise HTTPException(status_code=400, detail=error_msg)
                delete_calendar_event(db, current_user.id, event_id)
                delete_response = f"Deleted event ID {event_id}."
                responses.append(delete_response)
                # --- Save Additional AI Response ---
                save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=delete_response)
                # ---------------------------------
                return ProcessCommandResponse(responses=responses)

            case _: 
                print(f"Warning: Unhandled intent '{intent}' reached api.py match statement.")
                # The initial response_text was already saved
                return ProcessCommandResponse(responses=responses)

    except HTTPException as http_exc:
        # Don't save again if already saved before raising
        if http_exc.status_code != 400 or ('event_id' not in http_exc.detail.lower()):
             save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=http_exc.detail)
        raise http_exc
    except Exception as e:
        print(f"Error executing intent '{intent}': {e}")
        error_response = "Sorry, I encountered an error while trying to perform that action."
        # --- Save Final Error AI Response ---
        save_chat_message(db, user_id=current_user.id, sender=MessageSender.AI, text=error_response)
        # ----------------------------------
        return ProcessCommandResponse(responses=[error_response])

# --- New Endpoint for Chat History ---
# Define a Pydantic schema for the response (optional but good practice)
from pydantic import BaseModel
from datetime import datetime

class ChatMessageResponse(BaseModel):
    id: int
    sender: MessageSender # Use the enum directly
    text: str
    timestamp: datetime

    class Config:
        from_attributes = True # Allow Pydantic to work with ORM models

@router.get("/history", response_model=List[ChatMessageResponse])
def read_chat_history(current_user: User = Depends(get_current_user), db: Session = Depends(get_db)):
    """Retrieves the last 50 chat messages for the current user."""
    history = get_chat_history(db, user_id=current_user.id, limit=50)
    return history
# -------------------------------------