import time
from collections import defaultdict

from fastapi import APIRouter, HTTPException, Depends, Request
from app.models import ChatMessage, ChatResponse, ConversationResponse, MessageResponse, FeedbackCreate
from app.database import get_supabase
from app.dependencies import get_current_user, get_optional_user
from app.services.rag import rag_engine
from app.config import PLAN_LIMITS
from typing import List, Optional
from datetime import datetime
import uuid
import logging

logger = logging.getLogger(__name__)
router = APIRouter(tags=["Chat"])

# ── Simple in-memory rate limiter ────────────────────────────────────────────
_rate_store: dict = defaultdict(list)
_RATE_LIMIT = 30   # max requests
_RATE_WINDOW = 60  # per second window


def _check_rate_limit(client_ip: str):
    now = time.time()
    _rate_store[client_ip] = [t for t in _rate_store[client_ip] if now - t < _RATE_WINDOW]
    if len(_rate_store[client_ip]) >= _RATE_LIMIT:
        raise HTTPException(
            status_code=429,
            detail="Too many requests. Please wait before sending more messages.",
        )
    _rate_store[client_ip].append(now)


def _check_conversation_limit(chatbot: dict, supabase):
    """Check if the chatbot owner has remaining conversation quota this month."""
    company_id = chatbot.get("company_id")
    if not company_id:
        return

    company = supabase.table("companies").select("owner_id").eq("id", company_id).execute()
    if not company.data:
        return

    owner_id = company.data[0]["owner_id"]
    sub = supabase.table("subscriptions").select("plan").eq("user_id", owner_id).eq("status", "active").execute()
    plan = sub.data[0]["plan"] if sub.data else "free"
    limit = PLAN_LIMITS.get(plan, PLAN_LIMITS["free"]).get("conversations_limit", 100)

    if limit >= 999999:
        return  # unlimited

    month_start = datetime.utcnow().replace(day=1, hour=0, minute=0, second=0, microsecond=0).isoformat()
    chatbots = supabase.table("chatbots").select("id").eq("company_id", company_id).execute()
    chatbot_ids = [c["id"] for c in (chatbots.data or [])]
    if not chatbot_ids:
        return

    count_result = supabase.table("conversations").select("id", count="exact") \
        .in_("chatbot_id", chatbot_ids) \
        .gte("created_at", month_start) \
        .execute()

    used = count_result.count or 0
    if used >= limit:
        raise HTTPException(
            status_code=429,
            detail=f"This chatbot's monthly conversation limit ({limit}) has been reached. Please try again next month.",
        )


def _get_public_chatbot(chatbot_id: str, supabase) -> dict:
    """Get a published chatbot (or any chatbot for preview)"""
    result = supabase.table("chatbots").select("*, companies(name, logo_url)").eq("id", chatbot_id).execute()
    if not result.data:
        raise HTTPException(status_code=404, detail="Chatbot not found")
    return result.data[0]


@router.post("/chat/{chatbot_id}", response_model=ChatResponse)
async def chat(
        chatbot_id: str,
        message: ChatMessage,
        request: Request,
        user=Depends(get_optional_user),
):
    # Rate limiting by IP
    client_ip = request.client.host if request.client else "unknown"
    _check_rate_limit(client_ip)

    supabase = get_supabase()
    chatbot = _get_public_chatbot(chatbot_id, supabase)

    # Allow preview access for owner, require published for public
    if not chatbot.get("is_published"):
        if not user:
            raise HTTPException(status_code=403, detail="This chatbot is in preview mode")
        # Check ownership
        company = supabase.table("companies").select("id").eq("owner_id", user.id).execute()
        if not company.data or company.data[0]["id"] != chatbot.get("company_id"):
            raise HTTPException(status_code=403, detail="This chatbot is in preview mode")

    collection_name = chatbot.get("qdrant_collection_name")
    if not collection_name:
        raise HTTPException(status_code=400, detail="Chatbot has no knowledge base configured")

    # Get or create conversation
    session_id = message.session_id or str(uuid.uuid4())

    # Only enforce conversation limit for new sessions (not ongoing ones)
    is_existing = supabase.table("conversations").select("id") \
        .eq("chatbot_id", chatbot_id).eq("session_id", session_id).execute()
    if not is_existing.data:
        _check_conversation_limit(chatbot, supabase)

    conversation = _get_or_create_conversation(
        chatbot_id=chatbot_id,
        session_id=session_id,
        user_id=user.id if user else None,
        language=message.language,
        supabase=supabase,
    )

    # Get conversation history
    history = _get_conversation_history(conversation["id"], supabase)

    # If an agent has taken over this conversation, stop the bot from responding
    conv_status = conversation.get("status", "open")
    if conv_status == "agent_handling":
        return ChatResponse(
            response="",
            session_id=session_id,
            sources=[],
            model_used="",
            tokens_used=0,
            needs_lead_capture=False,
            handoff=False,
        )

    # Get company info for context
    company_data = chatbot.get("companies", {}) or {}
    chatbot_config = {
        **chatbot,
        "company_name": company_data.get("name", ""),
    }

    # If booking is enabled, inject a note into the system prompt so the bot
    # can guide users to the booking page
    if chatbot.get("booking_enabled"):
        from app.config import settings as _cfg
        booking_url = f"{_cfg.app_url}/book/{chatbot_id}"
        booking_note = (
            f"\n\nAppointment booking: This business accepts appointments online. "
            f"If the user wants to book an appointment, meeting, or consultation, "
            f"provide them this booking link: {booking_url}"
        )
        existing_prompt = chatbot_config.get("system_prompt") or ""
        chatbot_config["system_prompt"] = existing_prompt + booking_note

    # Run RAG
    result = await rag_engine.process_query(
        query=message.message,
        collection_name=collection_name,
        chatbot_config=chatbot_config,
        conversation_history=history,
        language=message.language,
    )

    # Compute confidence score
    confidence_score = max((s.score for s in result.get("sources", [])), default=0.0)

    # Check handoff
    is_handoff = False
    if chatbot.get("handoff_enabled"):
        handoff_keywords = chatbot.get("handoff_keywords", [])
        msg_lower = message.message.lower()
        if any(kw.lower() in msg_lower for kw in handoff_keywords):
            is_handoff = True
            # Fire n8n notification (async, non-blocking)
            try:
                from app.services.n8n_service import send_handoff_notification
                from app.config import settings as _settings
                company_data_for_handoff = chatbot.get("companies", {}) or {}
                await send_handoff_notification(
                    chatbot_name=chatbot.get("name", ""),
                    owner_email=chatbot.get("handoff_email") or "",
                    conversation_history=history,
                    trigger_message=message.message,
                    chatbot_id=chatbot_id,
                    conversation_id=conversation["id"],
                    webhook_url=_settings.n8n_handoff_webhook_url,
                )
            except Exception:
                pass  # never block chat on handoff failure

    # Check lead capture
    needs_lead_capture = False
    if (
        chatbot.get("lead_capture_enabled")
        and chatbot.get("lead_capture_trigger") == "after_first_message"
        and len(history) == 0
    ):
        needs_lead_capture = True

    # Save messages
    _save_message(conversation["id"], "user", message.message, supabase)
    _save_message(
        conversation["id"],
        "assistant",
        result["response"],
        supabase,
        sources=[s.model_dump() for s in result.get("sources", [])],
        model=result.get("model", ""),
        confidence_score=confidence_score,
        is_handoff=is_handoff,
    )

    # Update conversation message count
    supabase.table("conversations").update({
        "message_count": len(history) + 2
    }).eq("id", conversation["id"]).execute()

    return ChatResponse(
        response=result["response"],
        session_id=session_id,
        sources=result.get("sources", []),
        model_used=result.get("model", ""),
        tokens_used=result.get("tokens_used", 0),
        needs_lead_capture=needs_lead_capture,
        handoff=is_handoff,
    )


@router.get("/chat/{chatbot_id}/history/{session_id}", response_model=List[MessageResponse])
async def get_chat_history(
        chatbot_id: str,
        session_id: str,
        user=Depends(get_optional_user),
):
    supabase = get_supabase()

    conversation = supabase.table("conversations").select("*") \
        .eq("chatbot_id", chatbot_id) \
        .eq("session_id", session_id) \
        .execute()

    if not conversation.data:
        return []

    conv_id = conversation.data[0]["id"]
    messages = supabase.table("messages").select("*") \
        .eq("conversation_id", conv_id) \
        .order("created_at", desc=False) \
        .execute()

    return [
        MessageResponse(
            id=m["id"],
            role=m["role"],
            content=m["content"],
            sources=m.get("sources"),
            created_at=m.get("created_at"),
        )
        for m in (messages.data or [])
    ]


@router.post("/chat/{chatbot_id}/feedback")
async def submit_feedback(chatbot_id: str, data: FeedbackCreate):
    """Submit feedback (thumbs up/down) for a message. No auth required."""
    import uuid as _uuid
    if data.feedback not in ("positive", "negative"):
        raise HTTPException(status_code=400, detail="Feedback must be 'positive' or 'negative'")

    supabase = get_supabase()

    # Verify message exists
    msg = supabase.table("messages").select("id, conversation_id").eq("id", data.message_id).execute()
    if not msg.data:
        raise HTTPException(status_code=404, detail="Message not found")

    supabase.table("message_feedback").insert({
        "id": str(_uuid.uuid4()),
        "message_id": data.message_id,
        "chatbot_id": chatbot_id,
        "feedback": data.feedback,
    }).execute()

    return {"success": True}


# ── OLD analytics endpoint REMOVED ───────────────────────────────────────────
# The /analytics/{chatbot_id} endpoint that was here has been replaced by
# the dedicated analytics router (app/routers/analytics.py) which provides:
#   GET /api/v1/analytics/overview      — All chatbots overview
#   GET /api/v1/analytics/chatbot/{id}  — Single chatbot detail
# The old endpoint conflicted with the new router because FastAPI matched
# "overview" as a chatbot_id UUID, causing a 500 error.
# ─────────────────────────────────────────────────────────────────────────────


# ── Helpers ───────────────────────────────────────────────────────────────────

def _get_or_create_conversation(
        chatbot_id: str,
        session_id: str,
        user_id: Optional[str],
        language: str,
        supabase,
) -> dict:
    existing = supabase.table("conversations").select("*") \
        .eq("chatbot_id", chatbot_id) \
        .eq("session_id", session_id) \
        .execute()

    if existing.data:
        return existing.data[0]

    new_conv = {
        "id": str(uuid.uuid4()),
        "chatbot_id": chatbot_id,
        "user_id": user_id,
        "session_id": session_id,
        "language": language,
        "message_count": 0,
    }
    result = supabase.table("conversations").insert(new_conv).execute()
    return result.data[0]


def _get_conversation_history(conversation_id: str, supabase) -> List[dict]:
    """
    Returns conversation history in chronological order (oldest first)
    for the LLM to correctly understand the conversation flow.
    """
    messages = supabase.table("messages").select("role, content") \
        .eq("conversation_id", conversation_id) \
        .order("created_at", desc=False) \
        .limit(20) \
        .execute()
    return messages.data or []


def _save_message(
        conversation_id: str,
        role: str,
        content: str,
        supabase,
        sources: Optional[list] = None,
        model: str = "",
        confidence_score: Optional[float] = None,
        is_handoff: bool = False,
):
    supabase.table("messages").insert({
        "id": str(uuid.uuid4()),
        "conversation_id": conversation_id,
        "role": role,
        "content": content,
        "sources": sources,
        "model": model,
        "confidence_score": confidence_score,
        "is_handoff": is_handoff,
    }).execute()