import json
import os
from typing import Any, Dict, List, Optional

from supabase import Client, create_client


_SUPABASE_CLIENT: Optional[Client] = None


def _get_client() -> Client:
    """Create (or reuse) a Supabase client for database interactions."""
    global _SUPABASE_CLIENT
    if _SUPABASE_CLIENT is None:
        url = os.getenv("SUPABASE_URL")
        service_role_key = os.getenv("SUPABASE_SERVICE_ROLE_KEY")
        if not url or not service_role_key:
            raise RuntimeError(
                "SUPABASE_URL and SUPABASE_SERVICE_ROLE_KEY must be set for database access."
            )
        _SUPABASE_CLIENT = create_client(url, service_role_key)
    return _SUPABASE_CLIENT


def _execute(query):
    response = query.execute()
    if response.error:
        raise RuntimeError(f"Supabase error: {response.error.message}")
    return response


def _ensure_user_profile(user_id: str) -> None:
    client = _get_client()
    _execute(
        client.table("user_profiles").upsert({"user_id": user_id}, on_conflict="user_id")
    )


def get_user_profile(user_id: str) -> Optional[Dict[str, Any]]:
    client = _get_client()
    response = _execute(
        client.table("user_profiles")
        .select("user_id, name, preferences, personality_summary, last_updated, created_at")
        .eq("user_id", user_id)
        .limit(1)
    )
    if not response.data:
        return None
    record = response.data[0]
    if isinstance(record.get("preferences"), str):
        try:
            record["preferences"] = json.loads(record["preferences"])
        except json.JSONDecodeError:
            record["preferences"] = {}
    return record


def update_user_profile(
    user_id: str,
    *,
    name: Optional[str] = None,
    preferences: Optional[str] = None,
    personality_summary: Optional[str] = None,
) -> None:
    updates: Dict[str, Any] = {}
    if name is not None:
        updates["name"] = name
    if preferences is not None:
        updates["preferences"] = preferences
    if personality_summary is not None:
        updates["personality_summary"] = personality_summary

    if not updates:
        return

    client = _get_client()
    _ensure_user_profile(user_id)
    _execute(client.table("user_profiles").update(updates).eq("user_id", user_id))


def save_conversation(user_id: str, user_message: str, ai_response: str) -> str:
    client = _get_client()
    _ensure_user_profile(user_id)
    response = _execute(
        client.table("conversations").insert(
            {
                "user_id": user_id,
                "user_message": user_message,
                "ai_response": ai_response,
            }
        )
    )
    inserted = response.data[0]
    return str(inserted.get("id"))


def get_recent_conversations(user_id: str, limit: Optional[int] = None) -> List[Dict[str, Any]]:
    client = _get_client()
    query = (
        client.table("conversations")
        .select("user_message, ai_response, created_at")
        .eq("user_id", user_id)
        .order("created_at", desc=True)
    )
    if limit is not None:
        query = query.limit(limit)
    response = _execute(query)
    return response.data or []


def get_conversation_history(user_id: str) -> List[Dict[str, Any]]:
    client = _get_client()
    response = _execute(
        client.table("conversations")
        .select("user_message, ai_response, created_at")
        .eq("user_id", user_id)
        .order("created_at", desc=False)
    )
    return response.data or []


def count_user_messages(user_id: str) -> int:
    client = _get_client()
    response = _execute(
        client.table("conversations")
        .select("id", count="exact")
        .eq("user_id", user_id)
    )
    return response.count or 0


def update_user_profile_summary(user_id: str, summary: str) -> None:
    update_user_profile(user_id, personality_summary=summary)


def get_user_embeddings(user_id: str) -> List[Dict[str, Any]]:
    client = _get_client()
    response = _execute(
        client.table("embeddings")
        .select("text, embedding")
        .eq("user_id", user_id)
        .order("created_at", desc=True)
    )
    items: List[Dict[str, Any]] = []
    for record in response.data or []:
        embedding = record.get("embedding")
        if isinstance(embedding, str):
            try:
                embedding = json.loads(embedding)
            except json.JSONDecodeError:
                embedding = []
        items.append({"text": record.get("text", ""), "embedding": embedding})
    return items


def add_embedding(user_id: str, text: str, embedding: List[float]) -> None:
    client = _get_client()
    _ensure_user_profile(user_id)
    _execute(
        client.table("embeddings").insert(
            {
                "user_id": user_id,
                "text": text,
                "embedding": embedding,
            }
        )
    )