import uuid
from datetime import datetime
from typing import List, Optional
from core.memory import get_redis_client
from .models import GoalCreate, GoalUpdate, GoalInDB

def _get_redis_key(user_id: str, goal_id: str) -> str:
    return f"user:{user_id}:goals:{goal_id}"

def _get_index_key(user_id: str) -> str:
    return f"user:{user_id}:goals:index"

def create_goal(user_id: str, goal_data: GoalCreate) -> GoalInDB:
    redis_client = get_redis_client()
    if not redis_client:
        raise RuntimeError("Redis connection unavailable.")

    goal_id = str(uuid.uuid4())
    now = datetime.utcnow()
    goal_dict = {
        "id": goal_id,
        "user_id": user_id,
        "title": goal_data.title,
        "description": goal_data.description or "",
        "target_date": goal_data.target_date.isoformat() if goal_data.target_date else "",
        "created_at": now.isoformat(),
        "updated_at": now.isoformat()
    }

    redis_client.hset(_get_redis_key(user_id, goal_id), mapping=goal_dict)
    redis_client.zadd(_get_index_key(user_id), {goal_id: now.timestamp()})

    return GoalInDB(**goal_dict)

def get_goals(user_id: str) -> List[GoalInDB]:
    redis_client = get_redis_client()
    if not redis_client:
        return []

    goal_ids = redis_client.zrange(_get_index_key(user_id), 0, -1)
    goals = []

    for gid in goal_ids:
        raw_goal = redis_client.hgetall(_get_redis_key(user_id, gid))
        if raw_goal:
            # Parse dates back to datetime objects
            raw_goal["target_date"] = datetime.fromisoformat(raw_goal["target_date"]) if raw_goal["target_date"] else None
            raw_goal["created_at"] = datetime.fromisoformat(raw_goal["created_at"])
            raw_goal["updated_at"] = datetime.fromisoformat(raw_goal["updated_at"])
            goals.append(GoalInDB(**raw_goal))

    return goals

def get_goal_by_id(user_id: str, goal_id: str) -> Optional[GoalInDB]:
    redis_client = get_redis_client()
    if not redis_client:
        return None

    raw_goal = redis_client.hgetall(_get_redis_key(user_id, goal_id))
    if not raw_goal:
        return None

    raw_goal["target_date"] = datetime.fromisoformat(raw_goal["target_date"]) if raw_goal["target_date"] else None
    raw_goal["created_at"] = datetime.fromisoformat(raw_goal["created_at"])
    raw_goal["updated_at"] = datetime.fromisoformat(raw_goal["updated_at"])

    return GoalInDB(**raw_goal)

def update_goal(user_id: str, goal_id: str, updates: GoalUpdate) -> Optional[GoalInDB]:
    redis_client = get_redis_client()
    if not redis_client:
        return None

    raw_goal = redis_client.hgetall(_get_redis_key(user_id, goal_id))
    if not raw_goal:
        return None

    # Apply updates
    update_data = updates.dict(exclude_unset=True)
    for field, value in update_data.items():
        if isinstance(value, datetime):
            raw_goal[field] = value.isoformat()
        else:
            raw_goal[field] = value

    raw_goal["updated_at"] = datetime.utcnow().isoformat()

    redis_client.hset(_get_redis_key(user_id, goal_id), mapping=raw_goal)

    parsed_goal = raw_goal.copy()
    parsed_goal["target_date"] = datetime.fromisoformat(parsed_goal["target_date"]) if parsed_goal["target_date"] else None
    parsed_goal["created_at"] = datetime.fromisoformat(parsed_goal["created_at"])
    parsed_goal["updated_at"] = datetime.fromisoformat(parsed_goal["updated_at"])

    return GoalInDB(**parsed_goal)

def delete_goal(user_id: str, goal_id: str) -> bool:
    redis_client = get_redis_client()
    if not redis_client:
        return False

    pipe = redis_client.pipeline()
    pipe.delete(_get_redis_key(user_id, goal_id))
    pipe.zrem(_get_index_key(user_id), goal_id)
    results = pipe.execute()

    return results[0] > 0  # True if deleted