import uuid
from datetime import datetime

class GoalTracker:
    def __init__(self):
        self.goals = {}

    def add_goal(self, user_id: str, goal_text: str):
        goal_id = str(uuid.uuid4())
        self.goals[goal_id] = {
            "user_id": user_id,
            "goal": goal_text,
            "created": datetime.utcnow().isoformat(),
            "subtasks": [],
            "completed": False
        }
        return goal_id

    def add_subtask(self, goal_id: str, task_text: str):
        if goal_id in self.goals:
            self.goals[goal_id]["subtasks"].append({"task": task_text, "done": False})

    def complete_subtask(self, goal_id: str, index: int):
        if goal_id in self.goals and 0 <= index < len(self.goals[goal_id]["subtasks"]):
            self.goals[goal_id]["subtasks"][index]["done"] = True

    def list_goals(self, user_id: str):
        return {gid: g for gid, g in self.goals.items() if g["user_id"] == user_id}

    def mark_complete(self, goal_id: str):
        if goal_id in self.goals:
            self.goals[goal_id]["completed"] = True

    def summarize_goal(self, goal_id: str):
        g = self.goals.get(goal_id, {})
        summary = f"🎯 Goal: {g.get('goal')}\n"
        for i, task in enumerate(g.get("subtasks", [])):
            check = "✅" if task["done"] else "🔲"
            summary += f"{check} {i+1}. {task['task']}\n"
        return summary.strip()