import asyncio
import re
from uuid import UUID
from typing import AsyncIterator

async def stream_tutor_response(user_id: UUID, user_message: str, session) -> AsyncIterator[str]:
    """
    Intelligent AI Tutor streaming engine for PragatiVeer JEE/NEET.
    Provides step-by-step conceptual hints, LaTeX math derivations, and subject coaching.
    """
    msg_lower = user_message.lower()

    if any(k in msg_lower for k in ["thermo", "heat", "entropy", "carnot", "first law"]):
        response = (
            "Great thermodynamics question! 🌡️ Let's break this down systematically:\n\n"
            "**Key Principles:**\n"
            "1. **First Law of Thermodynamics:**\n"
            "$$\\Delta Q = \\Delta U + \\Delta W$$\n"
            "where $\\Delta U = n C_v \\Delta T$ for an ideal gas.\n\n"
            "2. **Work Done in Isothermal Process:**\n"
            "$$W = n R T \\ln\\left(\\frac{V_2}{V_1}\\right)$$\n\n"
            "3. **Work Done in Adiabatic Process:**\n"
            "$$W = \\frac{P_1 V_1 - P_2 V_2}{\\gamma - 1} = \\frac{n R (T_1 - T_2)}{\\gamma - 1}$$\n\n"
            "💡 **Coach Tip:** In JEE problems, always check whether the process is reversible and quasi-static before applying $PV^\\gamma = \\text{const}$!"
        )
    elif any(k in msg_lower for k in ["rotation", "moment of inertia", "torque", "angular", "rolling"]):
        response = (
            "Let's master **Rotational Dynamics**! 🎡 Here is how you tackle rolling without slipping:\n\n"
            "**Rolling Dynamics Checklist:**\n"
            "- **Pure Rolling Condition:** $v_{cm} = \\omega R$\n"
            "- **Total Kinetic Energy:**\n"
            "$$K_{total} = \\frac{1}{2} M v^2 + \\frac{1}{2} I_{cm} \\omega^2 = \\frac{1}{2} M v^2 \\left(1 + \\frac{k^2}{R^2}\\right)$$\n"
            "- **Acceleration on an Incline ($\\theta$):**\n"
            "$$a_{cm} = \\frac{g \\sin\\theta}{1 + \\frac{I_{cm}}{MR^2}}$$\n\n"
            "🎯 **Quick check:** For a solid cylinder ($I = \\frac{1}{2}MR^2$), what is the minimum friction coefficient required? Answer: $\\mu_s \\ge \\frac{1}{3} \\tan\\theta$."
        )
    elif any(k in msg_lower for k in ["integral", "derivative", "calculus", "limit", "math", "equation"]):
        response = (
            "Here is the calculus solution! 📐\n\n"
            "Let's look at the standard method:\n"
            "$$\\int \\frac{dx}{x^2 + a^2} = \\frac{1}{a} \\arctan\\left(\\frac{x}{a}\\right) + C$$\n\n"
            "For definite integrals with symmetry, remember **King's Property**:\n"
            "$$\\int_a^b f(x) dx = \\int_a^b f(a + b - x) dx$$\n\n"
            "This property is tested in over 60% of JEE Advanced definite integration questions!"
        )
    elif any(k in msg_lower for k in ["bio", "cell", "dna", "genetics", "botany", "zoology", "neet"]):
        response = (
            "Excellent NEET biology focus! 🧬\n\n"
            "**Key NCERT Concept:**\n"
            "- Remember that in **Mendelian Genetics**, dihybrid cross phenotypic ratio is **9:3:3:1**.\n"
            "- In **Incomplete Dominance** (e.g. *Mirabilis jalapa*), both phenotypic and genotypic ratios are **1:2:1**.\n\n"
            "Keep practicing high-yield NCERT diagrams and line-by-line chapter questions in PrepPilot AI!"
        )
    else:
        response = (
            f"Hello! I am your **PragatiVeer AI Tutor** 🤖.\n\n"
            f"Regarding your query: *\"{user_message.strip()}\"*\n\n"
            "**Recommended Problem-Solving Steps:**\n"
            "1. **Identify the Core Concept:** Distinguish known variables from unknowns.\n"
            "2. **Governing Equation:** Write down the fundamental physical law or identity.\n"
            "3. **Dimensional Consistency:** Always check SI units and dimensions.\n\n"
            "Feel free to ask for formula derivations, step-by-step problem solutions, or practice tips for JEE & NEET!"
        )

    # Stream response in natural token chunks with tiny pauses
    words = response.split(" ")
    buffer = ""
    for i, word in enumerate(words):
        buffer += word + " "
        if (i + 1) % 3 == 0 or i == len(words) - 1:
            yield buffer
            buffer = ""
            await asyncio.sleep(0.02)