back/tools.py

import math
import requests
import ast
import operator
from typing import Union, Dict, Any

# ==============================
# MATH TOOL
# ==============================

def calculate_expression(expression: str) -> Union[float, str]:
    """
    Safely evaluate a mathematical expression.
    Supported operators: +, -, *, /, **, %, ^ (as power), sqrt, abs, round, sin, cos, tan, log, pi, e
    """
    # Safe operators map
    operators = {
        ast.Add: operator.add,
        ast.Sub: operator.sub,
        ast.Mult: operator.mul,
        ast.Div: operator.truediv,
        ast.Pow: operator.pow,
        ast.Mod: operator.mod,
        ast.USub: operator.neg,
        ast.UAdd: operator.pos,
    }

    # Safe functions map
    functions = {
        "sqrt": math.sqrt,
        "abs": abs,
        "round": round,
        "sin": math.sin,
        "cos": math.cos,
        "tan": math.tan,
        "log": math.log,
        "max": max,
        "min": min,
        "ceil": math.ceil,
        "floor": math.floor,
        "degrees": math.degrees,
        "radians": math.radians,
    }

    # Safe constants
    constants = {
        "pi": math.pi,
        "e": math.e,
        "tau": math.tau,
    }

    def eval_node(node):
        if isinstance(node, ast.Num):  # < 3.8
            return node.n
        elif isinstance(node, ast.Constant):  # >= 3.8
            if isinstance(node.value, (int, float)):
                return node.value
            raise ValueError(f"Unsupported constant type: {type(node.value)}")
        elif isinstance(node, ast.BinOp): # <left> <operator> <right>
            op = type(node.op)
            if op not in operators:
                raise ValueError(f"Unsupported operator: {op}")
            return operators[op](eval_node(node.left), eval_node(node.right))
        elif isinstance(node, ast.UnaryOp): # <operator> <operand> (e.g., -1)
            op = type(node.op)
            if op not in operators:
                raise ValueError(f"Unsupported unary operator: {op}")
            return operators[op](eval_node(node.operand))
        elif isinstance(node, ast.Call): # Function calls like sqrt(4)
            if not isinstance(node.func, ast.Name):
                raise ValueError("Only named functions are supported")
            if node.func.id not in functions:
                raise ValueError(f"Unsupported function: {node.func.id}")
            args = [eval_node(arg) for arg in node.args]
            return functions[node.func.id](*args)
        elif isinstance(node, ast.Name): # Variables/Constants
            if node.id in constants:
                return constants[node.id]
            raise ValueError(f"Unsupported name: {node.id}")
        else:
            raise TypeError(f"Unsupported expression node: {type(node)}")

    try:
        # Pre-process: replace ^ with ** for power
        expression = expression.replace("^", "**")
        node = ast.parse(expression, mode='eval')
        result = eval_node(node.body)
        return float(result)
    except Exception as e:
        return f"Error calculating '{expression}': {str(e)}"

# ==============================
# WEATHER TOOL
# ==============================

def get_current_weather(location: str) -> Dict[str, Any]:
    """
    Get current weather for a specific city using Open-Meteo API.
    Returns temperature (C), humidity, wind speed, etc.
    """
    try:
        # 1. Geocoding
        geo_url = "https://geocoding-api.open-meteo.com/v1/search"
        geo_params = {"name": location, "count": 1, "language": "en", "format": "json"}
        
        geo_res = requests.get(geo_url, params=geo_params, timeout=5)
        geo_data = geo_res.json()

        if not geo_data.get("results"):
            return {"error": f"City '{location}' not found."}

        location = geo_data["results"][0]
        lat = location["latitude"]
        lon = location["longitude"]
        city_name = location["name"]
        country = location.get("country", "")

        # 2. Weather Data
        weather_url = "https://api.open-meteo.com/v1/forecast"
        weather_params = {
            "latitude": lat,
            "longitude": lon,
            "current": "temperature_2m,relative_humidity_2m,apparent_temperature,precipitation,rain,showers,snowfall,weather_code,cloud_cover,wind_speed_10m",
            "timezone": "auto"
        }

        w_res = requests.get(weather_url, params=weather_params, timeout=5)
        w_data = w_res.json()

        if "current" not in w_data:
            return {"error": "{location} Weather data not available."}

        current = w_data["current"]
        current_units = w_data["current_units"]

        # Decode WMO Weather Code
        # source: https://open-meteo.com/en/docs
        wmo_code = current["weather_code"]
        condition = "Unknown"
        if wmo_code == 0: condition = "Clear sky"
        elif 1 <= wmo_code <= 3: condition = "Mainly clear, partly cloudy, and overcast"
        elif 45 <= wmo_code <= 48: condition = "Fog and depositing rime fog"
        elif 51 <= wmo_code <= 55: condition = "Drizzle: Light, moderate, and dense intensity"
        elif 56 <= wmo_code <= 57: condition = "Freezing Drizzle: Light and dense intensity"
        elif 61 <= wmo_code <= 65: condition = "Rain: Slight, moderate and heavy intensity"
        elif 66 <= wmo_code <= 67: condition = "Freezing Rain: Light and heavy intensity"
        elif 71 <= wmo_code <= 75: condition = "Snow fall: Slight, moderate, and heavy intensity"
        elif 77: condition = "Snow grains"
        elif 80 <= wmo_code <= 82: condition = "Rain showers: Slight, moderate, and violent"
        elif 85 <= wmo_code <= 86: condition = "Snow showers slight and heavy"
        elif 95: condition = "Thunderstorm: Slight or moderate"
        elif 96 <= wmo_code <= 99: condition = "Thunderstorm with slight and heavy hail"

        return {
            "location": f"{city_name}, {country}",
            "temperature": f"{current['temperature_2m']} {current_units['temperature_2m']}",
            "feels_like": f"{current['apparent_temperature']} {current_units['apparent_temperature']}",
            "humidity": f"{current['relative_humidity_2m']} {current_units['relative_humidity_2m']}",
            "wind_speed": f"{current['wind_speed_10m']} {current_units['wind_speed_10m']}",
            "condition": condition,
            "cloud_cover": f"{current['cloud_cover']} {current_units['cloud_cover']}",
            "timestamp": current["time"]
        }

    except Exception as e:
        return {"error": f"Failed to fetch weather: {str(e)}"}