helpers.py

import os
import requests
import urllib.parse

from flask import redirect, render_template, request, session
from functools import wraps


def apology(message, code=400):
    """Render message as an apology to user."""

    def escape(s):
        """
        Escape special characters.

        https://github.com/jacebrowning/memegen#special-characters
        """
        for old, new in [
            ("-", "--"),
            (" ", "-"),
            ("_", "__"),
            ("?", "~q"),
            ("%", "~p"),
            ("#", "~h"),
            ("/", "~s"),
            ('"', "''"),
        ]:
            s = s.replace(old, new)
        return s

    return render_template("apology.html", top=code, bottom=escape(message)), code


def login_required(f):
    """
    Decorate routes to require login.

    http://flask.pocoo.org/docs/1.0/patterns/viewdecorators/
    """

    @wraps(f)
    def decorated_function(*args, **kwargs):
        if session.get("user_id") is None:
            return redirect("/login")
        return f(*args, **kwargs)

    return decorated_function


def lookup(symbol):
    """Look up quote for symbol."""

    # Contact API
    try:
        api_key = os.environ.get("API_KEY")
        response = requests.get(
            f"https://cloud-sse.iexapis.com/stable/stock/{urllib.parse.quote_plus(symbol)}/quote?token={api_key}"
        )
        response.raise_for_status()
    except requests.RequestException:
        return None

    # Parse response
    try:
        quote = response.json()
        return {
            "name": quote["companyName"],
            "price": float(quote["latestPrice"]),
            "symbol": quote["symbol"],
        }
    except (KeyError, TypeError, ValueError):
        return None


def get_all_symbols():
    """Get all stock symbols."""

    # Contact API
    try:
        api_key = os.environ.get("API_KEY")
        response = requests.get(
            f"https://cloud-sse.iexapis.com/stable/ref-data/symbols?token={api_key}"
        )
        response.raise_for_status()
    except requests.RequestException:
        return None

    # Parse response
    try:
        symbols = []
        stock_data = response.json()
        for stock in stock_data:
            symbols.append(stock["symbol"])
        return symbols
    except (KeyError, TypeError, ValueError):
        return None


def usd(value):
    """Format value as USD."""
    return f"${value:,.2f}"


def validate_transaction(symbol=None, shares=None):
    # validate the transaction and get the current stock data
    # ensure the user has entered a stock symbol
    if not symbol:
        return ("must provide a stock symbol", 418)

    # ensure the user has submitted a number of shares
    if not shares:
        return ("must provide an amount of shares", 418)

    # validate that user is entering a number of shares
    # the form itself should also protect against this
    try:
        shares = int(shares)
    except ValueError:
        return ("must provide a number of shares", 418)