text: import os
  
  from cs50 import SQL
  from flask import Flask, flash, jsonify, redirect, render_template, request, session
  from flask_session import Session
  from tempfile import mkdtemp
  from werkzeug.exceptions import default_exceptions, HTTPException, InternalServerError
  from werkzeug.security import check_password_hash, generate_password_hash
  
  from helpers import apology, login_required, lookup, usd
  
  # Configure application
  app = Flask(__name__)
  
  # Ensure templates are auto-reloaded
  app.config["TEMPLATES_AUTO_RELOAD"] = True
  
  # Ensure responses aren't cached
  
  
  @app.after_request
  def after_request(response):
      response.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
      response.headers["Expires"] = 0
      response.headers["Pragma"] = "no-cache"
      return response
  
  
  # Custom filter
  app.jinja_env.filters["usd"] = usd
  
  # Configure session to use filesystem (instead of signed cookies)
  app.config["SESSION_FILE_DIR"] = mkdtemp()
  app.config["SESSION_PERMANENT"] = False
  app.config["SESSION_TYPE"] = "filesystem"
  Session(app)
  
  # Configure CS50 Library to use SQLite database
  db = SQL("sqlite:///finance.db")
  
  # Make sure API key is set
  if not os.environ.get("API_KEY"):
      raise RuntimeError("API_KEY not set")
  
  
  @app.route("/")
  @login_required
  def index():
      """Show portfolio of stocks"""
      rows = db.execute("SELECT cash FROM users WHERE id = :id", id=session["user_id"])
      balance = rows[0]['cash']
      grandtotal = balance
      rows = db.execute("SELECT symbol FROM tranzact WHERE user_id=:id", id=session["user_id"])
      symbols = []
      for row in rows:
          symbols.append(row['symbol'])
      symbols = list(set(symbols))
      data = []
      print(symbols)
      for i in range(len(symbols)):
          rows = db.execute("SELECT symbol, SUM(shares) FROM tranzact WHERE user_id=:id AND symbol=:symbol",
                            id=session["user_id"], symbol=symbols[i])
          quote = lookup(symbols[i])
          rows[0]['price'] = quote['price']
          rows[0]['name'] = quote['name']
          rows[0]['symbol'] = quote['symbol']
          rows[0]['total'] = rows[0]['SUM(shares)']*rows[0]['price']
          if rows[0]['SUM(shares)'] > 0:
              data.append(rows[0])
              grandtotal += rows[0]['total']
      print(data)
      return render_template("index.html", bigdata=data, balance=balance, grandtotal=grandtotal)
  
  
  @app.route("/buy", methods=["GET", "POST"])
  @login_required
  def buy():
      """Buy shares of stock"""
      if request.method == "POST":
          symbol = request.form.get("symbol")
          try:
              shares = int(request.form.get("shares"))
          except ValueError:
              return apology("you can only supply an integer", 400)
          if not symbol:
              return apology("must provide symbol", 400)
          quote = lookup(symbol)
          if not quote:
              return apology("Enter a valid symbol plix", 400)
          if not shares:
              return apology("must provide shares", 400)
          if shares < 1:
              return apology("shares should be a positive integer", 400)
          price = shares * quote["price"]
          rows = db.execute("SELECT cash FROM users WHERE id = :id", id=session["user_id"])
          cash = rows[0]['cash']
          if cash < price:
              return apology("Sorry ... You can't afford this", 400)
          balance = cash - price
          symbol = quote['symbol']
          db.execute("INSERT INTO tranzact (user_id, symbol, shares, price) VALUES (:user, :symbol, :shares, :price)",
                     user=session["user_id"], symbol=symbol, shares=shares, price=quote["price"])
          db.execute("UPDATE users SET cash=:balance WHERE id=:id", balance=balance, id=session["user_id"])
          # Redirect user to home page
          return redirect("/")
      else:
          return render_template("buy.html")
  
  
  @app.route("/check", methods=["GET"])
  def check():
      """Return true if username available, else false, in JSON format"""
      username = request.args.get("username")
      print(username)
      # Query database for username
      rows = db.execute("SELECT * FROM users WHERE username = :username", username=username)
      print(rows)
      # Ensure username exists and password is correct
      if len(rows) >= 1:
          return jsonify(False)
      else:
          return jsonify(True)
  
  
  @app.route("/history")
  @login_required
  def history():
      """Show history of transactions"""
      rows = db.execute("SELECT symbol, shares, price, time FROM tranzact WHERE user_id=:id ORDER BY time DESC",
                        id=session["user_id"])
      print(rows)
      return render_template("history.html", bigdata=rows)
  
  
  @app.route("/login", methods=["GET", "POST"])
  def login():
      """Log user in"""
      # Forget any user_id
      session.clear()
      # User reached route via POST (as by submitting a form via POST)
      if request.method == "POST":
          username = request.form.get("username").strip()
          password = request.form.get("password")
          # Ensure username was submitted
          if not username:
              return apology("must provide username", 403)
          # Ensure password was submitted
          elif not password:
              return apology("must provide password", 403)
          username = request.form.get("username")
          # Query database for username
          rows = db.execute("SELECT * FROM users WHERE username = :username", username=username)
          # Ensure username exists and password is correct
          if len(rows) != 1 or not check_password_hash(rows[0]["hash"], password):
              return apology("invalid username and/or password", 403)
          print
          # Remember which user has logged in
          session["user_id"] = rows[0]["id"]
          # Redirect user to home page
          return redirect("/")
      # User reached route via GET (as by clicking a link or via redirect)
      else:
          return render_template("login.html")
  
  
  @app.route("/logout")
  def logout():
      """Log user out"""
      # Forget any user_id
      session.clear()
      # Redirect user to login form
      return redirect("/")
  
  
  @app.route("/quote", methods=["GET", "POST"])
  @login_required
  def quote():
      """Get stock quote."""
      if request.method == "POST":
          symbol = request.form.get("symbol")
          if not symbol:
              return apology("must provide symbol", 400)
          quote = lookup(symbol)
          if not quote:
              return apology("Enter a valid symbol plix", 400)
          return render_template("quoted.html", quote=quote)
      else:
          return render_template("quote.html")
  
  
  @app.route("/register", methods=["GET", "POST"])
  def register():
      """Register user"""
      # Forget any user_id
      session.clear()
      # User reached route via POST (as by submitting a form via POST)
      if request.method == "POST":
          username = request.form.get("username").strip()
          password = request.form.get("password")
          confirmation = request.form.get("confirmation")
          # Ensure username was submitted
          if not username:
              return apology("must provide username", 400)
          # Ensure password was submitted
          elif not password:
              return apology("must provide password", 400)
          if password != confirmation:
              return apology("passwords must match", 400)
          else:
              rows = db.execute("SELECT * FROM users WHERE username = :username", username=username)
              # Ensure username exists and password is correct
              if len(rows) >= 1:
                  return apology("User already exists", 400)
              hash = generate_password_hash(password, method='pbkdf2:sha256', salt_length=8)
              db.execute("INSERT INTO users (username, hash) VALUES (:username, :hash)", username=username, hash=hash)
          # Query database for username
          rows = db.execute("SELECT * FROM users WHERE username = :username", username=username)
          # Remember which user has logged in
          session["user_id"] = rows[0]["id"]
          # Redirect user to home page
          return redirect("/")
      # User reached route via GET (as by clicking a link or via redirect)
      else:
          return render_template("register.html")
  
  
  @app.route("/sell", methods=["GET", "POST"])
  @login_required
  def sell():
      """Sell shares of stock"""
      if request.method == "POST":
          symbol = request.form.get("symbol")
          shares = int(request.form.get("shares"))
          if not symbol:
              return apology("must provide symbol", 400)
          quote = lookup(symbol)
          if not quote:
              return apology("Enter a valid symbol plix", 400)
          if not shares:
              return apology("must provide shares", 400)
          if shares < 1:
              return apology("shares should be a positive integer", 400)
          symbol = quote['symbol']
          rows = db.execute("SELECT SUM(shares) FROM tranzact WHERE user_id = :id AND symbol = :symbol",
                            id=session["user_id"], symbol=symbol)
          stock = rows[0]['SUM(shares)']
          if not stock:
              return apology(f"Sorry ... You don't have any shares with {quote['name']}", 400)
          if stock < shares:
              return apology(f"Sorry ... You don't have enough {quote['name']} shares to sell", 400)
          price = shares * quote['price']
          shares = -shares
          db.execute("INSERT INTO tranzact (user_id, symbol, shares, price) VALUES (:user, :symbol, :shares, :price)",
                     user=session["user_id"], symbol=symbol, shares=shares, price=quote["price"])
          rows = db.execute("SELECT cash FROM users WHERE id = :id", id=session["user_id"])
          cash = rows[0]['cash']
          balance = cash + price
          db.execute("UPDATE users SET cash=:balance WHERE id=:id", balance=balance, id=session["user_id"])
          # Redirect user to home page
          return redirect("/")
      else:
          rows = db.execute("SELECT symbol FROM tranzact WHERE user_id=:id", id=session["user_id"])
          symbols = []
          for row in rows:
              symbols.append(row['symbol'])
          symbols = list(set(symbols))
          data = []
          for symbol in symbols:
              rows = db.execute("SELECT symbol, SUM(shares) FROM tranzact WHERE user_id=:id AND symbol=:symbol",
                                id=session["user_id"], symbol=symbol)
              if rows[0]['SUM(shares)'] > 0:
                  data.append(rows[0]['symbol'])
          print(data)
          return render_template("sell.html", data=data)
  
  
  def errorhandler(e):
      """Handle error"""
      if not isinstance(e, HTTPException):
          e = InternalServerError()
      return apology(e.name, e.code)
  
  
  # Listen for errors
  for code in default_exceptions:
      app.errorhandler(code)(errorhandler)