I wish to build a simple website using python, HTML and javascript. it is a just a personal note taking and photo storage website.

can you write me a simple webpage that has the following features:
1. signup/sign-in authentication using google
2. a notes tab in which it is possible to enter text messages and send them to the site and view previously sent messages via scrolling up and down
3. an image database tab in which it is possible to upload an image and view past uploaded images via scrolling up and down

Also, can write a minimal backend server that is locally hosted using a mongodb dataset that holds the images and text messages uploaded for each user?
Sure, I can give you a sample code for the web application you described. Please note that this is just a sample code and you would need to make some modifications based on your specific needs.

Here's the HTML code for the login page, which will redirect the user to the notes and image database pages after successful authentication:
```html
<!DOCTYPE html>
<html>
  <head>
    <title>Login with Google</title>
  </head>
  <body>
    <h1>Login with Google</h1>
    <div class="g-signin2" data-onsuccess="onSignIn"></div>
    <script src="https://apis.google.com/js/platform.js" async defer></script>
    <script>
      function onSignIn(googleUser) {
        var id_token = googleUser.getAuthResponse().id_token;
        // send the id_token to the server to authenticate the user
        // if successful, redirect to the notes page
        window.location.href = "/notes";
      }
    </script>
  </body>
</html>
```
Here's the HTML code for the notes page, which includes a form to submit new notes and a container to display existing notes:
```html
<!DOCTYPE html>
<html>
  <head>
    <title>Notes</title>
  </head>
  <body>
    <h1>Notes</h1>
    <form id="note-form">
      <textarea id="note-text"></textarea>
      <button type="submit">Save</button>
    </form>
    <div id="note-container"></div>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/axios/0.21.1/axios.min.js"></script>
    <script>
      // get the user id from the server
      var userId = "123456";
      var noteForm = document.getElementById("note-form");
      var noteText = document.getElementById("note-text");
      var noteContainer = document.getElementById("note-container");
      noteForm.addEventListener("submit", function (event) {
        event.preventDefault();
        var note = {
          text: noteText.value,
          userId: userId,
        };
        axios.post("/api/notes", note).then(function (response) {
          noteText.value = "";
          getNotes();
        });
      });
      function getNotes() {
        axios.get("/api/notes?userId=" + userId).then(function (response) {
          noteContainer.innerHTML = "";
          response.data.forEach(function (note) {
            var noteElement = document.createElement("div");
            noteElement.innerHTML = note.text;
            noteContainer.appendChild(noteElement);
          });
        });
      }
      getNotes();
    </script>
  </body>
</html>
```
Here's the HTML code for the image database page, which includes a form to upload new images and a container to display existing images:
```html
<!DOCTYPE html>
<html>
  <head>
    <title>Image Database</title>
  </head>
  <body>
    <h1>Image Database</h1>
    <form id="image-form">
      <input type="file" id="image-file">
      <button type="submit">Upload</button>
    </form>
    <div id="image-container"></div>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/axios/0.21.1/axios.min.js"></script>
    <script>
      // get the user id from the server
      var userId = "123456";
      var imageForm = document.getElementById("image-form");
      var imageFile = document.getElementById("image-file");
      var imageContainer = document.getElementById("image-container");
      imageForm.addEventListener("submit", function (event){
    event.preventDefault();
    var formData = new FormData();
    formData.append("file", imageFile.files[0]);
    formData.append("userId", userId);
    axios.post("/api/images", formData).then(function (response) {
      imageFile.value = "";
      getImages();
    });
  });
  function getImages() {
    axios.get("/api/images?userId=" + userId).then(function (response) {
      imageContainer.innerHTML = "";
      response.data.forEach(function (image) {
        var imageElement = document.createElement("img");
        imageElement.src = "data:image/jpeg;base64," + image.data;
        imageContainer.appendChild(imageElement);
      });
    });
  }
  getImages();
</script>
  </body>
</html>
```
And here's a sample Python code for the backend server using Flask and PyMongo:
```python
from flask import Flask, request, jsonify
from flask_pymongo import PyMongo
from bson.objectid import ObjectId

app = Flask(__name__)
app.config["MONGO_URI"] = "mongodb://localhost:27017/mydatabase"
mongo = PyMongo(app)

@app.route("/api/notes", methods=["POST"])
def add_note():
    note = {
        "text": request.json["text"],
        "userId": request.json["userId"],
    }
    mongo.db.notes.insert_one(note)
    return jsonify(str(note["_id"]))

@app.route("/api/notes", methods=["GET"])
def get_notes():
    user_id = request.args.get("userId")
    notes = mongo.db.notes.find({"userId": user_id})
    return jsonify([{"_id": str(note["_id"]), "text": note["text"]} for note in notes])

@app.route("/api/images", methods=["POST"])
def add_image():
    image = {
        "data": request.files["file"].read(),
        "userId": request.form["userId"],
    }
    mongo.db.images.insert_one(image)
    return jsonify(str(image["_id"]))

@app.route("/api/images", methods=["GET"])
def get_images():
    user_id = request.args.get("userId")
    images = mongo.db.images.find({"userId": user_id})
    return jsonify([{"_id": str(image["_id"]), "data": image["data"].decode()} for image in images])

if __name__ == "__main__":
    app.run()

```
This code sets up a basic Flask web server and connects to a local MongoDB database. It includes two routes for adding and retrieving notes and two routes for adding and retrieving images. The user ID is passed as a query parameter in the URL for all requests.