serve.py

import pickle
from pathlib import Path

from flask import Flask, request
app = Flask(__name__)

seen_video_ids_path = Path("video_ids.pkl")
if seen_video_ids_path.is_file():
    with open(str(seen_video_ids_path), 'rb') as dump:
        seen_videos = pickle.load(dump)
else:
    seen_videos = []
print(len(seen_videos))


@app.route('/view/<video_id>')
def view(video_id):
    global seen_videos
    if not viewed(video_id):
        seen_videos.append(video_id)
        with open(str(seen_video_ids_path), 'bw') as dump:
            pickle.dump(seen_videos, dump)
    return "200"

def viewed(video_id):
    global seen_videos
    return video_id in seen_videos

@app.route('/chk/<video_id>')
def chk(video_id):
    msg = "not viewed"
    if viewed(video_id):
        print(video_id)
        msg = "viewed"
    return msg