server.py

import os, json, threading
from flask import Flask, request, jsonify, send_from_directory

app = Flask(__name__)

DATA_DIR = "/data" if os.path.isdir("/data") else "/app"
COMMENTS_FILE = os.path.join(DATA_DIR, "comments.json")
lock = threading.Lock()

# Schema: { "problem_id": [ {text, author, timestamp}, ... ] }

def load_comments():
    with lock:
        if os.path.exists(COMMENTS_FILE):
            with open(COMMENTS_FILE) as f:
                data = json.load(f)
            # Migrate old format (single comment per problem) to list format
            if data and isinstance(next(iter(data.values()), None), dict):
                migrated = {}
                for pid, entry in data.items():
                    if isinstance(entry, dict) and "text" in entry:
                        migrated[pid] = [entry]
                    elif isinstance(entry, list):
                        migrated[pid] = entry
                return migrated
            return data
    return {}

def save_comments(comments):
    with lock:
        with open(COMMENTS_FILE, "w") as f:
            json.dump(comments, f, indent=2)

@app.route("/")
def index():
    return send_from_directory("/app", "index.html")

@app.route("/api/comments", methods=["GET"])
def get_comments():
    return jsonify(load_comments())

@app.route("/api/comments", methods=["POST"])
def post_comment():
    body = request.json
    pid = body.get("problem_id")
    text = body.get("text", "").strip()
    author = body.get("author", "anonymous")
    timestamp = body.get("timestamp", "")

    comments = load_comments()

    if pid not in comments:
        comments[pid] = []

    # Find existing comment by this author on this problem
    existing_idx = None
    for i, c in enumerate(comments[pid]):
        if c.get("author") == author:
            existing_idx = i
            break

    if text:
        entry = {"text": text, "author": author, "timestamp": timestamp}
        if existing_idx is not None:
            comments[pid][existing_idx] = entry
        else:
            comments[pid].append(entry)
    else:
        # Empty text = delete this author's comment
        if existing_idx is not None:
            comments[pid].pop(existing_idx)
        if not comments[pid]:
            del comments[pid]

    save_comments(comments)
    total = sum(len(v) for v in comments.values())
    return jsonify({"ok": True, "count": total})

if __name__ == "__main__":
    print(f"Comments stored at: {COMMENTS_FILE}")
    app.run(host="0.0.0.0", port=7860)