server.py

import gradio as gr
import pandas as pd
import threading
from datetime import datetime
import os
import json
import sqlite3
import time
from dotenv import load_dotenv

DEMO_MODE = os.getenv("DEMO_MODE", "True").lower() == 'true'
# --- Load Environment & Configuration ---
load_dotenv()
try:
    from datasets import load_dataset, Dataset, DatasetDict, Features, Value
    HF_DATASETS_AVAILABLE = True
except ImportError:
    HF_DATASETS_AVAILABLE = False
    Features, Value = None, None

STORAGE_BACKEND_CONFIG = os.getenv("STORAGE_BACKEND", "HF_DATASET").upper()
HF_DATASET_REPO = os.getenv("HF_DATASET_REPO")
HF_TOKEN = os.getenv("HF_TOKEN")
HF_BACKUP_THRESHOLD = int(os.getenv("HF_BACKUP_THRESHOLD", 10))
DB_FILE_JSON = "social_data.json"
DB_FILE_SQLITE = "social_data.db"

db_lock = threading.Lock()
dirty_operations_count = 0

# --- Database Initialization and Persistence ---

def force_persist_data():
    global dirty_operations_count
    with db_lock:
        storage_backend = STORAGE_BACKEND_CONFIG
        if storage_backend == "RAM":
            return True, "RAM backend. No persistence."
        elif storage_backend == "SQLITE":
            with sqlite3.connect(DB_FILE_SQLITE) as conn:
                users_df = pd.DataFrame(list(users_db.items()), columns=['username', 'password'])
                users_df.to_sql('users', conn, if_exists='replace', index=False)
                posts_df.to_sql('posts', conn, if_exists='replace', index=False)
                comments_df.to_sql('comments', conn, if_exists='replace', index=False)
            return True, "Successfully saved to SQLite."
        elif storage_backend == "JSON":
            with open(DB_FILE_JSON, "w") as f:
                json.dump({"users": users_db, "posts": posts_df.to_dict('records'), "comments": comments_df.to_dict('records')}, f, indent=2)
            return True, "Successfully saved to JSON file."
        elif storage_backend == "HF_DATASET":
            if not all([HF_DATASETS_AVAILABLE, HF_TOKEN, HF_DATASET_REPO]):
                return False, "HF_DATASET backend is not configured correctly."
            try:
                print("Pushing data to Hugging Face Hub...")
                dataset_dict = DatasetDict({
                    'users': Dataset.from_pandas(pd.DataFrame(list(users_db.items()), columns=['username', 'password'])),
                    'posts': Dataset.from_pandas(posts_df),
                    'comments': Dataset.from_pandas(comments_df)
                })
                dataset_dict.push_to_hub(HF_DATASET_REPO, token=HF_TOKEN, private=True)
                dirty_operations_count = 0
                return True, f"Successfully pushed data to {HF_DATASET_REPO}."
            except Exception as e:
                return False, f"Error pushing to Hugging Face Hub: {e}"
    return False, "Unknown backend."

def handle_persistence_after_change():
    global dirty_operations_count
    storage_backend = STORAGE_BACKEND_CONFIG
    if storage_backend in ["JSON", "SQLITE"]:
        force_persist_data()
    elif storage_backend == "HF_DATASET":
        with db_lock:
            dirty_operations_count += 1
            print(f"HF_DATASET: {dirty_operations_count}/{HF_BACKUP_THRESHOLD} operations until next auto-backup.")
            if dirty_operations_count >= HF_BACKUP_THRESHOLD:
                print(f"Threshold of {HF_BACKUP_THRESHOLD} reached. Triggering auto-backup.")
                force_persist_data()

def load_data():
    global STORAGE_BACKEND_CONFIG
    storage_backend = STORAGE_BACKEND_CONFIG
    with db_lock:
        users, posts, comments = {"admin": "password"}, pd.DataFrame(columns=["post_id", "username", "content", "timestamp"]), pd.DataFrame(columns=["comment_id", "post_id", "username", "content", "timestamp", "reply_to_comment_id"])

        if storage_backend == "SQLITE":
            try:
                with sqlite3.connect(DB_FILE_SQLITE) as conn:
                    cursor = conn.cursor()
                    cursor.execute("CREATE TABLE IF NOT EXISTS users (username TEXT PRIMARY KEY, password TEXT NOT NULL)")
                    cursor.execute("CREATE TABLE IF NOT EXISTS posts (post_id INTEGER PRIMARY KEY, username TEXT, content TEXT, timestamp TEXT)")
                    cursor.execute("CREATE TABLE IF NOT EXISTS comments (comment_id INTEGER PRIMARY KEY, post_id INTEGER, username TEXT, content TEXT, timestamp TEXT, reply_to_comment_id INTEGER)")
                    cursor.execute("INSERT OR IGNORE INTO users (username, password) VALUES (?, ?)", ("admin", "password"))
                    conn.commit()
                    users = dict(conn.execute("SELECT username, password FROM users").fetchall())
                    posts = pd.read_sql_query("SELECT * FROM posts", conn)
                    comments = pd.read_sql_query("SELECT * FROM comments", conn)
            except Exception as e:
                print(f"CRITICAL: Failed to load or create SQLite DB at '{DB_FILE_SQLITE}'. Falling back to RAM. Error: {e}")
                STORAGE_BACKEND_CONFIG = "RAM"
        
        elif storage_backend == "JSON":
            if os.path.exists(DB_FILE_JSON):
                try:
                    with open(DB_FILE_JSON, "r") as f:
                        data = json.load(f)
                    users, posts, comments = data.get("users", users), pd.DataFrame(data.get("posts", [])), pd.DataFrame(data.get("comments", []))
                except (json.JSONDecodeError, KeyError):
                    print(f"Warning: JSON file '{DB_FILE_JSON}' is corrupted or empty. Starting with fresh data.")
            else:
                print(f"JSON file '{DB_FILE_JSON}' not found. Will be created on first change.")

        elif storage_backend == "HF_DATASET":
            if all([HF_DATASETS_AVAILABLE, HF_TOKEN, HF_DATASET_REPO]):
                try:
                    print(f"Attempting to load data from HF Dataset: {HF_DATASET_REPO}")
                    ds_dict = load_dataset(HF_DATASET_REPO, token=HF_TOKEN, trust_remote_code=True)
                    users = dict(zip(ds_dict['users']['username'], ds_dict['users']['password']))
                    posts = ds_dict['posts'].to_pandas()
                    comments = ds_dict['comments'].to_pandas()
                    print("Successfully loaded data from HF Dataset.")
                except Exception as e:
                    print(f"Could not load from HF Dataset '{HF_DATASET_REPO}'. Attempting to initialize a new one. Error: {e}")
                    try:
                        user_features = Features({'username': Value('string'), 'password': Value('string')})
                        post_features = Features({'post_id': Value('int64'), 'username': Value('string'), 'content': Value('string'), 'timestamp': Value('string')})
                        comment_features = Features({'comment_id': Value('int64'), 'post_id': Value('int64'), 'username': Value('string'), 'content': Value('string'), 'timestamp': Value('string'), 'reply_to_comment_id': Value('int64')})
                        
                        dataset_dict = DatasetDict({
                            'users': Dataset.from_pandas(pd.DataFrame(list(users.items()), columns=['username', 'password']), features=user_features),
                            'posts': Dataset.from_pandas(posts, features=post_features),
                            'comments': Dataset.from_pandas(comments, features=comment_features)
                        })
                        dataset_dict.push_to_hub(HF_DATASET_REPO, token=HF_TOKEN, private=True)
                        print(f"Successfully initialized new empty HF Dataset at {HF_DATASET_REPO}.")
                    except Exception as e_push:
                        print(f"CRITICAL: Failed to create new HF Dataset. Falling back to RAM for this session. Push Error: {e_push}")
                        STORAGE_BACKEND_CONFIG = "RAM"
            else:
                 print("HF_DATASET backend not fully configured (check env vars and library install). Falling back to RAM for this session.")
                 STORAGE_BACKEND_CONFIG = "RAM"

    if "reply_to_comment_id" not in comments.columns:
        comments["reply_to_comment_id"] = None
        
    post_counter = int(posts['post_id'].max()) if not posts.empty else 0
    comment_counter = int(comments['comment_id'].max()) if not comments.empty else 0
    return users, posts, comments, post_counter, comment_counter

users_db, posts_df, comments_df, post_counter, comment_counter = load_data()

# --- API Functions ---
def api_register(username, password):
    if not username or not password: return "[Auth API] Failed: Username/password cannot be empty."
    with db_lock:
        if username in users_db: return f"[Auth API] Failed: Username '{username}' already exists."
        users_db[username] = password
        handle_persistence_after_change()
    return f"[Auth API] Success: User '{username}' registered."

def api_login(username, password):
    return f"{username}:{password}" if username in users_db and users_db.get(username) == password else "[Auth API] Failed: Invalid credentials."

def _get_user_from_token(auth_token):
    if not auth_token or ':' not in auth_token: return None
    try:
        username, password = auth_token.split(':', 1)
        return username if username in users_db and users_db.get(username) == password else None
    except (ValueError, TypeError): return None

def api_create_post(auth_token, content):
    global posts_df, post_counter
    username = _get_user_from_token(auth_token)
    if not username: return "[Post API] Failed: Invalid auth token."
    if not content or not content.strip(): return "[Post API] Failed: Post content cannot be empty."
    with db_lock:
        post_counter += 1
        new_post = pd.DataFrame([{"post_id": post_counter, "username": username, "content": content, "timestamp": datetime.utcnow().strftime("%Y-%m-%d %H:%M:%S")}])
        posts_df = pd.concat([posts_df, new_post], ignore_index=True)
        handle_persistence_after_change()
    return f"[Post API] Success: Post created with ID {post_counter}."

def api_create_comment(auth_token, post_id, content, reply_to_comment_id=None):
    global comments_df, comment_counter
    username = _get_user_from_token(auth_token)
    if not username: return "[Comment API] Failed: Invalid auth token."
    if not content or not content.strip(): return "[Comment API] Failed: Comment content cannot be empty."
    with db_lock:
        try: target_post_id = int(post_id)
        except (ValueError, TypeError): return f"[Comment API] Failed: Post ID must be a number."
        if target_post_id not in posts_df['post_id'].values: return f"[Comment API] Failed: Post with ID {post_id} not found."
        
        target_reply_id = None
        if reply_to_comment_id is not None:
            try: target_reply_id = int(reply_to_comment_id)
            except (ValueError, TypeError): return "[Comment API] Failed: Reply ID must be a number."
            if target_reply_id not in comments_df['comment_id'].values: return f"[Comment API] Failed: Comment to reply to (ID {target_reply_id}) not found."

        comment_counter += 1
        new_comment_data = {"comment_id": comment_counter, "post_id": target_post_id, "username": username, "content": content, "timestamp": datetime.utcnow().strftime("%Y-%m-%d %H:%M:%S"), "reply_to_comment_id": target_reply_id}
        new_comment = pd.DataFrame([new_comment_data])
        comments_df = pd.concat([comments_df, new_comment], ignore_index=True)
        handle_persistence_after_change()
    return f"[Comment API] Success: Comment created on post {post_id}."

def _format_comments_threaded(post_id, all_comments_df, parent_id=None, depth=0):
    thread = []
    # Match NaN correctly for top-level comments
    if parent_id is None:
        children = all_comments_df[(all_comments_df['post_id'] == post_id) & (all_comments_df['reply_to_comment_id'].isna())]
    else:
        children = all_comments_df[all_comments_df['reply_to_comment_id'] == parent_id]
        
    for _, comment in children.iterrows():
        indent = "  " * depth
        thread.append(f"{indent}  - (ID: {comment['comment_id']}) @{comment['username']}: {comment['content']}")
        thread.extend(_format_comments_threaded(post_id, all_comments_df, parent_id=comment['comment_id'], depth=depth + 1))
    return thread

def api_get_feed(search_query: str = None):
    with db_lock:
        current_posts, current_comments = posts_df.copy(), comments_df.copy()
    if current_posts.empty: return pd.DataFrame(columns=["post_id", "username", "content", "timestamp", "comments"])
    display_posts = current_posts[current_posts['content'].str.contains(search_query, case=False, na=False)] if search_query and not search_query.isspace() else current_posts
    sorted_posts = display_posts.sort_values(by="timestamp", ascending=False)
    
    feed_data = []
    for _, post in sorted_posts.iterrows():
        threaded_comments = _format_comments_threaded(post['post_id'], current_comments)
        feed_data.append({"post_id": post['post_id'], "username": post['username'], "content": post['content'], "timestamp": post['timestamp'], "comments": "\n".join(threaded_comments)})
        
    return pd.DataFrame(feed_data) if feed_data else pd.DataFrame(columns=["post_id", "username", "content", "timestamp", "comments"])

# --- UI Helper Functions ---
def ui_manual_post(username, password, content):
    if not username or not password:
        return "Username and password are required.", api_get_feed()
    auth_token = api_login(username, password)
    if "Failed" in auth_token:
        return "Login failed. Check credentials.", api_get_feed()
    result = api_create_post(auth_token, content)
    return result, api_get_feed()

def ui_manual_comment(username, password, post_id, reply_id, content):
    if not username or not password:
        return "Username and password are required.", api_get_feed()
    auth_token = api_login(username, password)
    if "Failed" in auth_token:
        return "Login failed. Check credentials.", api_get_feed()
    result = api_create_comment(auth_token, post_id, content, reply_to_comment_id=reply_id)
    return result, api_get_feed()

with gr.Blocks(theme=gr.themes.Soft(), title="Social App") as demo:
    gr.Markdown("# iLearnHub")
    gr.Markdown(f"This app provides an API for iLearn agents to interact with. **Storage Backend: `{STORAGE_BACKEND_CONFIG}`**")
    gr.Markdown(f"This Server address: https://broadfield-dev-ilearnhub.hf.space")
    
    with gr.Tabs():
        with gr.TabItem("Live Feed"):
            feed_df_display = gr.DataFrame(label="Feed", headers=["post_id", "username", "content", "timestamp", "comments"], interactive=False, wrap=True)
            refresh_btn = gr.Button("Refresh Feed")
        
        with gr.TabItem("Manual Actions & Settings"):
            manual_action_status = gr.Textbox(label="Action Status", interactive=False)
            gr.Markdown("## DEMO_MODE", visible=True if DEMO_MODE else False)
            with gr.Row(visible=False if DEMO_MODE else True):
                with gr.Group():
                    gr.Markdown("### Manually Create Post")
                    post_user = gr.Textbox(label="Username", value="admin")
                    post_pass = gr.Textbox(label="Password", type="password", value="password")
                    post_content = gr.Textbox(label="Post Content", lines=3, placeholder="What's on your mind?")
                    post_button = gr.Button("Submit Post", variant="primary")
                with gr.Group():
                    gr.Markdown("### Manually Create Comment")
                    comment_user = gr.Textbox(label="Username", value="admin")
                    comment_pass = gr.Textbox(label="Password", type="password", value="password")
                    comment_post_id = gr.Number(label="Target Post ID", precision=0)
                    comment_reply_id = gr.Number(label="Reply to Comment ID (optional)", precision=0)
                    comment_content = gr.Textbox(label="Comment Content", lines=2, placeholder="Add a comment...")
                    comment_button = gr.Button("Submit Comment", variant="primary")
            with gr.Group():
                gr.Markdown("### Settings")
                feed_refresh_interval_slider = gr.Slider(minimum=5, maximum=120, value=15, step=5, label="Feed Refresh Interval (seconds)")

        with gr.TabItem("Admin", visible=(STORAGE_BACKEND_CONFIG == "HF_DATASET")):
            gr.Markdown("### Hugging Face Dataset Control")
            backup_btn = gr.Button("Force Backup to Hugging Face Hub", visible=not DEMO_MODE)
            backup_status = gr.Textbox(label="Backup Status", interactive=False)

    # Event Handlers
    post_button.click(
        fn=ui_manual_post, 
        inputs=[post_user, post_pass, post_content], 
        outputs=[manual_action_status, feed_df_display]
    )
    comment_button.click(
        fn=ui_manual_comment, 
        inputs=[comment_user, comment_pass, comment_post_id, comment_reply_id, comment_content], 
        outputs=[manual_action_status, feed_df_display]
    )
    
    last_refresh_time = time.time()
    def timed_feed_refresh(interval):
        global last_refresh_time
        if time.time() - last_refresh_time > interval:
            last_refresh_time = time.time()
            return api_get_feed()
        return gr.update()

    gr.Timer(1).tick(
        fn=timed_feed_refresh,
        inputs=[feed_refresh_interval_slider],
        outputs=[feed_df_display]
    )

    refresh_btn.click(api_get_feed, None, feed_df_display)
    
    def admin_backup_handler():
        success, message = force_persist_data()
        return message
        
    if STORAGE_BACKEND_CONFIG == "HF_DATASET":
        backup_btn.click(admin_backup_handler, None, backup_status)
    
    demo.load(api_get_feed, None, feed_df_display)

    with gr.Column(visible=False if DEMO_MODE else True):
        gr.Interface(api_register, ["text", gr.Textbox(type="password")], "text", api_name="register", allow_flagging="never")
        gr.Interface(api_login, ["text", gr.Textbox(type="password")], "text", api_name="login", allow_flagging="never")
        gr.Interface(api_create_post, ["text", "text"], "text", api_name="create_post", allow_flagging="never")
        gr.Interface(api_create_comment, ["text", "number", "text", "number"], "text", api_name="create_comment", allow_flagging="never")
        gr.Interface(api_get_feed, ["text"], "dataframe", api_name="get_feed", allow_flagging="never")

if __name__ == "__main__":
    print(f"Starting Social Media App server with {STORAGE_BACKEND_CONFIG} backend.")
    if STORAGE_BACKEND_CONFIG == "HF_DATASET" and not HF_DATASETS_AVAILABLE:
        print("\nWARNING: 'datasets' library not found. Please run `pip install datasets huggingface_hub` to use the HF_DATASET backend.\n")
    app_port = int(os.getenv("GRADIO_PORT", 7860))
    demo.queue().launch(server_name="0.0.0.0", server_port=app_port, share=True, mcp_server=True, debug=True)