import os
import json
import threading
from uuid import uuid4
import numpy as np
import pandas as pd


from dotenv import load_dotenv

from flask import (
    Flask, render_template, request, jsonify,
    redirect, url_for, flash, session, send_from_directory  # ← add this
)

from werkzeug.utils import secure_filename
from werkzeug.security import generate_password_hash, check_password_hash

# ML
import tensorflow as tf
from tensorflow.keras.models import load_model
from tensorflow.keras.preprocessing import image

# Gemini
import google.generativeai as genai



from datetime import datetime

# in-memory chat history: username -> list of sessions
# each session: {"id": "...", "pest": "wasp", "created_at": "...", "messages": [{"role": "user"/"assistant","text": "..."}]}



# ---------------------------------------------------------
# Boot
# ---------------------------------------------------------
load_dotenv()
app = Flask(__name__)
# Use a persistent secret key so Flask sessions survive restarts
app.secret_key = os.getenv("FLASK_SECRET_KEY", "my-name-is-prabhat007")

# Keep user sessions alive across reloads
app.config['PERMANENT_SESSION_LIFETIME'] = 86400  # 1 day (in seconds)
app.config['SESSION_PERMANENT'] = True
#app.config['SESSION_COOKIE_SECURE'] = False  # Required for HTTP (HF Spaces handles HTTPS)
app.config['SESSION_COOKIE_HTTPONLY'] = True
#app.config['SESSION_COOKIE_SAMESITE'] = 'Lax'
# use HTTPS on HF spaces — set Secure=True and SameSite=None
app.config['SESSION_COOKIE_SECURE'] = True
app.config['SESSION_COOKIE_SAMESITE'] = 'None'


@app.before_request
def make_session_permanent():
    session.permanent = True

# ---------------------------------------------------------
# 1) Model loading & config
# ---------------------------------------------------------
MODEL_PATH = 'dhanush_model.h5'
CLASS_NAMES = [
    'ants', 'bees', 'beetle', 'caterpillar', 'earthworms', 'earwig',
    'Grasshopper', 'moth', 'slug', 'snail', 'wasp', 'weevil'
]
IMG_SIZE = (224, 224)

DATA_DIR = os.environ.get("DATA_DIR", "/data")
UPLOAD_FOLDER = os.path.join(DATA_DIR, "uploads")
HISTORY_DIR = os.path.join(DATA_DIR, "chat_history")
os.makedirs(UPLOAD_FOLDER, exist_ok=True)
os.makedirs(HISTORY_DIR, exist_ok=True)
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER



# Load model
try:
    pest_model = load_model(MODEL_PATH)
    print(f"✅ Model loaded successfully from {MODEL_PATH}")
except Exception as e:
    print(f"❌ Error loading model: {e}")
    pest_model = None

# Threshold (from diagnostics/thresholds.json if present)
GLOBAL_TAU = 0.45
try:
    with open("diagnostics/thresholds.json", "r") as f:
        GLOBAL_TAU = float(json.load(f).get("global_tau", 0.0))
        print(f"✅ Loaded global threshold τ = {GLOBAL_TAU:.3f}")
except Exception as _:
    print("ℹ️ No diagnostics/thresholds.json found; using τ = 0.0")

# ---------------------------------------------------------
# 2) Gemini API & RAG setup
# ---------------------------------------------------------
# ===================== Gemini API & RAG setup =====================


# global chat sessions (per pest type)
chat_sessions = {}
# cache the most recent prediction per user, to attach image to first chat turn
latest_pred_by_user = {}  # username -> {"pest": str, "image_url": str, "ts": "..."}



# Simple in-memory chat history store (for demo / dev)
# Structure: user_sessions[username] -> list of sessions
# session: { id, pest, created_at, messages: [ {role, text, ts} ] }
user_sessions = {}
_user_sessions_lock = threading.Lock()

import glob

def _history_path_for(username: str) -> str:
    safe = (username or "__anon__").replace(":", "_")
    return os.path.join(HISTORY_DIR, f"{safe}.json")

def _persist_user(username: str):
    """Write this user's sessions to disk as JSON."""
    if not username:
        username = "__anon__"
    path = _history_path_for(username)
    with _user_sessions_lock:
        data = user_sessions.get(username, [])
        try:
            with open(path, "w", encoding="utf-8") as f:
                json.dump(data, f, ensure_ascii=False, indent=2)
        except Exception as e:
            print(f"⚠️ Failed to persist history for {username}: {e}")

def _load_all_users_on_boot():
    """Load any previously saved sessions from disk into memory."""
    loaded = 0
    for p in glob.glob(os.path.join(HISTORY_DIR, "*.json")):
        try:
            with open(p, "r", encoding="utf-8") as f:
                sessions = json.load(f)
            username = os.path.splitext(os.path.basename(p))[0]
            username = "__anon__" if username == "__anon__" else username
            with _user_sessions_lock:
                user_sessions[username] = sessions
            loaded += 1
        except Exception as e:
            print(f"⚠️ Failed to load history file {p}: {e}")
    print(f"📚 Loaded chat history for {loaded} user(s) from disk.")
# Load any persisted chat history when the app starts
_load_all_users_on_boot()


def _make_session(username, pest, image_url=None):
    sid = f"{username}:{pest}:{uuid4().hex[:8]}"
    session = {
        "id": sid,
        "pest": pest,
        "created_at": datetime.utcnow().isoformat(),
        "image_url": image_url,   # NEW: persist the prediction image for this chat
        "messages": []
    }
    with _user_sessions_lock:
        user_sessions.setdefault(username, []).append(session)
    _persist_user(username)
    return sid


def _find_session_id_for_user_pest(username, pest):
    """Return the most recent session id for user+pest or None."""
    with _user_sessions_lock:
        sessions = user_sessions.get(username, [])
        for s in reversed(sessions):
            if (s.get("pest") or "").lower() == (pest or "").lower():
                return s["id"]
    return None

def _append_history(username, pest, role, text, session_id=None):
    """
    Append a message to history.
    If session_id is None, create a new session for username+pest.
    Returns session_id used.
    """
    if not username:
        username = "__anon__"
    with _user_sessions_lock:
        if session_id is None:
            # try to reuse most recent session for this user/pest; otherwise create new
            sid = _find_session_id_for_user_pest(username, pest)
            if sid is None:
                sid = _make_session(username, pest)
        else:
            sid = session_id

        # find session object
        sessions = user_sessions.setdefault(username, [])
        sess_obj = next((s for s in sessions if s["id"] == sid), None)
        if sess_obj is None:
            # if not found, create
            sid = _make_session(username, pest)
            sess_obj = next(s for s in user_sessions[username] if s["id"] == sid)

    
        sess_obj["messages"].append({"role": role, "text": text, "ts": datetime.utcnow().isoformat()})
    _persist_user(username)     
    return sid

try:
    GOOGLE_API_KEY = os.environ.get("GOOGLE_API_KEY")
    if not GOOGLE_API_KEY:
        raise ValueError("GOOGLE_API_KEY not found in environment variables.")
    genai.configure(api_key=GOOGLE_API_KEY)

    # Use a widely available model name to avoid 404s
    rag_model = genai.GenerativeModel(model_name="gemini-2.0-flash-lite")
    print("✅ Gemini API configured successfully with 'gemini-2.5-pro'.")

    # Load the file references you created with upload_files.py
    with open('file_references.json', 'r') as f:
        file_references = json.load(f)
    print("✅ Document file references loaded.")

except Exception as e:
    print(f"❌ Gemini API or File Reference Error: {e}")
    rag_model = None
    file_references = {}
# ================================================================

# ---------------------------------------------------------
# 3) Product recommendations (sample data)
# ---------------------------------------------------------
PRODUCT_RECOMMENDATIONS = {
    'wasp': [
        {
            'name': 'Wasp & Hornet Killer Spray',
            'image_url': 'https://placehold.co/150x150/e9d5ff/4c1d95?text=Wasp+Spray',
            'link': '#',
            'description': 'Fast-acting spray that kills wasps, hornets, and yellow jackets on contact.'
        },
        {
            'name': 'Reusable Wasp Trap',
            'image_url': 'https://placehold.co/150x150/dbeafe/1e3a8a?text=Wasp+Trap',
            'link': '#',
            'description': 'Eco-friendly trap to lure and capture wasps without harmful chemicals.'
        }
    ],
    'ants': [
        {
            'name': 'Ants',
            'image_url': "https://m.media-amazon.com/images/I/71HxltbUHUL._UF350,350_QL80_.jpg",
            'link': 'https://www.syngentapmp.com/product/advion-ant-gel-insecticide',
            'description': 'Professional gel bait for colony control (good for sweet- and protein-feeding ants).'
        }
    ],
    'caterpillar': [
        {
            'name': 'Bacillus Thuringiensis (BT) Spray',
            'image_url': 'https://m.media-amazon.com/images/I/61r5VSrCMqL._UF1000,1000_QL80_.jpg',
            'link': 'https://www.amazon.in/insecticide-for-caterpillar/s?k=insecticide+for+caterpillar&utm_source=chatgpt.com',
            'description': 'Natural pesticide effective against caterpillars; safe for most beneficials.'
        }
    ],
    'beetle': [
        {
            'name': 'Rhinoceros Beetle Lure',
            'image_url': 'https://lilaagrotech.com/wp-content/uploads/2024/08/Live_Earth-Worms-removebg-preview.webp',
            'link': 'https://www.bighaat.com/products/rhinoceros-beetle-lure-pest-control-india',
            'description': 'A lure to attract and trap rhinoceros beetles in orchards.'
        }
    ],
    'earthworms': [
        {
            'name': 'Aquaritin Shield',
            'image_url': 'https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTtkun_yTRqurn0uQ4L9zEN6zmlWr29_OvnbA&s',
            'link': 'https://www.kisaantrade.com/product/aquaritin-shield-turf-s?utm_source=chatgpt.com',
            'description': 'Biodegradable nano-emulsion to deter casts on turf without harming worms.'
        }
    ],
    'earwig': [
        {
            'name': 'Neem Oil',
            'image_url': 'https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQWQKVOjI4FH_C5djSIgfiQXLtJPa27kiaWcA&s',
            'link': 'https://environmentalfactor.com/natural-remedies-for-earwig-control-safe-and-eco-friendly-solutions/?utm_source=chatgpt.com',
            'description': 'Botanical insecticide/repellent effective against earwigs and other pests.'
        }
    ],
    'default': [
        {
            'name': 'General Garden Pest Control',
            'image_url': 'https://placehold.co/150x150/f0f9ff/082f49?text=Pest+Spray',
            'link': '#',
            'description': 'Multi-purpose insecticide—always read the label before use.'
        }
    ]
}

# ---------------------------------------------------------
# Utility: model inference (identity_uint8 + global threshold)
# ---------------------------------------------------------
def model_predict(img_path):
    """
    Loads image -> uint8 array -> model -> softmax if needed.
    Applies global threshold GLOBAL_TAU; returns (label, confidence) or (None, confidence).
    """
    if pest_model is None:
        raise Exception("Model is not loaded.")

    img_obj = image.load_img(img_path, target_size=IMG_SIZE)
    x = image.img_to_array(img_obj)           # keep uint8 [0..255], as diagnostics showed
    x = np.expand_dims(x, axis=0)             # (1, H, W, C)

    preds = pest_model.predict(x, verbose=0)  # logits or probs
    # convert to probabilities if needed
    if preds.ndim == 2 and not np.allclose(preds.sum(axis=1, keepdims=True), 1.0, atol=1e-3):
        probs = tf.nn.softmax(preds, axis=1).numpy()
    else:
        probs = preds

    i = int(np.argmax(probs[0]))
    conf = float(probs[0][i])
    label = CLASS_NAMES[i]

    if conf < float(GLOBAL_TAU):
        return None, conf
    return label, conf

# ---------------------------------------------------------
# 4) Routes
# ---------------------------------------------------------
@app.route('/', methods=['GET'])
def index():
    if not session.get('user'):
        return redirect(url_for('welcome_page'))
    return render_template('index.html', username=session.get('user'))

# Upload/predict
ALLOWED_EXTS = {"png", "jpg", "jpeg", "webp"}

@app.route('/predict', methods=['POST'])
def upload():
    if pest_model is None:
        return jsonify({'error': 'Model not loaded.'}), 500

    file = request.files.get('file')
    if not file or file.filename == '':
        return jsonify({'error': 'No file provided'}), 400

    orig_name = secure_filename(file.filename)
    _, ext = os.path.splitext(orig_name)
    ext = (ext or '').lower().lstrip('.')
    if ext not in ALLOWED_EXTS:
        return jsonify({'error': f'Unsupported file type: .{ext}. Allowed: {", ".join(sorted(ALLOWED_EXTS))}'}), 400

    unique_name = f"{uuid4().hex}.{ext}"
    filepath = os.path.join(app.config['UPLOAD_FOLDER'], unique_name)

    try:
        file.save(filepath)

        label, confidence = model_predict(filepath)
        print(f"Prediction result: {label} (confidence={confidence:.4f})")

        if label is None:
            # do NOT clear other sessions
            msg = f"No confident pest detected (confidence={confidence:.2f}). Please upload a clearer pest image."
            return jsonify({
                'success': False,
                'message': msg,
                'confidence': float(confidence),
                'image_url': f'/files/uploads/{unique_name}'

            }), 200
        
        # === NEW: remember this user's last prediction (pest + image) ===
        _username = session.get('user') or "__anon__"
        latest_pred_by_user[_username] = {
            "pest": str(label),
            "image_url": f"/files/uploads/{unique_name}",
            "ts": datetime.utcnow().isoformat()
        }
     

        # Clear only current user's sessions (fresh context)
        _clear_user_sessions(session.get('user'))
        return jsonify({
            'success': True,
            'prediction': str(label),
            'confidence': float(confidence),
            'image_url': f'/files/uploads/{unique_name}'

        }), 200

    except Exception as e:
        print(f"Prediction Error: {e}")
        return jsonify({'error': f'Prediction failed: {e}'}), 500

# Recommendations
@app.route('/get_recommendations/<pest_name>')
def get_recommendations(pest_name):
    pest_name_lower = (pest_name or '').lower().strip()
    recommendations = PRODUCT_RECOMMENDATIONS.get(pest_name_lower, PRODUCT_RECOMMENDATIONS['default'])
    return jsonify(recommendations)

# Optional: default recommendations route (in case frontend calls without pest)
@app.route('/get_recommendations')
def get_recommendations_default():
    return jsonify(PRODUCT_RECOMMENDATIONS['default'])

# Chatbot (Gemini)
def _chat_key(username: str, pest: str) -> str:
    u = username or "__anon__"
    return f"{u}:{(pest or '').lower()}"

def _clear_user_sessions(username: str):
    if not username:
        return
    prefix = f"{username}:".lower()
    to_del = [k for k in chat_sessions.keys() if k.lower().startswith(prefix)]
    for k in to_del:
        del chat_sessions[k]
    if to_del:
        print(f"🧹 Cleared {len(to_del)} chat session(s) for user '{username}'")


@app.route('/chatbot', methods=['POST'])
def chatbot_response():
    # Ensure RAG/gemini is available
    if not rag_model or not file_references:
        return jsonify({'response': 'Chatbot service is unavailable.', 'error': 'CONFIG_ERROR'}), 503

    data = request.get_json(silent=True) or {}
    user_message = data.get('message')
    pest_type = data.get('pest_type')

    if not user_message or not pest_type:
        return jsonify({'response': 'Missing message or pest type.'}), 400

    # Use Flask session username if available; fall back to anon
    username = session.get('user') or "__anon__"
    chat_key = f"{username}:{pest_type}".lower()

    try:
        # --- FIRST TURN: RAG over the pest-specific document ---
        if chat_key not in chat_sessions:
            app.logger.debug("New conversation for '%s' (user=%s). Using RAG.", pest_type, username)

            file_uri = file_references.get(pest_type.lower())
            if not file_uri:
                return jsonify({'response': f"Sorry, no document found for '{pest_type}'."}), 404

            # prepare file resource and prompt
            file_id = file_uri.split('/')[-1]
            file_resource_name = f'files/{file_id}'
            file_to_use = genai.get_file(name=file_resource_name)

            prompt = [
                f"Answer the following question based only on the provided document about '{pest_type}'.",
                file_to_use,
                f"Question: {user_message}"
            ]

            # RAG generate
            response = rag_model.generate_content(prompt)
            text = getattr(response, "text", None) or (response.get("text") if isinstance(response, dict) else str(response))

            # create the interactive chat object seeded with the first exchange
            chat = rag_model.start_chat(history=[
                {'role': 'user', 'parts': [user_message]},
                {'role': 'model', 'parts': [text]}
            ])

            # save the chat object for future follow-ups (keyed by user+pest)
            chat_sessions[chat_key] = chat

            # attach last prediction image if it matches this pest
            lp = latest_pred_by_user.get(username or "__anon__")
            img_for_session = None
            if lp and (lp.get("pest","").lower() == pest_type.lower()):
                img_for_session = lp.get("image_url")

            # persist history and return session id (now with image_url)
            sid = _make_session(username, pest_type, image_url=img_for_session)
            _append_history(username, pest_type, "user", user_message, session_id=sid)
            _append_history(username, pest_type, "assistant", text, session_id=sid)

            return jsonify({'response': text, 'pest_type': pest_type, 'session_id': sid})


        # --- FOLLOW-UP turns: continue the conversation with the saved chat object ---
        else:
            app.logger.debug("Continuing conversation for '%s' (user=%s).", pest_type, username)
            chat = chat_sessions[chat_key]

            # find or create a session id to append to
            sid = _find_session_id_for_user_pest(username, pest_type)
            if sid is None:
                # attach last prediction image if it matches this pest
                lp = latest_pred_by_user.get(username or "__anon__")
                img_for_session = None
                if lp and (lp.get("pest","").lower() == pest_type.lower()):
                    img_for_session = lp.get("image_url")

                sid = _make_session(username, pest_type, image_url=img_for_session)


            # append user message to history
            _append_history(username, pest_type, "user", user_message, session_id=sid)

            # send the message via the interactive chat object
            response = chat.send_message(user_message)
            reply_text = getattr(response, "text", None) or (response.get("text") if isinstance(response, dict) else str(response))

            # append assistant reply to history
            _append_history(username, pest_type, "assistant", reply_text, session_id=sid)

            return jsonify({'response': reply_text, 'pest_type': pest_type, 'session_id': sid})

    except Exception as e:
        error_message = str(e)
        app.logger.exception("❌ Gemini API call failed")
        return jsonify({'response': f'API Call Failed: {error_message}', 'error_type': 'API_CALL_FAIL'}), 500


# ---------------------------------------------------------
# 5) Auth (Excel-based; dev/demo only)
# ---------------------------------------------------------
USERS_FILE = os.path.join(os.getcwd(), "users.xlsx")
_users_lock = threading.Lock()

def _ensure_users_file():
    if not os.path.exists(USERS_FILE):
        df = pd.DataFrame(columns=["username", "password_hash"])
        df.to_excel(USERS_FILE, index=False)

def read_users_df():
    _ensure_users_file()
    try:
        df = pd.read_excel(USERS_FILE, engine="openpyxl")
    except Exception:
        df = pd.DataFrame(columns=["username", "password_hash"])
        df.to_excel(USERS_FILE, index=False)
    return df

def username_exists(username: str) -> bool:
    df = read_users_df()
    if 'username' not in df.columns:
        return False
    return username.lower().strip() in df['username'].str.lower().str.strip().tolist()

def add_user(username: str, password: str) -> bool:
    with _users_lock:
        df = read_users_df()
        if 'username' in df.columns and username.lower().strip() in df['username'].str.lower().str.strip().tolist():
            return False
        hashed = generate_password_hash(password)
        new_row = {"username": username.strip(), "password_hash": hashed}
        df = pd.concat([df, pd.DataFrame([new_row])], ignore_index=True)
        df.to_excel(USERS_FILE, index=False)
        return True

def verify_user(username: str, password: str) -> bool:
    df = read_users_df()
    if 'username' not in df.columns or 'password_hash' not in df.columns:
        return False
    match = df[df['username'].str.lower().str.strip() == username.lower().strip()]
    if match.empty:
        return False
    stored_hash = match.iloc[0]['password_hash']
    return check_password_hash(stored_hash, password)

@app.route("/home")
def home_redirect():
    if session.get("user"):
        return redirect(url_for("dashboard"))
    return redirect(url_for("index"))

@app.route("/register", methods=["GET", "POST"])
def register():
    if request.method == "POST":
        username = request.form.get("username", "").strip()
        password = request.form.get("password", "")
        confirm = request.form.get("confirm_password", "")

        if not username or not password:
            flash("Please provide both username and password.", "danger")
            return redirect(url_for("register"))

        if len(password) < 6:
            flash("Password should be at least 6 characters long.", "warning")
            return redirect(url_for("register"))

        if password != confirm:
            flash("Password and confirm password do not match.", "warning")
            return redirect(url_for("register"))

        if username_exists(username):
            flash("Username already exists. Please choose a different username or login.", "warning")
            return redirect(url_for("register"))

        ok = add_user(username, password)
        if ok:
            session['user'] = username
            session.permanent = True
            session.modified = True
            print(f"✅ REGISTER - Set session user: {username}")
            print(f"✅ REGISTER - Session after set: {dict(session)}")  # Force save
            flash(f"Welcome {username}! Account created successfully.", "success")
            return redirect(url_for('dashboard'))
        else:
            flash("Could not create account. Try again.", "danger")
            return redirect(url_for("register"))

    return render_template("register.html", title="Register")

@app.route("/login", methods=["GET", "POST"])
def login():
    if request.method == "POST":
        username = request.form.get("username", "").strip()
        password = request.form.get("password", "")

        if not username or not password:
            flash("Please enter both username and password.", "warning")
            return redirect(url_for("login"))

        if not username_exists(username):
            flash("User not existed. Please register.", "warning")
            return redirect(url_for("register"))

        if verify_user(username, password):
            session['user'] = username
            session.permanent = True
            session.modified = True  # Force save
            print(f"✅ LOGIN - Set session user: {username}")
            print(f"✅ LOGIN - Session after set: {dict(session)}")
            flash(f"Welcome back {username}!", "success")
            return redirect(url_for('dashboard'))  # Go directly to dashboard
        else:
            flash("Incorrect password.", "danger")
            return redirect(url_for("login"))

    return render_template("login.html", title="Login")

@app.route("/dashboard")
def dashboard():
    print(f"🔍 DASHBOARD - Session user: {session.get('user')}")
    print(f"🔍 DASHBOARD - Full session: {dict(session)}")
    if not session.get("user"):
        flash("Please login first.", "warning")
        return redirect(url_for("login"))
    return render_template("chat_dashboard.html", title="Dashboard")

@app.route("/logout")
def logout():
    session.pop("user", None)
    flash("You have been logged out.", "info")
    return redirect(url_for("login"))

@app.route('/welcome')
def welcome_page():
    if session.get('user'):
        return redirect(url_for('dashboard'))
    return render_template('landing.html')

@app.route('/greeting')
def greeting():
    username = request.args.get('username', 'friend')
    mode = request.args.get('mode', 'welcome')

    print(f"🔍 GREETING - Session user: {session.get('user')}")
    print(f"🔍 GREETING - Username from args: {username}")


    if mode == 'welcome':
        title_text = f"Welcome aboard, {username}!"
        subtitle_text = "We're delighted to have you. 🌱"
    else:
        title_text = f"Welcome back, {username}!"
        subtitle_text = "Great to see you again — ready to identify and remedy pests? 👋"

    return render_template('greeting.html', title_text=title_text, subtitle_text=subtitle_text)

# Replace the existing /chat_history and /chat_history/<id> routes with these.

from flask import make_response

def _safe_username():
    """Return logged-in username or '__anon__' (same logic used elsewhere)."""
    return session.get('user') or "__anon__"

@app.route('/chat_history', methods=['GET'])
def list_chat_history():
    """Return light-weight listing of sessions for the current logged-in user.
       Uses the same in-memory user_sessions store that _append_history/_make_session use.
    """
    username = session.get('user')
    if not username:
        return jsonify({'error': 'not_logged_in'}), 401

    with _user_sessions_lock:
        sessions = user_sessions.get(username, [])[:]

    # return small summary list (reverse so recent first)
    lite = [{"id": s["id"], "pest": s["pest"], "created_at": s.get("created_at")} for s in sessions[::-1]]
    return jsonify({'username': username, 'sessions': lite})


# Serve uploaded files from /data/uploads with a clean URL.
# e.g. /files/uploads/abc123.jpg
@app.route("/files/uploads/<path:filename>")
def serve_uploaded_file(filename):
    return send_from_directory(UPLOAD_FOLDER, filename, as_attachment=False)


@app.route('/chat_history/<session_id>', methods=['GET'])
def get_chat_session(session_id):
    """Return the full session object (messages) for the logged-in user."""
    username = session.get('user')
    if not username:
        return jsonify({'error': 'not_logged_in'}), 401

    with _user_sessions_lock:
        sessions = user_sessions.get(username, [])

    for s in sessions:
        if s.get('id') == session_id:
            return jsonify(s)
    return jsonify({'error': 'not_found'}), 404



# ---------------------------------------------------------
# Main
# ---------------------------------------------------------
if __name__ == '__main__':
    port = int(os.environ.get("PORT", 7860))  # Hugging Face uses 7860 by default
    app.run(host="0.0.0.0", port=port, debug=True)