Update frontend/app.py

frontend/app.py

@@ -1,10 +1,13 @@
-import streamlit as st
-import requests
+import os
 import json
-import pandas as pd
 from datetime import datetime
 
-API_URL = "http://127.0.0.1:8001"
+import pandas as pd
+import requests
+import streamlit as st
+
+# ================== CONFIG ==================
+API_URL = os.getenv("API_URL", "http://127.0.0.1:8001")
 
 st.set_page_config(
     page_title="LearnLanguage 2026 • Tutor",
@@ -12,48 +15,72 @@ st.set_page_config(
     layout="wide",
 )
 
-# ---------------- SESSION ----------------
-if "messages" not in st.session_state:
-    st.session_state.messages = []
+# ================== HELPERS ==================
+def api_alive() -> bool:
+    """Check if backend is reachable."""
+    try:
+        r = requests.get(f"{API_URL}/", timeout=3)
+        return r.status_code == 200
+    except Exception:
+        return False
 
-if "last" not in st.session_state:
-    st.session_state.last = None
 
-if "mode" not in st.session_state:
-    st.session_state.mode = "conversation"
+def safe_post(url: str, payload: dict, headers: dict | None = None, timeout: int = 30):
+    """POST helper with nice error handling."""
+    try:
+        r = requests.post(url, json=payload, headers=headers, timeout=timeout)
+        return r
+    except requests.exceptions.RequestException as e:
+        st.error(f"Connection error: {e}")
+        return None
 
-if "token" not in st.session_state:
-    st.session_state.token = None
+
+def safe_get(url: str, headers: dict | None = None, timeout: int = 10):
+    """GET helper with nice error handling."""
+    try:
+        r = requests.get(url, headers=headers, timeout=timeout)
+        return r
+    except requests.exceptions.RequestException as e:
+        st.error(f"Connection error: {e}")
+        return None
 
 
-# ---------------- STREAM FUNCTION ----------------
 def stream_chat(message: str):
+    """Call backend /chat endpoint (non-streaming in your backend, returns final JSON)."""
+    payload = {"message": message, "mode": st.session_state.mode}
+    headers = {"Authorization": f"Bearer {st.session_state.token}"}
 
-    payload = {
-        "message": message,
-        "mode": st.session_state.mode
-    }
+    r = safe_post(f"{API_URL}/chat", payload, headers=headers, timeout=180)
+    if r is None:
+        raise RuntimeError("Backend not reachable.")
+    r.raise_for_status()
+    data = r.json()
+    yield ("final", data)
 
-    headers = {
-        "Authorization": f"Bearer {st.session_state.token}"
-    }
 
-    r = requests.post(
-        f"{API_URL}/chat",
-        json=payload,
-        headers=headers,
-        timeout=180
-    )
+# ================== SESSION STATE ==================
+if "messages" not in st.session_state:
+    st.session_state.messages = []
 
-    r.raise_for_status()
+if "last" not in st.session_state:
+    st.session_state.last = None
 
-    data = r.json()
+if "mode" not in st.session_state:
+    st.session_state.mode = "conversation"
 
-    yield ("final", data)
-# ---------------- SIDEBAR AUTH ----------------
+if "token" not in st.session_state:
+    st.session_state.token = None
+
+# ================== SIDEBAR ==================
 with st.sidebar:
     st.markdown("## 🔐 Account")
 
+    # Show backend status
+    if api_alive():
+        st.success("Backend: online ✅")
+    else:
+        st.error("Backend: offline ❌")
+
     tabL, tabR = st.tabs(["Login", "Register"])
 
     with tabL:
@@ -61,13 +88,22 @@ with st.sidebar:
         pwd = st.text_input("Password", type="password", key="login_pwd")
 
         if st.button("Login", use_container_width=True):
-            r = requests.post(
+            r = safe_post(
                 f"{API_URL}/auth/login",
-                json={"email": email, "password": pwd}
+                {"email": email, "password": pwd},
+                timeout=20
             )
 
+            if r is None:
+                st.stop()
+
             if r.status_code == 200:
-                st.session_state.token = r.json()["token"]
+                try:
+                    st.session_state.token = r.json()["token"]
+                except Exception:
+                    st.error("Login response is not valid JSON.")
+                    st.stop()
+
                 st.success("Logged in ✅")
                 st.rerun()
             else:
@@ -79,43 +115,67 @@ with st.sidebar:
         pwd2 = st.text_input("Password", type="password", key="reg_pwd")
 
         if st.button("Create account", use_container_width=True):
-            r = requests.post(
+            r = safe_post(
                 f"{API_URL}/auth/register",
-                json={"email": email2, "username": username2, "password": pwd2}
+                {"email": email2, "username": username2, "password": pwd2},
+                timeout=20
             )
 
+            if r is None:
+                st.stop()
+
             if r.status_code == 200:
-                st.session_state.token = r.json()["token"]
+                try:
+                    st.session_state.token = r.json()["token"]
+                except Exception:
+                    st.error("Register response is not valid JSON.")
+                    st.stop()
+
                 st.success("Account created ✅")
                 st.rerun()
             else:
                 st.error(r.text)
 
+    # If user logged in: show profile + logout
     if st.session_state.token:
-        me = requests.get(
+        me = safe_get(
             f"{API_URL}/auth/me",
-            headers={"Authorization": f"Bearer {st.session_state.token}"}
+            headers={"Authorization": f"Bearer {st.session_state.token}"},
+            timeout=10
         )
 
-        if me.status_code == 200:
-            st.success(f"Connected as: {me.json()['username']}")
+        if me is not None and me.status_code == 200:
+            try:
+                st.success(f"Connected as: {me.json().get('username', '—')}")
+            except Exception:
+                st.info("Connected, but /auth/me returned invalid JSON.")
 
         if st.button("Logout", use_container_width=True):
             st.session_state.token = None
             st.session_state.messages = []
+            st.session_state.last = None
             st.rerun()
 
+# Stop early if backend is down
+if not api_alive():
+    st.error("API backend not running (FastAPI). Check Space Logs.")
+    st.stop()
 
-# ---------------- MAIN HEADER ----------------
+# ================== MAIN ==================
 st.title("🧠 LearnLanguage • Streaming Tutor")
 st.caption("Streaming replies • Corrections • Exercises • Progress-ready")
 
-
-# ---------------- INPUT ----------------
 if not st.session_state.token:
     st.warning("Please login first to start chatting.")
     st.stop()
 
+# Optional: mode selector
+st.session_state.mode = st.selectbox(
+    "Mode",
+    options=["conversation", "correction", "exercise"],
+    index=["conversation", "correction", "exercise"].index(st.session_state.mode)
+)
+
 colA, colB = st.columns([5, 1])
 
 with colA:
@@ -127,28 +187,19 @@ with colA:
 with colB:
     send = st.button("Send 🚀", use_container_width=True)
 
-
-# ---------------- SEND LOGIC ----------------
+# ================== SEND LOGIC ==================
 if send and user_msg.strip():
-
     ts = datetime.now().strftime("%H:%M")
 
-    st.session_state.messages.append({
-        "role": "user",
-        "text": user_msg,
-        "ts": ts
-    })
+    st.session_state.messages.append({"role": "user", "text": user_msg, "ts": ts})
 
-    streamed_text = ""
     placeholder = st.empty()
 
     try:
         for kind, data in stream_chat(user_msg):
-
             if kind == "text":
-                streamed_text += data
-                placeholder.markdown(f"**Tutor (streaming…)**\n\n{streamed_text}")
-
+                # (your backend currently returns final JSON only)
+                placeholder.markdown(f"**Tutor (streaming…)**\n\n{data}")
             else:
                 res = data
                 st.session_state.last = res
@@ -161,11 +212,12 @@ if send and user_msg.strip():
 
         st.rerun()
 
+    except requests.HTTPError as e:
+        st.error(f"API returned an error: {e}")
     except Exception as e:
         st.error(f"Streaming error: {e}")
 
-
-# ---------------- CHAT HISTORY ----------------
+# ================== CHAT HISTORY ==================
 st.markdown("## 💬 Conversation")
 
 for m in st.session_state.messages[-30:]:
@@ -173,12 +225,10 @@ for m in st.session_state.messages[-30:]:
     st.markdown(f"**{who} • {m['ts']}**")
     st.write(m["text"])
 
-
-# ---------------- TUTOR PANEL ----------------
+# ================== TUTOR PANEL ==================
 st.markdown("## 🧾 Tutor Panel")
 
 res = st.session_state.last or {}
-
 tabs = st.tabs(["Feedback", "Exercises", "Raw JSON"])
 
 with tabs[0]: