import streamlit as st
from engine import run
from datetime import datetime

# =========================
# PAGE CONFIG
# =========================
st.set_page_config(
    page_title="Text-to-SQL AI",
    layout="wide"
)

st.title("🧠 Text-to-SQL Assistant")
st.caption("Ask questions in natural language. I’ll generate SQL using your database metadata.")

# =========================
# SESSION STATE
# =========================
if "messages" not in st.session_state:
    st.session_state.messages = []

if "transcript" not in st.session_state:
    st.session_state.transcript = []

# =========================
# CHAT HISTORY
# =========================
for msg in st.session_state.messages:
    with st.chat_message(msg["role"]):
        st.markdown(msg["content"], unsafe_allow_html=True)

# =========================
# USER INPUT
# =========================
user_input = st.chat_input("Ask something like: 'Show employees in IT department'")

if user_input:
    # Display user message
    st.session_state.messages.append(
        {"role": "user", "content": user_input}
    )

    with st.chat_message("user"):
        st.markdown(user_input)

    # Call engine
    with st.spinner("Generating SQL..."):
        try:
            result = run(user_input)
        except Exception as e:
            result = {
                "status": "error",
                "message": str(e)
            }

    # =========================
    # BUILD RESPONSE
    # =========================
    reply = ""

    if result.get("status") == "ok":
        if result.get("message"):
            reply += f"### ✅ Result\n{result['message']}\n\n"

        if result.get("sql"):
            reply += "### 🧾 Generated SQL\n"
            reply += f"```sql\n{result['sql']}\n```"

    else:
        reply = f"❌ **Error:** {result.get('message')}"

    # Save transcript
    st.session_state.transcript.append({
        "timestamp": datetime.utcnow().isoformat(),
        "question": user_input,
        "reply": reply,
        "sql": result.get("sql"),
        "error": result.get("message") if result.get("status") != "ok" else None
    })

    # Show assistant reply
    st.session_state.messages.append(
        {"role": "assistant", "content": reply}
    )

    with st.chat_message("assistant"):
        st.markdown(reply, unsafe_allow_html=True)

# =========================
# DOWNLOAD LOG
# =========================
def download_transcript():
    lines = []
    for i, t in enumerate(st.session_state.transcript, 1):
        lines.append(f"\n--- Query {i} ---")
        lines.append(f"Time: {t['timestamp']}")
        lines.append(f"Question: {t['question']}")
        lines.append(f"Reply:\n{t['reply']}")
        if t.get("sql"):
            lines.append(f"SQL:\n{t['sql']}")
    return "\n".join(lines)

if st.session_state.transcript:
    st.divider()
    st.download_button(
        "⬇️ Download Query Log",
        data=download_transcript(),
        file_name="text_to_sql_log.txt",
        mime="text/plain",
        use_container_width=True
    )