src/streamlit_app.py

import streamlit as st
import chess
import chess.svg

st.set_page_config(page_title="♟️ Chess Game", layout="centered")

st.title("♟️ Chess Game")

# --- Initialize session ---
if "board" not in st.session_state:
    st.session_state.board = chess.Board()
    st.session_state.move_history = []
    st.session_state.last_move_msg = ""

board = st.session_state.board

# --- Layout ---
col_board, col_controls = st.columns([2, 1])

# ================= BOARD =================
with col_board:
    st.subheader("Board")
    board_svg = chess.svg.board(board=board, size=500)
    st.image(board_svg)

# ================= CONTROLS =================
with col_controls:
    st.subheader("Controls")

    st.info(f"Turn: {'White' if board.turn else 'Black'}")

    squares = [chess.square_name(sq) for sq in chess.SQUARES]

    from_sq = st.selectbox("From", squares, key="from")
    to_sq = st.selectbox("To", squares, key="to")

    if st.button("♟️ Move"):
        try:
            move = chess.Move.from_uci(from_sq + to_sq)

            if move in board.legal_moves:
                board.push(move)
                st.session_state.move_history.append(move.uci())

                # ✅ Store message once
                st.session_state.last_move_msg = f"Moved: {from_sq} → {to_sq}"

            else:
                st.session_state.last_move_msg = "❌ Illegal move!"

        except:
            st.session_state.last_move_msg = "❌ Invalid input!"

    # ✅ Show message ONCE (not repeating)
    if st.session_state.last_move_msg:
        st.success(st.session_state.last_move_msg)
        st.session_state.last_move_msg = ""   # clear after showing

    # --- Buttons ---
    col_btn1, col_btn2 = st.columns(2)

    with col_btn1:
        if st.button("↩️ Undo"):
            if board.move_stack:
                board.pop()
                st.session_state.move_history.pop()

    with col_btn2:
        if st.button("🔄 Reset"):
            st.session_state.board = chess.Board()
            st.session_state.move_history = []

# ================= HISTORY =================
st.subheader("📜 Move History")

if st.session_state.move_history:
    st.write(", ".join(st.session_state.move_history))
else:
    st.write("No moves yet")

# ================= STATUS =================
st.subheader("Game Status")

if board.is_checkmate():
    st.error("♟️ Checkmate!")
elif board.is_stalemate():
    st.warning("Stalemate!")
elif board.is_check():
    st.warning("Check!")
else:
    st.success("Game in progress...")