"""
Chess AI - Hugging Face Spaces
Entry point: app.py
"""
import sys
import os
sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

import streamlit as st
import chess
import chess.svg
import base64

st.set_page_config(
    page_title="Chess AI",
    page_icon="♟️",
    layout="centered",
    initial_sidebar_state="expanded",
)

st.markdown("""
<style>
@import url('https://fonts.googleapis.com/css2?family=Playfair+Display:wght@700&family=IBM+Plex+Mono:wght@400;500&display=swap');

html, body, [class*="css"] {
    font-family: 'IBM Plex Mono', monospace;
    background-color: #0f0f0f;
    color: #e8e0d0;
}
h1, h2, h3 { font-family: 'Playfair Display', serif; color: #f0c060; }
.stButton > button {
    background: #1a1a1a; color: #f0c060;
    border: 1px solid #f0c060; border-radius: 2px;
    font-family: 'IBM Plex Mono', monospace; font-size: 13px;
    transition: all 0.2s;
}
.stButton > button:hover { background: #f0c060; color: #0f0f0f; }
.move-log {
    background: #1a1a1a; border: 1px solid #333; border-radius: 4px;
    padding: 10px; height: 200px; overflow-y: auto;
    font-size: 12px; color: #aaa; font-family: 'IBM Plex Mono', monospace;
}
.status-bar {
    background: #1a1a1a; border-left: 3px solid #f0c060;
    padding: 8px 14px; margin: 10px 0; font-size: 13px;
}
.info-chip {
    display: inline-block; background: #222; border: 1px solid #444;
    border-radius: 2px; padding: 2px 8px; font-size: 11px; margin: 2px;
}
</style>
""", unsafe_allow_html=True)


# ─── Cached resource loading ─────────────────────────────────────────────────
@st.cache_resource(show_spinner="Đang tải Chess Engine...")
def load_engine():
    from src import config, engine
    return config, engine

@st.cache_resource(show_spinner="Đang tải ML Model...")
def load_ml_agent():
    try:
        from src.ai_battle import MLAgent
        return MLAgent(), None
    except Exception as e:
        return None, str(e)


# ─── Session state ────────────────────────────────────────────────────────────
def init_state():
    defaults = {
        "board": chess.Board(),
        "move_log": [],
        "game_over": False,
        "status_msg": "Lượt của bạn ♙",
        "depth": 2,
        "game_mode": "human_vs_minimax",
        "input_key": 0,
    }
    for k, v in defaults.items():
        if k not in st.session_state:
            st.session_state[k] = v

init_state()


# ─── Helpers ─────────────────────────────────────────────────────────────────
def board_to_html(board: chess.Board, last_move: chess.Move = None) -> str:
    arrows = []
    if last_move:
        arrows.append(chess.svg.Arrow(last_move.from_square, last_move.to_square, color="#f0c06088"))
    svg = chess.svg.board(
        board, size=460, arrows=arrows,
        colors={
            "square light": "#ede0c8",
            "square dark": "#b58863",
            "square light lastmove": "#cdd16e",
            "square dark lastmove": "#aaa23a",
        }
    )
    b64 = base64.b64encode(svg.encode()).decode()
    return f'<img src="data:image/svg+xml;base64,{b64}" width="460"/>'

def get_last_move(board):
    try:
        return board.peek()
    except IndexError:
        return None

def reset_game():
    st.session_state.board = chess.Board()
    st.session_state.move_log = []
    st.session_state.game_over = False
    st.session_state.status_msg = "Lượt của bạn ♙"
    st.session_state.input_key = 0

def check_game_over(board: chess.Board) -> bool:
    if board.is_checkmate():
        winner = "Đen" if board.turn == chess.WHITE else "Trắng"
        st.session_state.status_msg = f"♚ Chiếu hết! {winner} thắng!"
        st.session_state.game_over = True
    elif board.is_stalemate():
        st.session_state.status_msg = "🤝 Hòa (Stalemate)"
        st.session_state.game_over = True
    elif board.is_insufficient_material():
        st.session_state.status_msg = "🤝 Hòa (thiếu quân)"
        st.session_state.game_over = True
    elif board.is_seventyfive_moves():
        st.session_state.status_msg = "🤝 Hòa (75 nước)"
        st.session_state.game_over = True
    return st.session_state.game_over

def do_minimax_move(board: chess.Board):
    config, engine = load_engine()
    move = engine.find_best_move(board, config.STANDARD_WEIGHTS, st.session_state.depth)
    if move and move in board.legal_moves:
        st.session_state.move_log.append(f"Minimax (d{st.session_state.depth}): {move.uci()}")
        board.push(move)
        if not check_game_over(board):
            st.session_state.status_msg = "Lượt của bạn ♙"

def do_ml_move(board: chess.Board):
    ml_agent, err = load_ml_agent()
    if err:
        st.error(f"ML Agent lỗi: {err}")
        return
    move = ml_agent.get_move(board, time_limit=15.0)
    if move and move in board.legal_moves:
        st.session_state.move_log.append(f"ML Agent: {move.uci()}")
        board.push(move)
        if not check_game_over(board):
            st.session_state.status_msg = "Lượt của bạn ♙"
    else:
        import random
        legal = list(board.legal_moves)
        if legal:
            fb = random.choice(legal)
            board.push(fb)
            st.session_state.move_log.append(f"ML Agent (fallback): {fb.uci()}")
            check_game_over(board)


# ─── Sidebar ──────────────────────────────────────────────────────────────────
with st.sidebar:
    st.markdown("## ♟️ Chess AI")
    st.markdown("---")

    new_mode = st.radio(
        "Chế độ chơi",
        ["Người vs Minimax", "Người vs ML Agent"],
    )
    new_mode_key = "human_vs_minimax" if "Minimax" in new_mode else "human_vs_ml"

    # Reset tự động nếu đổi chế độ
    if new_mode_key != st.session_state.game_mode:
        st.session_state.game_mode = new_mode_key
        reset_game()

    if new_mode_key == "human_vs_minimax":
        st.session_state.depth = st.slider("Độ sâu Minimax", 1, 4, 2)
        st.caption("Depth 1-2: nhanh · Depth 3-4: mạnh hơn nhưng chậm")

    st.markdown("---")
    if st.button("🔄 Ván mới"):
        reset_game()
        st.rerun()

    st.markdown("---")
    st.markdown("**Hướng dẫn**")
    st.markdown("Chọn ô nguồn → ô đích → nhấn **Đi**  \nPhong cấp tự động lên Hậu")
    st.markdown("---")
    st.markdown(
        '<a href="https://github.com/ncn2569/Chess-game-with-AI-and-ML" '
        'target="_blank">📂 GitHub</a>',
        unsafe_allow_html=True,
    )


# ─── Main ─────────────────────────────────────────────────────────────────────
st.markdown("# Chess AI")

board = st.session_state.board
col_board, col_ctrl = st.columns([3, 2], gap="medium")

with col_board:
    st.markdown(board_to_html(board, get_last_move(board)), unsafe_allow_html=True)
    st.markdown(
        f'<div class="status-bar">{st.session_state.status_msg}</div>',
        unsafe_allow_html=True,
    )
    if board.is_check() and not st.session_state.game_over:
        st.warning("⚠️ Chiếu!")

with col_ctrl:
    # ── Input nước đi (người luôn chơi Trắng)
    if not st.session_state.game_over and board.turn == chess.WHITE:
        st.markdown("### Nước đi của bạn")

        legal_from = sorted({
            chess.SQUARE_NAMES[m.from_square] for m in board.legal_moves
        })
        from_sq = st.selectbox("Từ ô", [""] + legal_from, key=f"from_sq_{st.session_state.input_key}")

        valid_to = []
        if from_sq:
            try:
                from_idx = chess.parse_square(from_sq)
                valid_to = sorted({
                    chess.SQUARE_NAMES[m.to_square]
                    for m in board.legal_moves if m.from_square == from_idx
                })
            except ValueError:
                pass
        to_sq = st.selectbox("Đến ô", [""] + valid_to, key=f"to_sq_{st.session_state.input_key}")

        if st.button("▶ Đi", disabled=not (from_sq and to_sq)):
            try:
                uci = f"{from_sq}{to_sq}"
                piece = board.piece_at(chess.parse_square(from_sq))
                if piece and piece.piece_type == chess.PAWN:
                    if (board.turn == chess.WHITE and to_sq[1] == "8") or \
                        (board.turn == chess.BLACK and to_sq[1] == "1"):
                        uci += "q"
                move = chess.Move.from_uci(uci)
                if move in board.legal_moves:
                    st.session_state.move_log.append(f"Bạn: {uci}")
                    board.push(move)
                    st.session_state.input_key += 1
                    if not check_game_over(board):
                        st.session_state.status_msg = "AI đang suy nghĩ..."
                    st.rerun()
                else:
                    st.error("Nước đi không hợp lệ!")
            except ValueError:
                pass  # from_sq rỗng hoặc không hợp lệ, im lặng bỏ qua
            except Exception as e:
                st.error(f"Lỗi: {e}")

    # ── AI tự động đi khi đến lượt Đen
    if not st.session_state.game_over and board.turn == chess.BLACK:
        placeholder = st.empty()
        with st.spinner("AI đang suy nghĩ..."):
            if st.session_state.game_mode == "human_vs_minimax":
                do_minimax_move(board)
            else:
                do_ml_move(board)
        placeholder.empty()
        st.rerun()

    # ── Lịch sử
    st.markdown("---")
    st.markdown("### Lịch sử")
    log_html = "<br>".join(st.session_state.move_log[-30:][::-1]) or "<i>Chưa có</i>"
    st.markdown(f'<div class="move-log">{log_html}</div>', unsafe_allow_html=True)

    # ── Thông tin quân còn lại
    st.markdown("---")
    for name, pt in [("♙Tốt", chess.PAWN), ("♘Mã", chess.KNIGHT),
                     ("♗Tượng", chess.BISHOP), ("♖Xe", chess.ROOK), ("♛Hậu", chess.QUEEN)]:
        w = len(board.pieces(pt, chess.WHITE))
        b = len(board.pieces(pt, chess.BLACK))
        st.markdown(
            f'<span class="info-chip">{name} ⬜{w} ⬛{b}</span>',
            unsafe_allow_html=True,
        )
    st.markdown(
        f'<span class="info-chip">Nước #{board.fullmove_number}</span>',
        unsafe_allow_html=True,
    )