# app.py
import os
import shutil
import gradio as gr
import chess
import chess.svg
import chess.engine

# ---------- Engine discovery ----------
def detect_stockfish_candidates():
    cands = []
    # env var
    env = os.environ.get("STOCKFISH_PATH")
    if env:
        cands.append(env)
    # PATH
    which = shutil.which("stockfish")
    if which:
        cands.append(which)
    # common paths
    cands += ["/usr/bin/stockfish", "/usr/games/stockfish", "/bin/stockfish", "/opt/conda/bin/stockfish"]
    # de-dup while preserving order
    seen = set(); uniq = []
    for p in cands:
        if p and p not in seen:
            uniq.append(p); seen.add(p)
    return uniq

def choose_stockfish_path(manual_path: str | None = None):
    """Pick first executable path from manual path or detected candidates."""
    if manual_path:
        if os.path.isfile(manual_path) and os.access(manual_path, os.X_OK):
            return manual_path
    for p in detect_stockfish_candidates():
        if os.path.isfile(p) and os.access(p, os.X_OK):
            return p
    return None

DEFAULT_THREADS = max(1, os.cpu_count() or 2)
DEFAULT_HASH_MB = 512
DEFAULT_MOVETIME_MS = 1500

def board_svg(board: chess.Board, last_move=None) -> str:
    return chess.svg.board(
        board=board,
        lastmove=last_move,
        check=board.is_check(),
        coordinates=True,
        size=520,
    )

def new_engine(path: str, threads=DEFAULT_THREADS, hash_mb=DEFAULT_HASH_MB, ponder=False):
    if not path:
        raise FileNotFoundError("Geen Stockfish-pad opgegeven.")
    if not (os.path.isfile(path) and os.access(path, os.X_OK)):
        raise FileNotFoundError(f"Stockfish niet uitvoerbaar op pad: {path}")
    engine = chess.engine.SimpleEngine.popen_uci(path)
    opts = {
        "Threads": int(threads),
        "Hash": int(hash_mb),
        "UCI_LimitStrength": False,
        "Skill Level": 20,
        "Ponder": ponder,
        "Move Overhead": 30,
    }
    try:
        engine.configure(opts)
    except Exception as e:
        print("UCI-opties zetten gaf een fout (doorgaan):", e)
    return engine

def init_state(engine_color: str, movetime_ms: int, depth: int | None, threads: int, hash_mb: int, engine_path: str | None):
    board = chess.Board()
    # Probeer engine te starten, maar laat UI werken zonder crash
    engine = None
    picked = choose_stockfish_path(engine_path)
    error = None
    if picked:
        try:
            engine = new_engine(picked, threads=threads, hash_mb=hash_mb)
        except Exception as e:
            error = str(e)
    state = {
        "board": board,
        "engine": engine,
        "engine_color": engine_color,
        "movetime_ms": movetime_ms,
        "depth": depth if depth and depth > 0 else None,
        "last_move": None,
        "engine_path": picked or (engine_path or ""),
        "engine_error": error,
    }
    # Alleen automatisch zetten als engine beschikbaar is én engine wit is
    if state["engine"] is not None and engine_color == "white":
        _ = engine_move(state)
    return state

def engine_limit(state):
    if state["depth"] is not None:
        return chess.engine.Limit(depth=int(state["depth"]))
    return chess.engine.Limit(time=max(0.05, state["movetime_ms"]/1000.0))

def render(state):
    svg = board_svg(state["board"], last_move=state["last_move"])
    return svg, state["board"].fen()

# --------- Actions ---------
def new_game(engine_color, movetime_ms, depth, threads, hash_mb, engine_path):
    state = init_state(engine_color, int(movetime_ms), int(depth) if depth else None, int(threads), int(hash_mb), engine_path.strip() or None)
    img, fen = render(state)
    if state["engine"]:
        msg = f"Nieuwe partij gestart. Engine pad: {state['engine_path']}"
    else:
        diag = diagnostics()  # show where we looked
        msg = (
            "Nieuwe partij gestart ZONDER engine. "
            "Vul het correcte pad in en klik 'Herstart engine'.\n\n"
            + diag
        )
    return state, img, fen, msg, state["engine_path"]

def diagnostics():
    lines = ["🔎 Stockfish-detectie:"]
    for p in detect_stockfish_candidates():
        ok = "✅" if os.path.isfile(p) and os.access(p, os.X_OK) else "❌"
        lines.append(f"{ok} {p}")
    env = os.environ.get("STOCKFISH_PATH")
    if env:
        lines.append(f"Env STOCKFISH_PATH={env}")
    lines.append("\nTip: zorg dat je in de Space een bestand 'apt.txt' hebt met:\nstockfish\n"
                 "en rebuild de Space. Of zet Settings → Variables → STOCKFISH_PATH naar bv. /usr/games/stockfish.")
    return "\n".join(lines)

def restart_engine(state, threads, hash_mb, engine_path):
    # sluit oude engine
    try:
        if state.get("engine"):
            state["engine"].quit()
    except Exception:
        pass
    # start nieuwe
    picked = choose_stockfish_path(engine_path.strip() or None)
    if not picked:
        state["engine"] = None
        state["engine_error"] = "Geen uitvoerbare Stockfish gevonden."
        msg = "❌ Geen engine gevonden.\n" + diagnostics()
    else:
        try:
            state["engine"] = new_engine(picked, threads=int(threads), hash_mb=int(hash_mb))
            state["engine_error"] = None
            state["engine_path"] = picked
            msg = f"✅ Engine gestart op: {picked}"
        except Exception as e:
            state["engine"] = None
            state["engine_error"] = str(e)
            msg = f"❌ Engine-fout: {e}\n" + diagnostics()
    img, fen = render(state)
    return state, img, fen, msg, state.get("engine_path","")

def make_move(state, user_move):
    board: chess.Board = state["board"]
    if board.is_game_over():
        return state, *render(state), f"Partij is al afgelopen: {board.result()}."

    try:
        mv = chess.Move.from_uci(user_move.strip())
        if mv not in board.legal_moves:
            return state, *render(state), "Ongeldige zet (niet legaal in deze stelling)."
        board.push(mv)
        state["last_move"] = mv
    except Exception as e:
        return state, *render(state), f"Ongeldige invoer: {e}"

    if board.is_game_over():
        img, fen = render(state)
        return state, img, fen, f"Partij afgelopen: {board.result()}."

    side_to_move = "white" if board.turn == chess.WHITE else "black"
    if side_to_move == state["engine_color"]:
        if state["engine"] is None:
            msg = "Engine niet beschikbaar — vul 'Engine pad' in en klik 'Herstart engine'."
        else:
            msg = engine_move(state)
    else:
        msg = "Jij bent aan zet."
    img, fen = render(state)
    return state, img, fen, msg

def engine_move(state):
    board: chess.Board = state["board"]
    engine: chess.engine.SimpleEngine = state["engine"]
    if engine is None:
        return "Engine niet beschikbaar."
    if board.is_game_over():
        return f"Partij afgelopen: {board.result()}."
    try:
        result = engine.play(board, engine_limit(state))
        board.push(result.move)
        state["last_move"] = result.move
        if board.is_game_over():
            return f"Engine zet {result.move}. Partij afgelopen: {board.result()}."
        else:
            return f"Engine zet {result.move}. Jij bent aan zet."
    except Exception as e:
        return f"Engine-fout: {e}"

def undo_move(state):
    board: chess.Board = state["board"]
    if len(board.move_stack) == 0:
        return state, *render(state), "Geen zetten om terug te nemen."
    board.pop()
    # Neem er eentje extra terug als engine aan zet zou komen
    if state["engine_color"] == ("white" if board.turn == chess.WHITE else "black") and len(board.move_stack) > 0:
        board.pop()
    state["last_move"] = board.move_stack[-1] if board.move_stack else None
    return state, *render(state), "Zet(ten) teruggenomen."

def resign(state):
    board: chess.Board = state["board"]
    outcome = "1-0" if board.turn == chess.BLACK else "0-1"
    return state, *render(state), f"Opgegeven. Resultaat: {outcome}"

# ---------- UI ----------
CSS = """
#board { display: flex; justify-content: center; }
#board svg { max-width: 100%; height: auto; }
"""

with gr.Blocks(title="Boss Chess (Stockfish)", css=CSS) as demo:
    gr.Markdown("# ♟️ Boss Chess (Stockfish)\nSpeel tegen een sterke NNUE-engine (Stockfish) in je browser.")

    with gr.Row():
        board_html = gr.HTML(label="Bord", elem_id="board")
        fen_out = gr.Textbox(label="FEN", interactive=False)

    with gr.Row():
        user_move = gr.Textbox(label="Jouw zet (UCI, bv. e2e4)", placeholder="e2e4", scale=2)
        btn_move = gr.Button("Zet uitvoeren", variant="primary")
        btn_undo = gr.Button("Undo")
        btn_resign = gr.Button("Resign")

    status = gr.Markdown("Klaar.")

    with gr.Accordion("⚙️ Instellingen", open=False):
        engine_color = gr.Radio(choices=["white","black"], value="black", label="Engine kleur")
        movetime = gr.Slider(200, 5000, value=DEFAULT_MOVETIME_MS, step=100, label="Engine denktijd (ms/zet)")
        depth = gr.Slider(0, 30, value=0, step=1, label="Max diepte (0=uit)")
        threads = gr.Slider(1, DEFAULT_THREADS, value=DEFAULT_THREADS, step=1, label="Threads")
        hash_mb = gr.Slider(64, 2048, value=DEFAULT_HASH_MB, step=64, label="Hash (MB)")
        engine_path = gr.Textbox(label="Engine pad (optioneel, bv. /usr/games/stockfish)", placeholder="/usr/games/stockfish", value="")
        btn_new = gr.Button("Nieuwe partij / herstart")
        btn_restart = gr.Button("Herstart engine")

    state = gr.State()

    # Bindings
    btn_new.click(new_game, [engine_color, movetime, depth, threads, hash_mb, engine_path],
                  [state, board_html, fen_out, status, engine_path])
    btn_restart.click(restart_engine, [state, threads, hash_mb, engine_path],
                      [state, board_html, fen_out, status, engine_path])
    btn_move.click(make_move, [state, user_move], [state, board_html, fen_out, status])
    btn_undo.click(undo_move, [state], [state, board_html, fen_out, status])
    btn_resign.click(resign, [state], [state, board_html, fen_out, status])

    # Auto-start
    demo.load(new_game, [engine_color, movetime, depth, threads, hash_mb, engine_path],
              [state, board_html, fen_out, status, engine_path])

if __name__ == "__main__":
    demo.launch()