import io, json, os, base64, math
from pathlib import Path
import streamlit as st
import pandas as pd
import numpy as np
import joblib

# matplotlib only for PREVIEW modal
import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt

import plotly.graph_objects as go
from sklearn.metrics import r2_score, mean_squared_error, mean_absolute_error

# =========================
# Constants (simple & robust)
# =========================
FEATURES = ["Q, gpm", "SPP(psi)", "T (kft.lbf)", "WOB (klbf)", "ROP (ft/h)"]
TARGET = "UCS"
MODELS_DIR = Path("models")
DEFAULT_MODEL = MODELS_DIR / "ucs_rf.joblib"
MODEL_FALLBACKS = [MODELS_DIR / "model.joblib", MODELS_DIR / "model.pkl"]
COLORS = {"pred": "#1f77b4", "actual": "#f2b702", "ref": "#5a5a5a"}

# ---- Plot sizing controls (edit here) ----
CROSS_W = 500; CROSS_H = 500      # square cross-plot (Build + Validate)
TRACK_W = 400; TRACK_H = 950      # log-strip style (all pages)
FONT_SZ  = 15
PLOT_COLS = [30, 1, 20]         # 3-column band: left • spacer • right (Build + Validate)
CROSS_NUDGE = 0.06                # push cross-plot to the RIGHT inside its band:
                                  # inner columns [CROSS_NUDGE : 1] → bigger = more right

# =========================
# Page / CSS
# =========================
st.set_page_config(page_title="ST_GeoMech_UCS", page_icon="logo.png", layout="wide")
st.markdown("<style>header, footer{visibility:hidden !important;}</style>", unsafe_allow_html=True)
st.markdown(
    """
    <style>
      .stApp { background:#fff; }
      section[data-testid="stSidebar"] { background:#F6F9FC; }
      .block-container { padding-top:.5rem; padding-bottom:.5rem; }
      .stButton>button { background:#007bff; color:#fff; font-weight:600; border-radius:8px; border:none; }
      .stButton>button:hover { background:#0056b3; }
      .st-hero { display:flex; align-items:center; gap:16px; padding-top: 4px; }
      .st-hero .brand { width:110px; height:110px; object-fit:contain; }
      .st-hero h1 { margin:0; line-height:1.05; }
      .st-hero .tagline { margin:2px 0 0 2px; color:#6b7280; font-size:1.05rem; font-style:italic; }
      [data-testid="stBlock"]{ margin-top:0 !important; }
    </style>
    """,
    unsafe_allow_html=True
)

# =========================
# Password gate (define first, then call)
# =========================
def inline_logo(path="logo.png") -> str:
    try:
        p = Path(path)
        if not p.exists(): return ""
        return f"data:image/png;base64,{base64.b64encode(p.read_bytes()).decode('ascii')}"
    except Exception:
        return ""

def add_password_gate() -> None:
    try:
        required = st.secrets.get("APP_PASSWORD", "")
    except Exception:
        required = os.environ.get("APP_PASSWORD", "")

    if not required:
        st.markdown(
            f"""
            <div style="display:flex;align-items:center;gap:14px;margin:8px 0 6px 0;">
              <img src="{inline_logo()}" style="width:56px;height:56px;object-fit:contain"/>
              <div>
                <div style="font-size:1.9rem;font-weight:800;">ST_GeoMech_UCS</div>
                <div style="color:#667085;">Smart Thinking • Secure Access</div>
              </div>
            </div>
            <div style="font-size:1.25rem;font-weight:700;margin:8px 0 4px 0;">Protected Area</div>
            <div style="color:#6b7280;margin-bottom:14px;">
              Set <code>APP_PASSWORD</code> in <b>Settings → Secrets</b> (or environment) and restart.
            </div>
            """,
            unsafe_allow_html=True,
        )
        st.stop()

    if st.session_state.get("auth_ok", False):
        return

    st.markdown(
        f"""
        <div style="display:flex;align-items:center;gap:14px;margin:8px 0 6px 0;">
          <img src="{inline_logo()}" style="width:56px;height:56px;object-fit:contain"/>
          <div>
            <div style="font-size:1.9rem;font-weight:800;">ST_GeoMech_UCS</div>
            <div style="color:#667085;">Smart Thinking • Secure Access</div>
          </div>
        </div>
        <div style="font-size:1.25rem;font-weight:700;margin:8px 0 4px 0;">Protected</div>
        <div style="color:#6b7280;margin-bottom:14px;">Please enter your access key to continue.</div>
        """,
        unsafe_allow_html=True
    )

    pwd = st.text_input("Access key", type="password", placeholder="••••••••")
    if st.button("Unlock", type="primary"):
        if pwd == required:
            st.session_state.auth_ok = True
            st.rerun()
        else:
            st.error("Incorrect key.")
    st.stop()

add_password_gate()

# =========================
# Utilities
# =========================
try:
    dialog = st.dialog
except AttributeError:
    def dialog(title):
        def deco(fn):
            def wrapper(*args, **kwargs):
                with st.expander(title, expanded=True):
                    return fn(*args, **kwargs)
            return wrapper
        return deco

def rmse(y_true, y_pred): return float(np.sqrt(mean_squared_error(y_true, y_pred)))

@st.cache_resource(show_spinner=False)
def load_model(model_path: str):
    return joblib.load(model_path)

@st.cache_data(show_spinner=False)
def parse_excel(data_bytes: bytes):
    bio = io.BytesIO(data_bytes)
    xl = pd.ExcelFile(bio)
    return {sh: xl.parse(sh) for sh in xl.sheet_names}

def read_book_bytes(b: bytes): return parse_excel(b) if b else {}

def ensure_cols(df, cols):
    miss = [c for c in cols if c not in df.columns]
    if miss:
        st.error(f"Missing columns: {miss}\nFound: {list(df.columns)}")
        return False
    return True

def find_sheet(book, names):
    low2orig = {k.lower(): k for k in book.keys()}
    for nm in names:
        if nm.lower() in low2orig: return low2orig[nm.lower()]
    return None

def _nice_tick0(xmin: float, step: int = 100) -> float:
    """Round xmin down to a sensible multiple so the first tick sits at the left edge."""
    if not np.isfinite(xmin):
        return xmin
    return step * math.floor(xmin / step)

# ---------- Plot builders ----------
def cross_plot(actual, pred):
    a = pd.Series(actual).astype(float)
    p = pd.Series(pred).astype(float)

    fixed_min = 6000
    fixed_max = 10000

    fig = go.Figure()

    # Scatter points
    fig.add_trace(go.Scatter(
        x=a, y=p, mode="markers",
        marker=dict(size=6, color=COLORS["pred"]),
        hovertemplate="Actual: %{x:.0f}<br>Pred: %{y:.0f}<extra></extra>",
        showlegend=False
    ))

    # 1:1 reference line from bottom-left to top-right
    fig.add_trace(go.Scatter(
        x=[fixed_min, fixed_max], y=[fixed_min, fixed_max], mode="lines",
        line=dict(color=COLORS["ref"], width=1.2, dash="dash"),
        hoverinfo="skip", showlegend=False
    ))

    fig.update_layout(
        width=CROSS_W, height=CROSS_H,
        paper_bgcolor="#fff", plot_bgcolor="#fff",
        margin=dict(l=64, r=18, t=10, b=48),
        hovermode="closest",
        font=dict(size=FONT_SZ),
        dragmode=False  # disables zooming
    )

    fig.update_xaxes(
        title_text="<b>Actual UCS (psi)</b>",
        range=[fixed_min, fixed_max],
        tickformat=",.0f", ticks="outside",
        showline=True, linewidth=1.2, linecolor="#444", mirror=True,
        showgrid=True, gridcolor="rgba(0,0,0,0.12)",
        automargin=True, fixedrange=True  # disables zooming
    )

    fig.update_yaxes(
        title_text="<b>Predicted UCS (psi)</b>",
        range=[fixed_min, fixed_max],
        tickformat=",.0f", ticks="outside",
        showline=True, linewidth=1.2, linecolor="#444", mirror=True,
        showgrid=True, gridcolor="rgba(0,0,0,0.12)",
        scaleanchor="x", scaleratio=1,
        automargin=True, fixedrange=True  # disables zooming
    )

    return fig


def track_plot(df, include_actual=True):
    depth_col = next((c for c in df.columns if 'depth' in str(c).lower()), None)
    if depth_col is not None:
        y = pd.Series(df[depth_col]).astype(float)
        ylab = depth_col
        y_min, y_max = float(y.min()), float(y.max())
        y_range = [y_max, y_min]   # reversed for log profile style
    else:
        y = pd.Series(np.arange(1, len(df) + 1))
        ylab = "Point Index"
        y_min, y_max = float(y.min()), float(y.max())
        y_range = [y_max, y_min]

    # X (UCS) range & ticks
    x_series = pd.Series(df.get("UCS_Pred", pd.Series(dtype=float))).astype(float)
    if include_actual and TARGET in df.columns:
        x_series = pd.concat([x_series, pd.Series(df[TARGET]).astype(float)], ignore_index=True)
    x_lo, x_hi = float(x_series.min()), float(x_series.max())
    x_pad = 0.03 * (x_hi - x_lo if x_hi > x_lo else 1.0)
    xmin, xmax = x_lo - x_pad, x_hi + x_pad
    tick0 = _nice_tick0(xmin, step=100)

    fig = go.Figure()

    fig.add_trace(go.Scatter(
        x=df["UCS_Pred"], y=y, mode="lines",
        line=dict(color=COLORS["pred"], width=1.8),
        name="UCS_Pred",
        hovertemplate="UCS_Pred: %{x:.0f}<br>" + ylab + ": %{y}<extra></extra>"
    ))

    if include_actual and TARGET in df.columns:
        fig.add_trace(go.Scatter(
            x=df[TARGET], y=y, mode="lines",
            line=dict(color=COLORS["actual"], width=2.0, dash="dot"),
            name="UCS (actual)",
            hovertemplate="UCS (actual): %{x:.0f}<br>" + ylab + ": %{y}<extra></extra>"
        ))

    fig.update_layout(
        width=TRACK_W, height=TRACK_H,
        paper_bgcolor="#fff", plot_bgcolor="#fff",
        margin=dict(l=72, r=18, t=36, b=48),
        hovermode="closest",
        font=dict(size=FONT_SZ),
        legend=dict(
            x=0.98, y=0.05, xanchor="right", yanchor="bottom",
            bgcolor="rgba(255,255,255,0.75)", bordercolor="#ccc", borderwidth=1
        ),
        legend_title_text=""
    )

    fig.update_xaxes(
        title_text="<b>UCS (psi)</b>",
        title_font=dict(size=16),
        side="top", range=[xmin, xmax],
        ticks="outside", tickformat=",.0f",
        tickmode="auto", tick0=tick0,
        showline=True, linewidth=1.2, linecolor="#444", mirror=True,
        showgrid=True, gridcolor="rgba(0,0,0,0.12)", automargin=True
    )

    fig.update_yaxes(
        title_text=f"<b>{ylab}</b>",
        title_font=dict(size=16),
        range=y_range,
        ticks="outside",
        showline=True, linewidth=1.2, linecolor="#444", mirror=True,
        showgrid=True, gridcolor="rgba(0,0,0,0.12)", automargin=True
    )

    # Add a border rectangle to enclose the full figure space
    fig.add_shape(
        type="rect",
        xref="paper", yref="paper",
        x0=-0.12, y0=-0.12, x1=1.12, y1=1.12,
        line=dict(color="#000", width=1.5),
        layer="below"
    )

    return fig



# ---------- Preview modal (matplotlib) ----------
def preview_tracks(df: pd.DataFrame, cols: list[str]):
    cols = [c for c in cols if c in df.columns]
    n = len(cols)
    if n == 0:
        fig, ax = plt.subplots(figsize=(4, 2))
        ax.text(0.5,0.5,"No selected columns",ha="center",va="center")
        ax.axis("off")
        return fig
    fig, axes = plt.subplots(1, n, figsize=(2.2*n, 7.0), sharey=True, dpi=100)
    if n == 1: axes = [axes]
    idx = np.arange(1, len(df) + 1)
    for ax, col in zip(axes, cols):
        ax.plot(df[col], idx, '-', lw=1.4, color="#333")
        ax.set_xlabel(col); ax.xaxis.set_label_position('top'); ax.xaxis.tick_top(); ax.invert_yaxis()
        ax.grid(True, linestyle=":", alpha=0.3)
        for s in ax.spines.values(): s.set_visible(True)
    axes[0].set_ylabel("Point Index")
    return fig

try:
    dialog = st.dialog
except AttributeError:
    def dialog(title):
        def deco(fn):
            def wrapper(*args, **kwargs):
                with st.expander(title, expanded=True):
                    return fn(*args, **kwargs)
            return wrapper
        return deco

@dialog("Preview data")
def preview_modal(book: dict[str, pd.DataFrame]):
    if not book:
        st.info("No data loaded yet."); return
    names = list(book.keys())
    tabs = st.tabs(names)
    for t, name in zip(tabs, names):
        with t:
            df = book[name]
            t1, t2 = st.tabs(["Tracks", "Summary"])
            with t1: st.pyplot(preview_tracks(df, FEATURES), use_container_width=True)
            with t2:
                tbl = df[FEATURES].agg(['min','max','mean','std']).T.rename(columns={"min":"Min","max":"Max","mean":"Mean","std":"Std"})
                st.dataframe(tbl.reset_index(names="Feature"), use_container_width=True)

# =========================
# Load model (simple)
# =========================
def ensure_model() -> Path|None:
    for p in [DEFAULT_MODEL, *MODEL_FALLBACKS]:
        if p.exists() and p.stat().st_size > 0: return p
    url = os.environ.get("MODEL_URL", "")
    if not url: return None
    try:
        import requests
        DEFAULT_MODEL.parent.mkdir(parents=True, exist_ok=True)
        with requests.get(url, stream=True, timeout=30) as r:
            r.raise_for_status()
            with open(DEFAULT_MODEL, "wb") as f:
                for chunk in r.iter_content(1<<20):
                    if chunk: f.write(chunk)
        return DEFAULT_MODEL
    except Exception:
        return None

mpath = ensure_model()
if not mpath:
    st.error("Model not found. Upload models/ucs_rf.joblib (or set MODEL_URL).")
    st.stop()
try:
    model = load_model(str(mpath))
except Exception as e:
    st.error(f"Failed to load model: {e}")
    st.stop()

meta_path = MODELS_DIR / "meta.json"
if meta_path.exists():
    try:
        meta = json.loads(meta_path.read_text(encoding="utf-8"))
        FEATURES = meta.get("features", FEATURES); TARGET = meta.get("target", TARGET)
    except Exception:
        pass

# =========================
# Session state
# =========================
st.session_state.setdefault("app_step", "intro")
st.session_state.setdefault("results", {})
st.session_state.setdefault("train_ranges", None)
st.session_state.setdefault("dev_file_name","")
st.session_state.setdefault("dev_file_bytes",b"")
st.session_state.setdefault("dev_file_loaded",False)
st.session_state.setdefault("dev_preview",False)

# =========================
# Hero
# =========================
st.markdown(
    f"""
    <div class="st-hero">
      <img src="{inline_logo()}" class="brand" />
      <div>
        <h1>ST_GeoMech_UCS</h1>
        <div class="tagline">Real-Time UCS Tracking While Drilling</div>
      </div>
    </div>
    """,
    unsafe_allow_html=True,
)

# =========================
# INTRO
# =========================
if st.session_state.app_step == "intro":
    st.header("Welcome!")
    st.markdown("This software is developed by *Smart Thinking AI-Solutions Team* to estimate UCS from drilling data.")
    st.subheader("How It Works")
    st.markdown(
        "1) **Upload your data to build the case and preview the performance of our model.**  \n"
        "2) Click **Run Model** to compute metrics and plots.  \n"
        "3) **Proceed to Validation** (with actual UCS) or **Proceed to Prediction** (no UCS)."
    )
    if st.button("Start Showcase", type="primary"):
        st.session_state.app_step = "dev"; st.rerun()

# =========================
# CASE BUILDING
# =========================
if st.session_state.app_step == "dev":
    st.sidebar.header("Case Building")
    up = st.sidebar.file_uploader("Upload Train/Test Excel", type=["xlsx","xls"])
    if up is not None:
        st.session_state.dev_file_bytes = up.getvalue()
        st.session_state.dev_file_name = up.name
        st.session_state.dev_file_loaded = True
        st.session_state.dev_preview = False
    if st.session_state.dev_file_loaded:
        tmp = read_book_bytes(st.session_state.dev_file_bytes)
        if tmp:
            df0 = next(iter(tmp.values()))
            st.sidebar.caption(f"**Data loaded:** {st.session_state.dev_file_name} • {df0.shape[0]} rows × {df0.shape[1]} cols")

    if st.sidebar.button("Preview data", use_container_width=True, disabled=not st.session_state.dev_file_loaded):
        preview_modal(read_book_bytes(st.session_state.dev_file_bytes))
        st.session_state.dev_preview = True

    run = st.sidebar.button("Run Model", type="primary", use_container_width=True)
    # always available nav
    if st.sidebar.button("Proceed to Validation ▶", use_container_width=True): st.session_state.app_step="validate"; st.rerun()
    if st.sidebar.button("Proceed to Prediction ▶", use_container_width=True): st.session_state.app_step="predict"; st.rerun()

    # ---- Pinned helper at the very top of the page ----
    helper_top = st.container()
    with helper_top:
        st.subheader("Case Building")
        if st.session_state.dev_file_loaded and st.session_state.dev_preview:
            st.info("Previewed ✓ — now click **Run Model**.")
        elif st.session_state.dev_file_loaded:
            st.info("📄 **Preview uploaded data** using the sidebar button, then click **Run Model**.")
        else:
            st.write("**Upload your data to build a case, then run the model to review development performance.**")

    if run and st.session_state.dev_file_bytes:
        book = read_book_bytes(st.session_state.dev_file_bytes)
        sh_train = find_sheet(book, ["Train","Training","training2","train","training"])
        sh_test  = find_sheet(book, ["Test","Testing","testing2","test","testing"])
        if sh_train is None or sh_test is None:
            st.error("Workbook must include Train/Training/training2 and Test/Testing/testing2 sheets."); st.stop()
        tr = book[sh_train].copy(); te = book[sh_test].copy()
        if not (ensure_cols(tr, FEATURES+[TARGET]) and ensure_cols(te, FEATURES+[TARGET])):
            st.error("Missing required columns."); st.stop()
        tr["UCS_Pred"] = model.predict(tr[FEATURES])
        te["UCS_Pred"] = model.predict(te[FEATURES])

        st.session_state.results["Train"]=tr; st.session_state.results["Test"]=te
        st.session_state.results["m_train"]={"R2":r2_score(tr[TARGET],tr["UCS_Pred"]), "RMSE":rmse(tr[TARGET],tr["UCS_Pred"]), "MAE":mean_absolute_error(tr[TARGET],tr["UCS_Pred"])}
        st.session_state.results["m_test"] ={"R2":r2_score(te[TARGET],te["UCS_Pred"]), "RMSE":rmse(te[TARGET],te["UCS_Pred"]), "MAE":mean_absolute_error(te[TARGET],te["UCS_Pred"])}

        tr_min = tr[FEATURES].min().to_dict(); tr_max = tr[FEATURES].max().to_dict()
        st.session_state.train_ranges = {f:(float(tr_min[f]), float(tr_max[f])) for f in FEATURES}
        st.success("Case has been built and results are displayed below.")

    def _dev_block(df, m):
        c1,c2,c3 = st.columns(3)
        c1.metric("R²", f"{m['R2']:.4f}"); c2.metric("RMSE", f"{m['RMSE']:.4f}"); c3.metric("MAE", f"{m['MAE']:.4f}")
        left, spacer, right = st.columns(PLOT_COLS)
        with left:
            pad, plotcol = left.columns([CROSS_NUDGE, 1])  # shift cross-plot right inside its band
            with plotcol:
                st.plotly_chart(
                    cross_plot(df[TARGET], df["UCS_Pred"]),
                    use_container_width=False,
                    config={"displayModeBar": False, "scrollZoom": True}
                )
        with right:
            st.plotly_chart(
                track_plot(df, include_actual=True),
                use_container_width=False,
                config={"displayModeBar": False, "scrollZoom": True}
            )

    if "Train" in st.session_state.results or "Test" in st.session_state.results:
        tab1, tab2 = st.tabs(["Training", "Testing"])
        if "Train" in st.session_state.results:
            with tab1: _dev_block(st.session_state.results["Train"], st.session_state.results["m_train"])
        if "Test" in st.session_state.results:
            with tab2: _dev_block(st.session_state.results["Test"],  st.session_state.results["m_test"])

# =========================
# VALIDATION (with actual UCS)
# =========================
if st.session_state.app_step == "validate":
    st.sidebar.header("Validate the Model")
    up = st.sidebar.file_uploader("Upload Validation Excel", type=["xlsx","xls"])
    if up is not None:
        book = read_book_bytes(up.getvalue())
        if book:
            df0 = next(iter(book.values()))
            st.sidebar.caption(f"**Data loaded:** {up.name} • {df0.shape[0]} rows × {df0.shape[1]} cols")
    if st.sidebar.button("Preview data", use_container_width=True, disabled=(up is None)):
        preview_modal(read_book_bytes(up.getvalue()))
    go_btn = st.sidebar.button("Predict", type="primary", use_container_width=True)
    if st.sidebar.button("⬅ Back to Case Building", use_container_width=True): st.session_state.app_step="dev"; st.rerun()
    if st.sidebar.button("Proceed to Prediction ▶", use_container_width=True): st.session_state.app_step="predict"; st.rerun()

    st.subheader("Validate the Model")
    st.write("Upload a dataset with the same **features** and **UCS** to evaluate performance.")

    if go_btn and up is not None:
        book = read_book_bytes(up.getvalue())
        name = find_sheet(book, ["Validation","Validate","validation2","Val","val"]) or list(book.keys())[0]
        df = book[name].copy()
        if not ensure_cols(df, FEATURES+[TARGET]): st.error("Missing required columns."); st.stop()
        df["UCS_Pred"] = model.predict(df[FEATURES])
        st.session_state.results["Validate"]=df

        ranges = st.session_state.train_ranges; oor_pct = 0.0; tbl=None
        if ranges:
            any_viol = pd.DataFrame({f:(df[f]<ranges[f][0])|(df[f]>ranges[f][1]) for f in FEATURES}).any(axis=1)
            oor_pct = float(any_viol.mean()*100.0)
            if any_viol.any():
                tbl = df.loc[any_viol, FEATURES].copy()
                tbl["Violations"] = pd.DataFrame({f:(df[f]<ranges[f][0])|(df[f]>ranges[f][1]) for f in FEATURES}).loc[any_viol].apply(lambda r:", ".join([c for c,v in r.items() if v]), axis=1)
        st.session_state.results["m_val"]={"R2":r2_score(df[TARGET],df["UCS_Pred"]), "RMSE":rmse(df[TARGET],df["UCS_Pred"]), "MAE":mean_absolute_error(df[TARGET],df["UCS_Pred"])}
        st.session_state.results["sv_val"]={"n":len(df),"pred_min":float(df["UCS_Pred"].min()),"pred_max":float(df["UCS_Pred"].max()),"oor":oor_pct}
        st.session_state.results["oor_tbl"]=tbl

    if "Validate" in st.session_state.results:
        m = st.session_state.results["m_val"]
        c1,c2,c3 = st.columns(3)
        c1.metric("R²", f"{m['R2']:.4f}"); c2.metric("RMSE", f"{m['RMSE']:.4f}"); c3.metric("MAE", f"{m['MAE']:.4f}")

        left, spacer, right = st.columns(PLOT_COLS)
        with left:
            pad, plotcol = left.columns([CROSS_NUDGE, 1])  # same nudge
            with plotcol:
                st.plotly_chart(
                    cross_plot(st.session_state.results["Validate"][TARGET],
                               st.session_state.results["Validate"]["UCS_Pred"]),
                    use_container_width=False, config={"displayModeBar": False, "scrollZoom": True}
                )
        with right:
            st.plotly_chart(
                track_plot(st.session_state.results["Validate"], include_actual=True),
                use_container_width=False, config={"displayModeBar": False, "scrollZoom": True}
            )

        sv = st.session_state.results["sv_val"]
        if sv["oor"] > 0: st.warning("Some inputs fall outside **training min–max** ranges.")
        if st.session_state.results["oor_tbl"] is not None:
            st.write("*Out-of-range rows (vs. Training min–max):*")
            st.dataframe(st.session_state.results["oor_tbl"], use_container_width=True)

# =========================
# PREDICTION (no actual UCS)
# =========================
if st.session_state.app_step == "predict":
    st.sidebar.header("Prediction (No Actual UCS)")
    up = st.sidebar.file_uploader("Upload Prediction Excel", type=["xlsx","xls"])
    if up is not None:
        book = read_book_bytes(up.getvalue())
        if book:
            df0 = next(iter(book.values()))
            st.sidebar.caption(f"**Data loaded:** {up.name} • {df0.shape[0]} rows × {df0.shape[1]} cols")
    if st.sidebar.button("Preview data", use_container_width=True, disabled=(up is None)):
        preview_modal(read_book_bytes(up.getvalue()))
    go_btn = st.sidebar.button("Predict", type="primary", use_container_width=True)
    if st.sidebar.button("⬅ Back to Case Building", use_container_width=True): st.session_state.app_step="dev"; st.rerun()

    st.subheader("Prediction")
    st.write("Upload a dataset with the feature columns (no **UCS**).")

    if go_btn and up is not None:
        book = read_book_bytes(up.getvalue()); name = list(book.keys())[0]
        df = book[name].copy()
        if not ensure_cols(df, FEATURES): st.error("Missing required columns."); st.stop()
        df["UCS_Pred"] = model.predict(df[FEATURES])
        st.session_state.results["PredictOnly"]=df

        ranges = st.session_state.train_ranges; oor_pct = 0.0
        if ranges:
            any_viol = pd.DataFrame({f:(df[f]<ranges[f][0])|(df[f]>ranges[f][1]) for f in FEATURES}).any(axis=1)
            oor_pct = float(any_viol.mean()*100.0)
        st.session_state.results["sv_pred"]={
            "n":len(df),
            "pred_min":float(df["UCS_Pred"].min()),
            "pred_max":float(df["UCS_Pred"].max()),
            "pred_mean":float(df["UCS_Pred"].mean()),
            "pred_std":float(df["UCS_Pred"].std(ddof=0)),
            "oor":oor_pct
        }

    if "PredictOnly" in st.session_state.results:
        df = st.session_state.results["PredictOnly"]; sv = st.session_state.results["sv_pred"]

        left, spacer, right = st.columns(PLOT_COLS)
        with left:
            table = pd.DataFrame({
                "Metric": ["# points","Pred min","Pred max","Pred mean","Pred std","OOR %"],
                "Value":  [sv["n"], sv["pred_min"], sv["pred_max"], sv["pred_mean"], sv["pred_std"], f'{sv["oor"]:.1f}%']
            })
            st.success("Predictions ready ✓")
            st.dataframe(table, use_container_width=True, hide_index=True)
            st.caption("**★ OOR** = % of rows whose input features fall outside the training min–max range.")
        with right:
            st.plotly_chart(
                track_plot(df, include_actual=False),
                use_container_width=False, config={"displayModeBar": False, "scrollZoom": True}
            )

# =========================
# Footer
# =========================
st.markdown("---")
st.markdown(
    """
    <div style='text-align:center; color:#6b7280; line-height:1.6'>
      ST_GeoMech_UCS • © Smart Thinking<br/>
      <strong>Visit our website:</strong> <a href='https://www.smartthinking.com.sa' target='_blank'>smartthinking.com.sa</a>
    </div>
    """,
    unsafe_allow_html=True
)