import streamlit as st
import numpy as np
import pandas as pd
import plotly.express as px
import plotly.graph_objects as go
from plotly.subplots import make_subplots
from datetime import datetime, timedelta
from sklearn.linear_model import LinearRegression
import warnings
warnings.filterwarnings('ignore')

st.set_page_config(
    page_title="Profitability Intelligence Suite",
    page_icon="📊",
    layout="wide",
    initial_sidebar_state="collapsed"
)

# Custom CSS
st.markdown("""
<style>
    .main-header {
        font-size: 2.8rem;
        font-weight: 700;
        color: #1f77b4;
        text-align: center;
        margin-bottom: 0.5rem;
    }
    .sub-header {
        font-size: 1.2rem;
        color: #666;
        text-align: center;
        margin-bottom: 2rem;
    }
    .insight-box {
        background: #f8f9fa;
        border-left: 5px solid #1f77b4;
        padding: 1.5rem;
        margin: 1rem 0;
        border-radius: 8px;
        box-shadow: 0 4px 8px rgba(0,0,0,0.05);
    }
    .warning-box {
        background: #fff3cd;
        border-left: 5px solid #ffc107;
        padding: 1.5rem;
        margin: 1rem 0;
        border-radius: 8px;
    }
    .recommendation-card {
        background: white;
        border: 2px solid #e9ecef;
        border-radius: 12px;
        padding: 1.5rem;
        margin: 1rem 0;
        box-shadow: 0 4px 12px rgba(0,0,0,0.08);
    }
    .positive-impact {
        color: #28a745;
        font-weight: 700;
        font-size: 1.5rem;
    }
    .negative-impact {
        color: #dc3545;
        font-weight: 700;
        font-size: 1.5rem;
    }
</style>
""", unsafe_allow_html=True)

@st.cache_data(show_spinner=False)
def generate_synthetic_data(days=60, seed=42, rows_per_day=600):
    """Generate data with REALISTIC variance patterns"""
    rng = np.random.default_rng(seed)
    start_date = datetime.today().date() - timedelta(days=days)
    dates = pd.date_range(start_date, periods=days, freq="D")
    products = ["Premium Widget", "Standard Widget", "Economy Widget", "Deluxe Widget"]
    regions = ["Americas", "EMEA", "Asia Pacific"]
    channels = ["Direct Sales", "Distribution Partners", "E-Commerce"]

    base_price = {"Premium Widget": 120, "Standard Widget": 135, "Economy Widget": 110, "Deluxe Widget": 150}
    base_cost = {"Premium Widget": 70, "Standard Widget": 88, "Economy Widget": 60, "Deluxe Widget": 95}
    region_price_bump = {"Americas": 1.00, "EMEA": 1.03, "Asia Pacific": 0.97}
    region_cost_bump = {"Americas": 1.00, "EMEA": 1.02, "Asia Pacific": 1.01}
    channel_discount_mean = {"Direct Sales": 0.06, "Distribution Partners": 0.12, "E-Commerce": 0.04}
    channel_discount_std = {"Direct Sales": 0.02, "Distribution Partners": 0.03, "E-Commerce": 0.02}

    # Elasticity varies by segment
    seg_epsilon = {}
    for p in products:
        for r in regions:
            for c in channels:
                # More realistic elasticity range: -0.5 to -2.5
                base_eps = rng.uniform(-2.5, -0.5)
                if c == "Distribution Partners":
                    base_eps -= rng.uniform(0.3, 0.8)  # More price sensitive
                if c == "E-Commerce":
                    base_eps -= rng.uniform(0.2, 0.5)  # Also price sensitive
                seg_epsilon[(p, r, c)] = base_eps

    records = []
    for idx, d in enumerate(dates):
        dow = d.weekday()
        dow_mult = 1.0 + (0.08 if dow in (5, 6) else 0)

        # Add realistic seasonality and random shocks
        seasonal = 1.0 + 0.05*np.sin((d.toordinal()%365)/365*2*np.pi)

        # Random market shocks (some days have big changes)
        if rng.random() < 0.15:  # 15% of days have shocks
            market_shock = rng.uniform(0.85, 1.15)
        else:
            market_shock = 1.0

        # Gradual cost trends
        cost_trend = 1.0 + (idx / len(dates)) * 0.03  # 3% cost increase over period

        n = int(rows_per_day * market_shock * seasonal)
        prod = rng.choice(products, size=n, p=[0.35, 0.3, 0.2, 0.15])
        reg = rng.choice(regions, size=n, p=[0.4, 0.35, 0.25])
        ch = rng.choice(channels, size=n, p=[0.45, 0.35, 0.20])

        base_p = np.array([base_price[x] for x in prod]) * np.array([region_price_bump[x] for x in reg])
        base_c = np.array([base_cost[x] for x in prod]) * np.array([region_cost_bump[x] for x in reg]) * cost_trend

        # More variance in discounts
        discount = np.clip(
            np.array([channel_discount_mean[x] for x in ch]) +
            rng.normal(0, [channel_discount_std[x] * 2 for x in ch]),  # Double the variance
            0, 0.45
        )

        list_price = rng.normal(base_p, 8)  # More price variance
        net_price = np.clip(list_price * (1 - discount), 20, None)
        unit_cost = np.clip(rng.normal(base_c, 6), 10, None)

        eps = np.array([seg_epsilon[(pp, rr, cc)] for pp, rr, cc in zip(prod, reg, ch)])
        ref_price = np.array([base_price[x] for x in prod])
        qty_mu = np.exp(eps * (net_price - ref_price) / np.maximum(ref_price, 1e-6))
        qty = np.maximum(1, rng.poisson(8 * dow_mult * seasonal * market_shock * qty_mu))

        revenue = net_price * qty
        cogs = unit_cost * qty
        gm_val = revenue - cogs
        gm_pct = np.where(revenue > 0, gm_val / revenue, 0.0)

        for i in range(n):
            records.append({
                "date": d,
                "product": prod[i],
                "region": reg[i],
                "channel": ch[i],
                "list_price": float(list_price[i]),
                "discount_pct": float(discount[i]),
                "net_price": float(net_price[i]),
                "unit_cost": float(unit_cost[i]),
                "qty": int(qty[i]),
                "revenue": float(revenue[i]),
                "cogs": float(cogs[i]),
                "gm_value": float(gm_val[i]),
                "gm_pct": float(gm_pct[i]),
                "dow": dow
            })

    df = pd.DataFrame(records)
    return df

def analyze_margin_bridge(df, current_date, prior_date):
    """Professional Price-Volume-Mix (PVM) analysis"""
    current_data = df[df["date"] == current_date].copy()
    prior_data = df[df["date"] == prior_date].copy()

    current_total_revenue = current_data["revenue"].sum()
    current_total_cogs = current_data["cogs"].sum()
    current_total_gm = current_total_revenue - current_total_cogs
    current_gm_pct = current_total_gm / current_total_revenue if current_total_revenue > 0 else 0

    prior_total_revenue = prior_data["revenue"].sum()
    prior_total_cogs = prior_data["cogs"].sum()
    prior_total_gm = prior_total_revenue - prior_total_cogs
    prior_gm_pct = prior_total_gm / prior_total_revenue if prior_total_revenue > 0 else 0

    total_gm_variance = current_total_gm - prior_total_gm

    current_seg = current_data.groupby(["product", "region", "channel"]).agg({
        "revenue": "sum",
        "cogs": "sum",
        "qty": "sum",
        "net_price": "mean",
        "unit_cost": "mean"
    }).reset_index()
    current_seg["gm"] = current_seg["revenue"] - current_seg["cogs"]
    current_seg["gm_pct"] = current_seg["gm"] / current_seg["revenue"]

    prior_seg = prior_data.groupby(["product", "region", "channel"]).agg({
        "revenue": "sum",
        "cogs": "sum",
        "qty": "sum",
        "net_price": "mean",
        "unit_cost": "mean"
    }).reset_index()
    prior_seg["gm"] = prior_seg["revenue"] - prior_seg["cogs"]
    prior_seg["gm_pct"] = prior_seg["gm"] / prior_seg["revenue"]

    merged = pd.merge(
        current_seg, 
        prior_seg, 
        on=["product", "region", "channel"], 
        suffixes=("_curr", "_prior"),
        how="outer"
    ).fillna(0)

    # PVM Decomposition
    merged["price_effect"] = (merged["net_price_curr"] - merged["net_price_prior"]) * merged["qty_curr"]
    merged["volume_effect"] = (merged["qty_curr"] - merged["qty_prior"]) * merged["net_price_prior"] * merged["gm_pct_prior"]
    merged["cost_effect"] = -(merged["unit_cost_curr"] - merged["unit_cost_prior"]) * merged["qty_curr"]
    merged["gm_variance"] = merged["gm_curr"] - merged["gm_prior"]
    merged["mix_effect"] = merged["gm_variance"] - (merged["price_effect"] + merged["volume_effect"] + merged["cost_effect"])

    return merged, {
        "total_gm_variance": total_gm_variance,
        "price_effect_total": merged["price_effect"].sum(),
        "volume_effect_total": merged["volume_effect"].sum(),
        "cost_effect_total": merged["cost_effect"].sum(),
        "mix_effect_total": merged["mix_effect"].sum(),
        "current_gm": current_total_gm,
        "prior_gm": prior_total_gm,
        "current_gm_pct": current_gm_pct,
        "prior_gm_pct": prior_gm_pct
    }

def estimate_segment_elasticity(df, product, region, channel):
    """Estimate price elasticity for a segment"""
    seg_df = df[(df["product"]==product)&(df["region"]==region)&(df["channel"]==channel)]
    if len(seg_df) < 100 or seg_df["net_price"].std() < 1e-6 or seg_df["qty"].std() < 1e-6:
        return -1.2, False  # Default elasticity
    try:
        x = np.log(np.clip(seg_df["net_price"].values, 1e-6, None)).reshape(-1,1)
        y = np.log(np.clip(seg_df["qty"].values, 1e-6, None))
        lin = LinearRegression().fit(x, y)
        elasticity = float(lin.coef_[0])
        # Bound elasticity to realistic range
        elasticity = np.clip(elasticity, -5.0, -0.3)
        return elasticity, True
    except:
        return -1.2, False

def find_optimal_discount(base_data, elasticity, search_range=(-10, 10)):
    """
    Find profit-maximizing discount using price elasticity of demand
    Can recommend INCREASING or DECREASING discount
    """
    current_discount = base_data["discount_pct"]
    current_list_price = base_data["list_price"]
    current_price = base_data["net_price"]
    current_cost = base_data["unit_cost"]
    current_qty = base_data["qty"]

    # Test discount changes from -10pp to +10pp
    discount_changes = np.linspace(search_range[0], search_range[1], 41)
    results = []

    for disc_change in discount_changes:
        new_discount = np.clip(current_discount + (disc_change/100), 0.0, 0.50)
        new_price = current_list_price * (1 - new_discount)

        # Apply elasticity
        if current_price > 0:
            price_ratio = new_price / current_price
            new_qty = current_qty * (price_ratio ** elasticity)
        else:
            new_qty = current_qty

        new_revenue = new_price * new_qty
        new_cogs = current_cost * new_qty
        new_gm = new_revenue - new_cogs

        results.append({
            "discount_change": disc_change,
            "new_discount": new_discount * 100,
            "new_price": new_price,
            "new_qty": new_qty,
            "new_gm": new_gm,
            "new_revenue": new_revenue
        })

    results_df = pd.DataFrame(results)
    optimal_idx = results_df["new_gm"].idxmax()
    optimal = results_df.iloc[optimal_idx]

    current_gm = current_price * current_qty - current_cost * current_qty

    return {
        "current_discount": current_discount * 100,
        "optimal_discount": optimal["new_discount"],
        "discount_change": optimal["discount_change"],
        "current_price": current_price,
        "optimal_price": optimal["new_price"],
        "current_qty": current_qty,
        "optimal_qty": optimal["new_qty"],
        "current_gm": current_gm,
        "optimal_gm": optimal["new_gm"],
        "gm_uplift": optimal["new_gm"] - current_gm,
        "elasticity": elasticity,
        "all_scenarios": results_df
    }

# Main App
st.markdown('<h1 class="main-header">🎯 Daily Profitability Variance Analysis</h1>', unsafe_allow_html=True)
st.markdown('<p class="sub-header">Understanding What Drives Daily Margin Changes</p>', unsafe_allow_html=True)

# Generate data with realistic variance
with st.spinner("🔄 Loading business data..."):
    df = generate_synthetic_data(days=60, seed=42, rows_per_day=600)

# Calculate daily aggregates
daily = df.groupby("date").agg(
    revenue=("revenue","sum"),
    cogs=("cogs","sum"),
    gm_value=("gm_value","sum"),
    qty=("qty","sum")
).reset_index()
daily["gm_pct"] = np.where(daily["revenue"]>0, daily["gm_value"]/daily["revenue"], 0.0)

current_date = daily["date"].max()
prior_date = current_date - timedelta(days=1)
current_row = daily[daily["date"]==current_date].iloc[0]
prior_row = daily[daily["date"]==prior_date].iloc[0]
week_ago_row = daily.iloc[-8] if len(daily) > 7 else current_row
roll7 = daily["gm_pct"].tail(7).mean()

gm_variance_pp = (current_row["gm_pct"] - prior_row["gm_pct"]) * 100
gm_variance_dollar = current_row["gm_value"] - prior_row["gm_value"]

# Executive Dashboard
st.markdown("### 📊 Executive Summary")

col1, col2, col3, col4 = st.columns(4)

with col1:
    st.metric(
        label="Gross Margin %",
        value=f"{current_row['gm_pct']*100:.2f}%",
        delta=f"{gm_variance_pp:+.2f}pp",
        delta_color="normal"
    )

with col2:
    st.metric(
        label="Gross Margin $",
        value=f"${current_row['gm_value']/1e6:.2f}M",
        delta=f"${gm_variance_dollar/1e6:+.2f}M",
        delta_color="normal"
    )

with col3:
    revenue_var_pct = ((current_row["revenue"] - prior_row["revenue"]) / prior_row["revenue"] * 100) if prior_row["revenue"] > 0 else 0
    st.metric(
        label="Revenue",
        value=f"${current_row['revenue']/1e6:.2f}M",
        delta=f"{revenue_var_pct:+.1f}%",
        delta_color="normal"
    )

with col4:
    volume_var_pct = ((current_row["qty"] - prior_row["qty"]) / prior_row["qty"] * 100) if prior_row["qty"] > 0 else 0
    st.metric(
        label="Volume (Units)",
        value=f"{current_row['qty']:,.0f}",
        delta=f"{volume_var_pct:+.1f}%",
        delta_color="normal"
    )

# Trend chart with REAL variance
st.markdown("#### 📈 Gross Margin Trend (Last 30 Days)")
recent_daily = daily.tail(30)

fig_trend = go.Figure()
fig_trend.add_trace(go.Scatter(
    x=recent_daily["date"],
    y=recent_daily["gm_pct"]*100,
    mode='lines+markers',
    name="GM%",
    line=dict(color="#1f77b4", width=3),
    fill='tozeroy',
    fillcolor="rgba(31, 119, 180, 0.1)"
))
fig_trend.add_hline(y=roll7*100, line_dash="dash", line_color="red", 
                   annotation_text=f"7-Day Avg: {roll7*100:.2f}%", annotation_position="right")
fig_trend.update_layout(
    xaxis_title="Date",
    yaxis_title="Gross Margin %",
    height=350,
    hovermode="x unified"
)
st.plotly_chart(fig_trend, use_container_width=True)

st.markdown("---")

# Perform margin bridge analysis
with st.spinner("🔬 Performing Price-Volume-Mix analysis..."):
    variance_detail, summary = analyze_margin_bridge(df, current_date, prior_date)

# Main Tabs
tab1, tab2, tab3 = st.tabs(["📊 Margin Bridge (PVM)", "🔍 Segment Deep Dive", "💡 Optimal Pricing"])

with tab1:
    st.markdown(f"### Gross Margin Bridge: {prior_date.strftime('%b %d')} → {current_date.strftime('%b %d')}")

    st.markdown(f"""
    <div class="insight-box">
    <b>📋 Variance Summary:</b><br>
    Gross margin changed by <b>${gm_variance_dollar/1000:+.1f}K</b> ({gm_variance_pp:+.2f} percentage points)<br>
    from {prior_row['gm_pct']*100:.2f}% to {current_row['gm_pct']*100:.2f}%
    </div>
    """, unsafe_allow_html=True)

    # Waterfall Chart
    st.markdown("#### Price-Volume-Mix (PVM) Waterfall Analysis")

    waterfall_data = pd.DataFrame({
        "Category": [
            f"{prior_date.strftime('%b %d')}<br>Gross Margin",
            "Price<br>Effect",
            "Volume<br>Effect",
            "Cost<br>Effect",
            "Mix<br>Effect",
            f"{current_date.strftime('%b %d')}<br>Gross Margin"
        ],
        "Value": [
            summary["prior_gm"],
            summary["price_effect_total"],
            summary["volume_effect_total"],
            summary["cost_effect_total"],
            summary["mix_effect_total"],
            summary["current_gm"]
        ],
        "Type": ["absolute", "relative", "relative", "relative", "relative", "total"]
    })

    fig_waterfall = go.Figure(go.Waterfall(
        orientation="v",
        measure=waterfall_data["Type"],
        x=waterfall_data["Category"],
        y=waterfall_data["Value"],
        text=[f"${v/1000:.1f}K" if abs(v) > 100 else f"${v:.0f}" for v in waterfall_data["Value"]],
        textposition="outside",
        connector={"line": {"color": "rgb(63, 63, 63)"}},
        increasing={"marker": {"color": "#28a745"}},
        decreasing={"marker": {"color": "#dc3545"}},
        totals={"marker": {"color": "#1f77b4"}}
    ))

    fig_waterfall.update_layout(
        title="Gross Margin Variance Breakdown",
        showlegend=False,
        height=450,
        yaxis_title="Gross Margin ($)"
    )
    st.plotly_chart(fig_waterfall, use_container_width=True)

    # Explanations
    col_exp1, col_exp2 = st.columns(2)

    with col_exp1:
        st.markdown(f"""
        <div class="insight-box">
        <b>💰 Price Effect:</b> ${summary['price_effect_total']/1000:+.1f}K<br>
        <small>Impact of changes in realized selling prices</small>
        </div>
        """, unsafe_allow_html=True)

        st.markdown(f"""
        <div class="insight-box">
        <b>📦 Volume Effect:</b> ${summary['volume_effect_total']/1000:+.1f}K<br>
        <small>Impact of selling more/fewer units</small>
        </div>
        """, unsafe_allow_html=True)

    with col_exp2:
        st.markdown(f"""
        <div class="insight-box">
        <b>🏭 Cost Effect:</b> ${summary['cost_effect_total']/1000:+.1f}K<br>
        <small>Impact of changes in unit costs</small>
        </div>
        """, unsafe_allow_html=True)

        st.markdown(f"""
        <div class="insight-box">
        <b>🔀 Mix Effect:</b> ${summary['mix_effect_total']/1000:+.1f}K<br>
        <small>Impact of product/channel mix shifts</small>
        </div>
        """, unsafe_allow_html=True)

with tab2:
    st.markdown("### Segment-Level Variance Analysis")

    variance_detail_sorted = variance_detail.sort_values("gm_variance", ascending=False)

    col_seg1, col_seg2 = st.columns(2)

    with col_seg1:
        st.markdown("#### 📈 Top 5 Margin Gainers")
        for _, row in variance_detail_sorted.head(5).iterrows():
            if row["gm_variance"] > 0:
                st.markdown(f"""
                <div class="recommendation-card" style="border-left: 4px solid #28a745;">
                <b>{row['product']}</b><br>
                <small>{row['region']} • {row['channel']}</small><br>
                <span class="positive-impact">+${row['gm_variance']:.2f}</span><br>
                <small>Price: ${row['price_effect']:+.2f} | Volume: ${row['volume_effect']:+.2f} | Cost: ${row['cost_effect']:+.2f}</small>
                </div>
                """, unsafe_allow_html=True)

    with col_seg2:
        st.markdown("#### 📉 Top 5 Margin Losers")
        for _, row in variance_detail_sorted.tail(5).iterrows():
            if row["gm_variance"] < 0:
                st.markdown(f"""
                <div class="recommendation-card" style="border-left: 4px solid #dc3545;">
                <b>{row['product']}</b><br>
                <small>{row['region']} • {row['channel']}</small><br>
                <span class="negative-impact">${row['gm_variance']:.2f}</span><br>
                <small>Price: ${row['price_effect']:+.2f} | Volume: ${row['volume_effect']:+.2f} | Cost: ${row['cost_effect']:+.2f}</small>
                </div>
                """, unsafe_allow_html=True)

with tab3:
    st.markdown("### Optimal Pricing Analysis")
    st.markdown("""
    <div class="insight-box">
    <b>🎯 Profit Maximization:</b> Using price elasticity of demand to find the optimal discount level.
    <br>May recommend <b>increasing</b> or <b>decreasing</b> discount depending on elasticity.
    </div>
    """, unsafe_allow_html=True)

    # Get segments with meaningful volume
    recent_segments = df[df["date"] >= (current_date - timedelta(days=7))].groupby(["product", "region", "channel"]).agg({
        "qty": "sum",
        "gm_value": "sum"
    }).reset_index()
    recent_segments = recent_segments[recent_segments["qty"] > 100]  # Minimum volume threshold

    optimization_results = []

    for _, seg in recent_segments.iterrows():
        p, r, c = seg["product"], seg["region"], seg["channel"]
        hist = df[(df["product"]==p)&(df["region"]==r)&(df["channel"]==c)].sort_values("date")

        if hist.empty or len(hist) < 100:
            continue

        elasticity, is_valid = estimate_segment_elasticity(hist, p, r, c)

        if not is_valid:
            continue

        current_state = hist.iloc[-1]
        optimal_result = find_optimal_discount(current_state, elasticity)

        if abs(optimal_result["gm_uplift"]) > 5:  # Only show meaningful opportunities
            optimization_results.append({
                "Product": p,
                "Region": r,
                "Channel": c,
                "Current Discount": optimal_result["current_discount"],
                "Optimal Discount": optimal_result["optimal_discount"],
                "Discount Change": optimal_result["discount_change"],
                "Price Elasticity": elasticity,
                "Current GM/Day": optimal_result["current_gm"],
                "Optimal GM/Day": optimal_result["optimal_gm"],
                "Daily GM Uplift": optimal_result["gm_uplift"],
                "Direction": "Increase Discount" if optimal_result["discount_change"] > 0 else "Decrease Discount",
                "all_scenarios": optimal_result["all_scenarios"]
            })

    opt_df = pd.DataFrame(optimization_results).sort_values("Daily GM Uplift", ascending=False)

    if len(opt_df) > 0:
        st.markdown("#### 🏆 Top 5 Optimization Opportunities")

        for i, (_, rec) in enumerate(opt_df.head(5).iterrows()):
            direction_color = "#ff7f0e" if rec["Direction"] == "Increase Discount" else "#1f77b4"

            st.markdown(f"""
            <div class="recommendation-card" style="border-left: 5px solid {direction_color};">
                <h4>#{i+1}: {rec['Product']} • {rec['Region']} • {rec['Channel']}</h4>
                <p><b>Elasticity:</b> {rec['Price Elasticity']:.2f} ({"Elastic" if rec['Price Elasticity'] < -1.5 else "Inelastic"})</p>
                <p><b>Recommendation:</b> {rec['Direction']} by {abs(rec['Discount Change']):.1f}pp</p>
                <p><small>Current: {rec['Current Discount']:.1f}% → Optimal: {rec['Optimal Discount']:.1f}%</small></p>
                <p class="positive-impact">💰 Expected Uplift: ${rec['Daily GM Uplift']:.2f}/day</p>
                <p><small>Annual Impact: ${rec['Daily GM Uplift']*365/1000:.1f}K</small></p>
            </div>
            """, unsafe_allow_html=True)

            # Show elasticity curve
            with st.expander(f"📊 View Profit Curve for {rec['Product']} • {rec['Region']} • {rec['Channel']}"):
                scenario_df = rec["all_scenarios"]

                fig_curve = go.Figure()
                fig_curve.add_trace(go.Scatter(
                    x=scenario_df["new_discount"],
                    y=scenario_df["new_gm"],
                    mode='lines',
                    name='Gross Margin',
                    line=dict(color='#1f77b4', width=3)
                ))

                fig_curve.add_vline(x=rec["Current Discount"], line_dash="dash", line_color="red",
                                   annotation_text=f"Current: {rec['Current Discount']:.1f}%")
                fig_curve.add_vline(x=rec["Optimal Discount"], line_dash="dash", line_color="green",
                                   annotation_text=f"Optimal: {rec['Optimal Discount']:.1f}%")

                fig_curve.update_layout(
                    title=f"Profit Maximization Curve (Elasticity: {rec['Price Elasticity']:.2f})",
                    xaxis_title="Discount Level (%)",
                    yaxis_title="Expected Gross Margin ($)",
                    height=400
                )
                st.plotly_chart(fig_curve, use_container_width=True)

        st.markdown("---")
        st.markdown("#### Complete Optimization List")

        display_opt = opt_df[[
            "Product", "Region", "Channel", "Current Discount", "Optimal Discount",
            "Discount Change", "Price Elasticity", "Daily GM Uplift", "Direction"
        ]].copy()

        st.dataframe(display_opt.style.format({
            "Current Discount": "{:.1f}%",
            "Optimal Discount": "{:.1f}%",
            "Discount Change": "{:+.1f}pp",
            "Price Elasticity": "{:.2f}",
            "Daily GM Uplift": "${:,.2f}"
        }).background_gradient(subset=["Daily GM Uplift"], cmap="Greens"),
        use_container_width=True, height=400)

        st.download_button(
            label="📥 Download Optimization Plan (CSV)",
            data=opt_df.drop(columns=["all_scenarios"]).to_csv(index=False).encode("utf-8"),
            file_name=f"optimal_pricing_plan_{current_date.strftime('%Y%m%d')}.csv",
            mime="text/csv"
        )
    else:
        st.info("All segments are currently near optimal pricing levels.")

st.markdown("---")
st.markdown("""
<div style="text-align: center; color: #666; padding: 1rem;">
    <small>🔒 Demo Mode: Using synthetic transaction data with realistic variance patterns</small>
</div>
""", unsafe_allow_html=True)