ifixkart-backend/Backend/app/api/v1/routers/DashboardRouter.py

from fastapi import APIRouter, Depends
from sqlalchemy.orm import Session
from sqlalchemy import text
from app.core.database.db_session import get_db
from app.core.permissions.RoleChecker import get_current_user
from typing import Any, Dict
import datetime

router = APIRouter(prefix="/api/v1/dashboard", tags=["Dashboard"])


@router.get("/stats", response_model=Dict[str, Any])
def get_dashboard_stats(
    db: Session = Depends(get_db),
    current_user: Any = Depends(get_current_user),
):
    """
    Returns real-time KPI metrics for the admin dashboard:
    - Catalog counts (users, orders, products, brands, models, categories)
    - Revenue totals (all time, last 30 days, last 7 days)
    - Order status breakdown
    - Revenue by day for chart (last 30 days)
    - Top products by revenue
    - Recent orders
    """

    # ── Core Catalog Counts ──────────────────────────────────────────────────
    total_users = db.execute(text("SELECT COUNT(*) FROM ecom_customers")).scalar() or 0
    total_orders = db.execute(text("SELECT COUNT(*) FROM orders")).scalar() or 0
    total_products = db.execute(text("SELECT COUNT(*) FROM products")).scalar() or 0
    total_brands = db.execute(text("SELECT COUNT(*) FROM brands")).scalar() or 0
    total_device_models = db.execute(text("SELECT COUNT(*) FROM device_models")).scalar() or 0
    total_categories = db.execute(text("SELECT COUNT(*) FROM categories")).scalar() or 0
    total_device_series = db.execute(text("SELECT COUNT(*) FROM device_series")).scalar() or 0

    # ── Revenue ──────────────────────────────────────────────────────────────
    revenue_all = db.execute(text(
        "SELECT COALESCE(SUM(final_amount), 0) FROM orders WHERE status != 'cancelled'"
    )).scalar() or 0

    revenue_30d = db.execute(text(
        "SELECT COALESCE(SUM(final_amount), 0) FROM orders "
        "WHERE status != 'cancelled' AND created_at >= DATE_SUB(NOW(), INTERVAL 30 DAY)"
    )).scalar() or 0

    revenue_7d = db.execute(text(
        "SELECT COALESCE(SUM(final_amount), 0) FROM orders "
        "WHERE status != 'cancelled' AND created_at >= DATE_SUB(NOW(), INTERVAL 7 DAY)"
    )).scalar() or 0

    # ── Order Status Breakdown ───────────────────────────────────────────────
    order_statuses = db.execute(text(
        "SELECT status, COUNT(*) as cnt FROM orders GROUP BY status"
    )).fetchall()
    orders_by_status = {row[0]: row[1] for row in order_statuses}

    # ── Revenue by Day (last 30 days) for chart ──────────────────────────────
    daily_revenue_rows = db.execute(text("""
        SELECT 
            DATE(created_at) AS day,
            COALESCE(SUM(final_amount), 0) AS revenue,
            COUNT(*) AS order_count
        FROM orders
        WHERE created_at >= DATE_SUB(NOW(), INTERVAL 30 DAY)
          AND status != 'cancelled'
        GROUP BY DATE(created_at)
        ORDER BY day ASC
    """)).fetchall()

    # Build a complete 30-day series filling zeros for missing days
    today = datetime.date.today()
    day_map = {row[0]: {"revenue": float(row[1]), "orders": int(row[2])} for row in daily_revenue_rows}
    revenue_chart = []
    for i in range(29, -1, -1):
        d = today - datetime.timedelta(days=i)
        revenue_chart.append({
            "date": d.strftime("%d %b"),
            "revenue": day_map.get(d, {}).get("revenue", 0),
            "orders": day_map.get(d, {}).get("orders", 0),
        })

    # ── Revenue by Month (last 12 months) for chart ──────────────────────────
    monthly_revenue_rows = db.execute(text("""
        SELECT 
            DATE_FORMAT(created_at, '%Y-%m') AS month,
            DATE_FORMAT(created_at, '%b %Y') AS label,
            COALESCE(SUM(final_amount), 0) AS revenue,
            COUNT(*) AS order_count
        FROM orders
        WHERE created_at >= DATE_SUB(NOW(), INTERVAL 12 MONTH)
          AND status != 'cancelled'
        GROUP BY DATE_FORMAT(created_at, '%Y-%m'), DATE_FORMAT(created_at, '%b %Y')
        ORDER BY month ASC
    """)).fetchall()

    revenue_monthly_chart = [
        {
            "label": row[1],
            "revenue": float(row[2]),
            "orders": int(row[3]),
        }
        for row in monthly_revenue_rows
    ]

    # ── Top Products by Revenue ──────────────────────────────────────────────
    top_products = db.execute(text("""
        SELECT 
            oi.product_name,
            SUM(oi.quantity) AS total_sold,
            SUM(oi.total_price) AS total_revenue
        FROM order_items oi
        INNER JOIN orders o ON o.order_id = oi.order_id
        WHERE o.status != 'cancelled'
        GROUP BY oi.product_name
        ORDER BY total_revenue DESC
        LIMIT 5
    """)).fetchall()

    top_products_list = [
        {
            "name": row[0],
            "total_sold": int(row[1]),
            "total_revenue": float(row[2]),
        }
        for row in top_products
    ]

    # ── Recent Orders ────────────────────────────────────────────────────────
    recent_orders = db.execute(text("""
        SELECT 
            o.order_no,
            o.final_amount,
            o.status,
            o.payment_status,
            o.created_at,
            c.first_name,
            c.last_name,
            c.email
        FROM orders o
        LEFT JOIN ecom_customers c ON c.customer_id = o.customer_id
        ORDER BY o.created_at DESC
        LIMIT 5
    """)).fetchall()

    recent_orders_list = [
        {
            "order_no": row[0],
            "amount": float(row[1]),
            "status": row[2],
            "payment_status": row[3],
            "created_at": row[4].isoformat() if row[4] else None,
            "customer_name": f"{row[5] or ''} {row[6] or ''}".strip() or row[7] or "Guest",
            "customer_email": row[7],
        }
        for row in recent_orders
    ]

    # ── Inventory Summary ────────────────────────────────────────────────────
    low_stock_count = db.execute(text("""
        SELECT COUNT(*) FROM product_variants pv
        LEFT JOIN (
            SELECT variant_id, SUM(qty) as stock
            FROM inventory_ledger
            GROUP BY variant_id
        ) l ON pv.variant_id = l.variant_id
        WHERE COALESCE(l.stock, 0) <= pv.low_stock_threshold AND COALESCE(l.stock, 0) >= 0
    """)).scalar() or 0

    out_of_stock_count = db.execute(text("""
        SELECT COUNT(*) FROM product_variants pv
        LEFT JOIN (
            SELECT variant_id, SUM(qty) as stock
            FROM inventory_ledger
            GROUP BY variant_id
        ) l ON pv.variant_id = l.variant_id
        WHERE COALESCE(l.stock, 0) = 0
    """)).scalar() or 0

    total_variant_stock = db.execute(text("""
        SELECT COALESCE(SUM(qty), 0) FROM inventory_ledger
    """)).scalar() or 0

    return {
        # Counts
        "total_users": total_users,
        "total_orders": total_orders,
        "total_products": total_products,
        "total_brands": total_brands,
        "total_device_models": total_device_models,
        "total_device_series": total_device_series,
        "total_categories": total_categories,

        # Revenue
        "revenue_all_time": float(revenue_all),
        "revenue_last_30_days": float(revenue_30d),
        "revenue_last_7_days": float(revenue_7d),

        # Orders breakdown
        "orders_by_status": orders_by_status,

        # Charts
        "revenue_chart_daily": revenue_chart,
        "revenue_chart_monthly": revenue_monthly_chart,

        # Lists
        "top_products": top_products_list,
        "recent_orders": recent_orders_list,

        # Inventory
        "low_stock_variants": low_stock_count,
        "out_of_stock_variants": out_of_stock_count,
        "total_stock_units": int(total_variant_stock),
    }