-- Description: Calculates and updates daily aggregated product data for recent days.
--              Uses UPSERT (INSERT ON CONFLICT UPDATE) for idempotency.
-- Dependencies: Core import tables (products, orders, purchase_orders), calculate_status table.
-- Frequency: Hourly (Run ~5-10 minutes after hourly data import completes).

DO $$
DECLARE
    _module_name TEXT := 'daily_snapshots';
    _start_time TIMESTAMPTZ := clock_timestamp(); -- Time execution started
    _last_calc_time TIMESTAMPTZ;
    _target_date DATE; -- Will be set in the loop
    _total_records INT := 0;
    _has_orders BOOLEAN := FALSE;
    _process_days INT := 5; -- Number of days to check/process (today plus previous 4 days)
    _day_counter INT;
    _missing_days INT[] := ARRAY[]::INT[]; -- Array to store days with missing or incomplete data
BEGIN
    -- Get the timestamp before the last successful run of this module
    SELECT last_calculation_timestamp INTO _last_calc_time
    FROM public.calculate_status
    WHERE module_name = _module_name;

    RAISE NOTICE 'Running % script. Start Time: %', _module_name, _start_time;
    
    -- First, check which days need processing by comparing orders data with snapshot data
    FOR _day_counter IN 0..(_process_days-1) LOOP
        _target_date := CURRENT_DATE - (_day_counter * INTERVAL '1 day');
        
        -- Check if this date needs updating by comparing orders to snapshot data
        -- If the date has orders but not enough snapshots, or if snapshots show zero sales but orders exist, it's incomplete
        SELECT 
            CASE WHEN (
                -- We have orders for this date but not enough snapshots, or snapshots with wrong total
                (EXISTS (SELECT 1 FROM public.orders WHERE date::date = _target_date) AND
                 (
                    -- No snapshots exist for this date
                    NOT EXISTS (SELECT 1 FROM public.daily_product_snapshots WHERE snapshot_date = _target_date) OR
                    -- Or snapshots show zero sales but orders exist
                    (SELECT COALESCE(SUM(units_sold), 0) FROM public.daily_product_snapshots WHERE snapshot_date = _target_date) = 0 OR
                    -- Or the count of snapshot records is significantly less than distinct products in orders
                    (SELECT COUNT(*) FROM public.daily_product_snapshots WHERE snapshot_date = _target_date) < 
                    (SELECT COUNT(DISTINCT pid) FROM public.orders WHERE date::date = _target_date) * 0.8
                 )
                )
            ) THEN TRUE ELSE FALSE END
        INTO _has_orders;
        
        IF _has_orders THEN
            -- This day needs processing - add to our array
            _missing_days := _missing_days || _day_counter;
            RAISE NOTICE 'Day % needs updating (incomplete or missing data)', _target_date;
        END IF;
    END LOOP;
    
    -- If no days need updating, exit early
    IF array_length(_missing_days, 1) IS NULL THEN
        RAISE NOTICE 'No days need updating - all snapshot data appears complete';
        
        -- Still update the calculate_status to record this run
        UPDATE public.calculate_status
        SET last_calculation_timestamp = _start_time
        WHERE module_name = _module_name;
        
        RETURN;
    END IF;
    
    RAISE NOTICE 'Need to update % days with missing or incomplete data', array_length(_missing_days, 1);

    -- Process only the days that need updating
    FOREACH _day_counter IN ARRAY _missing_days LOOP
        _target_date := CURRENT_DATE - (_day_counter * INTERVAL '1 day');
        RAISE NOTICE 'Processing date: %', _target_date;
        
        -- IMPORTANT: First delete any existing data for this date to prevent duplication
        DELETE FROM public.daily_product_snapshots 
        WHERE snapshot_date = _target_date;

        -- Proceed with calculating daily metrics only for products with actual activity
        WITH SalesData AS (
            SELECT
                p.pid,
                p.sku,
                -- Track number of orders to ensure we have real data
                COUNT(o.id) as order_count,
                -- Aggregate Sales (Quantity > 0, Status not Canceled/Returned)
                COALESCE(SUM(CASE WHEN o.quantity > 0 AND COALESCE(o.status, 'pending') NOT IN ('canceled', 'returned') THEN o.quantity ELSE 0 END), 0) AS units_sold,
                COALESCE(SUM(CASE WHEN o.quantity > 0 AND COALESCE(o.status, 'pending') NOT IN ('canceled', 'returned') THEN o.price * o.quantity ELSE 0 END), 0.00) AS gross_revenue_unadjusted, -- Before discount
                COALESCE(SUM(CASE WHEN o.quantity > 0 AND COALESCE(o.status, 'pending') NOT IN ('canceled', 'returned') THEN o.discount ELSE 0 END), 0.00) AS discounts,
                COALESCE(SUM(CASE WHEN o.quantity > 0 AND COALESCE(o.status, 'pending') NOT IN ('canceled', 'returned') THEN COALESCE(o.costeach, p.landing_cost_price, p.cost_price) * o.quantity ELSE 0 END), 0.00) AS cogs,
                COALESCE(SUM(CASE WHEN o.quantity > 0 AND COALESCE(o.status, 'pending') NOT IN ('canceled', 'returned') THEN p.regular_price * o.quantity ELSE 0 END), 0.00) AS gross_regular_revenue, -- Use current regular price for simplicity here

                -- Aggregate Returns (Quantity < 0 or Status = Returned)
                COALESCE(SUM(CASE WHEN o.quantity < 0 OR COALESCE(o.status, 'pending') = 'returned' THEN ABS(o.quantity) ELSE 0 END), 0) AS units_returned,
                COALESCE(SUM(CASE WHEN o.quantity < 0 OR COALESCE(o.status, 'pending') = 'returned' THEN o.price * ABS(o.quantity) ELSE 0 END), 0.00) AS returns_revenue
            FROM public.products p -- Start from products to include those with no orders today
            JOIN public.orders o -- Changed to INNER JOIN to only process products with orders
                ON p.pid = o.pid
               AND o.date::date = _target_date -- Cast to date to ensure compatibility regardless of original type
            GROUP BY p.pid, p.sku
            -- No HAVING clause here - we always want to include all orders
        ),
        ReceivingData AS (
            SELECT
                r.pid,
                -- Track number of receiving docs to ensure we have real data
                COUNT(DISTINCT r.receiving_id) as receiving_doc_count,
                -- Sum the quantities received on this date
                SUM(r.qty_each) AS units_received,
                -- Calculate the cost received (qty * cost)
                SUM(r.qty_each * r.cost_each) AS cost_received
            FROM public.receivings r
            WHERE r.received_date::date = _target_date
              -- Optional: Filter out canceled receivings if needed
              -- AND r.status <> 'canceled'
            GROUP BY r.pid
            -- Only include products with actual receiving activity
            HAVING COUNT(DISTINCT r.receiving_id) > 0 OR SUM(r.qty_each) > 0
        ),
        CurrentStock AS (
            -- Select current stock values directly from products table
            SELECT
                pid,
                stock_quantity,
                COALESCE(landing_cost_price, cost_price, 0.00) as effective_cost_price,
                COALESCE(price, 0.00) as current_price,
                COALESCE(regular_price, 0.00) as current_regular_price
            FROM public.products
        ),
        ProductsWithActivity AS (
            -- Quick pre-filter to only process products with activity
            SELECT DISTINCT pid 
            FROM (
                SELECT pid FROM SalesData
                UNION
                SELECT pid FROM ReceivingData
            ) a
        )
        -- Now insert records, but ONLY for products with actual activity
        INSERT INTO public.daily_product_snapshots (
            snapshot_date,
            pid,
            sku,
            eod_stock_quantity,
            eod_stock_cost,
            eod_stock_retail,
            eod_stock_gross,
            stockout_flag,
            units_sold,
            units_returned,
            gross_revenue,
            discounts,
            returns_revenue,
            net_revenue,
            cogs,
            gross_regular_revenue,
            profit,
            units_received,
            cost_received,
            calculation_timestamp
        )
        SELECT
            _target_date AS snapshot_date,
            COALESCE(sd.pid, rd.pid) AS pid,  -- Use sales or receiving PID
            COALESCE(sd.sku, p.sku) AS sku,   -- Get SKU from sales data or products table
            -- Inventory Metrics (Using CurrentStock)
            cs.stock_quantity AS eod_stock_quantity,
            cs.stock_quantity * cs.effective_cost_price AS eod_stock_cost,
            cs.stock_quantity * cs.current_price AS eod_stock_retail,
            cs.stock_quantity * cs.current_regular_price AS eod_stock_gross,
            (cs.stock_quantity <= 0) AS stockout_flag,
            -- Sales Metrics (From SalesData)
            COALESCE(sd.units_sold, 0),
            COALESCE(sd.units_returned, 0),
            COALESCE(sd.gross_revenue_unadjusted, 0.00),
            COALESCE(sd.discounts, 0.00),
            COALESCE(sd.returns_revenue, 0.00),
            COALESCE(sd.gross_revenue_unadjusted, 0.00) - COALESCE(sd.discounts, 0.00) AS net_revenue,
            COALESCE(sd.cogs, 0.00),
            COALESCE(sd.gross_regular_revenue, 0.00),
            (COALESCE(sd.gross_revenue_unadjusted, 0.00) - COALESCE(sd.discounts, 0.00)) - COALESCE(sd.cogs, 0.00) AS profit, -- Basic profit: Net Revenue - COGS
            -- Receiving Metrics (From ReceivingData)
            COALESCE(rd.units_received, 0),
            COALESCE(rd.cost_received, 0.00),
            _start_time -- Timestamp of this calculation run
        FROM SalesData sd
        FULL OUTER JOIN ReceivingData rd ON sd.pid = rd.pid
        JOIN ProductsWithActivity pwa ON COALESCE(sd.pid, rd.pid) = pwa.pid
        LEFT JOIN public.products p ON COALESCE(sd.pid, rd.pid) = p.pid
        LEFT JOIN CurrentStock cs ON COALESCE(sd.pid, rd.pid) = cs.pid
        WHERE p.pid IS NOT NULL; -- Ensure we only insert for existing products

        -- Get the total number of records inserted for this date
        GET DIAGNOSTICS _total_records = ROW_COUNT;
        RAISE NOTICE 'Created % daily snapshot records for % with sales/receiving activity', _total_records, _target_date;
    END LOOP;

    -- Update the status table with the timestamp from the START of this run
    UPDATE public.calculate_status
    SET last_calculation_timestamp = _start_time
    WHERE module_name = _module_name;

    RAISE NOTICE 'Finished % processing for multiple dates. Duration: %', _module_name, clock_timestamp() - _start_time;

END $$;

-- Return the total records processed for tracking
SELECT 
    COUNT(*) as rows_processed,
    COUNT(DISTINCT snapshot_date) as days_processed,
    MIN(snapshot_date) as earliest_date,
    MAX(snapshot_date) as latest_date,
    SUM(units_sold) as total_units_sold,
    SUM(units_received) as total_units_received
FROM public.daily_product_snapshots
WHERE calculation_timestamp >= (NOW() - INTERVAL '5 minutes'); -- Recent updates only