[ADD] inventory: aging report

closes odoo/documentation#9433

Signed-off-by: Felicia Kuan (feku) <feku@odoo.com>
Co-authored-by: Jess Rogers <104637850+jero-odoo@users.noreply.github.com>
Co-authored-by: Zachary Straub <zst@odoo.com>
Co-authored-by: Sam Lieber (sali) <36018073+samueljlieber@users.noreply.github.com>

content/applications/inventory_and_mrp/inventory/warehouses_storage/reporting.rst

@@ -9,3 +9,4 @@ Reporting
 
    reporting/stock
    reporting/moves_history
+   reporting/aging

content/applications/inventory_and_mrp/inventory/warehouses_storage/reporting/aging.rst

@@ -0,0 +1,98 @@
+======================
+Inventory aging report
+======================
+
+.. |SVLs| replace:: :abbr:`SVLs (stock valuation layers)`
+
+The inventory aging report evaluates all items in stock, providing insights into potentially sunken
+purchase costs and delays in profitability.
+
+Create customized pivot tables to analyze product, operation types, month, or company breakdowns.
+This helps identify products in stock that are at risk of passing their expiration or viability
+dates, or instances of rot/decay for fast-expiring items.
+
+.. note::
+   The *Reporting* menu in *Inventory* is only accessible to users with :doc:`admin access
+   <../../../../general/users/access_rights>`.
+
+To access the inventory aging report, go to :menuselection:`Inventory app --> Reporting -->
+Inventory Aging`.
+
+.. _inventory/warehouses_storage/aging-report:
+
+Navigate the inventory aging report
+===================================
+
+By default, the :guilabel:`Inventory Aging` report displays a pivot table, with the month in
+columns, and product category in rows. The default filters, :guilabel:`Incoming` and :guilabel:`Has
+Remaining Qty`, show only products from receipts, and are currently in stock.
+
+:guilabel:`Remaining Qty` displays the number of on-hand items, and :guilabel:`Remaining Value`
+displays the total cost of purchasing these items.
+
+Clicking the :icon:`fa-plus-square` :guilabel:`(plus)` icon in each column or row reveals options to
+expand the pivot table and show a detailed breakdown of the :guilabel:`Remaining Qty` and
+:guilabel:`Remaining Value` by :guilabel:`Product`, :guilabel:`Product Category`, :guilabel:`Date`,
+or :guilabel:`Company`. Clicking the :icon:`fa-minus-square-o` :guilabel:`(minus)` icon collapses it
+back to its previous state.
+
+.. figure:: aging/inventory-aging.png
+   :align: center
+   :alt: Inventory aging report.
+
+   Inventory aging report, showing each **Product** in rows and each reception **Date** in columns,
+   to better monitor products with fast expiration dates. Each row shows the the total on-hand
+   quantity and inventory valuation of items purchased on each day.
+
+.. note::
+   Records in the :guilabel:`Inventory Aging` report are *stock valuation layers* (SVLs),
+   representing product moves that impact stock valuation.
+
+   Inventory adjustments do **not** create |SVLs|; only items purchased from vendors do.
+
+Generate reports
+================
+
+After learning how to :ref:`navigate the inventory aging report
+<inventory/warehouses_storage/aging-report>`, it can be used to create and share different reports.
+
+A few common reports that can be created using the :guilabel:`Inventory Aging` report are detailed
+below.
+
+Rotating stock report
+---------------------
+
+To create a report to identify items that have been in stock for a while, follow these steps:
+
+#. Navigate to :menuselection:`Inventory app --> Reporting --> Inventory Aging`.
+#. On the :guilabel:`Inventory Aging` report, click the :icon:`fa-caret-down` :guilabel:`(caret
+   down)` icon in the :guilabel:`Search...` bar to see a drop-down list of :guilabel:`Filters`,
+   :guilabel:`Group By`, and :guilabel:`Favorite` options.
+#. Choose :guilabel:`Product` under the :guilabel:`Group By` section. Doing so expands the pivot
+   table to show a product in each row.
+#. Click the :icon:`fa-plus-square` :guilabel:`(plus)` icon to the left of the date column. Hover
+   over :guilabel:`Date` from the drop-down menu and choose :guilabel:`Year`, :guilabel:`Quarter`,
+   :guilabel:`Month`, :guilabel:`Week`, or :guilabel:`Day`. Doing so expands the columns to show the
+   :guilabel:`Remaining Qty` and :guilabel:`Remaining Value` by the selected time period.
+
+   .. tip::
+      For products that have a longer shelf life, choose longer time periods such as
+      :guilabel:`Month` or :guilabel:`Quarter` when expanding columns by :guilabel:`Date`.
+
+   .. image:: aging/column-expand-icon.png
+      :align: center
+      :alt: Pivot table, highlighting the plus icon to expand columns.
+
+#. The report now displays the on-hand stock of items, and their total purchasing cost, for each
+   time period.
+
+   .. example::
+      Inventory aging report, with the :guilabel:`Group By`: :guilabel:`Product` option selected,
+      and with the :guilabel:`Date` column set to :guilabel:`Day`. It gives insight into how much
+      raw fish sashimi products were purchased on each day, and how much it cost. This informs the
+      business owners how much stock is at risk of rotting in stock, per day.
+
+      .. image:: aging/inventory-aging.png
+        :align: center
+        :alt: Inventory aging report, showing product row items and day columns.
+