[REF] stock_account: support valuation at date

For the standard and average cost method, we use `qty_available` at date
and the `product.price.history` table.

For FIFO, the normal way would have been to get the `qty_available` at
date and value this quantity with the more recent IN moves at this date.

But there's two main obstacles preventing to use this solution:
- when editing a done move to change the quantity, the change is
  reflected at the date, the `qty_available` at date will be incremented
- in the same usecase, the remaining_qty and remaining_value is
  incremented in place, which mean that even if the layer was already
  consumed, it's now appearing again at the bottom of the fifo layer

Fixing this issue by adding a stock move at the date of today instead of
editing in place in v11 and adding a proper "cost layer" model in master
was deemed too complex as well as unnecessary by our bosses

So we now say we continue to update in place, and when looking at the
quantity at date
- if periodic, we sum the value of the move since the beginning of times
- if perpetual, we sum the balance of the account move lines since the
  beginning of times. Also, in this case, the quantity at date is
  computed across account move lines too, via the "quantity" field on
  aml.

This commit adds three non stored computed field:
- qty_at_date: will be computed across stock moves if fifo periodic and
  across account move line if fifo perpetual to reflect the design
  choice: if periodic, we *really* edit in the past ; if perpetual, no,
  the change is done at today's date
- stock_fifo_real_time_aml_ids: the used aml to compute qty_at_date
- stock_fifo_manual_move_ids: the used move to compute qty_at_date

addons/stock_account/models/product.py

@@ -63,7 +63,7 @@ class ProductTemplate(models.Model):
         if self.property_cost_method == 'fifo' and self.cost_method in ['average', 'standard']:
             # Cannot use the `stock_value` computed field as it's already invalidated when
             # entering this method.
-            valuation = sum([variant._sum_remaining_values() for variant in self.product_variant_ids])
+            valuation = sum([variant._sum_remaining_values()[0] for variant in self.product_variant_ids])
             qty_available = self.with_context(company_owned=True).qty_available
             if qty_available:
                 self.standard_price = valuation / qty_available
@@ -111,6 +111,12 @@ class ProductProduct(models.Model):
 
     stock_value = fields.Float(
         'Value', compute='_compute_stock_value')
+    qty_at_date = fields.Float(
+        'Quantity', compute='_compute_stock_value')
+    stock_fifo_real_time_aml_ids = fields.Many2many(
+        'account.move.line', compute='_compute_stock_value')
+    stock_fifo_manual_move_ids = fields.Many2many(
+        'stock.move', compute='_compute_stock_value')
 
     @api.multi
     def do_change_standard_price(self, new_price, account_id):
@@ -173,16 +179,66 @@ class ProductProduct(models.Model):
         StockMove = self.env['stock.move']
         domain = [('product_id', '=', self.id)] + StockMove._get_all_base_domain()
         moves = StockMove.search(domain)
-        return sum(moves.mapped('remaining_value'))
+        return sum(moves.mapped('remaining_value')), moves
 
     @api.multi
-    @api.depends('stock_move_ids.product_qty', 'stock_move_ids.state', 'stock_move_ids.remaining_value', 'product_tmpl_id.cost_method', 'product_tmpl_id.standard_price')
+    @api.depends('stock_move_ids.product_qty', 'stock_move_ids.state', 'stock_move_ids.remaining_value', 'product_tmpl_id.cost_method', 'product_tmpl_id.standard_price', 'product_tmpl_id.property_valuation', 'product_tmpl_id.categ_id.property_valuation')
     def _compute_stock_value(self):
+        StockMove = self.env['stock.move']
+        to_date = self.env.context.get('to_date')
+
+        self.env['account.move.line'].check_access_rights('read')
+        fifo_automated_values = {}
+        query = """SELECT aml.product_id, aml.account_id, sum(aml.debit) - sum(aml.credit), sum(quantity), array_agg(aml.id)
+                     FROM account_move_line AS aml
+                    WHERE aml.product_id IS NOT NULL AND aml.company_id=%%s %s
+                 GROUP BY aml.product_id, aml.account_id"""
+        params = (self.env.user.company_id.id,)
+        if to_date:
+            query = query % ('AND aml.date <= %s',)
+            params = params + (to_date,)
+        else:
+            query = query % ('',)
+        self.env.cr.execute(query, params=params)
+
+        res = self.env.cr.fetchall()
+        for row in res:
+            fifo_automated_values[(row[0], row[1])] = (row[2], row[3], list(row[4]))
+
         for product in self:
             if product.cost_method in ['standard', 'average']:
-                product.stock_value = product.standard_price * product.with_context(company_owned=True).qty_available
+                qty_available = product.with_context(company_owned=True).qty_available
+                price_used = product.standard_price
+                if to_date:
+                    price_used = product.get_history_price(
+                        self.env.user.company_id.id,
+                        date=to_date,
+                    )
+                product.stock_value = price_used * qty_available
+                product.qty_at_date = qty_available
             elif product.cost_method == 'fifo':
-                product.stock_value = product._sum_remaining_values()
+                if to_date:
+                    if product.product_tmpl_id.valuation == 'manual_periodic':
+                        domain = [('product_id', '=', product.id), ('date', '<=', to_date)] + StockMove._get_all_base_domain()
+                        moves = StockMove.search(domain)
+                        product.stock_value = sum(moves.mapped('value'))
+                        product.qty_at_date = product.with_context(company_owned=True).qty_available
+                        product.stock_fifo_manual_move_ids = StockMove.browse(moves.ids)
+                    elif product.product_tmpl_id.valuation == 'real_time':
+                        valuation_account_id = product.categ_id.property_stock_valuation_account_id.id
+                        value, quantity, aml_ids = fifo_automated_values.get((product.id, valuation_account_id)) or (0, 0, [])
+                        product.stock_value = value
+                        product.qty_at_date = quantity
+                        product.stock_fifo_real_time_aml_ids = self.env['account.move.line'].browse(aml_ids)
+                else:
+                    product.stock_value, moves = product._sum_remaining_values()
+                    product.qty_at_date = product.with_context(company_owned=True).qty_available
+                    if product.product_tmpl_id.valuation == 'manual_periodic':
+                        product.stock_fifo_manual_move_ids = moves
+                    elif product.product_tmpl_id.valuation == 'real_time':
+                        valuation_account_id = product.categ_id.property_stock_valuation_account_id.id
+                        value, quantity, aml_ids = fifo_automated_values.get((product.id, valuation_account_id)) or (0, 0, [])
+                        product.stock_fifo_real_time_aml_ids = self.env['account.move.line'].browse(aml_ids)
 
     @api.multi
     def action_open_product_moves(self):