Show the invoice subtotal, taxes, and total when creating it

deploy/compute_new_invoice_amount.sql

@@ -0,0 +1,64 @@
+-- Deploy numerus:compute_new_invoice_amount to pg
+-- requires: schema_numerus
+-- requires: company
+-- requires: currency
+-- requires: tax
+-- requires: new_invoice_product
+-- requires: new_invoice_amount
+
+begin;
+
+set search_path to numerus, public;
+
+create or replace function compute_new_invoice_amount(company_id integer, products new_invoice_product[]) returns new_invoice_amount as
+$$
+declare
+	result new_invoice_amount;
+begin
+	if array_length(products, 1) is null then
+		select to_price(0, decimal_digits), array[]::text[][], to_price(0, decimal_digits)
+		from company
+		join currency using (currency_code)
+		where company.company_id = compute_new_invoice_amount.company_id
+		into result.subtotal, result.taxes, result.total;
+	else
+		with product as (
+			select round(parse_price(price, currency.decimal_digits) * quantity * (1 - discount_rate))::integer as subtotal
+			, tax
+			, decimal_digits
+			from unnest(products)
+			join company on company.company_id = compute_new_invoice_amount.company_id
+			join currency using (currency_code)
+		)
+		, tax_amount as (
+			select tax_id
+			, sum(round(subtotal * tax.rate)::integer)::integer as amount
+			, decimal_digits
+			from product, unnest(product.tax) as product_tax(tax_id)
+			join tax using (tax_id)
+			group by tax_id, decimal_digits
+		)
+		, tax_total as (
+			select sum(amount)::integer as amount, array_agg(array[name, to_price(amount, decimal_digits)]) as taxes
+			from tax_amount
+			join tax using (tax_id)
+		)
+		select to_price(sum(subtotal)::integer, decimal_digits)
+		, coalesce(taxes, array[]::text[][])
+		, to_price(sum(subtotal)::integer + coalesce(tax_total.amount, 0), decimal_digits) as total
+		from product, tax_total
+		group by tax_total.amount, taxes, decimal_digits
+		into result.subtotal, result.taxes, result.total;
+	end if;
+
+	return result;
+end
+$$
+language plpgsql
+stable;
+
+revoke execute on function compute_new_invoice_amount(integer, new_invoice_product[]) from public;
+grant execute on function compute_new_invoice_amount(integer, new_invoice_product[]) to invoicer;
+grant execute on function compute_new_invoice_amount(integer, new_invoice_product[]) to admin;
+
+commit;

deploy/new_invoice_amount.sql

@@ -0,0 +1,14 @@
+-- Deploy numerus:new_invoice_amount to pg
+-- requires: schema_numerus
+
+begin;
+
+set search_path to numerus, public;
+
+create type new_invoice_amount as (
+	subtotal text,
+	taxes text[][],
+	total text
+);
+
+commit;

pkg/invoices.go

@@ -66,10 +66,31 @@ func GetInvoiceForm(w http.ResponseWriter, r *http.Request, params httprouter.Pa
 	}
 }
 
+type newInvoicePage struct {
+	Form     *invoiceForm
+	Subtotal string
+	Taxes    [][]string
+	Total    string
+}
+
+func newNewInvoicePage(form *invoiceForm, r *http.Request) *newInvoicePage {
+	page := &newInvoicePage{
+		Form: form,
+	}
+	conn := getConn(r)
+	company := mustGetCompany(r)
+	err := conn.QueryRow(r.Context(), "select subtotal, taxes, total from compute_new_invoice_amount($1, $2)", company.Id, NewInvoiceProductArray(form.Products)).Scan(&page.Subtotal, &page.Taxes, &page.Total)
+	if err != nil {
+		panic(err)
+	}
+	return page
+}
+
 func mustRenderNewInvoiceForm(w http.ResponseWriter, r *http.Request, form *invoiceForm) {
 	locale := getLocale(r)
 	form.Customer.EmptyLabel = gettext("Select a customer to bill.", locale)
-	mustRenderAppTemplate(w, r, "invoices/new.gohtml", form)
+	page := newNewInvoicePage(form, r)
+	mustRenderAppTemplate(w, r, "invoices/new.gohtml", page)
 }
 
 func mustRenderNewInvoiceProductsForm(w http.ResponseWriter, r *http.Request, form *invoiceForm) {
@@ -158,7 +179,7 @@ func HandleAddProductsToInvoice(w http.ResponseWriter, r *http.Request, _ httpro
 
 	index := len(form.Products)
 	productsId := r.Form["id"]
-	rows := conn.MustQuery(r.Context(), "select product_id, name, description, to_price(price, decimal_digits), 1 as quantity, 0 as discount, array_agg(tax_id) from product join company using (company_id) join currency using (currency_code) left join product_tax using (product_id) where product_id = any ($1) group by product_id, name, description, price, decimal_digits", productsId)
+	rows := conn.MustQuery(r.Context(), "select product_id, name, description, to_price(price, decimal_digits), 1 as quantity, 0 as discount, array_remove(array_agg(tax_id), null) from product join company using (company_id) join currency using (currency_code) left join product_tax using (product_id) where product_id = any ($1) group by product_id, name, description, price, decimal_digits", productsId)
 	defer rows.Close()
 	for rows.Next() {
 		product := newInvoiceProductForm(index, company, locale, form.Tax.Options)

revert/compute_new_invoice_amount.sql

@@ -0,0 +1,7 @@
+-- Revert numerus:compute_new_invoice_amount from pg
+
+begin;
+
+drop function if exists numerus.compute_new_invoice_amount(integer, numerus.new_invoice_product[]);
+
+commit;

revert/new_invoice_amount.sql

@@ -0,0 +1,7 @@
+-- Revert numerus:new_invoice_amount from pg
+
+begin;
+
+drop type if exists numerus.new_invoice_amount;
+
+commit;

sqitch.plan

@@ -58,3 +58,5 @@ next_invoice_number [schema_numerus invoice_number_counter] 2023-02-17T13:21:48Z
 add_invoice [schema_numerus invoice company currency parse_price new_invoice_product tax invoice_product invoice_product_tax next_invoice_number] 2023-02-16T21:12:46Z jordi fita mas <jordi@tandem.blog> # Add function to create new invoices
 invoice_tax_amount [schema_numerus invoice_product invoice_product_tax] 2023-02-22T12:08:35Z jordi fita mas <jordi@tandem.blog> # Add view for invoice tax amount
 invoice_amount [schema_numerus invoice_product invoice_tax_amount] 2023-02-22T12:58:46Z jordi fita mas <jordi@tandem.blog> # Add view to compute subtotal and total for invoices
+new_invoice_amount [schema_numerus] 2023-02-23T12:08:25Z jordi fita mas <jordi@tandem.blog> # Add type to return when computing new invoice amounts
+compute_new_invoice_amount [schema_numerus company currency tax new_invoice_product new_invoice_amount] 2023-02-23T12:20:13Z jordi fita mas <jordi@tandem.blog> # Add function to compute the subtotal, taxes, and total amounts for a new invoice

test/compute_new_invoice_amount.sql

@@ -0,0 +1,66 @@
+-- Test compute_new_invoice_amount
+set client_min_messages to warning;
+create extension if not exists pgtap;
+reset client_min_messages;
+
+begin;
+
+select plan(14);
+
+set search_path to numerus, auth, public;
+
+select has_function('numerus', 'compute_new_invoice_amount', array ['integer', 'new_invoice_product[]']);
+select function_lang_is('numerus', 'compute_new_invoice_amount', array ['integer', 'new_invoice_product[]'], 'plpgsql');
+select function_returns('numerus', 'compute_new_invoice_amount', array ['integer', 'new_invoice_product[]'], 'new_invoice_amount');
+select isnt_definer('numerus', 'compute_new_invoice_amount', array ['integer', 'new_invoice_product[]']);
+select volatility_is('numerus', 'compute_new_invoice_amount', array ['integer', 'new_invoice_product[]'], 'stable');
+select function_privs_are('numerus', 'compute_new_invoice_amount', array ['integer', 'new_invoice_product[]'], 'guest', array []::text[]);
+select function_privs_are('numerus', 'compute_new_invoice_amount', array ['integer', 'new_invoice_product[]'], 'invoicer', array ['EXECUTE']);
+select function_privs_are('numerus', 'compute_new_invoice_amount', array ['integer', 'new_invoice_product[]'], 'admin', array ['EXECUTE']);
+select function_privs_are('numerus', 'compute_new_invoice_amount', array ['integer', 'new_invoice_product[]'], 'authenticator', array []::text[]);
+
+set client_min_messages to warning;
+truncate tax cascade;
+truncate company cascade;
+reset client_min_messages;
+
+insert into company (company_id, business_name, vatin, trade_name, phone, email, web, address, city, province, postal_code, country_code, currency_code)
+values (1, 'Company 1', 'XX123', '', '555-555-555', 'a@a', '', '', '', '', '', 'ES', 'EUR')
+;
+
+insert into tax (tax_id, company_id, name, rate)
+values (2, 1, 'IRPF -15 %', -0.15)
+     , (3, 1, 'IVA 4 %', 0.04)
+     , (4, 1, 'IVA 10 %', 0.10)
+     , (5, 1, 'IVA 21 %', 0.21)
+;
+
+select is(
+	compute_new_invoice_amount(1, '{}'),
+	'(0.00,"{}",0.00)'::new_invoice_amount
+);
+
+select is(
+	compute_new_invoice_amount(1, '{"(6,P,D,1.00,1,0.0,\"{2,5}\")","(6,P,D,2.00,2,0.1,{3})"}'),
+	'(4.60,"{{IRPF -15 %,-0.15},{IVA 4 %,0.14},{IVA 21 %,0.21}}",4.80)'::new_invoice_amount
+);
+
+select is(
+	compute_new_invoice_amount(1, '{"(6,P,D,2.22,3,0.0,\"{2,4,5}\")","(6,P,D,3.33,4,0.2,{4})"}'),
+	'(17.32,"{{IRPF -15 %,-1.00},{IVA 10 %,1.74},{IVA 21 %,1.40}}",19.46)'::new_invoice_amount
+);
+
+select is(
+	compute_new_invoice_amount(1, '{"(6,P,D,4.44,5,0.0,\"{4,5}\")","(6,P,D,5.55,6,0.1,\"{5,3}\")"}'),
+	'(52.17,"{{IVA 4 %,1.20},{IVA 10 %,2.22},{IVA 21 %,10.95}}",66.54)'::new_invoice_amount
+);
+
+select is(
+	compute_new_invoice_amount(1, '{"(6,P,D,7.77,8,0.0,\"{}\")"}'),
+	'(62.16,"{}",62.16)'::new_invoice_amount
+);
+
+select *
+from finish();
+
+rollback;

test/new_invoice_amount.sql

@@ -0,0 +1,22 @@
+-- Test new_invoice_amount
+set client_min_messages to warning;
+create extension if not exists pgtap;
+reset client_min_messages;
+
+begin;
+
+select plan(5);
+
+set search_path to numerus, public;
+
+select has_composite('numerus', 'new_invoice_amount', 'Composite type numerus.new_invoice_amount should exist');
+select columns_are('numerus', 'new_invoice_amount', array['subtotal', 'taxes', 'total']);
+select col_type_is('numerus'::name, 'new_invoice_amount'::name, 'subtotal'::name, 'text');
+select col_type_is('numerus'::name, 'new_invoice_amount'::name, 'taxes'::name, 'text[]');
+select col_type_is('numerus'::name, 'new_invoice_amount'::name, 'total'::name, 'text');
+
+
+select *
+from finish();
+
+rollback;

verify/compute_new_invoice_amount.sql

@@ -0,0 +1,7 @@
+-- Verify numerus:compute_new_invoice_amount on pg
+
+begin;
+
+select has_function_privilege('numerus.compute_new_invoice_amount(integer, numerus.new_invoice_product[])', 'execute');
+
+rollback;

verify/new_invoice_amount.sql

@@ -0,0 +1,7 @@
+-- Verify numerus:new_invoice_amount on pg
+
+begin;
+
+select pg_catalog.has_type_privilege('numerus.new_invoice_amount', 'usage');
+
+rollback;

web/template/invoices/new.gohtml

@@ -16,6 +16,7 @@
         <form method="POST" action="{{ companyURI "/invoices" }}">
             {{ csrfToken }}
 
+            {{ with .Form -}}
                 {{ template "select-field" .Customer }}
                 {{ template "input-field" .Number }}
                 {{ template "input-field" .Date }}
@@ -32,6 +33,26 @@
                         {{ template "select-field" .Tax }}
                     </fieldset>
                 {{- end }}
+            {{- end }}
+
+            <table>
+                <tbody>
+                <tr>
+                    <th scope="row">{{(pgettext "Subtotal" "title")}}</th>
+                    <td class="numeric">{{ .Subtotal | formatPrice }}</td>
+                </tr>
+                {{- range $tax := .Taxes }}
+                    <tr>
+                        <th scope="row">{{ index . 0 }}</th>
+                        <td class="numeric">{{ index . 1 | formatPrice }}</td>
+                    </tr>
+                {{- end }}
+                <tr>
+                    <th scope="row">{{(pgettext "Total" "title")}}</th>
+                    <td class="numeric">{{ .Total | formatPrice }}</td>
+                </tr>
+                </tbody>
+            </table>
 
             <fieldset>
                 <button formnovalidate name="action" value="products"