Add the function to get the next invoice number

I can not use a PostgreSQL sequence because invoices need to be gapless,
and sequences are designed to not rollback, for performance reasons.  In
this case, the performance is secondary because the law does not care.

deploy/company.sql

@@ -26,6 +26,7 @@ create table company (
 	postal_code text not null,
 	country_code country_code not null references country,
 	currency_code currency_code not null references currency,
+	invoice_number_format text not null default '"FRA"YYYY0000',
 	created_at timestamptz not null default current_timestamp
 );
 

deploy/invoice_number_counter.sql

@@ -0,0 +1,32 @@
+-- Deploy numerus:invoice_number_counter to pg
+-- requires: schema_numerus
+-- requires: company
+
+begin;
+
+set search_path to numerus, public;
+
+create table invoice_number_counter (
+	company_id integer not null,
+	year integer not null constraint year_always_positive check(year > 0),
+	currval integer not null constraint counter_always_positive check(currval > 0),
+	primary key (company_id, year)
+);
+
+grant select, insert, update on table invoice_number_counter to invoicer;
+grant select, insert, update on table invoice_number_counter to admin;
+
+alter table invoice_number_counter enable row level security;
+
+create policy company_policy
+on invoice_number_counter
+using (
+	exists(
+		select 1
+		from company_user
+		join user_profile using (user_id)
+		where company_user.company_id = invoice_number_counter.company_id
+	)
+);
+
+commit;

deploy/next_invoice_number.sql

@@ -0,0 +1,38 @@
+-- Deploy numerus:next_invoice_number to pg
+-- requires: schema_numerus
+-- requires: invoice_number_counter
+
+begin;
+
+set search_path to numerus, public;
+
+create or replace function next_invoice_number(company integer, invoice_date date) returns text
+as
+$$
+declare
+	num integer;
+	invoice_number text;
+begin
+	insert into invoice_number_counter (company_id, year, currval)
+	values (next_invoice_number.company, date_part('year', invoice_date), 1)
+	on conflict (company_id, year) do
+	update
+	set currval = invoice_number_counter.currval + 1
+	returning currval
+	into num;
+
+	select to_char(invoice_date, to_char(num, 'FM' || replace(invoice_number_format, '"', '\""')))
+	into invoice_number
+	from company
+	where company_id = next_invoice_number.company;
+
+	return invoice_number;
+end;
+$$
+language plpgsql;
+
+revoke execute on function next_invoice_number(integer, date) from public;
+grant execute on function next_invoice_number(integer, date) to invoicer;
+grant execute on function next_invoice_number(integer, date) to admin;
+
+commit;

revert/invoice_number_counter.sql

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

revert/next_invoice_number.sql

@@ -0,0 +1,7 @@
+-- Revert numerus:next_invoice_number from pg
+
+begin;
+
+drop function if exists numerus.next_invoice_number(integer, date);
+
+commit;

sqitch.plan

@@ -54,3 +54,5 @@ edit_product [schema_numerus product product_tax parse_price company currency] 2
 invoice_product_tax [schema_numerus invoice_product tax tax_rate] 2023-02-15T13:20:30Z jordi fita mas <jordi@tandem.blog> # Add relation for taxes in invoice products
 new_invoice_product [schema_numerus] 2023-02-16T21:06:01Z jordi fita mas <jordi@tandem.blog> # Add type for passing products to new invoices
 add_invoice [schema_numerus invoice company currency parse_price new_invoice_product tax invoice_product invoice_product_tax] 2023-02-16T21:12:46Z jordi fita mas <jordi@tandem.blog> # Add function to create new invoices
+invoice_number_counter [schema_numerus company] 2023-02-17T13:04:48Z jordi fita mas <jordi@tandem.blog> # Add relation to count invoice numbers
+next_invoice_number [schema_numerus invoice_number_counter] 2023-02-17T13:21:48Z jordi fita mas <jordi@tandem.blog> # Add function to retrieve the next invoice number

test/company.sql

@@ -5,7 +5,7 @@ reset client_min_messages;
 
 begin;
 
-select plan(80);
+select plan(85);
 
 set search_path to numerus, auth, public;
 
@@ -94,6 +94,12 @@ select col_type_is('company', 'currency_code', 'currency_code');
 select col_not_null('company', 'currency_code');
 select col_hasnt_default('company', 'currency_code');
 
+select has_column('company', 'invoice_number_format');
+select col_type_is('company', 'invoice_number_format', 'text');
+select col_not_null('company', 'invoice_number_format');
+select col_has_default('company', 'invoice_number_format');
+select col_default_is('company', 'invoice_number_format', '"FRA"YYYY0000');
+
 select has_column('company', 'created_at');
 select col_type_is('company', 'created_at', 'timestamp with time zone');
 select col_not_null('company', 'created_at');

test/invoice_number_counter.sql

@@ -0,0 +1,131 @@
+-- Test invoice_number_counter
+set client_min_messages to warning;
+create extension if not exists pgtap;
+reset client_min_messages;
+
+begin;
+
+select plan(25);
+
+set search_path to numerus, auth, public;
+
+select has_table('invoice_number_counter');
+select has_pk('invoice_number_counter' );
+select col_is_pk('invoice_number_counter', array['company_id', 'year']);
+
+select table_privs_are('invoice_number_counter', 'guest', array []::text[]);
+select table_privs_are('invoice_number_counter', 'invoicer', array ['SELECT', 'INSERT', 'UPDATE']);
+select table_privs_are('invoice_number_counter', 'admin', array ['SELECT', 'INSERT', 'UPDATE']);
+select table_privs_are('invoice_number_counter', 'authenticator', array []::text[]);
+
+select has_column('invoice_number_counter', 'company_id');
+select col_type_is('invoice_number_counter', 'company_id', 'integer');
+select col_not_null('invoice_number_counter', 'company_id');
+select col_hasnt_default('invoice_number_counter', 'company_id');
+
+select has_column('invoice_number_counter', 'year');
+select col_type_is('invoice_number_counter', 'year', 'integer');
+select col_not_null('invoice_number_counter', 'year');
+select col_hasnt_default('invoice_number_counter', 'year');
+
+select has_column('invoice_number_counter', 'currval');
+select col_type_is('invoice_number_counter', 'currval', 'integer');
+select col_not_null('invoice_number_counter', 'currval');
+select col_hasnt_default('invoice_number_counter', 'currval');
+
+
+set client_min_messages to warning;
+truncate invoice_number_counter cascade;
+truncate company_user cascade;
+truncate company cascade;
+truncate auth."user" cascade;
+reset client_min_messages;
+
+insert into auth."user" (user_id, email, name, password, role, cookie, cookie_expires_at)
+values (1, 'demo@tandem.blog', 'Demo', 'test', 'invoicer', '44facbb30d8a419dfd4bfbc44a4b5539d4970148dfc84bed0e', current_timestamp + interval '1 month')
+     , (5, 'admin@tandem.blog', 'Demo', 'test', 'admin', '12af4c88b528c2ad4222e3740496ecbc58e76e26f087657524', current_timestamp + interval '1 month')
+;
+
+insert into company (company_id, business_name, vatin, trade_name, phone, email, web, address, city, province, postal_code, country_code, currency_code)
+values (2, 'Company 2', 'XX123', '', '555-555-555', 'a@a', '', '', '', '', '', 'ES', 'EUR')
+     , (4, 'Company 4', 'XX234', '', '666-666-666', 'b@b', '', '', '', '', '', 'FR', 'USD')
+;
+
+insert into company_user (company_id, user_id)
+values (2, 1)
+     , (4, 5)
+;
+
+insert into contact (contact_id, company_id, business_name, vatin, trade_name, phone, email, web, address, city, province, postal_code, country_code)
+values (6, 2, 'Contact 1', 'XX555', '', '777-777-777', 'c@c', '', '', '', '', '', 'ES')
+     , (8, 4, 'Contact 2', 'XX666', '', '888-888-888', 'd@d', '', '', '', '', '', 'ES')
+;
+
+insert into invoice_number_counter (company_id, year, currval)
+values (2, 2010, 6)
+     , (2, 2011, 8)
+     , (4, 2010, 8)
+     , (4, 2012, 10)
+;
+
+
+prepare counter_data as
+select company_id, year, currval
+from invoice_number_counter
+;
+
+set role invoicer;
+select is_empty('counter_data', 'Should show no data when cookie is not set yet');
+reset role;
+
+select set_cookie('44facbb30d8a419dfd4bfbc44a4b5539d4970148dfc84bed0e/demo@tandem.blog');
+select bag_eq(
+	'counter_data',
+	$$ values (2, 2010, 6)
+	        , (2, 2011, 8)
+	$$,
+	'Should only list invoices of the companies where demo@tandem.blog is user of'
+);
+reset role;
+
+select set_cookie('12af4c88b528c2ad4222e3740496ecbc58e76e26f087657524/admin@tandem.blog');
+select bag_eq(
+	'counter_data',
+	$$ values (4, 2010, 8)
+	        , (4, 2012, 10)
+	$$,
+	'Should only list invoices of the companies where admin@tandem.blog is user of'
+);
+reset role;
+
+select set_cookie('not-a-cookie');
+select throws_ok(
+	'counter_data',
+	'42501', 'permission denied for table invoice_number_counter',
+	'Should not allow select to guest users'
+);
+reset role;
+
+
+select throws_ok( $$
+	insert into invoice_number_counter (company_id, year, currval)
+	values (2, 2008, 0)
+	$$,
+       '23514', 'new row for relation "invoice_number_counter" violates check constraint "counter_always_positive"',
+	'Should not allow starting a counter from zero'
+);
+
+select throws_ok( $$
+	insert into invoice_number_counter (company_id, year, currval)
+	values (2, -2008, 1)
+	$$,
+       '23514', 'new row for relation "invoice_number_counter" violates check constraint "year_always_positive"',
+	'Should not allow counters for invoices issued before Jesus Christ was born'
+);
+
+
+select *
+from finish();
+
+rollback;
+

test/next_invoice_number.sql

@@ -0,0 +1,50 @@
+-- Test next_invoice_number
+set client_min_messages to warning;
+create extension if not exists pgtap;
+reset client_min_messages;
+
+begin;
+
+select plan(17);
+
+set search_path to numerus, public;
+
+select has_function('numerus', 'next_invoice_number', array ['integer', 'date']);
+select function_lang_is('numerus', 'next_invoice_number', array ['integer', 'date'], 'plpgsql');
+select function_returns('numerus', 'next_invoice_number', array ['integer', 'date'], 'text');
+select isnt_definer('numerus', 'next_invoice_number', array ['integer', 'date']);
+select volatility_is('numerus', 'next_invoice_number', array ['integer', 'date'], 'volatile');
+select function_privs_are('numerus', 'next_invoice_number', array ['integer', 'date'], 'guest', array []::text[]);
+select function_privs_are('numerus', 'next_invoice_number', array ['integer', 'date'], 'invoicer', array ['EXECUTE']);
+select function_privs_are('numerus', 'next_invoice_number', array ['integer', 'date'], 'admin', array ['EXECUTE']);
+select function_privs_are('numerus', 'next_invoice_number', array ['integer', 'date'], 'authenticator', array []::text[]);
+
+
+set client_min_messages to warning;
+truncate invoice_number_counter 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, invoice_number_format)
+values (1, 'Company 2', 'XX123', '', '555-555-555', 'a@a', '', '', '', '', '', 'ES', 'EUR', '"F"YYYY0000')
+     , (2, 'Company 4', 'XX234', '', '666-666-666', 'b@b', '', '', '', '', '', 'FR', 'USD', '"INV"000-YY')
+;
+
+insert into invoice_number_counter (company_id, year, currval)
+values (1, 2010, 5)
+     , (2, 2010, 6)
+;
+
+select is( next_invoice_number(1, '2010-12-25'), 'F20100006' );
+select is( next_invoice_number(2, '2010-12-25'), 'INV007-10' );
+select is( next_invoice_number(1, '2010-10-17'), 'F20100007' );
+select is( next_invoice_number(2, '2010-10-17'), 'INV008-10' );
+select is( next_invoice_number(1, '2011-12-25'), 'F20110001' );
+select is( next_invoice_number(2, '2012-12-25'), 'INV001-12' );
+select is( next_invoice_number(1, '2011-12-25'), 'F20110002' );
+select is( next_invoice_number(2, '2012-12-25'), 'INV002-12' );
+
+select *
+from finish();
+
+rollback;

verify/company.sql

@@ -16,6 +16,7 @@ select company_id
      , postal_code
      , country_code
      , currency_code
+     , invoice_number_format
      , created_at
 from numerus.company
 where false;

verify/invoice_number_counter.sql

@@ -0,0 +1,14 @@
+-- Verify numerus:invoice_number_counter on pg
+
+begin;
+
+select company_id
+     , year
+     , currval
+from numerus.invoice_number_counter
+where false;
+
+select 1 / count(*) from pg_class where oid = 'numerus.invoice_number_counter'::regclass and relrowsecurity;
+select 1 / count(*) from pg_policy where polname = 'company_policy' and polrelid = 'numerus.invoice_number_counter'::regclass;
+
+rollback;

verify/next_invoice_number.sql

@@ -0,0 +1,7 @@
+-- Verify numerus:next_invoice_number on pg
+
+begin;
+
+select has_function_privilege('numerus.next_invoice_number(integer, date)', 'execute');
+
+rollback;