create table categories (
    id              smallserial                 not null,
    name            character varying (64)      not null,
    description     text                        not null,
    primary key (id),
    unique (name)
);

insert into categories (name, description) values
('Прикладное программное обеспечение', '[Описание категории]'),
('Системное программное обеспечение', '[Описание категории]'),
('Системы обеспечения IT-безопасности', '[Описание категории]'),
('Специализированное программное обеспечение', '[Описание категории]');

create table subcategories (
    category_id     smallint                    not null,
    id              smallint                    not null,
    name            character varying (64)      not null,
    description     text                        not null,
    foreign key (category_id) references categories on delete cascade,
    primary key (category_id, id),
    unique (category_id, name)
);

create function sfx_subcategories_id_seq() returns trigger as $$
    begin
        if new.id is null then
            new.id := (select
                coalesce(max(subcategories.id) + 1, 1)
            from
                subcategories
            where
                subcategories.category_id = new.category_id);
        end if;
        return new;
    end;
$$ language plpgsql;

create trigger subcategories_id_seq before insert on subcategories
    for each row execute procedure sfx_subcategories_id_seq();

insert into subcategories (category_id, name, description) values
(1, 'Программы 1С', '[Описание подкатегории]'),
(1, 'Программы ЭОС', '[Описание подкатегории]'),
(1, 'Собственные разработки на платформе 1С', '[Описание подкатегории]'),
(2, 'Продукция Astra Linux', '[Описание подкатегории]'),
(2, 'Продукция Alt Linux (Базальт-СПО)', '[Описание подкатегории]'),
(2, 'ПО для работы с текстом', '[Описание подкатегории]'),
(2, 'МойОфис', '[Описание подкатегории]'),
(3, 'Системы обеспечения сохранности данных', '[Описание подкатегории]'),
(3, 'Антивирусное ПО', '[Описание подкатегории]'),
(3, 'Системы защиты корпоративной информации', '[Описание подкатегории]'),
(3, 'Программный комплекс «Стахановец»', '[Описание подкатегории]'),
(3, 'Решение StaffCop Enterprise', '[Описание подкатегории]'),
(4, 'Графические редакторы Movavi', '[Описание подкатегории]'),
(4, 'Сметные программы', '[Описание подкатегории]'),
(4, 'Библиотеки нормативов и стандартов', '[Описание подкатегории]'),
(4, 'САПР', '[Описание подкатегории]'),
(4, 'Решения для совместной работы TrueConf', '[Описание подкатегории]'),
(4, 'Polys - система безопасных онлайн-голосований', '[Описание подкатегории]'),
(4, 'VISOCALL IP Телекоммуникация в медицине', '[Описание подкатегории]');

create table executors (
    id              bigserial                   not null,
    name            character varying (64)      not null,
    primary key (id),
    unique (name)
);

insert into executors (name) values
('Богатырёва Ю. И.'),
('Ванькова В. С.'),
('Даниленко С. В.'),
('Екатериничев А. Л.'),
('Клепиков А. К.'),
('Мартынюк Ю. М.'),
('Надеждин Е. Н.'),
('Привалов А. Н.'),
('Родионова О. В.');

create table executor_specialties (
    executor_id     bigint                      not null,
    category_id     smallint                    not null,
    subcategory_id  smallint                    not null,
    foreign key (executor_id) references executors on delete cascade,
    foreign key (category_id, subcategory_id) references subcategories on delete cascade,
    primary key (executor_id, category_id, subcategory_id)
);

insert into executor_specialties (executor_id, category_id, subcategory_id) values
(1, 1, 1),
(2, 1, 1),
(4, 1, 1),
(5, 1, 1),
(6, 1, 1),
(7, 1, 1),
(8, 1, 1),
(9, 1, 1),
(4, 1, 2),
(5, 1, 2),
(7, 1, 2),
(8, 1, 2),
(1, 1, 3),
(2, 1, 3),
(3, 1, 3),
(5, 1, 3),
(6, 1, 3),
(7, 1, 3),
(8, 1, 3),
(4, 2, 1),
(5, 2, 1),
(6, 2, 1),
(7, 2, 1),
(8, 2, 1),
(9, 2, 1),
(2, 2, 2),
(5, 2, 2),
(6, 2, 2),
(7, 2, 2),
(8, 2, 2),
(9, 2, 2),
(2, 2, 3),
(4, 2, 3),
(8, 2, 3),
(4, 2, 4),
(5, 2, 4),
(8, 2, 4),
(9, 2, 4),
(2, 3, 1),
(3, 3, 1),
(6, 3, 1),
(7, 3, 1),
(1, 3, 2),
(4, 3, 2),
(5, 3, 2),
(6, 3, 2),
(9, 3, 2),
(1, 3, 3),
(6, 3, 3),
(9, 3, 3),
(3, 3, 4),
(8, 3, 4),
(1, 3, 5),
(3, 3, 5),
(5, 3, 5),
(6, 3, 5),
(7, 3, 5),
(9, 3, 5),
(5, 4, 1),
(6, 4, 1),
(7, 4, 2),
(9, 4, 4),
(3, 4, 6),
(4, 4, 6);

create table time_ranges (
    id              smallserial                 not null,
    start_time      time                        not null,
    end_time        time                        not null,
    primary key (id)
);

insert into time_ranges (start_time, end_time) values
('9:00'::time, '12:00'::time),
('12:00'::time, '15:00'::time),
('15:00'::time, '18:00'::time);

create table orders (
    id              bigserial                   not null,
    category_id     smallint                    not null,
    subcategory_id  smallint                    not null,
    date            date                        not null,
    time_range_id   smallint                    not null,
    executor_id     bigint                      not null,
    telegram_id     bigint                      not null,
    email_address   character varying (256)     not null,
    phone_number    character varying (16)      not null,
    comment         character varying (1024)    not null,
    start_time      timestamp,
    end_time        timestamp,
    foreign key (category_id, subcategory_id) references subcategories on delete cascade,
    foreign key (time_range_id) references time_ranges on delete cascade,
    foreign key (executor_id) references executors on delete cascade,
    primary key (id)
);

create table issues (
    id              bigint                      not null,
    key             character varying (16)      not null,
    status          character varying (16)      not null,
    telegram_id     bigint                      not null,
    primary key (id),
    unique (key)
);

create table statistics (
    category_id     smallint                    not null,
    subcategory_id  smallint                    not null,
    execution_time  interval                    not null,
    foreign key (category_id, subcategory_id) references subcategories on delete cascade,
    primary key (category_id, subcategory_id)
);

insert into statistics (category_id, subcategory_id, execution_time) values
(1, 1, interval '15 minutes'),
(1, 2, interval '30 minutes'),
(1, 3, interval '15 minutes'),
(2, 1, interval '1 hour'),
(2, 2, interval '2 hours'),
(2, 3, interval '1 hour'),
(2, 4, interval '2 hours'),
(3, 1, interval '15 minutes'),
(3, 2, interval '30 minutes'),
(3, 3, interval '15 minutes'),
(3, 4, interval '30 minutes'),
(3, 5, interval '15 minutes'),
(4, 1, interval '1 hour'),
(4, 2, interval '2 hours'),
(4, 3, interval '1 hour'),
(4, 4, interval '2 hours'),
(4, 5, interval '1 hour'),
(4, 6, interval '2 hours'),
(4, 7, interval '1 hour');

create or replace function sfx_update_statistics(
        k integer
) returns void as $$
    declare subcategory subcategories;
    declare _order record;
    begin
        for subcategory in (
            select
                subcategories.category_id,
                subcategories.id
            from
                subcategories
        ) loop
            for _order in (
                select
                    count(t1) as count,
                    avg(t1.end_time - t1.start_time) as avg
                from
                    (
                        select
                            orders.start_time,
                            orders.end_time
                        from
                            orders
                        where
                            orders.category_id = subcategory.category_id and
                            orders.subcategory_id = subcategory.id and
                            orders.start_time is not null and
                            orders.end_time is not null
                        order by
                            orders.start_time desc
                        limit
                            k
                    ) t1
            ) loop
                if _order.count <> k then
                    continue;
                end if;
                update
                    statistics
                set
                    execution_time = _order.avg
                where
                    statistics.category_id = subcategory.category_id and
                    statistics.subcategory_id = subcategory.id;
            end loop;
        end loop;
    end;
$$ language plpgsql;

create or replace function sfx_read_free_to_order(
        _category_id smallint,
        _subcategory_id smallint
) returns table (
        date date,
        time_range_id smallint,
        executor_id bigint,
        busy_interval   interval
) as $$
    declare avg_interval interval := (
        select
            statistics.execution_time
        from
            statistics
        where
            statistics.category_id = _category_id and
            statistics.subcategory_id = _subcategory_id
    );
    declare max_interval interval := (
        select
            max(time_ranges.end_time - time_ranges.start_time)
        from
            time_ranges
    );
    declare executor executors;
    declare time_range time_ranges;
    declare _date date := now()::date;
    declare _busy_interval interval;
    begin
        if avg_interval > max_interval then
            raise '0x00000005';
        end if;
        create temporary table tmp (
            date            date        not null,
            time_range_id   smallint    not null,
            executor_id     bigint      not null,
            busy_interval   interval    not null
        ) on commit drop;
        while (
            select
                coalesce(count(t1.*), 0) < 6
            from
                (select distinct
                    tmp.date
                from
                    tmp) t1
        ) loop
            for executor in (
                select
                    executors.id
                from
                    executor_specialties
                left join executors on
                    executor_specialties.executor_id = executors.id
                where
                    executor_specialties.category_id = _category_id and
                    executor_specialties.subcategory_id = _subcategory_id
            ) loop
                for time_range in (
                    select
                        time_ranges.id,
                        time_ranges.start_time,
                        time_ranges.end_time
                    from
                        time_ranges
                ) loop
                    if _date = now()::date and time_range.start_time < now()::time then
                        continue;
                    end if;
                    _busy_interval := (
                        select
                            coalesce(sum(statistics.execution_time), '0s'::interval)
                        from
                            orders
                        left join statistics on
                            orders.category_id = statistics.category_id and
                            orders.subcategory_id = statistics.subcategory_id
                        where
                            orders.date = _date and
                            orders.time_range_id = time_range.id and
                            orders.executor_id = executor.id
                    );
                    if time_range.end_time - time_range.start_time - _busy_interval > avg_interval then
                        insert into tmp (
                            date,
                            time_range_id,
                            executor_id,
                            busy_interval
                        )
                        values (
                            _date,
                            time_range.id,
                            executor.id,
                            _busy_interval
                        );
                    end if;
                end loop;
            end loop;
            _date = _date + '1 day'::interval;
        end loop;
        return query (
            select
                tmp.*
            from
                tmp
        );
    end;
$$ language plpgsql;