vermietungs-tool/migrations/001_schema.sql

-- 001 schema.
--   * text is COLLATE "C" (byte order), dates are ISO text, money is double precision
--   * every foreign key is DEFERRABLE (INITIALLY IMMEDIATE): company and client point at each other

CREATE TABLE unit (
    id              bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    code            text COLLATE "C" NOT NULL UNIQUE,     -- short code shown in the lists
    name            text COLLATE "C" NOT NULL,
    subtitle        text COLLATE "C",
    address         text COLLATE "C",                     -- multi-line issuer address block
    place           text COLLATE "C",                     -- where invoices are issued ('<place>, am <date>')
    contact         text COLLATE "C",                     -- multi-line contact block of the invoice footer
    bank            text COLLATE "C",
    iban            text COLLATE "C",
    uid             text COLLATE "C",
    tvb_number      text COLLATE "C",                     -- Betriebsnummer for the tourist-tax report
    invoice_prefix  text COLLATE "C",                     -- '2026-' | '26-': the year is kept current
    logo            text COLLATE "C",                     -- file in app/static/invoice/, nullable
    photo           text COLLATE "C",
    theme           text COLLATE "C",                     -- 'green' | 'blue'
    is_current      integer NOT NULL DEFAULT 1,
    succeeded_by_id bigint REFERENCES unit(id) DEFERRABLE  -- a former operator reports under its successor
);

CREATE TABLE room (
    id        bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    number    text COLLATE "C" NOT NULL UNIQUE,           -- floor-coded, e.g. '21'
    category  text COLLATE "C",                           -- EZ | DZ | 3BZ | 4BZ | Garconniere
    capacity  integer,
    unit_id   bigint REFERENCES unit(id) DEFERRABLE,      -- current owner
    long_term integer NOT NULL DEFAULT 0,                 -- let long-term, left out of the free-bed count
    floor     text COLLATE "C"
);

CREATE TABLE company (
    id                bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    name              text COLLATE "C" NOT NULL,          -- canonical display name
    kind              text COLLATE "C" NOT NULL DEFAULT 'company',   -- company | private
    uid               text COLLATE "C",
    email             text COLLATE "C",
    phone             text COLLATE "C",
    notes             text COLLATE "C",
    current_client_id bigint                              -- the address version used for NEW invoices
);

CREATE TABLE client (
    id         bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    kind       text COLLATE "C" NOT NULL DEFAULT 'company',   -- company | private
    name       text COLLATE "C" NOT NULL,
    address    text COLLATE "C",
    postcode   text COLLATE "C",
    city       text COLLATE "C",
    country    text COLLATE "C",
    company_id bigint REFERENCES company(id) DEFERRABLE
);
ALTER TABLE company ADD FOREIGN KEY (current_client_id) REFERENCES client(id) DEFERRABLE;

CREATE TABLE company_key (
    key        text COLLATE "C" PRIMARY KEY,              -- normalize.company_key(spelling)
    company_id bigint NOT NULL REFERENCES company(id) DEFERRABLE
);

CREATE TABLE dismissed_finding (
    kind text COLLATE "C" NOT NULL,
    key  text COLLATE "C" NOT NULL,
    note text COLLATE "C",
    PRIMARY KEY (kind, key)
);

CREATE TABLE guest (
    id            bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    last_name     text COLLATE "C",
    first_name    text COLLATE "C",
    birth_date    text COLLATE "C",                       -- ISO yyyy-mm-dd
    nationality   text COLLATE "C",
    doc_type      text COLLATE "C",
    doc_number    text COLLATE "C",
    profession    text COLLATE "C",
    home_street   text COLLATE "C",
    home_postcode text COLLATE "C",
    home_city     text COLLATE "C",
    home_country  text COLLATE "C",
    phone         text COLLATE "C"
);

CREATE TABLE invoice (
    id             bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    unit_id        bigint REFERENCES unit(id) DEFERRABLE,
    client_id      bigint REFERENCES client(id) DEFERRABLE,
    number         text COLLATE "C",                      -- '2026-01'
    date           text COLLATE "C",
    paid_date      text COLLATE "C",
    payment_method text COLLATE "C",
    notes          text COLLATE "C",
    lines_stale    integer NOT NULL DEFAULT 0
);

-- One table for three kinds of rows, told apart by source_sheet: 'guestsheet' (a Gästeblatt in the guest
-- register), 'ledger' (a Zimmerbelegung row; its dates live on the charge) and 'invoice' (an invoice line).
CREATE TABLE stay (
    id                 bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    guest_id           bigint REFERENCES guest(id) DEFERRABLE,    -- null for ledger and invoice rows
    room_id            bigint REFERENCES room(id) DEFERRABLE,
    unit_id            bigint REFERENCES unit(id) DEFERRABLE,     -- the operator at the time
    employer_client_id bigint REFERENCES client(id) DEFERRABLE,
    arrival            text COLLATE "C",
    departure          text COLLATE "C",
    sheet_number       text COLLATE "C",
    label              text COLLATE "C",                  -- occupant text when guest_id is null
    notes              text COLLATE "C",
    source_sheet       text COLLATE "C",                  -- guestsheet | ledger | invoice
    hauptwohnsitz      integer,
    tourism_liable     integer
);

CREATE TABLE charge (
    id                bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    stay_id           bigint REFERENCES stay(id) DEFERRABLE,
    invoice_id        bigint REFERENCES invoice(id) DEFERRABLE,
    period_from       text COLLATE "C",
    period_to         text COLLATE "C",
    quantity          double precision,
    unit_type         text COLLATE "C",                   -- week | day | night | month
    gross_per_unit    double precision,
    line_net_override double precision,                   -- null => computed
    source_sheet      text COLLATE "C",
    persons           numeric,
    paid_date         text COLLATE "C",
    paid_status       text COLLATE "C",
    tourism_tax       double precision,
    art               text COLLATE "C",
    gb_ref            text COLLATE "C",
    vat_rate          double precision NOT NULL DEFAULT 0.10,
    kind              text COLLATE "C" NOT NULL DEFAULT 'stay',
    description       text COLLATE "C",
    rnr               text COLLATE "C",
    payer             text COLLATE "C",
    notes             text COLLATE "C"
);

CREATE TABLE payment (
    id        bigint GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    charge_id bigint NOT NULL REFERENCES charge(id) ON DELETE CASCADE DEFERRABLE,
    paid_date text COLLATE "C" NOT NULL,
    amount    double precision NOT NULL
);

CREATE INDEX idx_charge_invoice ON charge(invoice_id);
CREATE INDEX idx_charge_stay ON charge(stay_id);
CREATE INDEX idx_client_company ON client(company_id);
CREATE INDEX idx_stay_guest ON stay(guest_id);
CREATE INDEX idx_stay_room ON stay(room_id);
-- the company pages count stays and invoices per company in correlated subqueries
CREATE INDEX idx_stay_employer ON stay(employer_client_id);
CREATE INDEX idx_invoice_client ON invoice(client_id);
CREATE INDEX payment_charge ON payment(charge_id);

-- "Has anything changed?" for the page cache and the browser's frozen column widths: every statement that
-- writes a data table counts it up.
CREATE TABLE data_version (
    id      integer PRIMARY KEY DEFAULT 1 CHECK (id = 1),
    version bigint NOT NULL DEFAULT 0
);
INSERT INTO data_version (id, version) VALUES (1, 0);

CREATE FUNCTION bump_data_version() RETURNS trigger LANGUAGE plpgsql AS $$
BEGIN
    EXECUTE format('UPDATE %I.data_version SET version = version + 1', TG_TABLE_SCHEMA);
    RETURN NULL;
END $$;

DO $$
DECLARE t text;
BEGIN
    FOREACH t IN ARRAY ARRAY['unit', 'room', 'company', 'client', 'company_key', 'dismissed_finding', 'guest',
                             'invoice', 'stay', 'charge', 'payment'] LOOP
        EXECUTE format('CREATE TRIGGER %I AFTER INSERT OR UPDATE OR DELETE OR TRUNCATE ON %I '
                       'FOR EACH STATEMENT EXECUTE FUNCTION bump_data_version()', t || '_data_version', t);
    END LOOP;
END $$;