-- 0004_licence.sql: customer licences (PD-20) and plan prices (PD-19), in schema `licence`.
-- DRAFT, not applied. Applied after 0003 by a loader acting as fuel_owner (README in this folder).
-- fuel_ro has no access: its default privileges cover `public` only. The server gets its own role
-- when it starts checking licences. No customer's licence is seeded here; our admins write those.
BEGIN;
CREATE SCHEMA licence AUTHORIZATION fuel_owner;
SET LOCAL search_path = licence, fm, pg_catalog, public;   -- fm holds btree_gist

CREATE TABLE licence.plan (
  plan_code         text PRIMARY KEY,
  name              text NOT NULL
);
CREATE TABLE licence.plan_price (                -- per sensor per month (PD-19); a change is a new dated row
  plan_code         text NOT NULL REFERENCES licence.plan,
  payment_term      text NOT NULL CHECK (payment_term IN ('annual','monthly')),
  currency          text NOT NULL CHECK (currency ~ '^[A-Z]{3}$'),
  price             numeric(8,2) NOT NULL CHECK (price >= 0),
  valid_from        date NOT NULL, valid_to date,  -- NULL to = still valid
  EXCLUDE USING gist (plan_code WITH =, payment_term WITH =, currency WITH =,
          daterange(valid_from, valid_to, '[)') WITH &&)
);
CREATE TABLE licence.plan_entitlement (
  plan_code         text NOT NULL REFERENCES licence.plan,
  feature           text NOT NULL,
  limit_value       integer,                       -- NULL: no limit
  PRIMARY KEY (plan_code, feature)
);
CREATE TABLE licence.licence (                   -- a renewal is a new row
  licence_id        bigint GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
  operator_uid      text NOT NULL REFERENCES fm.operator,
  plan_code         text NOT NULL REFERENCES licence.plan,
  payment_term      text NOT NULL CHECK (payment_term IN ('annual','monthly')),
  valid_from        date NOT NULL,
  valid_until       date NOT NULL,                 -- last valid day
  grace_until       date NOT NULL,                 -- last day of grace; alarms stop after it
  status            text NOT NULL CHECK (status IN ('active','suspended')),
  contract_ref      text NOT NULL,                 -- the signed agreement or amendment the dates come from
  created_by        text NOT NULL,                 -- a role, never a person's name
  created_at        timestamptz NOT NULL DEFAULT now(),
  CHECK (valid_until >= valid_from),
  CHECK (grace_until >= valid_until),
  EXCLUDE USING gist (operator_uid WITH =, daterange(valid_from, valid_until, '[]') WITH &&)
);
CREATE TABLE licence.licence_override (
  licence_id        bigint NOT NULL REFERENCES licence.licence,
  feature           text NOT NULL,
  limit_value       integer,                       -- NULL: no limit
  PRIMARY KEY (licence_id, feature)
);

-- Prices decided on 30 Oct 2026 (PD-19). The pilot plan costs nothing on either term.
INSERT INTO licence.plan (plan_code, name) VALUES ('pilot', 'Pilot'), ('standard', 'Standard');
INSERT INTO licence.plan_price (plan_code, payment_term, currency, price, valid_from) VALUES
  ('pilot',    'annual',  'USD',  0.00, '2026-01-01'),
  ('pilot',    'monthly', 'USD',  0.00, '2026-01-01'),
  ('standard', 'annual',  'USD', 15.00, '2026-10-30'),
  ('standard', 'monthly', 'USD', 17.00, '2026-10-30');

-- Every change is logged (PD-20), and the log is never changed.
CREATE TABLE licence.licence_event (
  event_id          bigint GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
  table_name        text NOT NULL,
  action            text NOT NULL CHECK (action IN ('INSERT','UPDATE','DELETE')),
  old_row           jsonb, new_row jsonb,
  changed_by        text NOT NULL DEFAULT current_user,
  changed_at        timestamptz NOT NULL DEFAULT now()
);
CREATE FUNCTION licence.tg_log_change() RETURNS trigger LANGUAGE plpgsql AS $$
BEGIN
  INSERT INTO licence.licence_event (table_name, action, old_row, new_row)
  VALUES (TG_TABLE_NAME, TG_OP,
          CASE WHEN TG_OP <> 'INSERT' THEN to_jsonb(OLD) END,
          CASE WHEN TG_OP <> 'DELETE' THEN to_jsonb(NEW) END);
  RETURN NULL;
END $$;
DO $$
DECLARE t text;
BEGIN
  FOREACH t IN ARRAY ARRAY['plan','plan_price','plan_entitlement','licence','licence_override'] LOOP
    EXECUTE format('CREATE TRIGGER log_change AFTER INSERT OR UPDATE OR DELETE ON licence.%I
                    FOR EACH ROW EXECUTE FUNCTION licence.tg_log_change()', t);
  END LOOP;
END $$;
CREATE FUNCTION licence.tg_event_immutable() RETURNS trigger LANGUAGE plpgsql AS $$
BEGIN
  RAISE EXCEPTION 'licence_event: the log is never changed';
END $$;
CREATE TRIGGER event_immutable BEFORE UPDATE OR DELETE ON licence.licence_event
  FOR EACH ROW EXECUTE FUNCTION licence.tg_event_immutable();

COMMIT;