CREATE TABLE transport_type (
    id BIGSERIAL PRIMARY KEY,
    name TEXT NOT NULL UNIQUE
);

CREATE TABLE transport (
    id BIGSERIAL PRIMARY KEY,
    model TEXT NOT NULL,
    capacity INTEGER NOT NULL CHECK (capacity > 0),
    type_id BIGINT NOT NULL REFERENCES transport_type(id) ON DELETE CASCADE
);

CREATE TABLE route (
    id BIGSERIAL PRIMARY KEY,
    name TEXT NOT NULL UNIQUE,
    price NUMERIC(10,2) NOT NULL CHECK (price >= 0)
);

CREATE TABLE client (
    id BIGSERIAL PRIMARY KEY,
    name TEXT NOT NULL,
    is_regular BOOLEAN DEFAULT FALSE
);

CREATE TABLE cargo (
    id BIGSERIAL PRIMARY KEY,
    description TEXT NOT NULL,
    weight NUMERIC(10,2) NOT NULL CHECK (weight > 0)
);

CREATE TABLE shipment (
    id BIGSERIAL PRIMARY KEY,
    route_id BIGINT NOT NULL REFERENCES route(id) ON DELETE CASCADE,
    transport_id BIGINT NOT NULL REFERENCES transport(id) ON DELETE CASCADE,
    cargo_id BIGINT NOT NULL REFERENCES cargo(id) ON DELETE CASCADE,
    client_id BIGINT NOT NULL REFERENCES client(id) ON DELETE CASCADE,
    cost NUMERIC(10,2) NOT NULL CHECK (cost >= 0)
);

-- Индексы для оптимизации
CREATE INDEX idx_shipment_route ON shipment(route_id);
CREATE INDEX idx_shipment_transport ON shipment(transport_id);
CREATE INDEX idx_shipment_client ON shipment(client_id);