CREATE TABLE IF NOT EXISTS cluster_node_groups (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    cluster_id UUID NOT NULL REFERENCES clusters(id) ON DELETE CASCADE,
    parent_group_id UUID REFERENCES cluster_node_groups(id) ON DELETE SET NULL,
    name TEXT NOT NULL,
    description TEXT,
    sort_order INTEGER NOT NULL DEFAULT 0,
    metadata JSONB NOT NULL DEFAULT '{}'::JSONB,
    created_by_user_id UUID REFERENCES users(id) ON DELETE SET NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    CONSTRAINT cluster_node_groups_name_check CHECK (length(trim(name)) > 0),
    CONSTRAINT cluster_node_groups_not_self_parent CHECK (parent_group_id IS NULL OR parent_group_id <> id),
    UNIQUE (cluster_id, id)
);

CREATE UNIQUE INDEX IF NOT EXISTS idx_cluster_node_groups_unique_sibling_name
    ON cluster_node_groups(cluster_id, COALESCE(parent_group_id, '00000000-0000-0000-0000-000000000000'::uuid), lower(name));

CREATE INDEX IF NOT EXISTS idx_cluster_node_groups_parent
    ON cluster_node_groups(cluster_id, parent_group_id, sort_order, name);

CREATE TABLE IF NOT EXISTS cluster_node_group_memberships (
    cluster_id UUID NOT NULL,
    node_id UUID NOT NULL,
    group_id UUID NOT NULL,
    assigned_by_user_id UUID REFERENCES users(id) ON DELETE SET NULL,
    assigned_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    metadata JSONB NOT NULL DEFAULT '{}'::JSONB,
    PRIMARY KEY (cluster_id, node_id),
    FOREIGN KEY (cluster_id, node_id)
        REFERENCES cluster_memberships(cluster_id, node_id)
        ON DELETE CASCADE,
    FOREIGN KEY (cluster_id, group_id)
        REFERENCES cluster_node_groups(cluster_id, id)
        ON DELETE CASCADE
);

CREATE INDEX IF NOT EXISTS idx_cluster_node_group_memberships_group
    ON cluster_node_group_memberships(cluster_id, group_id);