-- ============================================
-- TEMPLATE-SAAS: User Invitations
-- Schema: users
-- Version: 1.0.0
-- ============================================

CREATE TABLE users.invitations (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    tenant_id UUID NOT NULL REFERENCES tenants.tenants(id) ON DELETE CASCADE,

    -- Invitation details
    email VARCHAR(255) NOT NULL,
    token VARCHAR(255) UNIQUE NOT NULL,

    -- Role assignment
    role_id UUID REFERENCES users.roles(id),

    -- Status
    status users.invitation_status DEFAULT 'pending' NOT NULL,

    -- Expiration
    expires_at TIMESTAMPTZ NOT NULL,

    -- Result
    accepted_at TIMESTAMPTZ,
    accepted_by_user_id UUID REFERENCES users.users(id),

    -- Metadata
    message TEXT,  -- Custom message from inviter
    metadata JSONB DEFAULT '{}'::jsonb,

    -- Audit
    created_at TIMESTAMPTZ DEFAULT NOW() NOT NULL,
    created_by UUID NOT NULL REFERENCES users.users(id),

    -- Constraints
    CONSTRAINT valid_invitation_email CHECK (email ~* '^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$')
);

-- Indexes
CREATE INDEX idx_invitations_tenant ON users.invitations(tenant_id);
CREATE INDEX idx_invitations_email ON users.invitations(tenant_id, email);
CREATE INDEX idx_invitations_token ON users.invitations(token);
CREATE INDEX idx_invitations_status ON users.invitations(tenant_id, status) WHERE status = 'pending';

-- RLS
ALTER TABLE users.invitations ENABLE ROW LEVEL SECURITY;

CREATE POLICY invitations_tenant_isolation ON users.invitations
    USING (tenant_id = current_setting('app.current_tenant_id', true)::UUID);

-- Function to auto-expire invitations
CREATE OR REPLACE FUNCTION users.expire_old_invitations()
RETURNS void AS $$
BEGIN
    UPDATE users.invitations
    SET status = 'expired'
    WHERE status = 'pending'
    AND expires_at < NOW();
END;
$$ LANGUAGE plpgsql;

-- Comments
COMMENT ON TABLE users.invitations IS 'User invitations to join tenant';
COMMENT ON COLUMN users.invitations.token IS 'Secure token for invitation link';