-- Unified Schedule & Cadence Layer (ADP v0.1)

CREATE TABLE schedules (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    tenant_id UUID NOT NULL REFERENCES tenants(id) ON DELETE CASCADE,
    schedule_kind VARCHAR(16) NOT NULL DEFAULT 'interval'
        CHECK (schedule_kind IN ('interval', 'weekdays')),
    interval_days INT NULL CHECK (interval_days IS NULL OR interval_days > 0),
    weekday_mask INT NOT NULL DEFAULT 0,
    pause_until DATE NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

CREATE INDEX idx_schedules_tenant ON schedules(tenant_id);

ALTER TABLE recurring_elements
    ADD COLUMN IF NOT EXISTS schedule_id UUID NULL
        REFERENCES schedules(id) ON DELETE SET NULL;

ALTER TABLE recurring_elements
    ADD COLUMN IF NOT EXISTS action_id UUID NULL
        REFERENCES actions(id) ON DELETE CASCADE;

CREATE UNIQUE INDEX idx_recurring_elements_action
    ON recurring_elements(action_id)
    WHERE action_id IS NOT NULL;

ALTER TABLE actions
    ADD COLUMN IF NOT EXISTS schedule_id UUID NULL
        REFERENCES schedules(id) ON DELETE SET NULL;

-- Backfill: one schedule per recurring without schedule_id
DO $$
DECLARE
    r RECORD;
    sid UUID;
    idays INT;
BEGIN
    FOR r IN
        SELECT id, tenant_id, interval_days
        FROM recurring_elements
        WHERE schedule_id IS NULL
    LOOP
        idays := GREATEST(COALESCE(r.interval_days, 1), 1);
        INSERT INTO schedules (tenant_id, schedule_kind, interval_days, weekday_mask)
        VALUES (r.tenant_id, 'interval', idays, 0)
        RETURNING id INTO sid;
        UPDATE recurring_elements SET schedule_id = sid WHERE id = r.id;
    END LOOP;
END $$;