-- Migration 1043: Idempotent accounting follow-up when prepaid cards reach 80% and 100% usage.
-- Existing card balances and transactions are left untouched.

CREATE TABLE IF NOT EXISTS tticket_prepaid_card_alerts (
    id SERIAL PRIMARY KEY,
    -- Keep the audit trail if an old card is later deleted.
    card_id INTEGER NOT NULL,
    alert_type VARCHAR(24) NOT NULL CHECK (alert_type IN ('usage_80_percent', 'usage_100_percent')),
    case_id INTEGER REFERENCES sag_sager(id) ON DELETE SET NULL,
    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    UNIQUE (card_id, alert_type)
);

CREATE INDEX IF NOT EXISTS idx_prepaid_card_alerts_case
    ON tticket_prepaid_card_alerts(case_id) WHERE case_id IS NOT NULL;

CREATE OR REPLACE FUNCTION notify_prepaid_card_usage_threshold()
RETURNS TRIGGER AS $$
DECLARE
    v_alert_id INTEGER;
    v_case_id INTEGER;
    v_group_id INTEGER;
    v_customer_name TEXT;
BEGIN
    IF COALESCE(NEW.purchased_hours, 0) <= 0 THEN
        RETURN NEW;
    END IF;

    IF NEW.used_hours >= NEW.purchased_hours * 0.80 THEN
        INSERT INTO tticket_prepaid_card_alerts (card_id, alert_type)
        VALUES (NEW.id, 'usage_80_percent')
        ON CONFLICT (card_id, alert_type) DO NOTHING
        RETURNING id INTO v_alert_id;

        IF v_alert_id IS NOT NULL THEN
            SELECT id INTO v_group_id
            FROM groups
            WHERE LOWER(TRIM(name)) IN ('bogholderi', 'økonomi', 'okonomi', 'accounting')
            ORDER BY CASE WHEN LOWER(TRIM(name)) = 'bogholderi' THEN 0 ELSE 1 END, id
            LIMIT 1;

            SELECT name INTO v_customer_name FROM customers WHERE id = NEW.customer_id;

            INSERT INTO sag_sager (
                titel, beskrivelse, type, template_key, status, customer_id,
                assigned_group_id, created_by_user_id
            ) VALUES (
                'Klippekort ' || NEW.card_number || ' har nået 80 %',
                format('Klippekort %s for %s har brugt %.2f af %.2f timer (%.1f%%). Vurder om kunden skal tilbydes et nyt klippekort. Der er ikke oprettet en ordre eller et nyt klippekort automatisk.',
                    NEW.card_number, COALESCE(v_customer_name, 'kunden'), NEW.used_hours,
                    NEW.purchased_hours, NEW.used_hours / NEW.purchased_hours * 100),
                'bogholderi', 'bogholderi', 'åben', NEW.customer_id,
                v_group_id, (SELECT user_id FROM users ORDER BY user_id LIMIT 1)
            ) RETURNING id INTO v_case_id;

            UPDATE tticket_prepaid_card_alerts SET case_id = v_case_id WHERE id = v_alert_id;
        END IF;
    END IF;

    IF NEW.used_hours >= NEW.purchased_hours THEN
        SELECT case_id INTO v_case_id
        FROM tticket_prepaid_card_alerts
        WHERE card_id = NEW.id AND alert_type = 'usage_80_percent';

        IF v_case_id IS NULL THEN
            -- Covers cards that were already above 80% when this migration was installed.
            INSERT INTO tticket_prepaid_card_alerts (card_id, alert_type)
            VALUES (NEW.id, 'usage_80_percent')
            ON CONFLICT (card_id, alert_type) DO NOTHING
            RETURNING id INTO v_alert_id;

            IF v_alert_id IS NOT NULL THEN
                SELECT id INTO v_group_id
                FROM groups
                WHERE LOWER(TRIM(name)) IN ('bogholderi', 'økonomi', 'okonomi', 'accounting')
                ORDER BY CASE WHEN LOWER(TRIM(name)) = 'bogholderi' THEN 0 ELSE 1 END, id
                LIMIT 1;
                SELECT name INTO v_customer_name FROM customers WHERE id = NEW.customer_id;
                INSERT INTO sag_sager (
                    titel, beskrivelse, type, template_key, status, customer_id,
                    assigned_group_id, created_by_user_id
                ) VALUES (
                    'Klippekort ' || NEW.card_number || ' har nået 80 %',
                    format('Klippekort %s for %s har nået fuldt forbrug. Vurder eventuelt nyt klippekort.',
                        NEW.card_number, COALESCE(v_customer_name, 'kunden')),
                    'bogholderi', 'bogholderi', 'åben', NEW.customer_id, v_group_id,
                    (SELECT user_id FROM users ORDER BY user_id LIMIT 1)
                ) RETURNING id INTO v_case_id;
                UPDATE tticket_prepaid_card_alerts SET case_id = v_case_id WHERE id = v_alert_id;
            END IF;
        END IF;

        INSERT INTO tticket_prepaid_card_alerts (card_id, alert_type, case_id)
        VALUES (NEW.id, 'usage_100_percent', v_case_id)
        ON CONFLICT (card_id, alert_type) DO NOTHING
        RETURNING id INTO v_alert_id;

        IF v_alert_id IS NOT NULL AND v_case_id IS NOT NULL THEN
            INSERT INTO sag_kommentarer (sag_id, forfatter, indhold, er_system_besked)
            VALUES (v_case_id, 'System',
                format('Klippekort %s er nu fuldt brugt og er lukket for nyt forbrug.', NEW.card_number), TRUE);
        END IF;

        UPDATE tticket_prepaid_cards SET status = 'depleted', updated_at = CURRENT_TIMESTAMP
        WHERE id = NEW.id AND status = 'active';
    END IF;

    RETURN NEW;
END;
$$ LANGUAGE plpgsql;

DROP TRIGGER IF EXISTS trg_prepaid_card_usage_thresholds ON tticket_prepaid_cards;
CREATE TRIGGER trg_prepaid_card_usage_thresholds
AFTER UPDATE OF used_hours ON tticket_prepaid_cards
FOR EACH ROW
WHEN (NEW.used_hours IS DISTINCT FROM OLD.used_hours)
EXECUTE FUNCTION notify_prepaid_card_usage_threshold();

COMMENT ON TABLE tticket_prepaid_card_alerts IS
    'One-time bookkeeping follow-up case references for prepaid card usage thresholds.';