@php
    use Modules\BookKeeping\Models\ExpenseLine;
@endphp

<script>
    window.ExpenseFieldNames = {
        lineNet:   @js(ExpenseLine::AMOUNT_NET),
        lineVat:   @js(ExpenseLine::VAT_AMOUNT),
        lineGross: @js(ExpenseLine::AMOUNT_GROSS),
    };

    class ExpenseCalculator {

        static get f() {
            return window.ExpenseFieldNames;
        }

        /**
         * Recalculate the current line's gross (net + vat).
         * Runs instantly in the browser on every keystroke — no server roundtrip.
         *
         * Header totals are handled server-side via afterStateUpdated + skipRenderAfterStateUpdated
         * because JS $get/$set cannot traverse parent paths (../../) outside the repeater item scope.
         *
         * Usage: ->afterStateUpdatedJs('window.ExpenseCalculator.recalculateLineGross($get, $set)')
         */
        static recalculateLineGross($get, $set) {
            const f = this.f;

            const lineNet   = this.num($get(f.lineNet));
            const lineVat   = this.num($get(f.lineVat));
            const lineGross = this.r2(lineNet + lineVat);

            $set(f.lineGross, lineGross);
        }

        static recalculateHeaderTotals($get, $set) {
            const rawLines = $get('../../expenseLines') ?? [];
            var lines = Object.values(rawLines ?? {});

            // console.log('Recalculating header totals...', { lines });
            lines = Object.values(lines).map(line => ({
                net: line['amount_net'],
                vat: line['vat_amount'],
                gross: line['amount_gross'],
            }));

            let totalNet = 0;
            let totalVat = 0;
            let totalGross = 0;

            for (const line of lines) {
                totalNet += parseFloat(line.net ?? 0);
                totalVat += parseFloat(line.vat ?? 0);
                totalGross += parseFloat(line.gross ?? 0);
            }

            const paid = parseFloat($get('../../paid') ?? 0);
            const balance = this.r2(totalGross - paid);

            $set('../../amount_net', this.r2(totalNet));
            $set('../../vat_amount', this.r2(totalVat));
            $set('../../amount_gross', this.r2(totalGross));
            $set('../../balance', balance);
        
        }

        // ---------- helpers ----------

        static r2(n) {
            return Math.round((Number(n) + Number.EPSILON) * 100) / 100;
        }

        static num(v) {
            const n = parseFloat(v);
            return Number.isFinite(n) ? n : 0;
        }
    }

    window.ExpenseCalculator = ExpenseCalculator;
</script>