58 lines
1.6 KiB
JavaScript
58 lines
1.6 KiB
JavaScript
'use strict';
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const { accountingActiveSql } = require('./paymentAccountingService');
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const { fromCents } = require('../utils/money');
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/**
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* Computes a suggested expected amount for a bill based on the rolling median
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* of the last 6 months of actual data. Prefers monthly_bill_state.actual_amount
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* (user-corrected values) over raw payment sums.
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*/
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function computeAmountSuggestion(db, billId, year, month) {
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const amounts = [];
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let y = year;
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let m = month;
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for (let i = 0; i < 6; i++) {
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m -= 1;
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if (m === 0) { m = 12; y -= 1; }
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const mbs = db.prepare(
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'SELECT actual_amount FROM monthly_bill_state WHERE bill_id = ? AND year = ? AND month = ?'
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).get(billId, y, m);
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if (mbs?.actual_amount != null) {
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amounts.push(mbs.actual_amount);
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continue;
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}
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const result = db.prepare(`
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SELECT COALESCE(SUM(amount), 0) AS total
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FROM payments
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WHERE bill_id = ?
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AND deleted_at IS NULL
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AND ${accountingActiveSql()}
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AND strftime('%Y', paid_date) = ?
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AND strftime('%m', paid_date) = ?
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`).get(billId, String(y), String(m).padStart(2, '0'));
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if (result.total > 0) amounts.push(result.total);
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}
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if (amounts.length === 0) return null;
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const sorted = [...amounts].sort((a, b) => a - b);
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const mid = Math.floor(sorted.length / 2);
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const median = sorted.length % 2 === 0
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? (sorted[mid - 1] + sorted[mid]) / 2
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: sorted[mid];
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return {
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suggestion: fromCents(Math.round(median)),
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months_used: amounts.length,
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confidence: amounts.length >= 3 ? 'high' : 'low',
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};
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}
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module.exports = { computeAmountSuggestion };
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