Files
fuel-price/app/Services/Prediction/Signals/AbstractSignal.php
Ovidiu U 27c82ef103 refactor: extract 6 prediction signals into Signal classes
The 803-line NationalFuelPredictionService had six private compute*Signal
methods, a private linearRegression helper, and a private disabledSignal
shape factory all crammed together. Each signal is now an independently
testable class.

- App\Services\Prediction\Signals\Signal — interface
- App\Services\Prediction\Signals\SignalContext — input value object
  (FuelType + optional lat/lng + hasCoordinates() helper)
- App\Services\Prediction\Signals\AbstractSignal — shared
  disabledSignal() and linearRegression() helpers
- TrendSignal, DayOfWeekSignal, BrandBehaviourSignal, StickinessSignal,
  RegionalMomentumSignal, OilSignal — one class each, extending
  AbstractSignal

NationalFuelPredictionService receives the 6 signal classes via constructor
injection and orchestrates them. The lat/lng null-guard for regional
momentum now lives inside RegionalMomentumSignal::compute() so the
coordinator no longer branches on coordinate presence.

Aggregation, weekly summary, and reasoning helpers stay in the service
for now — they are coupled to the public predict() output shape and are
candidates for a follow-up extraction once a stable API is locked in.

Service: 803 → 414 lines.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-29 19:43:28 +01:00

62 lines
1.6 KiB
PHP

<?php
namespace App\Services\Prediction\Signals;
abstract class AbstractSignal implements Signal
{
/** @return array{score: 0.0, confidence: 0.0, direction: 'stable', detail: string, data_points: 0, enabled: false} */
protected function disabledSignal(string $detail): array
{
return [
'score' => 0.0,
'confidence' => 0.0,
'direction' => 'stable',
'detail' => $detail,
'data_points' => 0,
'enabled' => false,
];
}
/**
* Least-squares linear regression. x = array index, y = value.
*
* @param float[] $values
* @return array{slope: float, r_squared: float}
*/
protected function linearRegression(array $values): array
{
$n = count($values);
if ($n < 2) {
return ['slope' => 0.0, 'r_squared' => 0.0];
}
$xMean = ($n - 1) / 2.0;
$yMean = array_sum($values) / $n;
$numerator = 0.0;
$denominator = 0.0;
foreach ($values as $i => $y) {
$x = $i - $xMean;
$numerator += $x * ($y - $yMean);
$denominator += $x * $x;
}
$slope = $denominator > 0.0 ? $numerator / $denominator : 0.0;
$ssRes = 0.0;
$ssTot = 0.0;
foreach ($values as $i => $y) {
$predicted = $yMean + $slope * ($i - $xMean);
$ssRes += ($y - $predicted) ** 2;
$ssTot += ($y - $yMean) ** 2;
}
$rSquared = $ssTot > 0.0 ? max(0.0, 1.0 - ($ssRes / $ssTot)) : 0.0;
return ['slope' => $slope, 'r_squared' => $rSquared];
}
}