<?php
/**
 * Scoring engine — combines weighted signals into a 0..100 score
 */
class AIT_AIPSEO_Score {

	public function __construct() {
		// Placeholder for parity; used by loader
	}

	public function calculate( array $signals ): array {
		$weight_title = AIT_AIPSEO_Settings::get('weight_title');
		$weight_meta = AIT_AIPSEO_Settings::get('weight_meta');
		$weight_headings = AIT_AIPSEO_Settings::get('weight_headings');
		$weight_readability = AIT_AIPSEO_Settings::get('weight_readability');
		$weight_links = AIT_AIPSEO_Settings::get('weight_links');
		$weight_images = AIT_AIPSEO_Settings::get('weight_images');
		
		$weights  = [
			'title'       => (int) ( $weight_title ?? 25 ),
			'meta'        => (int) ( $weight_meta ?? 20 ),
			'headings'    => (int) ( $weight_headings ?? 20 ),
			'readability' => (int) ( $weight_readability ?? 15 ),
			'links'       => (int) ( $weight_links ?? 10 ),
			'images'      => (int) ( $weight_images ?? 10 ),
		];

		$total_weight = max( 1, array_sum( $weights ) );
		$score = 0;

		foreach ( $weights as $key => $w ) {
			$signal = (float) ( $signals[ $key ] ?? 0 ); // 0..1
			$score += ( $signal * $w );
		}

		$final = max( 0, min( 100, ( $score / $total_weight ) * 100 ) );

		return [
			'score'     => round( $final, 1 ),
			'breakdown' => $this->build_breakdown( $signals, $weights ),
		];
	}

	private function build_breakdown( array $signals, array $weights ): array {
		$out = [];
		foreach ( $weights as $k => $w ) {
			$out[ $k ] = [
				'weight' => $w,
				'value'  => round( 100 * (float) ( $signals[ $k ] ?? 0 ), 1 ),
			];
		}
		return $out;
	}
}