<?php
/**
 * Performance Score - calculates a 0-100 performance score.
 *
 * @package Asmith_Speed_Optimizer
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

class Asmith_SO_Performance_Score {

	private static $instance = null;

	public static function instance() {
		if ( null === self::$instance ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	private function __construct() {
		add_action( 'wp_ajax_asmith_so_run_scan', array( $this, 'ajax_run_scan' ) );
		add_action( 'asmith_so_weekly_scan', array( $this, 'calculate_score' ) );
	}

	/**
	 * AJAX: Run a performance scan.
	 */
	public function ajax_run_scan() {
		check_ajax_referer( 'asmith_so_nonce', 'nonce' );

		if ( ! current_user_can( 'manage_options' ) ) {
			wp_send_json_error( __( 'Unauthorized.', 'a-smith-speed-optimizer' ) );
		}

		$results = $this->calculate_score();
		wp_send_json_success( $results );
	}

	/**
	 * Calculate the performance score.
	 *
	 * @return array
	 */
	public function calculate_score() {
		$score = 0;
		$max_score = 100;
		$details = array();

		// Optimization toggles points (up to 40 points).
		$optimizations = array(
			'asmith_so_lazy_load'   => 8,
			'asmith_so_minify_html' => 7,
			'asmith_so_defer_js'    => 7,
		);

		$active_optimizations = 0;
		foreach ( $optimizations as $option => $points ) {
			if ( get_option( $option, false ) ) {
				$score += $points;
				$active_optimizations++;
			}
		}
		$details['active_optimizations'] = $active_optimizations;
		$details['total_optimizations']  = count( $optimizations );

		// Bloat removal points (up to 30 points, 3 per item).
		$bloat_items = array(
			'asmith_so_remove_emoji',
			'asmith_so_remove_embeds',
			'asmith_so_remove_query_strings',
			'asmith_so_remove_dashicons',
			'asmith_so_remove_xmlrpc',
			'asmith_so_remove_rest_links',
			'asmith_so_remove_shortlinks',
			'asmith_so_remove_wlw',
			'asmith_so_remove_rsd',
			'asmith_so_remove_rss',
		);

		$active_bloat_removals = 0;
		foreach ( $bloat_items as $item ) {
			if ( get_option( $item, false ) ) {
				$score += 3;
				$active_bloat_removals++;
			}
		}
		$details['bloat_items_removed'] = $active_bloat_removals;
		$details['total_bloat_items']   = count( $bloat_items );

		// Asset count scoring (up to 20 points).
		$asset_counts = get_transient( 'asmith_so_asset_counts' );
		$scripts_count = isset( $asset_counts['scripts'] ) ? (int) $asset_counts['scripts'] : 0;
		$styles_count  = isset( $asset_counts['styles'] ) ? (int) $asset_counts['styles'] : 0;

		// Fewer assets = higher score.
		if ( $scripts_count <= 10 ) {
			$score += 10;
		} elseif ( $scripts_count <= 20 ) {
			$score += 7;
		} elseif ( $scripts_count <= 30 ) {
			$score += 4;
		} else {
			$score += 1;
		}

		if ( $styles_count <= 5 ) {
			$score += 10;
		} elseif ( $styles_count <= 10 ) {
			$score += 7;
		} elseif ( $styles_count <= 20 ) {
			$score += 4;
		} else {
			$score += 1;
		}

		$details['scripts_count'] = $scripts_count;
		$details['styles_count']  = $styles_count;

		// Cap score at max.
		$score = min( $score, $max_score );

		// Calculate grade.
		$grade = $this->score_to_grade( $score );

		// Build recommendations.
		$recommendations = $this->build_recommendations( $details );

		$results = array(
			'score'            => $score,
			'grade'            => $grade,
			'details'          => $details,
			'recommendations'  => $recommendations,
			'timestamp'        => time(),
		);

		// Store results.
		set_transient( 'asmith_so_score', $results, DAY_IN_SECONDS );
		update_option( 'asmith_so_last_scan', time() );

		/**
		 * Fires after the performance score is calculated.
		 *
		 * @param array $results The score results.
		 */
		do_action( 'asmith_so_after_score_calculation', $results );

		return $results;
	}

	/**
	 * Get the cached score results.
	 *
	 * @return array|false
	 */
	public function get_score() {
		return get_transient( 'asmith_so_score' );
	}

	/**
	 * Convert a numeric score to a letter grade.
	 *
	 * @param int $score The numeric score.
	 * @return string
	 */
	private function score_to_grade( $score ) {
		if ( $score >= 90 ) {
			return 'A';
		} elseif ( $score >= 80 ) {
			return 'B';
		} elseif ( $score >= 60 ) {
			return 'C';
		} elseif ( $score >= 40 ) {
			return 'D';
		}
		return 'F';
	}

	/**
	 * Build recommendations based on current optimization state.
	 *
	 * @param array $details Score details.
	 * @return array
	 */
	private function build_recommendations( $details ) {
		$recommendations = array();

		if ( ! get_option( 'asmith_so_lazy_load', false ) ) {
			$recommendations[] = array(
				'title'    => __( 'Enable Lazy Loading', 'a-smith-speed-optimizer' ),
				'message'  => __( 'Lazy loading defers offscreen images and iframes, reducing initial page weight.', 'a-smith-speed-optimizer' ),
				'priority' => 'high',
			);
		}

		if ( ! get_option( 'asmith_so_defer_js', false ) ) {
			$recommendations[] = array(
				'title'    => __( 'Enable JS Deferral', 'a-smith-speed-optimizer' ),
				'message'  => __( 'Deferring JavaScript prevents render-blocking and improves time to first paint.', 'a-smith-speed-optimizer' ),
				'priority' => 'high',
			);
		}

		if ( ! get_option( 'asmith_so_minify_html', false ) ) {
			$recommendations[] = array(
				'title'    => __( 'Enable HTML Minification', 'a-smith-speed-optimizer' ),
				'message'  => __( 'Minifying HTML removes unnecessary whitespace and comments, reducing page size.', 'a-smith-speed-optimizer' ),
				'priority' => 'medium',
			);
		}

		if ( ! get_option( 'asmith_so_remove_emoji', false ) ) {
			$recommendations[] = array(
				'title'    => __( 'Remove Emoji Scripts', 'a-smith-speed-optimizer' ),
				'message'  => __( 'WordPress emoji scripts add an extra HTTP request on every page load.', 'a-smith-speed-optimizer' ),
				'priority' => 'medium',
			);
		}

		if ( $details['scripts_count'] > 20 ) {
			$recommendations[] = array(
				'title'    => __( 'Too Many Scripts', 'a-smith-speed-optimizer' ),
				/* translators: %d: number of scripts loaded */
				'message'  => sprintf( __( 'Your site loads %d scripts. Consider deactivating unnecessary plugins.', 'a-smith-speed-optimizer' ), $details['scripts_count'] ),
				'priority' => 'high',
			);
		}

		if ( $details['styles_count'] > 15 ) {
			$recommendations[] = array(
				'title'    => __( 'Too Many Stylesheets', 'a-smith-speed-optimizer' ),
				/* translators: %d: number of stylesheets loaded */
				'message'  => sprintf( __( 'Your site loads %d stylesheets. Consider consolidating or removing unused CSS.', 'a-smith-speed-optimizer' ), $details['styles_count'] ),
				'priority' => 'medium',
			);
		}

		return $recommendations;
	}
}