<?php
/**
 * The summary cards — extracted from Saddle_Analytics_Report in Phase 17b so each
 * read-path file has one job. Callers keep using Saddle_Analytics_Report::summary(),
 * which delegates here — zero wiring changed.
 */

defined( 'ABSPATH' ) || exit;

final class Saddle_Analytics_Summary {

	public function __construct( private wpdb $db ) {}

	/**
	 * The summary cards: visitors, visits, pageviews, bounce rate, duration,
	 * online-now.
	 *
	 * With $compare, two extra keys are ADDED — 'previous' (the same shape over
	 * the preceding window of equal length) and 'delta' (fractional change per
	 * KPI, null where there is no previous value to divide by). Callers that
	 * ignore them see exactly the payload they saw before.
	 *
	 * $filters narrow every card to the visitors they match, as the breakdowns
	 * do (stored values, keyed by dimension; Saddle_Analytics_Dimensions).
	 */
	public function summary( string $range, ?string $from = null, ?string $to = null, bool $compare = false, array $filters = array() ): array {
		$window = Saddle_Analytics_Window::resolve( $range, $from, $to, time() );
		$cards  = $this->cards( $window, $filters );

		if ( ! $compare ) {
			return $cards;
		}

		$previous = Saddle_Analytics_Window::previous( $window );
		if ( null === $previous ) {
			// Lifetime has nothing before it; say so rather than inventing zeroes.
			return $cards + array( 'previous' => null, 'delta' => null );
		}

		$before = $this->cards( $previous, $filters );
		$delta  = array();
		foreach ( array( 'visitors', 'visits', 'pageviews', 'bounce_rate', 'duration' ) as $key ) {
			$delta[ $key ] = Saddle_Analytics_Window::delta( $cards[ $key ], $before[ $key ] );
		}

		return $cards + array(
			'previous' => $before,
			'delta'    => $delta,
		);
	}

	/** Prepared when there is anything to bind, so prepare() never sees a bare string. */
	private function bind( string $sql, array $params ): string {
		return $params ? $this->db->prepare( $sql, ...$params ) : $sql; // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
	}

	/** One window's cards. The whole of summary() before compare existed. */
	private function cards( array $window, array $filters = array() ): array {
		$t = Saddle_Analytics_Install::tables();

		list( $ts_bounds, $ts_params )   = Saddle_Analytics_Window::bounds( $window, 'ts' );
		list( $vis_bounds, $vis_params ) = Saddle_Analytics_Window::bounds( $window, 'last_seen' );
		list( $filter_sql, $filter_params ) = Saddle_Analytics_Dimensions::filter_clause( $filters );
		list( $scope_sql, $scope_params )   = Saddle_Analytics_Dimensions::visitor_scope( $filters );

		$vis_where  = $this->bind( 'WHERE 1=1' . $vis_bounds . $filter_sql, array_merge( $vis_params, $filter_params ) );
		$hits_where = $this->bind( 'WHERE event_type = 1' . $ts_bounds . $scope_sql, array_merge( $ts_params, $scope_params ) );

		$visitors = (int) $this->db->get_var( "SELECT COUNT(*) FROM {$t['visitors']} {$vis_where}" ); // phpcs:ignore WordPress.DB.PreparedSQL
		$online   = (int) $this->db->get_var(
			$this->db->prepare( "SELECT COUNT(*) FROM {$t['visitors']} WHERE last_seen >= %s{$filter_sql}", gmdate( 'Y-m-d H:i:s', time() - 5 * MINUTE_IN_SECONDS ), ...$filter_params ) // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		);

		// Session rollup: a visit bounces when it has one pageview; duration is last hit minus
		// first hit, so it holds even when the late duration beacon never arrived.
		// UNIX_TIMESTAMP + CASE (not TIMESTAMPDIFF / boolean SUM) so the SQLite driver
		// used by Studio/Playground can run it too. The range='all' scan is bounded in
		// practice by the daily 90-day prune of the hits table.
		$sessions = (array) $this->db->get_row(
			"SELECT COUNT(*) AS visits, COALESCE(SUM(pv),0) AS pageviews,
				COALESCE(SUM(CASE WHEN pv = 1 THEN 1 ELSE 0 END),0) AS bounces,
				COALESCE(ROUND(AVG(dur)),0) AS duration
				FROM (SELECT session_id, COUNT(*) AS pv,
					UNIX_TIMESTAMP(MAX(ts)) - UNIX_TIMESTAMP(MIN(ts)) AS dur
					FROM {$t['hits']} {$hits_where} GROUP BY session_id) s", // phpcs:ignore WordPress.DB.PreparedSQL
			ARRAY_A
		);
		$visits   = (int) ( $sessions['visits'] ?? 0 );

		return array(
			'visitors'    => $visitors,
			'visits'      => $visits,
			'pageviews'   => (int) ( $sessions['pageviews'] ?? 0 ),
			'bounce_rate' => $visits > 0 ? round( (int) $sessions['bounces'] / $visits, 4 ) : 0.0,
			'duration'    => (int) ( $sessions['duration'] ?? 0 ),
			'online'      => $online,
		);
	}
}