<?php
/**
 * The write path: INSERT hit + UPSERT visitor. No SELECTs, ever (rule 2).
 *
 * Attribution rules live in the SQL, not in PHP:
 * - first_* columns are absent from the ON DUPLICATE KEY UPDATE clause (rule 6).
 * - last_* assignments are wrapped in CASE WHEN new-session-with-attribution.
 *
 * CASE, never MySQL's IF(): the SQLite drop-in maps IF() onto a PHP function that
 * compares its condition with `true === $expression`, and PDO hands UDF arguments
 * over as ints — so IF() silently returned its ELSE branch on every row instead of
 * erroring, freezing `sessions` and killing last-touch attribution on SQLite for
 * fifteen phases. CASE is evaluated by the engine itself on both. See Phase 16.
 */

defined( 'ABSPATH' ) || exit;

final class Saddle_Analytics_Save {

	public function __construct( private wpdb $db ) {}

	public function hit( Saddle_Analytics_Hit $h ): void {
		$t = Saddle_Analytics_Install::tables();

		$this->db->insert(
			$t['hits'],
			array(
				'visitor_id' => $h->visitor_id,
				'session_id' => $h->session_id,
				'ts'         => $h->ts,
				'event_type' => $h->event_type,
				'path'       => $h->path,
				'is_entry'   => $h->is_entry ? 1 : 0,
				'duration'   => $h->duration,
				'target'     => $h->target,
			)
		);

		if ( Saddle_Analytics_Event::PAGEVIEW === $h->event_type ) {
			$this->upsert_visitor( $h );
		} else {
			$this->db->query(
				$this->db->prepare(
					"UPDATE {$t['visitors']} SET last_seen = %s WHERE visitor_id = %s", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
					$h->ts,
					$h->visitor_id
				)
			);
		}
	}

	private function upsert_visitor( Saddle_Analytics_Hit $h ): void {
		$t = Saddle_Analytics_Install::tables();
		// Direct return visits touch last_seen only; last_* survives (spec: visitor update rules).
		$new_session     = $h->is_new_session ? 1 : 0;
		$session_with_ref = ( $h->is_new_session && Saddle_Analytics_Channel::DIRECT !== $h->channel ) ? 1 : 0;

		$this->db->query(
			$this->db->prepare(
				"INSERT INTO {$t['visitors']}
				(visitor_id, first_seen, last_seen,
				 first_channel, first_referrer, first_source, first_medium, first_campaign, first_landing,
				 last_channel, last_referrer, last_campaign,
				 country, browser, os, device, pageviews, sessions)
				VALUES (%s, %s, %s,
				 %d, NULLIF(%s,''), NULLIF(%s,''), NULLIF(%s,''), NULLIF(%s,''), NULLIF(%s,''),
				 %d, NULLIF(%s,''), NULLIF(%s,''),
				 NULLIF(%s,''), NULLIF(%s,''), NULLIF(%s,''), NULLIF(%d,0), 1, 1)
				ON DUPLICATE KEY UPDATE
				 last_seen     = VALUES(last_seen),
				 pageviews     = pageviews + 1,
				 sessions      = sessions + CASE WHEN %d = 1 THEN 1 ELSE 0 END,
				 last_channel  = CASE WHEN %d = 1 THEN VALUES(last_channel)  ELSE last_channel  END,
				 last_referrer = CASE WHEN %d = 1 THEN VALUES(last_referrer) ELSE last_referrer END,
				 last_campaign = CASE WHEN %d = 1 THEN VALUES(last_campaign) ELSE last_campaign END", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
				$h->visitor_id,
				$h->ts,
				$h->ts,
				$h->channel,
				(string) $h->referrer_host,
				(string) $h->source,
				(string) $h->medium,
				(string) $h->campaign,
				(string) $h->landing,
				$h->channel,
				(string) $h->referrer_host,
				(string) $h->campaign,
				(string) $h->country,
				(string) $h->browser,
				(string) $h->os,
				(int) $h->device,
				$new_session,
				$session_with_ref,
				$session_with_ref,
				$session_with_ref
			)
		);
	}

	/** Late duration beacon: stamp the latest pageview of the session. Still no SELECT. */
	public function duration( string $visitor_id, string $session_id, int $seconds ): void {
		$t = Saddle_Analytics_Install::tables();
		$this->db->query(
			$this->db->prepare(
				"UPDATE {$t['hits']} SET duration = %d
				 WHERE visitor_id = %s AND session_id = %s AND event_type = %d
				 ORDER BY id DESC LIMIT 1", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
				min( 32767, max( 0, $seconds ) ),
				$visitor_id,
				$session_id,
				Saddle_Analytics_Event::PAGEVIEW
			)
		);
	}
}