<?php
/**
 * Zone B (Warm) handler for KV table with optional TTL.
 *
 * @package WP_Data_Optimizer
 */

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

/**
 * Zone B (Warm) handler — KV table with optional TTL auto-cleanup.
 *
 * Single table: wpdo_warm
 * Structure: post_id + meta_key + meta_value + expires_at
 *
 * Use for transient-like data that benefits from DB-backed persistence
 * but doesn't need to live forever (e.g. cached computations, temporary flags).
 *
 * Expired entries are cleaned up by the wpdo_warm_cleanup cron (hourly).
 */
class TMDO_Zone_Warm {

	/**
	 * Get the warm table name.
	 */
	public static function table(): string {
		return TMDO_DB::table( 'wpdo_warm' );
	}

	/**
	 * Read a value from the warm zone.
	 *
	 * Returns null if not found or if expired.
	 *
	 * @param int    $post_id  Post ID.
	 * @param string $meta_key Meta key.
	 * @return string|null
	 */
	public static function get( int $post_id, string $meta_key ): ?string {
		global $wpdb;
		$table = self::table();
		$now   = TMDO_DB::now();

		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name from TMDO_Zone_Warm::table() via TMDO_DB::table().
		$val = $wpdb->get_var(
			$wpdb->prepare(
				"SELECT meta_value FROM `{$table}`
				 WHERE post_id = %d AND meta_key = %s
				   AND (expires_at IS NULL OR expires_at > %s)
				 LIMIT 1",
				$post_id,
				$meta_key,
				$now
			)
		);
		// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared

		return $val;
	}

	/**
	 * Read all warm values for a post.
	 *
	 * @param int $post_id Post ID.
	 * @return array<string, string> meta_key => meta_value pairs.
	 */
	public static function get_all( int $post_id ): array {
		global $wpdb;
		$table = self::table();
		$now   = TMDO_DB::now();

		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name from TMDO_Zone_Warm::table() via TMDO_DB::table().
		$rows = $wpdb->get_results(
			$wpdb->prepare(
				"SELECT meta_key, meta_value FROM `{$table}`
				 WHERE post_id = %d AND (expires_at IS NULL OR expires_at > %s)",
				$post_id,
				$now
			),
			ARRAY_A
		);
		// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared

		$result = array();
		foreach ( $rows ?: array() as $row ) {
			$result[ $row['meta_key'] ] = $row['meta_value'];
		}

		return $result;
	}

	/**
	 * Set a value in the warm zone with optional TTL.
	 *
	 * @param int      $post_id  Post ID.
	 * @param string   $meta_key Meta key.
	 * @param string   $value    Value to store.
	 * @param int|null $ttl      TTL in seconds. Null = no expiry.
	 */
	public static function set( int $post_id, string $meta_key, string $value, ?int $ttl = null ): void {
		$table = self::table();
		$now   = TMDO_DB::now();

		$expires_at = ( $ttl && $ttl > 0 ) ? gmdate( 'Y-m-d H:i:s', time() + $ttl ) : null;

		TMDO_DB::upsert(
			$table,
			array(
				'post_id'    => $post_id,
				'meta_key'   => $meta_key,
				'meta_value' => $value,
				'expires_at' => $expires_at,
				'created_at' => $now,
			),
			array( 'meta_value', 'expires_at' ),
			array( 'post_id', 'meta_key' ),
			array( '%d', '%s', '%s', '%s', '%s' )
		);
	}

	/**
	 * Atomically increment an integer counter in the warm zone.
	 *
	 * Uses INSERT ... ON DUPLICATE KEY UPDATE to avoid the read-then-write race
	 * condition present in get()+set() patterns.
	 *
	 * @param int      $post_id  Post ID.
	 * @param string   $meta_key Counter key.
	 * @param int      $by       Amount to increment (default 1).
	 * @param int|null $ttl      TTL in seconds. Null = no expiry.
	 */
	public static function increment( int $post_id, string $meta_key, int $by = 1, ?int $ttl = null ): void {
		global $wpdb;
		$table      = self::table();
		$now        = TMDO_DB::now();
		$expires_at = ( $ttl && $ttl > 0 ) ? gmdate( 'Y-m-d H:i:s', time() + $ttl ) : null;

		// phpcs:disable WordPress.DB.DirectDatabaseQuery,WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table from self::table()
		$wpdb->query(
			$wpdb->prepare(
				"INSERT INTO `{$table}` (post_id, meta_key, meta_value, expires_at, created_at)
				VALUES (%d, %s, %d, %s, %s)
				ON DUPLICATE KEY UPDATE meta_value = CAST(COALESCE(meta_value, 0) AS SIGNED) + %d",
				$post_id,
				$meta_key,
				$by,
				$expires_at,
				$now,
				$by
			)
		);
		// phpcs:enable WordPress.DB.DirectDatabaseQuery,WordPress.DB.PreparedSQL.InterpolatedNotPrepared
	}

	/**
	 * Delete a specific key from the warm zone.
	 *
	 * @param int    $post_id  Post ID.
	 * @param string $meta_key Meta key to delete.
	 * @return void
	 */
	public static function delete( int $post_id, string $meta_key ): void {
		global $wpdb;
		$wpdb->delete(
			self::table(),
			array(
				'post_id'  => $post_id,
				'meta_key' => $meta_key,
			),
			array( '%d', '%s' )
		);
	}

	/**
	 * Delete all warm entries for a post.
	 *
	 * @param int $post_id Post ID.
	 * @return void
	 */
	public static function delete_all( int $post_id ): void {
		global $wpdb;
		$wpdb->delete( self::table(), array( 'post_id' => $post_id ), array( '%d' ) );
	}

	/**
	 * Purge all expired entries (called by cron).
	 *
	 * @return int Number of rows deleted.
	 */
	public static function purge_expired(): int {
		global $wpdb;
		$table = self::table();

		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Table name from TMDO_Zone_Warm::table() via TMDO_DB::table().
		return (int) $wpdb->query(
			$wpdb->prepare(
				"DELETE FROM `{$table}` WHERE expires_at IS NOT NULL AND expires_at < %s",
				TMDO_DB::now()
			)
		);
		// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
	}
}