bp_activity_thumbnail_content_images( string $content, string|bool $link = false, array|bool $args = false )

function bp_activity_thumbnail_content_images( $content, $link = false, $args = false ) {

	preg_match_all( '/<img[^>]*>/Ui', $content, $matches );

	// Remove <img> tags. Also remove caption shortcodes and caption text if present.
	$content = preg_replace('|(\[caption(.*?)\])?<img[^>]*>([^\[\[]*\[\/caption\])?|', '', $content );

	if ( !empty( $matches ) && !empty( $matches[0] ) ) {

		// Get the SRC value.
		preg_match( '/<img.*?(src\=[\'|"]{0,1}.*?[\'|"]{0,1})[\s|>]{1}/i',    $matches[0][0], $src    );

		// Get the width and height.
		preg_match( '/<img.*?(height\=[\'|"]{0,1}.*?[\'|"]{0,1})[\s|>]{1}/i', $matches[0][0], $height );
		preg_match( '/<img.*?(width\=[\'|"]{0,1}.*?[\'|"]{0,1})[\s|>]{1}/i',  $matches[0][0], $width  );

		if ( ! empty( $src ) ) {
			$src = substr( substr( str_replace( 'src=', '', $src[1] ), 0, -1 ), 1 );

			if ( isset( $width[1] ) ) {
				$width = substr( substr( str_replace( 'width=', '', $width[1] ), 0, -1 ), 1 );
			}

			if ( isset( $height[1] ) ) {
				$height = substr( substr( str_replace( 'height=', '', $height[1] ), 0, -1 ), 1 );
			}

			if ( empty( $width ) || empty( $height ) ) {
				$width  = 100;
				$height = 100;
			}

			$ratio      = (int) $width / (int) $height;
			$new_height = (int) $height >= 100 ? 100 : $height;
			$new_width  = $new_height * $ratio;
			$image      = '<img src="' . esc_url( $src ) . '" width="' . absint( $new_width ) . '" height="' . absint( $new_height ) . '" alt="' . __( 'Thumbnail', 'buddyboss' ) . '" class="align-left thumbnail" />';

			if ( !empty( $link ) ) {
				$image = '<a href="' . esc_url( $link ) . '">' . $image . '</a>';
			}

			$content = $image . $content;
		}
	}

	/**
	 * Filters the activity content that had a thumbnail replace images.
	 *
	 * @since BuddyPress 1.2.0
	 *
	 * @param string $content Activity content that had images replaced in.
	 * @param array  $matches Array of all image tags found in the posted content.
	 * @param array  $args    Arguments passed into function creating the activity update.
	 */
	return apply_filters( 'bp_activity_thumbnail_content_images', $content, $matches, $args );
}