<?php
/**
 * Member levels: names given at a number of points.
 *
 * @package SpaceBay
 */

namespace SpaceBay\Gamification;

use SpaceBay\Core\Settings;

defined( 'ABSPATH' ) || exit;

/**
 * Reads, checks and applies the level ladder from the settings.
 */
final class Levels {

	/**
	 * Most levels a community can have.
	 *
	 * @var int
	 */
	const MAX = 12;

	/**
	 * Longest level name.
	 *
	 * @var int
	 */
	const MAX_NAME = 30;

	/**
	 * The ladder new communities start with.
	 *
	 * @return array[] Rows of name and min (points).
	 */
	public static function defaults() {
		return array(
			array(
				'name' => __( 'Newcomer', 'spacebay' ),
				'min'  => 0,
			),
			array(
				'name' => __( 'Member', 'spacebay' ),
				'min'  => 50,
			),
			array(
				'name' => __( 'Regular', 'spacebay' ),
				'min'  => 200,
			),
			array(
				'name' => __( 'Contributor', 'spacebay' ),
				'min'  => 500,
			),
			array(
				'name' => __( 'Veteran', 'spacebay' ),
				'min'  => 1000,
			),
			array(
				'name' => __( 'Legend', 'spacebay' ),
				'min'  => 2500,
			),
		);
	}

	/**
	 * Cleans a ladder from the settings screen.
	 *
	 * Rows without a name are dropped, points are sorted from low to high,
	 * the first level always starts at 0 and two levels never share a number.
	 *
	 * @param array $input Raw rows.
	 * @return array[]|null Clean rows, or null when nothing usable is left.
	 */
	public static function sanitize( array $input ) {
		$rows = array();
		$seen = array();

		foreach ( array_slice( array_values( $input ), 0, self::MAX ) as $row ) {
			if ( ! is_array( $row ) ) {
				continue;
			}

			$name = mb_substr( trim( sanitize_text_field( (string) ( $row['name'] ?? '' ) ) ), 0, self::MAX_NAME );
			$min  = max( 0, min( 10000000, (int) ( $row['min'] ?? 0 ) ) );

			if ( '' === $name || isset( $seen[ $min ] ) ) {
				continue;
			}

			$seen[ $min ] = true;
			$rows[]       = array(
				'name' => $name,
				'min'  => $min,
			);
		}

		if ( ! $rows ) {
			return null;
		}

		usort(
			$rows,
			static function ( $a, $b ) {
				return $a['min'] - $b['min'];
			}
		);

		$rows[0]['min'] = 0;

		return $rows;
	}

	/**
	 * The ladder in use.
	 *
	 * @return array[]
	 */
	public static function all() {
		$levels = Settings::get( 'levels' );
		$levels = is_array( $levels ) ? self::sanitize( $levels ) : null;

		return $levels ? $levels : self::defaults();
	}

	/**
	 * The level reached with a number of points, with progress to the next one.
	 *
	 * @param int $points Points.
	 * @return array{number: int, name: string, min: int, next: array|null, progress: int}
	 */
	public static function for_points( $points ) {
		$points = (int) $points;
		$levels = self::all();
		$index  = 0;

		foreach ( $levels as $i => $level ) {
			if ( $points >= $level['min'] ) {
				$index = $i;
			}
		}

		$current = $levels[ $index ];
		$next    = $levels[ $index + 1 ] ?? null;
		$span    = $next ? max( 1, $next['min'] - $current['min'] ) : 1;

		return array(
			'number'   => $index + 1,
			'name'     => $current['name'],
			'min'      => $current['min'],
			'next'     => $next ? array(
				'name'      => $next['name'],
				'min'       => $next['min'],
				'remaining' => max( 0, $next['min'] - $points ),
			) : null,
			'progress' => $next ? max( 0, min( 100, (int) floor( 100 * ( $points - $current['min'] ) / $span ) ) ) : 100,
		);
	}
}