<?php

namespace App\Services;

use App\Models\AuditionedEnsemble;
use Carbon\Carbon;

readonly class AuditionEtudeService
{
    protected int $startYear;

    protected int $changeoverMonth;

    public function __construct()
    {
        $this->startYear = config('siteData.etude_start_year');
        $this->changeoverMonth = config('siteData.etude_changeover_month');
    }

    /**
     * Get the audition year for a given date.
     *
     * The audition year follows a cycle based on the configured changeover month.
     * Before the changeover month, returns the current calendar year.
     * On or after the changeover month, returns the next calendar year.
     *
     * @param  string|null  $date  Optional date string in 'YYYY-MM-DD' format. Defaults to the current date.
     * @return int The audition year
     *
     * @example
     * getCurrentAuditionYear('2024-01-15') // Returns 2024 (if changeover month is 3)
     * getCurrentAuditionYear('2024-03-01') // Returns 2025 (if changeover month is 3)
     * getCurrentAuditionYear() // Returns current audition year
     */
    public function getCurrentAuditionYear(?string $date = null): int
    {
        $date = $date ? Carbon::parse($date) : now();

        return $date->month < $this->changeoverMonth ? $date->year : $date->year + 1;
    }

    /**
     * Get the active school year as a string for a given date.
     *
     * @param  string|null  $date  Optional date string in 'YYYY-MM-DD' format. Defaults to the current date.
     * @return string The school year in "YYYY - YYYY" format
     *
     * @example
     * getActiveSchoolYear('2024-01-15') // Returns "2023 - 2024"
     * getActiveSchoolYear('2024-09-01') // Returns "2024 - 2025"
     */
    public function getActiveSchoolYear(?string $date = null): string
    {
        $auditionYear = $this->getCurrentAuditionYear($date);

        return ($auditionYear - 1).' - '.$auditionYear;
    }

    /**
     * Get the current set number for an ensemble in a given year.
     *
     * Sets rotate annually based on the ensemble's set count.
     * The rotation is calculated from the configured start year.
     *
     * @param  AuditionedEnsemble  $ensemble  The ensemble to get the set for
     * @param  int|null  $year  Optional year. Defaults to current audition year.
     * @return int The set number (1 to ensemble's set_count)
     *
     * @example
     * getSetForEnsemble($ensemble, 2024) // Returns the set number for 2024
     */
    public function getSetForEnsemble(AuditionedEnsemble $ensemble, ?int $year = null): int
    {
        $year = $year ?? $this->getCurrentAuditionYear();
        $setCount = $ensemble->set_count;
        $yearDiff = $year - $this->startYear;

        return ($yearDiff % $setCount) + 1;
    }
}