<?php
declare(strict_types=1);

namespace Unsupervised\Schedular\Offering;

use Unsupervised\Schedular\Val;

class Offering {

	public const KIND_PRIVATE_LESSON = 'private_lesson';
	public const KIND_GROUP_CLASS    = 'group_class';

	/**
	 * All valid offering kinds.
	 *
	 * @var list<string>
	 */
	public const VALID_KINDS = [ self::KIND_PRIVATE_LESSON, self::KIND_GROUP_CLASS ];

	public const BILLING_ONE_TIME  = 'one_time';
	public const BILLING_FULL_TERM = 'full_term';

	/**
	 * All valid billing modes.
	 *
	 * @var list<string>
	 */
	public const VALID_BILLING_MODES = [ self::BILLING_ONE_TIME, self::BILLING_FULL_TERM ];

	/** Listed in the public catalogue; anyone with `book_lesson` may enrol. */
	public const ACCESS_PUBLIC = 'public';

	/** Hidden from the catalogue; only invited/added students may enrol (group classes). */
	public const ACCESS_INVITE_ONLY = 'invite_only';

	/**
	 * All valid access modes.
	 *
	 * @var list<string>
	 */
	public const VALID_ACCESS_MODES = [ self::ACCESS_PUBLIC, self::ACCESS_INVITE_ONLY ];

	public function __construct(
		public readonly int $instructorId,
		public readonly string $kind,
		public readonly string $title,
		public readonly float $price = 0.0,
		public readonly string $currency = 'CAD',
		public readonly string $billingMode = self::BILLING_ONE_TIME,
		public readonly ?string $description = null,
		public readonly ?int $durationMinutes = null,
		public readonly bool $allowWeekly = false,
		public readonly ?int $capacity = null,
		public readonly ?string $termStart = null,
		public readonly ?string $termEnd = null,
		public readonly ?string $scheduleNote = null,
		public readonly ?string $etransferEmail = null,
		public readonly ?int $cancellationCutoffHours = null,
		public readonly string $accessMode = self::ACCESS_PUBLIC,
		public readonly bool $isActive = true,
		public readonly ?int $id = null,
	) {}

	/**
	 * Whether the offering is hidden from the public catalogue and reachable
	 * only by invited or directly-added students.
	 */
	public function isInviteOnly(): bool {
		return self::ACCESS_INVITE_ONLY === $this->accessMode;
	}

	/**
	 * Normalise a submitted term date to canonical `Y-m-d`, or null when it is
	 * not a real calendar date. Round-trips through DateTimeImmutable so
	 * strings PHP would silently coerce (e.g. `2026-02-30`) are rejected.
	 */
	public static function normalizeDate( string $value ): ?string {
		$date = \DateTimeImmutable::createFromFormat( '!Y-m-d', $value );

		return false !== $date && $date->format( 'Y-m-d' ) === $value ? $date->format( 'Y-m-d' ) : null;
	}

	/**
	 * Last class date of a weekly term: the start date plus `$occurrences - 1`
	 * weeks. A one-off class (one occurrence) ends the day it starts.
	 */
	public static function weeklyTermEnd( string $termStart, int $occurrences ): string {
		$weeks = max( 1, $occurrences ) - 1;

		return ( new \DateTimeImmutable( $termStart ) )->modify( '+' . ( 7 * $weeks ) . ' days' )->format( 'Y-m-d' );
	}

	public static function fromRow( \stdClass $row ): self {
		return new self(
			instructorId:    Val::int( $row->instructor_id ),
			kind:            Val::string( $row->kind ),
			title:           Val::string( $row->title ),
			price:           Val::float( $row->price ),
			currency:        Val::string( $row->currency ),
			billingMode:     Val::string( $row->billing_mode ),
			description:     Val::stringOrNull( $row->description ),
			durationMinutes: Val::intOrNull( $row->duration_minutes ),
			allowWeekly:     Val::bool( $row->allow_weekly ),
			capacity:        Val::intOrNull( $row->capacity ),
			termStart:       Val::stringOrNull( $row->term_start ),
			termEnd:         Val::stringOrNull( $row->term_end ),
			scheduleNote:    Val::stringOrNull( $row->schedule_note ),
			etransferEmail:  Val::stringOrNull( $row->etransfer_email ),
			cancellationCutoffHours: Val::intOrNull( $row->cancellation_cutoff_hours ),
			accessMode:      '' !== Val::string( $row->access_mode ?? '' ) ? Val::string( $row->access_mode ) : self::ACCESS_PUBLIC,
			isActive:        Val::bool( $row->is_active ),
			id:              Val::int( $row->id ),
		);
	}

	/**
	 * Returns a plain array representation of the offering.
	 *
	 * The e-transfer destination email is a private payment-routing detail, so it
	 * is only included when $includeEtransferEmail is true (e.g. manager-only
	 * responses). The public offerings listing must omit it.
	 *
	 * @return array<string, mixed>
	 */
	public function toArray( bool $includeEtransferEmail = true ): array {
		$out = [
			'id'                        => $this->id,
			'instructor_id'             => $this->instructorId,
			'kind'                      => $this->kind,
			'title'                     => $this->title,
			'description'               => $this->description,
			'duration_minutes'          => $this->durationMinutes,
			'price'                     => $this->price,
			'currency'                  => $this->currency,
			'billing_mode'              => $this->billingMode,
			'allow_weekly'              => $this->allowWeekly,
			'capacity'                  => $this->capacity,
			'term_start'                => $this->termStart,
			'term_end'                  => $this->termEnd,
			'schedule_note'             => $this->scheduleNote,
			'cancellation_cutoff_hours' => $this->cancellationCutoffHours,
			'access_mode'               => $this->accessMode,
			'is_active'                 => $this->isActive,
		];

		if ( $includeEtransferEmail ) {
			$out['etransfer_email'] = $this->etransferEmail;
		}

		return $out;
	}
}