<?php
declare(strict_types=1);

namespace Unsupervised\Schedular\GroupClass;

class EnrollmentRepository {

	private string $table;

	public function __construct( private \wpdb $db ) {
		$this->table = $db->prefix . 'us_group_enrollments';
	}

	public function insert( Enrollment $enrollment ): int {
		$this->db->insert(
			$this->table,
			[
				'offering_id'   => $enrollment->offeringId,
				'student_id'    => $enrollment->studentId,
				'instructor_id' => $enrollment->instructorId,
				'status'        => $enrollment->status,
				'payment_id'    => $enrollment->paymentId,
				'enrolled_at'   => current_time( 'mysql' ),
			],
			[ '%d', '%d', '%d', '%s', '%d', '%s' ]
		);

		return $this->db->insert_id;
	}

	public function findById( int $id ): ?Enrollment {
		$row = $this->db->get_row(
			$this->db->prepare( 'SELECT * FROM %i WHERE id = %d', $this->table, $id )
		);

		return $row ? Enrollment::fromRow( $row ) : null;
	}

	/**
	 * Count active enrolments for an offering (capacity check).
	 */
	public function countActiveForOffering( int $offeringId ): int {
		return (int) $this->db->get_var(
			$this->db->prepare(
				'SELECT COUNT(*) FROM %i WHERE offering_id = %d AND status = %s',
				$this->table,
				$offeringId,
				Enrollment::STATUS_ACTIVE
			)
		);
	}

	/**
	 * Count a student's active group-class enrolments.
	 */
	public function countActiveForStudent( int $studentId ): int {
		return (int) $this->db->get_var(
			$this->db->prepare(
				'SELECT COUNT(*) FROM %i WHERE student_id = %d AND status = %s',
				$this->table,
				$studentId,
				Enrollment::STATUS_ACTIVE
			)
		);
	}

	/**
	 * Whether a student already holds an active enrolment in an offering.
	 */
	public function hasActiveEnrollment( int $offeringId, int $studentId ): bool {
		$count = (int) $this->db->get_var(
			$this->db->prepare(
				'SELECT COUNT(*) FROM %i WHERE offering_id = %d AND student_id = %d AND status = %s',
				$this->table,
				$offeringId,
				$studentId,
				Enrollment::STATUS_ACTIVE
			)
		);

		return $count > 0;
	}

	/**
	 * A student's enrolments, newest first.
	 *
	 * @return list<Enrollment>
	 */
	public function findByStudent( int $studentId ): array {
		$rows = $this->db->get_results(
			$this->db->prepare(
				'SELECT * FROM %i WHERE student_id = %d ORDER BY enrolled_at DESC',
				$this->table,
				$studentId
			)
		);

		return array_map( Enrollment::fromRow( ... ), $rows ?? [] );
	}

	/**
	 * Enrolments in an instructor's group classes, newest first.
	 *
	 * @return list<Enrollment>
	 */
	public function findByInstructor( int $instructorId ): array {
		$rows = $this->db->get_results(
			$this->db->prepare(
				'SELECT * FROM %i WHERE instructor_id = %d ORDER BY enrolled_at DESC',
				$this->table,
				$instructorId
			)
		);

		return array_map( Enrollment::fromRow( ... ), $rows ?? [] );
	}

	/**
	 * All active enrolments across instructors (studio-admin view).
	 *
	 * @return list<Enrollment>
	 */
	public function findAllActive(): array {
		$rows = $this->db->get_results(
			$this->db->prepare(
				'SELECT * FROM %i WHERE status = %s ORDER BY enrolled_at DESC',
				$this->table,
				Enrollment::STATUS_ACTIVE
			)
		);

		return array_map( Enrollment::fromRow( ... ), $rows ?? [] );
	}

	/**
	 * Active enrolments whose group class bills on a scheduled mode (weekly /
	 * monthly) — the source rows for the daily billing scan. Filtered by joining
	 * the offering so only classes actually on a scheduled plan are returned.
	 *
	 * @param list<string> $modes Billing modes to include (e.g. weekly, monthly).
	 * @return list<Enrollment>
	 */
	public function findActiveByBillingModes( array $modes ): array {
		if ( [] === $modes ) {
			return [];
		}

		$offTable     = str_replace( 'us_group_enrollments', 'us_offerings', $this->table );
		$placeholders = implode( ', ', array_fill( 0, count( $modes ), '%s' ) );

		$rows = $this->db->get_results(
			$this->db->prepare(
				"SELECT e.* FROM %i e
				 JOIN %i o ON o.id = e.offering_id
				 WHERE e.status = %s
				   AND o.billing_mode IN ( {$placeholders} )
				 ORDER BY e.student_id ASC, e.offering_id ASC",
				$this->table,
				$offTable,
				Enrollment::STATUS_ACTIVE,
				...$modes
			)
		);

		return array_map( Enrollment::fromRow( ... ), $rows ?? [] );
	}

	public function setPaymentId( int $id, int $paymentId ): bool {
		return false !== $this->db->update(
			$this->table,
			[ 'payment_id' => $paymentId ],
			[ 'id' => $id ],
			[ '%d' ],
			[ '%d' ]
		);
	}

	public function updateStatus( int $id, string $status ): bool {
		if ( ! in_array( $status, Enrollment::VALID_STATUSES, true ) ) {
			return false;
		}

		return (bool) $this->db->update(
			$this->table,
			[ 'status' => $status ],
			[ 'id' => $id ],
			[ '%s' ],
			[ '%d' ]
		);
	}
}