<?php
declare(strict_types=1);

namespace Unsupervised\Schedular\GroupClass;

use Unsupervised\Schedular\Auth\Invite;
use Unsupervised\Schedular\Auth\InviteRepository;
use Unsupervised\Schedular\Auth\RegistrationController;
use Unsupervised\Schedular\Auth\RegistrationMailer;
use Unsupervised\Schedular\Auth\RoleManager;
use Unsupervised\Schedular\Auth\UserName;
use Unsupervised\Schedular\Offering\Offering;
use Unsupervised\Schedular\Offering\OfferingRepository;
use Unsupervised\Schedular\Payment\Payment;
use Unsupervised\Schedular\Payment\PaymentRepository;
use Unsupervised\Schedular\Payment\PaymentService;
use Unsupervised\Schedular\Val;

class GroupClassController {

	public function __construct(
		private EnrollmentRepository $enrollments,
		private OfferingRepository $offerings,
		private PaymentRepository $payments,
		private GroupAccessRepository $access,
		private PaymentService $paymentService,
		private InviteRepository $invites,
		private RegistrationMailer $mailer,
	) {}

	/**
	 * Studio-admin overview: every group class across instructors as a summary —
	 * who teaches it, when it meets, and how full it is — rather than a flat list
	 * of individual student enrolments. Selecting a class (`?class_id=<id>`) opens
	 * the same per-class details page instructors use, so a studio admin (including
	 * an owner-operator who also teaches) can view any class's roster and manage
	 * invite-only membership from here.
	 */
	public function renderPage(): void {
		if ( ! current_user_can( RoleManager::CAP_VIEW_ALL_LESSONS ) ) {
			wp_die( esc_html__( 'You do not have permission to view group classes.', 'unsupervised-schedular' ) );
		}

		$notice = '';
		if ( isset( $_POST['usc_action'] ) && check_admin_referer( 'usc_group_action' ) ) {
			$notice = $this->handleFormAction( get_current_user_id() );
		}

		$offerings = $this->offerings->findAll( 0, Offering::KIND_GROUP_CLASS );
		$baseUrl   = admin_url( 'admin.php?page=us-group-classes' );

		// View-state query param only (which class to drill into) — nothing is
		// mutated from it, so no nonce applies.
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended
		$classId = absint( Val::int( $_GET['class_id'] ?? 0 ) );
		$current = null;
		foreach ( $offerings as $offering ) {
			if ( $offering->id === $classId ) {
				$current = $offering;
				break;
			}
		}

		if ( null !== $current ) {
			// Enrolments are looked up by the class's own instructor; classDetail
			// filters them down to this offering.
			$class    = $this->classDetail( $current, $this->enrollments->findByInstructor( $current->instructorId ) );
			$students = $this->studentOptions();

			include USC_PLUGIN_DIR . 'templates/admin/my-group-class-detail.php';

			return;
		}

		$rows = array_map(
			function ( Offering $offering ): array {
				return [
					'id'          => $offering->id,
					'title'       => $offering->title,
					'instructor'  => $this->instructorName( $offering ),
					'when'        => $this->whenLabel( $offering ),
					'capacity'    => $offering->capacity,
					'enrolled'    => $this->enrollments->countActiveForOffering( (int) $offering->id ),
					'invite_only' => $offering->isInviteOnly(),
				];
			},
			$offerings
		);

		include USC_PLUGIN_DIR . 'templates/admin/group-classes.php';
	}

	/**
	 * Instructor view. By default a summary of the instructor's own group classes
	 * — each with when it meets and how many are enrolled — rather than a dump of
	 * every roster. A `class_id` query param drills into one class to show its
	 * roster of enrolled students and, for invite-only classes, the controls to
	 * add, grant access to, or email-invite students.
	 */
	public function renderInstructorPage(): void {
		if ( ! current_user_can( RoleManager::CAP_VIEW_LESSONS ) ) {
			wp_die( esc_html__( 'You do not have permission to view group classes.', 'unsupervised-schedular' ) );
		}

		$instructorId = get_current_user_id();

		$notice = '';
		if ( isset( $_POST['usc_action'] ) && check_admin_referer( 'usc_group_action' ) ) {
			$notice = $this->handleFormAction( $instructorId );
		}

		$offerings   = $this->offerings->findAll( $instructorId, Offering::KIND_GROUP_CLASS );
		$enrollments = $this->enrollments->findByInstructor( $instructorId );

		// View-state query param only (which class to drill into) — nothing is
		// mutated from it, so no nonce applies.
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended
		$classId = absint( Val::int( $_GET['class_id'] ?? 0 ) );
		$current = null;
		foreach ( $offerings as $offering ) {
			if ( $offering->id === $classId ) {
				$current = $offering;
				break;
			}
		}

		if ( null !== $current ) {
			$baseUrl  = admin_url( 'admin.php?page=us-my-group-classes' );
			$class    = $this->classDetail( $current, $enrollments );
			$students = $this->studentOptions();

			include USC_PLUGIN_DIR . 'templates/admin/my-group-class-detail.php';

			return;
		}

		$classes = array_map(
			fn( Offering $offering ): array => $this->classSummary( $offering, $enrollments ),
			$offerings
		);

		$baseUrl = admin_url( 'admin.php?page=us-my-group-classes' );

		include USC_PLUGIN_DIR . 'templates/admin/my-group-classes.php';
	}

	/**
	 * Summary row for one class in the instructor overview: its identity, when it
	 * meets, and how many active enrolments it holds against capacity.
	 *
	 * @param list<Enrollment> $enrollments
	 * @return array{id: int|null, title: string, when: string, capacity: int|null, enrolled: int, invite_only: bool}
	 */
	private function classSummary( Offering $offering, array $enrollments ): array {
		$enrolled = 0;
		foreach ( $enrollments as $enrollment ) {
			if ( $enrollment->offeringId === $offering->id && Enrollment::STATUS_ACTIVE === $enrollment->status ) {
				++$enrolled;
			}
		}

		return [
			'id'          => $offering->id,
			'title'       => $offering->title,
			'when'        => $this->whenLabel( $offering ),
			'capacity'    => $offering->capacity,
			'enrolled'    => $enrolled,
			'invite_only' => $offering->isInviteOnly(),
		];
	}

	/**
	 * Full details for one class: the summary fields, the class's own settings
	 * (instructor, price, duration, description, schedule, active state), the
	 * roster of enrolled students (with enrolment and payment status), and — for
	 * invite-only classes — the list of people invited but not yet enrolled.
	 *
	 * @param list<Enrollment> $enrollments
	 * @return array{id: int|null, title: string, when: string, capacity: int|null, enrolled: int, invite_only: bool, instructor: string, price: float, currency: string, duration: int|null, description: string|null, schedule_note: string|null, deadline: string, enrollment_open: bool, active: bool, roster: list<array{student: string, status: string, payment: string|null}>, invited: list<array{who: string, kind: string}>}
	 */
	private function classDetail( Offering $offering, array $enrollments ): array {
		$roster = [];
		foreach ( $enrollments as $enrollment ) {
			if ( $enrollment->offeringId !== $offering->id ) {
				continue;
			}

			$student = get_userdata( $enrollment->studentId );
			$payment = null !== $enrollment->paymentId ? $this->payments->findById( $enrollment->paymentId ) : null;

			$roster[] = [
				'student' => $student ? $student->display_name : (string) $enrollment->studentId,
				'status'  => $enrollment->status,
				'payment' => $payment?->status,
			];
		}

		$deadline = $offering->effectiveEnrollmentDeadline();

		return $this->classSummary( $offering, $enrollments ) + [
			'instructor'      => $this->instructorName( $offering ),
			'price'           => $offering->price,
			'currency'        => $offering->currency,
			'duration'        => $offering->durationMinutes,
			'description'     => $offering->description,
			'schedule_note'   => $offering->scheduleNote,
			'deadline'        => null !== $deadline ? (string) mysql2date( 'M j, Y', $deadline ) : '',
			'enrollment_open' => $offering->isEnrollmentOpen( Val::string( current_time( 'Y-m-d' ) ) ),
			'active'          => $offering->isActive,
			'roster'          => $roster,
			'invited'         => $offering->isInviteOnly() ? $this->pendingInvites( (int) $offering->id ) : [],
		];
	}

	/**
	 * The teaching instructor's display name — their real name or nickname, never
	 * the login. Falls back to the numeric id when the account is gone. See
	 * {@see UserName::format()}.
	 */
	private function instructorName( Offering $offering ): string {
		$user = get_userdata( $offering->instructorId );

		return UserName::format( $user instanceof \WP_User ? $user : null, $offering->instructorId );
	}

	/**
	 * Human-readable "when" label for a class: the class date (or weekly date
	 * range) and, when set, the start time. Empty when the class has no date.
	 */
	private function whenLabel( Offering $offering ): string {
		if ( null === $offering->termStart ) {
			return '';
		}

		$label = null === $offering->termEnd || $offering->termEnd === $offering->termStart
			? (string) mysql2date( 'M j, Y', $offering->termStart )
			: (string) mysql2date( 'M j, Y', $offering->termStart ) . ' – ' . (string) mysql2date( 'M j, Y', $offering->termEnd );

		if ( null !== $offering->classTime ) {
			$label .= ' · ' . (string) mysql2date( 'g:i a', $offering->termStart . ' ' . $offering->classTime );
		}

		return $label;
	}

	/**
	 * Pending (not-yet-enrolled) access grants for an invite-only class, shown so
	 * the instructor can see who has been invited but has not enrolled yet.
	 *
	 * @return list<array{who: string, kind: string}>
	 */
	private function pendingInvites( int $offeringId ): array {
		$out = [];
		foreach ( $this->access->findByOffering( $offeringId ) as $grant ) {
			if ( GroupAccess::STATUS_INVITED !== $grant->status ) {
				continue;
			}

			if ( null !== $grant->studentId ) {
				$user  = get_userdata( $grant->studentId );
				$out[] = [
					'who'  => $user ? $user->display_name : (string) $grant->studentId,
					'kind' => __( 'Granted', 'unsupervised-schedular' ),
				];
			} else {
				$out[] = [
					'who'  => $grant->email,
					'kind' => __( 'Email invite', 'unsupervised-schedular' ),
				];
			}
		}

		return $out;
	}

	/**
	 * Handle a posted management action, returning a status notice for display.
	 * The action is scoped to a group class the current instructor owns, unless
	 * the caller is a studio admin (`view_all_lessons`) — who may manage any
	 * instructor's class, since the studio-admin Group Classes page reaches the
	 * same controls for every class.
	 */
	private function handleFormAction( int $instructorId ): string {
		// Nonce is verified by the caller before this method runs.
		// phpcs:disable WordPress.Security.NonceVerification.Missing
		$action     = sanitize_key( Val::string( wp_unslash( $_POST['usc_action'] ?? '' ) ) );
		$offeringId = absint( Val::int( $_POST['offering_id'] ?? 0 ) );
		$offering   = $offeringId > 0 ? $this->offerings->findById( $offeringId ) : null;

		$ownsOrManagesAll = null !== $offering
			&& ( $offering->instructorId === $instructorId || current_user_can( RoleManager::CAP_VIEW_ALL_LESSONS ) );

		if ( null === $offering || ! $ownsOrManagesAll || Offering::KIND_GROUP_CLASS !== $offering->kind ) {
			return esc_html__( 'That group class was not found.', 'unsupervised-schedular' );
		}

		if ( 'add_direct' === $action ) {
			return $this->addDirect( $offering, $this->postedStudentIds() );
		}

		if ( 'grant_access' === $action ) {
			return $this->grantAccess( $offering, $this->postedStudentIds() );
		}

		if ( 'invite_email' === $action ) {
			$email = sanitize_email( Val::string( wp_unslash( $_POST['email'] ?? '' ) ) );

			return $this->inviteEmail( $offering, $email );
		}
		// phpcs:enable WordPress.Security.NonceVerification.Missing

		return '';
	}

	/**
	 * Directly enrol registered students, each with a pending payment at the
	 * class price (comp students are settled immediately by the payment service).
	 *
	 * This is the instructor's manual enrolment path and deliberately bypasses the
	 * enrolment deadline and capacity, so a student can be added as a late
	 * enrolment after the class has closed to self-enrolment.
	 *
	 * @param list<int> $studentIds
	 */
	private function addDirect( Offering $offering, array $studentIds ): string {
		$added = 0;
		foreach ( $studentIds as $studentId ) {
			if ( $this->enrollments->hasActiveEnrollment( (int) $offering->id, $studentId ) ) {
				continue;
			}

			$enrollmentId = $this->enrollments->insert(
				new Enrollment(
					offeringId:   (int) $offering->id,
					studentId:    $studentId,
					instructorId: $offering->instructorId,
				)
			);

			if ( $offering->price > 0.0 ) {
				$payment = $this->paymentService->createForRegistration(
					Payment::REG_ENROLLMENT,
					$enrollmentId,
					$studentId,
					$offering->instructorId,
					$offering->price,
					$offering->currency,
					$offering->etransferEmail
				);

				if ( null !== $payment && null !== $payment->id ) {
					$this->enrollments->setPaymentId( $enrollmentId, $payment->id );
				}
			}

			$this->access->markEnrolled( (int) $offering->id, $studentId );
			++$added;
		}

		/* translators: %d: number of students added. */
		return sprintf( esc_html__( '%d student(s) added to the class.', 'unsupervised-schedular' ), $added );
	}

	/**
	 * Grant registered students access to the class so it appears in their list
	 * for self-enrolment, notifying each by email.
	 *
	 * @param list<int> $studentIds
	 */
	private function grantAccess( Offering $offering, array $studentIds ): string {
		$granted = 0;
		foreach ( $studentIds as $studentId ) {
			if (
				$this->enrollments->hasActiveEnrollment( (int) $offering->id, $studentId )
				|| $this->access->hasGrant( (int) $offering->id, $studentId )
			) {
				continue;
			}

			$this->access->insert(
				new GroupAccess(
					offeringId: (int) $offering->id,
					studentId:  $studentId,
					status:     GroupAccess::STATUS_INVITED,
					invitedBy:  get_current_user_id(),
				)
			);

			$user = get_userdata( $studentId );
			if ( $user instanceof \WP_User ) {
				$this->mailer->sendClassAccessGranted( $user, $offering->title );
			}

			++$granted;
		}

		/* translators: %d: number of students granted access. */
		return sprintf( esc_html__( '%d student(s) granted access.', 'unsupervised-schedular' ), $granted );
	}

	/**
	 * Invite someone by email. A registered address is treated as a grant; an
	 * unknown address gets a tokenised registration invite tied to the class,
	 * reusing any pending invite already outstanding for that address (in which
	 * case no new link is sent).
	 */
	private function inviteEmail( Offering $offering, string $email ): string {
		if ( ! is_email( $email ) ) {
			return esc_html__( 'Enter a valid email address.', 'unsupervised-schedular' );
		}

		$existingUserId = email_exists( $email );
		if ( false !== $existingUserId ) {
			return $this->grantAccess( $offering, [ (int) $existingUserId ] );
		}

		// Reuse an outstanding invite rather than mailing a second link; still
		// attach a class grant so enrolment unlocks once they register.
		$pending = $this->invites->findPendingByEmail( $email );
		if ( null !== $pending ) {
			$this->access->insert(
				new GroupAccess(
					offeringId: (int) $offering->id,
					email:      $email,
					inviteId:   $pending->id,
					status:     GroupAccess::STATUS_INVITED,
					invitedBy:  get_current_user_id(),
				)
			);

			return esc_html__( 'This person already has a pending invitation; the class was added to it. No new link was sent.', 'unsupervised-schedular' );
		}

		$rawToken = wp_generate_password( 32, false );
		$inviteId = $this->invites->insert(
			new Invite(
				email:      $email,
				token:      Invite::hashToken( $rawToken ),
				invitedBy:  get_current_user_id(),
				offeringId: (int) $offering->id,
			)
		);

		if ( $inviteId <= 0 ) {
			return esc_html__( 'Could not create the invite. Deactivate and reactivate the plugin to update the database, then try again.', 'unsupervised-schedular' );
		}

		$this->access->insert(
			new GroupAccess(
				offeringId: (int) $offering->id,
				email:      $email,
				inviteId:   $inviteId,
				status:     GroupAccess::STATUS_INVITED,
				invitedBy:  get_current_user_id(),
			)
		);

		$this->mailer->sendClassInvite( $email, $this->registrationLink( $rawToken ), $offering->title );

		return esc_html__( 'Invitation sent.', 'unsupervised-schedular' );
	}

	/**
	 * Registered students to offer in the add/grant selects, by display name.
	 *
	 * @return list<array{id: int, name: string}>
	 */
	private function studentOptions(): array {
		$users = array_filter(
			get_users(
				[
					'role'    => RoleManager::STUDENT,
					'orderby' => 'display_name',
					'order'   => 'ASC',
				]
			),
			static fn( mixed $u ): bool => $u instanceof \WP_User
		);

		return array_values(
			array_map(
				static fn( \WP_User $u ): array => [
					'id'   => (int) $u->ID,
					'name' => '' !== (string) $u->display_name ? (string) $u->display_name : (string) $u->user_email,
				],
				$users
			)
		);
	}

	/**
	 * The de-duplicated positive student ids posted from a multi-select.
	 *
	 * @return list<int>
	 */
	private function postedStudentIds(): array {
		// Nonce is verified by the caller before this method runs.
		// phpcs:ignore WordPress.Security.NonceVerification.Missing, WordPress.Security.ValidatedSanitizedInput.MissingUnslash, WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- each element is coerced to a positive int below; slashes cannot survive integer coercion.
		$raw = (array) ( $_POST['student_ids'] ?? [] );
		$ids = array_filter( array_map( static fn( mixed $v ): int => absint( Val::int( $v ) ), $raw ) );

		return array_values( array_unique( $ids ) );
	}

	/**
	 * Build the registration URL for a raw invite token, mirroring the invites
	 * admin page so class invites land on the same registration page.
	 */
	private function registrationLink( string $rawToken ): string {
		$pageId   = Val::int( get_option( RegistrationController::OPTION_PAGE, 0 ) );
		$linkBase = $pageId > 0 ? (string) get_permalink( $pageId ) : '';

		return add_query_arg( 'us_invite', rawurlencode( $rawToken ), '' !== $linkBase ? $linkBase : home_url( '/' ) );
	}
}