<?php
declare(strict_types=1);

namespace Unsupervised\Schedular\Availability;

use Unsupervised\Schedular\Auth\RoleManager;
use Unsupervised\Schedular\Offering\Offering;
use Unsupervised\Schedular\Offering\OfferingRepository;
use Unsupervised\Schedular\Val;

class AvailabilityController {

	public function __construct(
		private AvailabilityRepository $repository,
		private OfferingRepository $offerings,
		private WindowValidator $validator,
	) {}

	public function renderPage(): void {
		if ( ! current_user_can( RoleManager::CAP_MANAGE_AVAILABILITY ) ) {
			wp_die( esc_html__( 'You do not have permission to manage availability.', 'unsupervised-schedular' ) );
		}

		$instructorId = get_current_user_id();
		$notice       = '';
		$error        = '';

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

		$slots           = $this->repository->findByInstructor( $instructorId );
		$offeringChoices = $this->offerings->findAll( $instructorId, Offering::KIND_PRIVATE_LESSON, true );

		// View-state query params only (which view, which week) — nothing is
		// mutated from them, so no nonce applies.
		// phpcs:disable WordPress.Security.NonceVerification.Recommended
		$view          = 'list' === sanitize_key( Val::string( wp_unslash( $_GET['usc_view'] ?? '' ) ) ) ? 'list' : 'week';
		$requestedWeek = sanitize_text_field( Val::string( wp_unslash( $_GET['usc_week'] ?? '' ) ) );
		// phpcs:enable WordPress.Security.NonceVerification.Recommended

		$weekStart = WeekCalendar::weekStart( $requestedWeek, Val::int( get_option( 'start_of_week', 1 ) ), current_time( 'Y-m-d' ) );
		$weekDays  = WeekCalendar::days( $weekStart, $slots );
		$prevWeek  = ( new \DateTimeImmutable( $weekStart ) )->modify( '-7 days' )->format( 'Y-m-d' );
		$nextWeek  = ( new \DateTimeImmutable( $weekStart ) )->modify( '+7 days' )->format( 'Y-m-d' );

		include USC_PLUGIN_DIR . 'templates/admin/availability.php';
	}

	/**
	 * Run the submitted action and report what happened. Every branch returns a
	 * message: a form that silently reloads leaves the instructor unable to tell
	 * "saved 41 slots" from "saved nothing".
	 *
	 * @return array{string, string} Success notice and error message; each is
	 *                               empty when it does not apply.
	 */
	private function handleFormAction( int $instructorId ): array {
		// Nonce is verified by the caller (renderPage) before this method runs.
		// phpcs:disable WordPress.Security.NonceVerification.Missing
		$action = sanitize_key( Val::string( wp_unslash( $_POST['usc_action'] ?? '' ) ) );

		if ( 'add' === $action ) {
			return $this->addSlot( $instructorId );
		}

		if ( 'delete' === $action ) {
			return $this->deleteOwnSlot( absint( Val::int( $_POST['slot_id'] ?? 0 ) ), $instructorId )
				? [ __( 'Availability slot deleted.', 'unsupervised-schedular' ), '' ]
				: [ '', __( 'That slot could not be deleted. It may already be booked, or belong to someone else.', 'unsupervised-schedular' ) ];
		}

		if ( 'bulk_delete' === $action ) {
			// The array itself carries no data; each element is coerced and
			// absint-sanitized individually below.
			// phpcs:ignore WordPress.Security.ValidatedSanitizedInput
			$rawIds  = $_POST['slot_ids'] ?? [];
			$deleted = 0;
			$failed  = 0;

			foreach ( is_array( $rawIds ) ? $rawIds : [] as $rawId ) {
				if ( $this->deleteOwnSlot( absint( Val::int( $rawId ) ), $instructorId ) ) {
					++$deleted;
					continue;
				}

				++$failed;
			}

			return $this->bulkDeleteResult( $deleted, $failed );
		}
		// phpcs:enable WordPress.Security.NonceVerification.Missing

		return [ '', '' ];
	}

	/**
	 * Wording for a bulk delete, which can partly succeed.
	 *
	 * @return array{string, string}
	 */
	private function bulkDeleteResult( int $deleted, int $failed ): array {
		$notice = $deleted > 0
			? sprintf(
				/* translators: %d: number of availability slots deleted. */
				_n( '%d slot deleted.', '%d slots deleted.', $deleted, 'unsupervised-schedular' ),
				$deleted
			)
			: '';

		$error = $failed > 0
			? sprintf(
				/* translators: %d: number of slots that could not be deleted. */
				_n(
					'%d slot could not be deleted — it may already be booked.',
					'%d slots could not be deleted — they may already be booked.',
					$failed,
					'unsupervised-schedular'
				),
				$failed
			)
			: '';

		if ( 0 === $deleted && 0 === $failed ) {
			$error = __( 'No slots were selected.', 'unsupervised-schedular' );
		}

		return [ $notice, $error ];
	}

	/**
	 * Delete a slot only when it exists and belongs to the given instructor.
	 * The repository additionally refuses to delete booked slots. Returns whether
	 * the row actually went away.
	 */
	private function deleteOwnSlot( int $slotId, int $instructorId ): bool {
		if ( $slotId <= 0 ) {
			return false;
		}

		$slot = $this->repository->findById( $slotId );

		if ( null === $slot || $slot->instructorId !== $instructorId ) {
			return false;
		}

		return $this->repository->delete( $slotId );
	}

	/**
	 * Validate and persist a submitted window.
	 *
	 * @return array{string, string}
	 */
	private function addSlot( int $instructorId ): array {
		// phpcs:disable WordPress.Security.NonceVerification.Missing
		$window = $this->validator->validate(
			$instructorId,
			sanitize_text_field( Val::string( wp_unslash( $_POST['start_dt'] ?? '' ) ) ),
			sanitize_text_field( Val::string( wp_unslash( $_POST['end_dt'] ?? '' ) ) ),
			absint( Val::int( $_POST['duration_minutes'] ?? 0 ) ),
			absint( Val::int( $_POST['offering_id'] ?? 0 ) ),
		);

		if ( $window instanceof \WP_Error ) {
			return [ '', $window->get_error_message() ];
		}

		$recurrence = sanitize_key( Val::string( wp_unslash( $_POST['recurrence'] ?? 'single' ) ) );
		$weeks      = absint( Val::int( $_POST['weeks'] ?? 1 ) );
		// phpcs:enable WordPress.Security.NonceVerification.Missing

		$ids = $this->repository->createFromWindow( $window, 'weekly' === $recurrence, $weeks );

		// The window was valid, so it split into at least one slot — an empty
		// result means every insert failed.
		if ( [] === $ids ) {
			return [ '', __( 'The availability could not be saved. Please try again.', 'unsupervised-schedular' ) ];
		}

		return [
			sprintf(
				/* translators: %d: number of bookable slots created. */
				_n( 'Added %d bookable slot.', 'Added %d bookable slots.', count( $ids ), 'unsupervised-schedular' ),
				count( $ids )
			),
			'',
		];
	}
}