<?php
declare(strict_types=1);

namespace Unsupervised\Schedular\Offering;

use Unsupervised\Schedular\Auth\RoleManager;
use Unsupervised\Schedular\Auth\UserName;
use Unsupervised\Schedular\GroupClass\GroupAccessRepository;
use Unsupervised\Schedular\Val;

class OfferingEndpoint {

	public function __construct(
		private OfferingRepository $repository,
		private GroupAccessRepository $access,
	) {}

	/**
	 * Registers this endpoint's REST routes.
	 *
	 * @param non-falsy-string $route_namespace REST namespace the routes are registered under (e.g. `us-scheduler/v1`).
	 */
	public function registerRoutes( string $route_namespace ): void {
		register_rest_route(
			$route_namespace,
			'/offerings',
			[
				[
					'methods'             => \WP_REST_Server::READABLE,
					'callback'            => [ $this, 'index' ],
					'permission_callback' => [ $this, 'canRead' ],
					'args'                => [
						'instructor_id' => [
							'type'    => 'integer',
							'default' => 0,
						],
						'kind'          => [
							'type'    => 'string',
							'default' => '',
						],
					],
				],
				[
					'methods'             => \WP_REST_Server::CREATABLE,
					'callback'            => [ $this, 'create' ],
					'permission_callback' => [ $this, 'canManage' ],
				],
			]
		);

		register_rest_route(
			$route_namespace,
			'/offerings/(?P<id>\d+)',
			[
				[
					'methods'             => \WP_REST_Server::EDITABLE,
					'callback'            => [ $this, 'update' ],
					'permission_callback' => [ $this, 'canManage' ],
				],
				[
					'methods'             => \WP_REST_Server::DELETABLE,
					'callback'            => [ $this, 'delete' ],
					'permission_callback' => [ $this, 'canManage' ],
				],
			]
		);
	}

	public function index( \WP_REST_Request $request ): \WP_REST_Response {
		$instructorId = Val::int( $request->get_param( 'instructor_id' ) );
		$kind         = Val::string( $request->get_param( 'kind' ) );

		// The public catalogue is public offerings only; invite-only classes are
		// hidden from it and surfaced separately to the students granted access.
		$offerings = $this->repository->findAll( $instructorId, $kind, activeOnly: true, accessMode: Offering::ACCESS_PUBLIC );

		foreach ( $this->grantedInviteOnly( $instructorId, $kind ) as $granted ) {
			$offerings[] = $granted;
		}

		// Public listing: omit the private e-transfer destination email, and
		// attach the assigned instructor's display name so the front end can show
		// students who teaches each class.
		return new \WP_REST_Response( array_map( [ $this, 'present' ], $offerings ), 200 );
	}

	/**
	 * A public-facing offering array with the assigned instructor's name added —
	 * their real name or nickname, never the login (empty when the instructor
	 * account no longer exists). See {@see UserName::format()}.
	 *
	 * @return array<string, mixed>
	 */
	private function present( Offering $offering ): array {
		$out  = $offering->toArray( includeEtransferEmail: false );
		$user = get_userdata( $offering->instructorId );

		$out['instructor_name'] = UserName::format( $user instanceof \WP_User ? $user : null );

		return $out;
	}

	/**
	 * The active invite-only offerings the caller has been granted access to,
	 * matching the same instructor/kind filters as the public catalogue.
	 *
	 * @return list<Offering>
	 */
	private function grantedInviteOnly( int $instructorId, string $kind ): array {
		$grantedIds = $this->access->findGrantedOfferingIds( get_current_user_id() );
		if ( [] === $grantedIds ) {
			return [];
		}

		$out = [];
		foreach ( $grantedIds as $offeringId ) {
			$offering = $this->repository->findById( $offeringId );

			if (
				null === $offering
				|| ! $offering->isActive
				|| ! $offering->isInviteOnly()
				|| ( $instructorId > 0 && $offering->instructorId !== $instructorId )
				|| ( '' !== $kind && $offering->kind !== $kind )
			) {
				continue;
			}

			$out[] = $offering;
		}

		return $out;
	}

	public function create( \WP_REST_Request $request ): \WP_REST_Response|\WP_Error {
		$title = sanitize_text_field( Val::string( $request->get_param( 'title' ) ) );
		if ( '' === $title ) {
			return $this->invalid( __( 'A title is required.', 'unsupervised-schedular' ) );
		}

		$kind = Val::string( $request->get_param( 'kind' ) );
		if ( ! in_array( $kind, Offering::VALID_KINDS, true ) ) {
			return $this->invalid( __( 'Invalid offering kind.', 'unsupervised-schedular' ) );
		}

		$billingMode = Val::string( $request->get_param( 'billing_mode' ) ?? Offering::BILLING_ONE_TIME );
		if ( ! in_array( $billingMode, Offering::VALID_BILLING_MODES, true ) ) {
			return $this->invalid( __( 'Invalid billing mode.', 'unsupervised-schedular' ) );
		}

		$scheduleNote   = $this->nullableText( $request->get_param( 'schedule_note' ) );
		$etransferEmail = $this->nullableEmail( $request->get_param( 'etransfer_email' ) );

		$lengthError = $this->checkLengths( $title, $scheduleNote, $etransferEmail );
		if ( $lengthError instanceof \WP_Error ) {
			return $lengthError;
		}

		$offering = new Offering(
			instructorId:    get_current_user_id(),
			kind:            $kind,
			title:           $title,
			price:           $this->price( $request->get_param( 'price' ) ),
			currency:        sanitize_text_field( Val::string( $request->get_param( 'currency' ) ?? 'CAD' ) ),
			billingMode:     $billingMode,
			description:     $this->nullableText( $request->get_param( 'description' ) ),
			durationMinutes: $this->nullableInt( $request->get_param( 'duration_minutes' ) ),
			allowWeekly:     (bool) $request->get_param( 'allow_weekly' ),
			capacity:        $this->nullableInt( $request->get_param( 'capacity' ) ),
			termStart:       $this->nullableText( $request->get_param( 'term_start' ) ),
			termEnd:         $this->nullableText( $request->get_param( 'term_end' ) ),
			enrollmentDeadline: $this->nullableText( $request->get_param( 'enrollment_deadline' ) ),
			scheduleNote:    $scheduleNote,
			etransferEmail:  $etransferEmail,
			cancellationCutoffHours: $this->nullableInt( $request->get_param( 'cancellation_cutoff_hours' ) ),
			accessMode:      $this->accessMode( $request->get_param( 'access_mode' ), Offering::ACCESS_PUBLIC ),
			isActive:        null === $request->get_param( 'is_active' ) ? true : (bool) $request->get_param( 'is_active' ),
		);

		$id = $this->repository->insert( $offering );

		return new \WP_REST_Response( [ 'id' => $id ], 201 );
	}

	public function update( \WP_REST_Request $request ): \WP_REST_Response|\WP_Error {
		$id       = absint( Val::int( $request->get_param( 'id' ) ) );
		$existing = $this->repository->findById( $id );

		if ( null === $existing ) {
			return new \WP_Error( 'not_found', __( 'Offering not found.', 'unsupervised-schedular' ), [ 'status' => 404 ] );
		}

		if ( ! $this->ownsOrManagesAll( $existing ) ) {
			return new \WP_Error( 'forbidden', __( 'You cannot edit this offering.', 'unsupervised-schedular' ), [ 'status' => 403 ] );
		}

		$kind = $request->has_param( 'kind' ) ? Val::string( $request->get_param( 'kind' ) ) : $existing->kind;
		if ( ! in_array( $kind, Offering::VALID_KINDS, true ) ) {
			return $this->invalid( __( 'Invalid offering kind.', 'unsupervised-schedular' ) );
		}

		$billingMode = $request->has_param( 'billing_mode' ) ? Val::string( $request->get_param( 'billing_mode' ) ) : $existing->billingMode;
		if ( ! in_array( $billingMode, Offering::VALID_BILLING_MODES, true ) ) {
			return $this->invalid( __( 'Invalid billing mode.', 'unsupervised-schedular' ) );
		}

		$title          = $request->has_param( 'title' ) ? sanitize_text_field( Val::string( $request->get_param( 'title' ) ) ) : $existing->title;
		$scheduleNote   = $request->has_param( 'schedule_note' ) ? $this->nullableText( $request->get_param( 'schedule_note' ) ) : $existing->scheduleNote;
		$etransferEmail = $request->has_param( 'etransfer_email' ) ? $this->nullableEmail( $request->get_param( 'etransfer_email' ) ) : $existing->etransferEmail;

		$lengthError = $this->checkLengths( $title, $scheduleNote, $etransferEmail );
		if ( $lengthError instanceof \WP_Error ) {
			return $lengthError;
		}

		$offering = new Offering(
			instructorId:    $existing->instructorId,
			kind:            $kind,
			title:           $title,
			price:           $request->has_param( 'price' ) ? $this->price( $request->get_param( 'price' ) ) : $existing->price,
			currency:        $request->has_param( 'currency' ) ? sanitize_text_field( Val::string( $request->get_param( 'currency' ) ) ) : $existing->currency,
			billingMode:     $billingMode,
			description:     $request->has_param( 'description' ) ? $this->nullableText( $request->get_param( 'description' ) ) : $existing->description,
			durationMinutes: $request->has_param( 'duration_minutes' ) ? $this->nullableInt( $request->get_param( 'duration_minutes' ) ) : $existing->durationMinutes,
			allowWeekly:     $request->has_param( 'allow_weekly' ) ? (bool) $request->get_param( 'allow_weekly' ) : $existing->allowWeekly,
			capacity:        $request->has_param( 'capacity' ) ? $this->nullableInt( $request->get_param( 'capacity' ) ) : $existing->capacity,
			termStart:       $request->has_param( 'term_start' ) ? $this->nullableText( $request->get_param( 'term_start' ) ) : $existing->termStart,
			termEnd:         $request->has_param( 'term_end' ) ? $this->nullableText( $request->get_param( 'term_end' ) ) : $existing->termEnd,
			enrollmentDeadline: $request->has_param( 'enrollment_deadline' ) ? $this->nullableText( $request->get_param( 'enrollment_deadline' ) ) : $existing->enrollmentDeadline,
			scheduleNote:    $scheduleNote,
			etransferEmail:  $etransferEmail,
			cancellationCutoffHours: $request->has_param( 'cancellation_cutoff_hours' ) ? $this->nullableInt( $request->get_param( 'cancellation_cutoff_hours' ) ) : $existing->cancellationCutoffHours,
			accessMode:      $request->has_param( 'access_mode' ) ? $this->accessMode( $request->get_param( 'access_mode' ), $existing->accessMode ) : $existing->accessMode,
			isActive:        $request->has_param( 'is_active' ) ? (bool) $request->get_param( 'is_active' ) : $existing->isActive,
			id:              $id,
		);

		$this->repository->update( $id, $offering );

		return new \WP_REST_Response( $offering->toArray(), 200 );
	}

	public function delete( \WP_REST_Request $request ): \WP_REST_Response|\WP_Error {
		$id       = absint( Val::int( $request->get_param( 'id' ) ) );
		$existing = $this->repository->findById( $id );

		if ( null === $existing ) {
			return new \WP_Error( 'not_found', __( 'Offering not found.', 'unsupervised-schedular' ), [ 'status' => 404 ] );
		}

		if ( ! $this->ownsOrManagesAll( $existing ) ) {
			return new \WP_Error( 'forbidden', __( 'You cannot delete this offering.', 'unsupervised-schedular' ), [ 'status' => 403 ] );
		}

		$this->repository->delete( $id );

		return new \WP_REST_Response( null, 204 );
	}

	public function canManage(): bool {
		return is_user_logged_in() && current_user_can( RoleManager::CAP_MANAGE_OFFERINGS );
	}

	/**
	 * Reading the offerings catalogue has no anonymous consumer, so it stays
	 * behind a login. Students reach it through the booking flow, and studio
	 * admins and instructors reach it from the block editor's group-class
	 * pickers — an administrator holds `manage_offerings` but not
	 * `book_lesson`, so both capabilities open the listing.
	 */
	public function canRead(): bool {
		return is_user_logged_in()
			&& ( current_user_can( RoleManager::CAP_BOOK_LESSON )
				|| current_user_can( RoleManager::CAP_MANAGE_OFFERINGS ) );
	}

	/**
	 * An offering may be changed by its owning instructor or by a studio admin
	 * (identified by the studio-only manage_instructors capability).
	 */
	private function ownsOrManagesAll( Offering $offering ): bool {
		return get_current_user_id() === $offering->instructorId
			|| current_user_can( RoleManager::CAP_MANAGE_INSTRUCTORS );
	}

	private function invalid( string $message ): \WP_Error {
		return new \WP_Error( 'invalid_offering', $message, [ 'status' => 400 ] );
	}

	/**
	 * Reject any fixed-size field whose value exceeds its column length, so an
	 * over-long value is refused with a clear 400 rather than silently dropped
	 * by the database.
	 */
	private function checkLengths( string $title, ?string $scheduleNote, ?string $etransferEmail ): ?\WP_Error {
		$fields = [
			[ __( 'title', 'unsupervised-schedular' ), $title, Offering::MAX_TITLE_LENGTH ],
			[ __( 'schedule note', 'unsupervised-schedular' ), $scheduleNote, Offering::MAX_SCHEDULE_NOTE_LENGTH ],
			[ __( 'e-transfer email', 'unsupervised-schedular' ), $etransferEmail, Offering::MAX_ETRANSFER_EMAIL_LENGTH ],
		];

		foreach ( $fields as [ $name, $value, $max ] ) {
			if ( null !== $value && mb_strlen( $value ) > $max ) {
				return $this->invalid(
					sprintf(
						/* translators: 1: field name, 2: maximum character count. */
						__( 'The %1$s must be %2$d characters or fewer.', 'unsupervised-schedular' ),
						$name,
						$max
					)
				);
			}
		}

		return null;
	}

	private function price( mixed $value ): float {
		return max( 0.0, Val::float( $value ) );
	}

	private function nullableEmail( mixed $value ): ?string {
		$email = sanitize_email( Val::string( $value ) );

		return '' !== $email ? $email : null;
	}

	private function accessMode( mixed $value, string $fallback ): string {
		$mode = Val::string( $value );

		return in_array( $mode, Offering::VALID_ACCESS_MODES, true ) ? $mode : $fallback;
	}

	private function nullableInt( mixed $value ): ?int {
		return ( null === $value || '' === $value ) ? null : Val::int( $value );
	}

	private function nullableText( mixed $value ): ?string {
		if ( null === $value || '' === $value ) {
			return null;
		}

		return sanitize_text_field( Val::string( $value ) );
	}
}