import express, {Request, Response} from 'express';
import * as UsersService from './users.admin.service.js';
import {toPermissions} from '../admin.schema.js';
import {sendServerError} from '../admin.errors.js';

export const usersAdminRouter = express.Router();

/**
 * User administration. Mounted behind requireAppAccess('admin'), so every
 * handler here can assume res.locals.admin is an admin.
 *
 * The guards below exist because this API can lock its own operators out: the
 * only way to grant a permission is through these routes, so an admin who
 * removes the last `admin` permission leaves nobody who can put it back short
 * of a manual SQL statement in production.
 */

const conflict = (res: Response, message: string): void => {
	res.status(409).send({status: 'CONFLICT', message});
};

const notFound = (res: Response): void => {
	res.status(404).send({status: 'NOT_FOUND', message: 'Benutzer nicht gefunden.'});
};

/**
 * @swagger
 * /admin/users:
 *      get:
 *          summary: List all users with their app permissions and status
 *          tags: [admin]
 *          responses:
 *              200:
 *                  description: Success
 *              401:
 *                  description: Not signed in
 *              403:
 *                  description: Missing the admin permission
 */
usersAdminRouter.get('/', async (req: Request, res: Response) => {
	try {
		res.status(200).send(await UsersService.listUsers());
	} catch (e: any) {
		sendServerError(res, e);
	}
});

/**
 * @swagger
 * /admin/users/{userId}:
 *      get:
 *          summary: One user with their active sessions and passkey count
 *          tags: [admin]
 *          parameters:
 *              - in: path
 *                name: userId
 *                required: true
 *                schema:
 *                    type: string
 *          responses:
 *              200:
 *                  description: Success
 *              404:
 *                  description: Unknown user
 */
usersAdminRouter.get('/:userId', async (req: Request, res: Response) => {
	try {
		const detail = await UsersService.getUserDetail(req.params.userId);
		if (!detail) {
			notFound(res);
			return;
		}
		res.status(200).send(detail);
	} catch (e: any) {
		sendServerError(res, e);
	}
});

/**
 * @swagger
 * /admin/users/{userId}/permissions:
 *      put:
 *          summary: Replace a user's app permissions
 *          description: Refuses to remove the caller's own admin permission or the last remaining active admin.
 *          tags: [admin]
 *          requestBody:
 *              required: true
 *              content:
 *                  application/json:
 *                      schema:
 *                          type: object
 *                          properties:
 *                              permissions:
 *                                  type: array
 *                                  description: >
 *                                      One entry per (app, role). `access` is the only role today.
 *                                      A plain array of app names is also accepted and means the
 *                                      same at the `access` role.
 *                                  items:
 *                                      type: object
 *                                      properties:
 *                                          app:
 *                                              type: string
 *                                              enum: [calendar, feedback, tickets, admin]
 *                                          role:
 *                                              type: string
 *                                              enum: [access]
 *          responses:
 *              200:
 *                  description: Success
 *              400:
 *                  description: Invalid app or role
 *              409:
 *                  description: Would lock the last admin out
 */
usersAdminRouter.put('/:userId/permissions', async (req: Request, res: Response) => {
	try {
		const userId = req.params.userId;

		// `permissions: [{app, role}]` is the real shape; `apps: ['tickets']` is
		// accepted as shorthand for the same thing at the `access` role, so a
		// caller that predates roles keeps working.
		const permissions = toPermissions(req.body?.permissions ?? req.body?.apps);

		if (!permissions) {
			res.status(400).send({status: 'BAD_REQUEST', message: 'Ungültige Berechtigungsliste.'});
			return;
		}

		if (!(await UsersService.userExists(userId))) {
			notFound(res);
			return;
		}

		const target = await UsersService.loadAccess(userId);
		const keepsAdmin = permissions.some(permission => permission.app === 'admin');
		const losesAdmin = Boolean(target?.apps.includes('admin')) && !keepsAdmin;

		// Self-lockout is checked here because it needs the caller's identity,
		// which the service has no business knowing. The last-admin check is
		// NOT done here: it has to be inside the write transaction to survive
		// two admins acting at the same time (see setPermissionsGuarded).
		if (losesAdmin && userId === res.locals.admin.id) {
			conflict(res, 'Du kannst dir die Admin-Berechtigung nicht selbst entziehen.');
			return;
		}

		const result = await UsersService.setPermissionsGuarded(userId, permissions, res.locals.admin.id);
		if (result === 'last-admin') {
			conflict(res, 'Die letzte Admin-Berechtigung kann nicht entzogen werden.');
			return;
		}

		res.status(200).send(await UsersService.getUserDetail(userId));
	} catch (e: any) {
		sendServerError(res, e);
	}
});

/**
 * @swagger
 * /admin/users/{userId}/disable:
 *      post:
 *          summary: Disable a user and revoke all of their sessions
 *          tags: [admin]
 *          responses:
 *              200:
 *                  description: Success
 *              409:
 *                  description: Would disable the caller or the last admin
 */
usersAdminRouter.post('/:userId/disable', async (req: Request, res: Response) => {
	try {
		const userId = req.params.userId;

		if (userId === res.locals.admin.id) {
			conflict(res, 'Du kannst dich nicht selbst deaktivieren.');
			return;
		}

		const target = await UsersService.loadAccess(userId);
		if (!target) {
			notFound(res);
			return;
		}

		const result = await UsersService.disableUserGuarded(userId);
		if (result === 'last-admin') {
			conflict(res, 'Der letzte aktive Admin kann nicht deaktiviert werden.');
			return;
		}

		res.status(200).send(await UsersService.getUserDetail(userId));
	} catch (e: any) {
		sendServerError(res, e);
	}
});

/**
 * @swagger
 * /admin/users/{userId}/enable:
 *      post:
 *          summary: Re-enable a disabled user
 *          description: Does not restore sessions - the user signs in again.
 *          tags: [admin]
 *          responses:
 *              200:
 *                  description: Success
 */
usersAdminRouter.post('/:userId/enable', async (req: Request, res: Response) => {
	try {
		if (!(await UsersService.userExists(req.params.userId))) {
			notFound(res);
			return;
		}

		await UsersService.enableUser(req.params.userId);
		res.status(200).send(await UsersService.getUserDetail(req.params.userId));
	} catch (e: any) {
		sendServerError(res, e);
	}
});

/**
 * @swagger
 * /admin/users/{userId}/sessions/{sessionId}:
 *      delete:
 *          summary: Revoke one session of a user
 *          tags: [admin]
 *          responses:
 *              204:
 *                  description: Revoked
 *              404:
 *                  description: Unknown session for this user
 */
usersAdminRouter.delete('/:userId/sessions/:sessionId', async (req: Request, res: Response) => {
	try {
		const revoked = await UsersService.revokeSession(req.params.userId, req.params.sessionId);
		if (!revoked) {
			res.status(404).send({status: 'NOT_FOUND', message: 'Sitzung nicht gefunden.'});
			return;
		}
		res.status(204).send();
	} catch (e: any) {
		sendServerError(res, e);
	}
});