import { Router } from 'express';
import { AppError } from '../lib/errors.js';
import { requireAuth, requirePolicy } from '../middleware/auth.js';
import { requireIdempotencyKey } from '../middleware/idempotency.js';
import { buildIdempotencyKey, readIdempotentResult, writeIdempotentResult } from '../services/idempotency-store.js';
import { commandBaseSchema } from '../contracts/commands/command-base.js';

function parseBody(body) {
  const parsed = commandBaseSchema.safeParse(body || {});
  if (!parsed.success) {
    throw new AppError('VALIDATION_ERROR', 'Invalid command payload', 400, {
      issues: parsed.error.issues,
    });
  }
  return parsed.data;
}

function createCommandResponse(route, requestId, idempotencyKey) {
  return {
    accepted: true,
    route,
    commandId: `${route}:${Date.now()}`,
    idempotencyKey,
    requestId,
  };
}

function buildCommandHandler(policyAction, policyResource) {
  return async (req, res, next) => {
    try {
      parseBody(req.body);

      const route = `${req.baseUrl}${req.route.path}`;
      const compositeKey = buildIdempotencyKey({
        userId: req.actor.uid,
        route,
        idempotencyKey: req.idempotencyKey,
      });

      const existing = await readIdempotentResult(compositeKey);
      if (existing) {
        return res.status(existing.statusCode).json(existing.payload);
      }

      const payload = createCommandResponse(route, req.requestId, req.idempotencyKey);
      const persisted = await writeIdempotentResult({
        compositeKey,
        userId: req.actor.uid,
        route,
        idempotencyKey: req.idempotencyKey,
        payload,
        statusCode: 200,
      });
      return res.status(persisted.statusCode).json(persisted.payload);
    } catch (error) {
      return next(error);
    }
  };
}

export function createCommandsRouter() {
  const router = Router();

  router.post(
    '/orders/create',
    requireAuth,
    requireIdempotencyKey,
    requirePolicy('orders.create', 'order'),
    buildCommandHandler('orders.create', 'order')
  );

  router.post(
    '/orders/:orderId/update',
    requireAuth,
    requireIdempotencyKey,
    requirePolicy('orders.update', 'order'),
    buildCommandHandler('orders.update', 'order')
  );

  router.post(
    '/orders/:orderId/cancel',
    requireAuth,
    requireIdempotencyKey,
    requirePolicy('orders.cancel', 'order'),
    buildCommandHandler('orders.cancel', 'order')
  );

  router.post(
    '/shifts/:shiftId/change-status',
    requireAuth,
    requireIdempotencyKey,
    requirePolicy('shifts.change-status', 'shift'),
    buildCommandHandler('shifts.change-status', 'shift')
  );

  router.post(
    '/shifts/:shiftId/assign-staff',
    requireAuth,
    requireIdempotencyKey,
    requirePolicy('shifts.assign-staff', 'shift'),
    buildCommandHandler('shifts.assign-staff', 'shift')
  );

  router.post(
    '/shifts/:shiftId/accept',
    requireAuth,
    requireIdempotencyKey,
    requirePolicy('shifts.accept', 'shift'),
    buildCommandHandler('shifts.accept', 'shift')
  );

  return router;
}