back: Add getSiblings method in Region Controller.

This commit introduces a new method getSiblings in regionController.js.
This method seeks to return sibling regions for a given region ID and
hierarchy ID. It also modifies the Hierarchy model to include a
getSiblings method and updates the regionRoutes.js to add a new route
for this functionality.

Issue: #159

Signed-off-by: Nikolay Martyanov <[email protected]>

backend/src/controllers/regionController.js

@@ -400,3 +400,29 @@ exports.getSubregions = async (req, res) => {
   ) : { message: subregions.message };
   return res.status(subregions.status).json(result);
 };
+
+exports.getSiblings = async (req, res) => {
+  const { regionId } = req.params;
+  const hierarchyId = req.query.hierarchyId || 1;
+
+  console.log('regionId: ', regionId);
+
+  // Check if the region exists
+  const region = await Hierarchy.findOne({
+    where: {
+      regionId,
+      hierarchyId,
+    },
+  });
+  if (!region) {
+    return res.status(404).json({ message: 'Region not found' });
+  }
+
+  try {
+    const siblings = await region.getSiblings();
+    return res.status(200).json(siblings.map((sibling) => sibling.toApiFormat()));
+  } catch (err) {
+    console.error(err);
+    return res.status(500).json({ message: 'Internal Server Error' });
+  }
+};

backend/src/models/Hierarchy.js

@@ -11,6 +11,15 @@ class Hierarchy extends Model {
     };
   }
 
+  async getSiblings() {
+    return Hierarchy.findAll({
+      where: {
+        parentId: this.parentId,
+        hierarchyId: this.hierarchyId,
+      },
+    });
+  }
+
   static async getAncestors(regionId, hierarchyId) {
     const ancestors = await sequelize.query(`
             WITH RECURSIVE Ancestors AS (

backend/src/routes/regionRoutes.js

@@ -104,4 +104,20 @@ router.get(
   },
 );
 
+router.get(
+  '/:regionId/siblings',
+  ...[
+    check('regionId').isInt().withMessage('Region ID must be an integer'),
+    check('hierarchyId').optional().isInt().withMessage('Hierarchy ID must be an integer'),
+  ],
+  async (req, res) => {
+    const errors = validationResult(req);
+    if (!errors.isEmpty()) {
+      const errorMessages = errors.array().map((error) => error.msg);
+      return res.status(400).json({ errors: errorMessages });
+    }
+    return regionController.getSiblings(req, res);
+  },
+);
+
 module.exports = router;