feat: complete day 2

day2/services/PaginationService.js

@@ -0,0 +1,82 @@
+const { Op } = require("sequelize");
+
+class PaginationService {
+  /**
+   * Handle offset-based pagination with sorting
+   */
+  static async paginateWithSort(model, options = {}) {
+    const {
+      page = 1,
+      limit = 10,
+      sort = "id",
+      direction = "ASC",
+      where = {},
+    } = options;
+
+    const offset = (page - 1) * limit;
+    const order = [[sort, direction.toUpperCase()]];
+
+    const { count, rows } = await model.findAndCountAll({
+      where,
+      order,
+      limit: parseInt(limit),
+      offset: parseInt(offset),
+    });
+
+    const totalPages = Math.ceil(count / limit);
+
+    return {
+      total: count,
+      page: parseInt(page),
+      totalPages,
+      list: rows,
+    };
+  }
+
+  /**
+   * Handle cursor-based pagination
+   */
+  static async paginateWithCursor(model, options = {}) {
+    const {
+      id,
+      limit = 10,
+      sort = "id",
+      direction = "ASC",
+      where = {},
+    } = options;
+
+    const order = [[sort, direction.toUpperCase()]];
+    const cursorWhere = {
+      ...where,
+      [sort]: {
+        [direction.toUpperCase() === "ASC" ? Op.gt : Op.lt]: id,
+      },
+    };
+
+    const rows = await model.findAll({
+      where: cursorWhere,
+      order,
+      limit: parseInt(limit),
+    });
+
+    return {
+      id: parseInt(id),
+      list: rows,
+    };
+  }
+
+  /**
+   * Get odd order IDs
+   */
+  static async getOddOrders(model) {
+    return await model.findAll({
+      where: {
+        id: {
+          [Op.mod]: [2, 1], // id % 2 = 1 (odd numbers)
+        },
+      },
+    });
+  }
+}
+
+module.exports = PaginationService;