diff --git a/src/modules/configuration.js b/src/modules/configuration.js
new file mode 100644
index 0000000..12461f6
--- /dev/null
+++ b/src/modules/configuration.js
@@ -0,0 +1,6 @@
+export const UnitsInGroupCount = 6
+export const RowsOfGroupsCount = 6
+export const ColumnsOfGroupsCount = 3
+export const StorageCenterLocation = { x: 8, y: 8, w: UnitsInGroupCount, h: 1 }
+// -1 by zarezerwować przestrzeń dla magazynu
+export const UnitsCount = (ColumnsOfGroupsCount * RowsOfGroupsCount - 1) * UnitsInGroupCount
diff --git a/src/modules/shop.js b/src/modules/shop.js
new file mode 100644
index 0000000..a761e5d
--- /dev/null
+++ b/src/modules/shop.js
@@ -0,0 +1,63 @@
+import { fromTable } from './utilities'
+import { RowsOfGroupsCount, StorageCenterLocation, UnitsCount } from './configuration'
+
+/**
+ * Zwraca koordynaty półek przy danym kafelku ścieżki
+ * @param {number} gridX 
+ * @param {number} gridY 
+ * @returns {{x:number;y:number}[]} Koordynaty sąsiednich półek do kafelka
+ */
+export function nearbyStorageUnitsCoords(gridX, gridY) {
+  function outsideOfStorageCenter(v) {
+    const { x, y, w, h } = StorageCenterLocation
+    return v.x <= x || v.x >= x + w || v.y <= y || v.y >= y + h
+  }
+  return (gridX % UnitsInGroupCount == 0 
+    ? (gridY % 3 == 1
+      ? /* skrzyżowanie */      [[-1, -1], [-1, 1], [1, -1], [1,1]]
+      : /* korytarz góra-dół */ [[-1, 0], [1, 0]])
+    : /* korytarz lewo-prawo */ [[0, -1], [0, 1]])
+    .map(([xoff, yoff]) => ({ x: gridX + xoff, y: yGrid + yoff }))
+    .filter(outsideOfStorageCenter)
+}
+
+/**
+ * Zwraca indeksy półek przy danym kafelku ścieżki
+ * @param {number} gridX 
+ * @param {number} gridY 
+ * @returns {{x:number;y:number}[]} Indeksy sąsiednich półek do kafelka
+ */
+export function nearbyStorageUnitsIndexes(gridX, gridY) {
+  return nearbyStorageUnitsCoords(gridX, gridY)
+    .map(({ x, y }) => x * UnitsCount + y * UnitsCount * RowsOfGroupsCount)
+}
+
+class Shop {
+  constructor() {
+    // pełna lista wszystkich możliwych produktów dostępnych w sklepie,
+    // w formacie [{ name: '', category: '', ... }, { name: '', category: '', ...}, ...]
+    // kolejność przedmiotów jest niezmienna, przez co można przechowywać ich indeksy zamiast referencji
+    this.products = fromTable(
+               ['name',    'category', 'intrest', '', 'icon'],
+      /*  0 */ ['Lodówka', 'AGD',      0.4,       '', '<path-to-icon>']
+    )
+
+    this.productPlacement = [...Array(UnitsCount)].map(_ => ({
+      productId: null,
+      count: 0,
+    }))
+  }
+
+  /**
+   * Zwraca listę produktów w okolicy danego kafelka ścieżki
+   * @param {number} gridX 
+   * @param {number} gridY 
+   */
+  nearbyProducts(gridX, gridY) {
+    return nearbyStorageUnitsIndexes(gridX, gridY)
+      .map(i => this.productPlacement[i])
+  }
+}
+
+const shop = new Shop()
+export default shop
diff --git a/src/modules/utilities.js b/src/modules/utilities.js
new file mode 100644
index 0000000..2203003
--- /dev/null
+++ b/src/modules/utilities.js
@@ -0,0 +1,23 @@
+/**
+ * Converts table like data to array of objects, where keys are from header
+ * and values are at the same offset as header for that field
+ * @param {string[]} header 
+ * @param {...any[]} rows 
+ * @returns 
+ */
+export function fromTable(header, ...rows) {
+  function tupleToRecord(names, array) {
+    return names.reduce((p, v, i) => ({ ...p, [v]: array[i] }), {})
+  }
+  return rows.reduce((p, row) => [...p, tupleToRecord(header, row)], [])
+}
+
+/** 
+ * returns v truncated to range [lo, hi]
+ * @param {number} v Value possibly out of range
+ * @param {number} lo Minimum return value
+ * @param {number} hi Maximum return value
+ * */
+export function clamp(v, lo, hi) {
+  return v <= lo ? lo : v >= hi ? hi : v
+}