add coords

mobile/lib/models/coordinate.dart

@@ -3,4 +3,8 @@ class Coordinate {
   final double y;
 
   Coordinate({required this.x, required this.y});
+
+  Coordinate.fromJson(Map<String, dynamic> json)
+      : x = json["x"],
+        y = json["y"];
 }

mobile/lib/server/backend_server.dart

@@ -3,6 +3,7 @@ import 'dart:convert';
 import 'package:flutter/material.dart';
 import 'package:http/http.dart' as http;
 import 'package:mobile/models/cart_item.dart';
+import 'package:mobile/models/coordinate.dart';
 import 'package:mobile/models/product.dart';
 import 'package:mobile/models/receipt.dart';
 import 'package:mobile/models/user.dart';
@@ -232,4 +233,26 @@ class BackendServer implements Server {
   Image productImage(int productId) {
     return Image.network("$_apiUrl/products/image.png?product_id=$productId");
   }
+
+  @override
+  Future<Result<Coordinate, String>> productCoords(int id) async {
+    final res = await _getJson(
+      path: "/products/coords?product_id=$id",
+      headers: {
+        "Content-Type": "application/json",
+        "Accept": "application/json",
+      },
+    );
+    return res.flatMap((body) {
+      if (body["ok"]) {
+        if (body["found"]) {
+          return Ok(
+              (Coordinate.fromJson(body["coords"] as Map<String, dynamic>)));
+        }
+        return const Err("Product has no coordinate");
+      } else {
+        return Err(body["msg"]);
+      }
+    });
+  }
 }

mobile/lib/server/mock_server.dart

@@ -152,4 +152,9 @@ class MockServer implements Server {
   Image productImage(int productId) {
     return Image.asset("assets/placeholder.png");
   }
+
+  @override
+  Future<Result<Coordinate, String>> productCoords(int id) async {
+    return Ok(Coordinate(x: 200, y: 100));
+  }
 }

mobile/lib/server/server.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:mobile/models/cart_item.dart';
+import 'package:mobile/models/coordinate.dart';
 import 'package:mobile/models/product.dart';
 import 'package:mobile/models/receipt.dart';
 import 'package:mobile/models/user.dart';
@@ -31,6 +32,8 @@ abstract class Server {
   Future<Result<List<ReceiptHeader>, String>> allReceipts(String token);
   Future<Result<Receipt, String>> oneReceipt(String token, int id);
 
+  Future<Result<Coordinate, String>> productCoords(int id);
+
   Image productImage(int productId);
 }