1 files changed, 55 insertions, 2 deletions
diff --git a/gui/src/ajax/backend.ts b/gui/src/ajax/backend.ts
index d58e513..90a7ea5 100644
--- a/gui/src/ajax/backend.ts
+++ b/gui/src/ajax/backend.ts
@@ -1,5 +1,58 @@
+import { BalanceMap, newCategoryBalanceMapFromDto } from "../types/balanceMap";
+import { BudgetMap, newBudgetMapFromDto } from "../types/budgetMap";
+import { Category, newCategoryFromDto } from "../types/category";
+
 const backendUrl = "http://localhost:8000";
 
-async function getAllAccounts(): Promise<Account[]> {
-  return;
+function makeGetter<T>(params: FetcherMakerParams<T>): Getter<T> {
+  const parser =
+    "parser" in params
+      ? params.parser
+      : (dto: unknown[]) => <T>dto.map(params.elementParser);
+
+  return async function () {
+    const response = await fetch(`${backendUrl}${params.path}`);
+    const dto = await response.json();
+
+    try {
+      return parser(dto);
+    } catch (err) {
+      console.error(`Error parsing DTO. ${err?.toString() ?? ""}`);
+      return null;
+    }
+  };
 }
+
+export const getAllCategories: Getter<Category[]> = async () => {
+  const balances = await getAllCategoryBalances();
+  const budgets = await getAllCurrentCategoryBudgets();
+  return makeGetter<Category[]>({
+    path: "/category",
+    elementParser: newCategoryFromDto(balances, budgets),
+  })();
+};
+
+export const getAllCategoryBalances: Getter<BalanceMap<Category>> = makeGetter<
+  BalanceMap<Category>
+>({
+  path: "/balance/category",
+  parser: newCategoryBalanceMapFromDto,
+});
+
+export const getAllCurrentCategoryBudgets: Getter<BudgetMap<Category>> =
+  makeGetter<BudgetMap<Category>>({
+    path: "/budget/category?current",
+    parser: newBudgetMapFromDto,
+  });
+
+type FetcherMakerParams<T> = {
+  path: string;
+} & AnyParser<T>;
+
+type Parser<T> = { parser: (dto: unknown) => T | null };
+type ElementParser<T> = { elementParser: (dto: unknown) => T | null };
+type AnyParser<T> = T extends any[]
+  ? Parser<T> | ElementParser<T[number]>
+  : Parser<T>;
+
+type Getter<T> = () => Promise<T | null>;