awesome ui changes and expense split restructured

src/lib/store/expense-store.ts

@@ -0,0 +1,96 @@
+"use client";
+import { create } from "zustand";
+import { calculateSplits, type Payment } from "@/lib/utils/expense";
+import type { Session } from "next-auth";
+import type { PublicUser } from "next-auth";
+
+export enum SplitTypeEnum {
+  Fixed = "fixed",
+  Percentage = "percentage",
+  Equal = "equal",
+}
+export type SplitType = keyof typeof SplitTypeEnum;
+export const splitTypeKeys = Object.keys(SplitTypeEnum);
+
+interface ExpenseStore {
+  amount: number;
+  session: Session | null;
+
+  participants: PublicUser[];
+  friendTarget?: string;
+  splitType: SplitType;
+  payments: Payment[];
+  splits: Record<string, string>;
+
+  setAmount: (amount: number) => void;
+  setSession: (session: Session) => void;
+
+  addParticipant: (user: PublicUser) => void;
+  removeParticipant: (userId: string) => void;
+
+  setFriendTarget: (id?: string) => void;
+  setSplitType: (type: SplitType) => void;
+  setPayments: (payments: Array<Payment>) => void;
+  recalculateSplits: () => void;
+  resetExpenseStore: () => void;
+}
+
+const defaultValues: Pick<
+  ExpenseStore,
+  | "amount"
+  | "participants"
+  | "friendTarget"
+  | "splitType"
+  | "payments"
+  | "splits"
+> = {
+  amount: 0,
+  participants: [],
+  friendTarget: undefined,
+  splitType: "Equal",
+  payments: [],
+  splits: {},
+};
+
+export const useExpenseStore = create<ExpenseStore>((set, get) => ({
+  ...defaultValues,
+  session: null,
+  setAmount: (amount) => set({ amount }),
+  setSession: (session) =>
+    set(
+      {
+        session,
+        participants: [session.user],
+        payments: [{ amount: get().amount, userId: session.user.id }],
+      },
+      false
+    ),
+
+  addParticipant: (newUser) => {
+    const { participants } = get();
+    if (!participants.find((user) => user.id === newUser.id)) {
+      set({ participants: [...participants, newUser] });
+    }
+  },
+
+  removeParticipant: (userId) => {
+    const filtered = get().participants.filter((user) => user.id !== userId);
+    set({ participants: filtered });
+  },
+
+  setFriendTarget: (id) => set({ friendTarget: id }),
+  setSplitType: (type) => set({ splitType: type }),
+  setPayments: (payments) => set({ payments }),
+
+  recalculateSplits: () => {
+    const { amount, participants, splitType } = get();
+    const splits = calculateSplits({
+      amount,
+      users: participants.map((u) => u.id!),
+      splitType,
+    });
+    set({ splits });
+  },
+
+  resetExpenseStore: () => set(defaultValues),
+}));