Add recurring expense functionality (#263)

* code complete

* Smaller updates

* delete ambitious TODOs (add to PR)

* add transactionality to recurring expense creation

* Remove unnecessary `let`s

* Add default english labels to non-en-US translations

* Accept `es.json` translations

* add condition to ensure links are only modified when applicable

prisma/migrations/20241103205027_add_recurring_expenses/migration.sql

@@ -0,0 +1,29 @@
+-- CreateEnum
+CREATE TYPE "RecurrenceRule" AS ENUM ('NONE', 'DAILY', 'WEEKLY', 'MONTHLY');
+
+-- AlterTable
+ALTER TABLE "Expense" ADD COLUMN     "recurrenceRule" "RecurrenceRule" DEFAULT 'NONE',
+ADD COLUMN     "recurringExpenseLinkId" TEXT;
+
+-- CreateTable
+CREATE TABLE "RecurringExpenseLink" (
+    "id" TEXT NOT NULL,
+    "groupId" TEXT NOT NULL,
+    "currentFrameExpenseId" TEXT NOT NULL,
+    "nextExpenseCreatedAt" TIMESTAMP(3),
+    "nextExpenseDate" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "RecurringExpenseLink_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "RecurringExpenseLink_currentFrameExpenseId_key" ON "RecurringExpenseLink"("currentFrameExpenseId");
+
+-- CreateIndex
+CREATE INDEX "RecurringExpenseLink_groupId_idx" ON "RecurringExpenseLink"("groupId");
+
+-- CreateIndex
+CREATE INDEX "RecurringExpenseLink_groupId_nextExpenseCreatedAt_nextExpen_idx" ON "RecurringExpenseLink"("groupId", "nextExpenseCreatedAt", "nextExpenseDate" DESC);
+
+-- AddForeignKey
+ALTER TABLE "RecurringExpenseLink" ADD CONSTRAINT "RecurringExpenseLink_currentFrameExpenseId_fkey" FOREIGN KEY ("currentFrameExpenseId") REFERENCES "Expense"("id") ON DELETE CASCADE ON UPDATE CASCADE;

prisma/schema.prisma

@@ -55,6 +55,10 @@ model Expense {
   createdAt       DateTime          @default(now())
   documents       ExpenseDocument[]
   notes           String?
+
+  recurrenceRule  RecurrenceRule?    @default(NONE)
+  recurringExpenseLink RecurringExpenseLink?
+  recurringExpenseLinkId String?
 }
 
 model ExpenseDocument {
@@ -73,6 +77,29 @@ enum SplitMode {
   BY_AMOUNT
 }
 
+model RecurringExpenseLink {
+  id String @id
+  groupId   String
+  currentFrameExpense Expense @relation(fields: [currentFrameExpenseId], references: [id], onDelete: Cascade)
+  currentFrameExpenseId String @unique
+
+  // Note: We do not want to link to the next expense because once it is created, it should be 
+  // treated as it's own independent entity. This means that if a user wants to delete an Expense
+  // and any prior related recurring expenses, they'll need to delete them one by one.
+  nextExpenseCreatedAt DateTime?
+  nextExpenseDate DateTime
+
+  @@index([groupId])
+  @@index([groupId, nextExpenseCreatedAt, nextExpenseDate(sort: Desc)])
+}
+
+enum RecurrenceRule {
+  NONE
+  DAILY
+  WEEKLY
+  MONTHLY
+}
+
 model ExpensePaidFor {
   expense       Expense     @relation(fields: [expenseId], references: [id], onDelete: Cascade)
   participant   Participant @relation(fields: [participantId], references: [id], onDelete: Cascade)