backend/api_test.go

@@ -2,10 +2,11 @@ package main
 
 import (
 	"fmt"
-	"github.com/gavv/httpexpect/v2"
 	"strconv"
 	"testing"
 	"time"
+
+	"github.com/gavv/httpexpect/v2"
 )
 
 const (
@@ -963,3 +964,88 @@ func createTestAllowance(e *httpexpect.Expect, name string, target float64, weig
 func createTestTask(e *httpexpect.Expect) int {
 	return createTestTaskWithAmount(e, 100)
 }
+
+// Transfer tests
+func TestTransferSuccessful(t *testing.T) {
+	e := startServer(t)
+
+	// Create two allowances for user 1
+	createTestAllowance(e, "From Allowance", 100, 1)
+	createTestAllowance(e, "To Allowance", 100, 1)
+
+	// Add 30 to allowance 1
+	req := map[string]interface{}{"amount": 30, "description": "funds"}
+	e.POST("/user/1/allowance/1/add").WithJSON(req).Expect().Status(200)
+
+	// Transfer 10 from 1 to 2
+	transfer := map[string]interface{}{"from": 1, "to": 2, "amount": 10}
+	e.POST("/transfer").WithJSON(transfer).Expect().Status(200).JSON().Object().Value("message").IsEqual("Transfer successful")
+
+	// Verify balances
+	allowances := e.GET("/user/1/allowance").Expect().Status(200).JSON().Array()
+	allowances.Value(1).Object().Value("progress").Number().InDelta(20.0, 0.01)
+	allowances.Value(2).Object().Value("progress").Number().InDelta(10.0, 0.01)
+}
+
+func TestTransferCapsAtTarget(t *testing.T) {
+	e := startServer(t)
+
+	// Create two allowances
+	createTestAllowance(e, "From Allowance", 100, 1)
+	createTestAllowance(e, "To Allowance", 5, 1)
+
+	// Add 10 to allowance 1
+	req := map[string]interface{}{"amount": 10, "description": "funds"}
+	e.POST("/user/1/allowance/1/add").WithJSON(req).Expect().Status(200)
+
+	// Transfer 10 from 1 to 2, but to only needs 5
+	transfer := map[string]interface{}{"from": 1, "to": 2, "amount": 10}
+	e.POST("/transfer").WithJSON(transfer).Expect().Status(200)
+
+	// Verify capped transfer
+	allowances := e.GET("/user/1/allowance").Expect().Status(200).JSON().Array()
+	allowances.Value(1).Object().Value("progress").Number().InDelta(5.0, 0.01) // from had 10, transferred 5 -> left 5
+	allowances.Value(2).Object().Value("progress").Number().InDelta(5.0, 0.01) // to reached target
+}
+
+func TestTransferDifferentUsersFails(t *testing.T) {
+	e := startServer(t)
+
+	// Create allowance for user 1 and user 2
+	createTestAllowance(e, "User1 Allowance", 100, 1)
+	// create for user 2
+	e.POST("/user/2/allowance").WithJSON(CreateAllowanceRequest{Name: "User2 Allowance", Target: 100, Weight: 1}).Expect().Status(201)
+
+	// Add to user1 allowance
+	req := map[string]interface{}{"amount": 10, "description": "funds"}
+	e.POST("/user/1/allowance/1/add").WithJSON(req).Expect().Status(200)
+
+	// Attempt transfer between different users
+	transfer := map[string]interface{}{"from": 1, "to": 1 /* wrong id to simulate different user's id? */}
+	// To ensure different user, fetch the allowance id for user2 (it's 1 for user2 in its own context but global id will be 2)
+	// Create above for user2 produced global id 2, so use that
+	transfer = map[string]interface{}{"from": 1, "to": 2, "amount": 5}
+	e.POST("/transfer").WithJSON(transfer).Expect().Status(400)
+}
+
+func TestTransferInsufficientFunds(t *testing.T) {
+	e := startServer(t)
+
+	// Create two allowances
+	createTestAllowance(e, "From Allowance", 100, 1)
+	createTestAllowance(e, "To Allowance", 100, 1)
+
+	// Ensure from has 0 balance
+	transfer := map[string]interface{}{"from": 1, "to": 2, "amount": 10}
+	resp := e.POST("/transfer").WithJSON(transfer).Expect().Status(400).JSON().Object()
+	// Error text should mention insufficient funds
+	resp.Value("error").String().Contains("insufficient")
+}
+
+func TestTransferNotFound(t *testing.T) {
+	e := startServer(t)
+
+	// No allowances exist yet (only user rows). Attempt transfer with non-existent IDs
+	transfer := map[string]interface{}{"from": 999, "to": 1000, "amount": 1}
+	e.POST("/transfer").WithJSON(transfer).Expect().Status(404)
+}

backend/db.go

@@ -711,3 +711,74 @@ func (db *Db) AddAllowanceAmount(userId int, allowanceId int, request AddAllowan
 
 	return tx.Commit()
 }
+
+// TransferAllowance transfers amount from one allowance goal to another.
+// Both allowance ids must exist and belong to the same user. The transfer
+// will not move more than the 'to' goal still needs (target - balance).
+func (db *Db) TransferAllowance(fromId int, toId int, amount float64) error {
+	if fromId == toId {
+		return nil
+	}
+	amountCents := int(math.Round(amount * 100.0))
+	if amountCents <= 0 {
+		return fmt.Errorf("amount must be positive")
+	}
+
+	tx, err := db.db.Begin()
+	if err != nil {
+		return err
+	}
+	defer tx.MustRollback()
+
+	// Fetch from allowance (user_id, balance)
+	var fromUserId int
+	var fromBalance int
+	err = tx.Query("select user_id, balance from allowances where id = ?").Bind(fromId).ScanSingle(&fromUserId, &fromBalance)
+	if err != nil {
+		return err
+	}
+
+	// Fetch to allowance (user_id, target, balance)
+	var toUserId int
+	var toTarget int
+	var toBalance int
+	err = tx.Query("select user_id, target, balance from allowances where id = ?").Bind(toId).ScanSingle(&toUserId, &toTarget, &toBalance)
+	if err != nil {
+		return err
+	}
+
+	// Ensure same owner
+	if fromUserId != toUserId {
+		return fmt.Errorf("allowances do not belong to the same user")
+	}
+
+	// Calculate how much the 'to' goal still needs
+	remainingTo := toTarget - toBalance
+	if remainingTo <= 0 {
+		// Nothing to transfer
+		return fmt.Errorf("target already reached")
+	}
+
+	// Limit transfer to what 'to' still needs
+	transfer := amountCents
+	if transfer > remainingTo {
+		transfer = remainingTo
+	}
+
+	// Ensure 'from' has enough balance
+	if fromBalance < transfer {
+		return fmt.Errorf("insufficient funds in source allowance")
+	}
+
+	// Perform updates
+	err = tx.Query("update allowances set balance = balance - ? where id = ? and user_id = ?").Bind(transfer, fromId, fromUserId).Exec()
+	if err != nil {
+		return err
+	}
+	err = tx.Query("update allowances set balance = balance + ? where id = ? and user_id = ?").Bind(transfer, toId, toUserId).Exec()
+	if err != nil {
+		return err
+	}
+
+	return tx.Commit()
+}

backend/dto.go

@@ -80,3 +80,10 @@ type AddAllowanceAmountRequest struct {
 	Amount      float64 `json:"amount"`
 	Description string  `json:"description"`
 }
+
+// TransferRequest represents a request to transfer amount between two goals.
+type TransferRequest struct {
+	From   int     `json:"from"`
+	To     int     `json:"to"`
+	Amount float64 `json:"amount"`
+}

backend/go.mod

@@ -4,14 +4,15 @@ go 1.24.2
 
 require (
 	gitea.seeseepuff.be/seeseemelk/mysqlite v0.14.0
+	github.com/adhocore/gronx v1.19.6
 	github.com/gavv/httpexpect/v2 v2.17.0
 	github.com/gin-contrib/cors v1.7.5
 	github.com/gin-gonic/gin v1.10.1
+	github.com/stretchr/testify v1.10.0
 )
 
 require (
 	github.com/TylerBrock/colorjson v0.0.0-20200706003622-8a50f05110d2 // indirect
-	github.com/adhocore/gronx v1.19.6 // indirect
 	github.com/ajg/form v1.5.1 // indirect
 	github.com/andybalholm/brotli v1.1.1 // indirect
 	github.com/bytedance/sonic v1.13.2 // indirect
@@ -48,7 +49,6 @@ require (
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	github.com/sanity-io/litter v1.5.8 // indirect
 	github.com/sergi/go-diff v1.3.1 // indirect
-	github.com/stretchr/testify v1.10.0 // indirect
 	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
 	github.com/ugorji/go/codec v1.2.14 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect

backend/go.sum

@@ -34,8 +34,6 @@ github.com/gin-contrib/cors v1.7.5 h1:cXC9SmofOrRg0w9PigwGlHG3ztswH6bqq4vJVXnvYM
 github.com/gin-contrib/cors v1.7.5/go.mod h1:4q3yi7xBEDDWKapjT2o1V7mScKDDr8k+jZ0fSquGoy0=
 github.com/gin-contrib/sse v1.1.0 h1:n0w2GMuUpWDVp7qSpvze6fAu9iRxJY4Hmj6AmBOU05w=
 github.com/gin-contrib/sse v1.1.0/go.mod h1:hxRZ5gVpWMT7Z0B0gSNYqqsSCNIJMjzvm6fqCz9vjwM=
-github.com/gin-gonic/gin v1.10.0 h1:nTuyha1TYqgedzytsKYqna+DfLos46nTv2ygFy86HFU=
-github.com/gin-gonic/gin v1.10.0/go.mod h1:4PMNQiOhvDRa013RKVbsiNwoyezlm2rm0uX/T7kzp5Y=
 github.com/gin-gonic/gin v1.10.1 h1:T0ujvqyCSqRopADpgPgiTT63DUQVSfojyME59Ei63pQ=
 github.com/gin-gonic/gin v1.10.1/go.mod h1:4PMNQiOhvDRa013RKVbsiNwoyezlm2rm0uX/T7kzp5Y=
 github.com/go-playground/assert/v2 v2.2.0 h1:JvknZsQTYeFEAhQwI4qEt9cyV5ONwRHC+lYKSsYSR8s=
@@ -129,8 +127,6 @@ github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf
 github.com/tailscale/depaware v0.0.0-20210622194025-720c4b409502/go.mod h1:p9lPsd+cx33L3H9nNoecRRxPssFKUwwI50I3pZ0yT+8=
 github.com/twitchyliquid64/golang-asm v0.15.1 h1:SU5vSMR7hnwNxj24w34ZyCi/FmDZTkS4MhqMhdFk5YI=
 github.com/twitchyliquid64/golang-asm v0.15.1/go.mod h1:a1lVb/DtPvCB8fslRZhAngC2+aY1QWCk3Cedj/Gdt08=
-github.com/ugorji/go/codec v1.2.12 h1:9LC83zGrHhuUA9l16C9AHXAqEV/2wBQ4nkvumAE65EE=
-github.com/ugorji/go/codec v1.2.12/go.mod h1:UNopzCgEMSXjBc6AOMqYvWC1ktqTAfzJZUZgYf6w6lg=
 github.com/ugorji/go/codec v1.2.14 h1:yOQvXCBc3Ij46LRkRoh4Yd5qK6LVOgi0bYOXfb7ifjw=
 github.com/ugorji/go/codec v1.2.14/go.mod h1:UNopzCgEMSXjBc6AOMqYvWC1ktqTAfzJZUZgYf6w6lg=
 github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=
@@ -220,8 +216,6 @@ modernc.org/fileutil v1.3.1 h1:8vq5fe7jdtEvoCf3Zf9Nm0Q05sH6kGx0Op2CPx1wTC8=
 modernc.org/fileutil v1.3.1/go.mod h1:HxmghZSZVAz/LXcMNwZPA/DRrQZEVP9VX0V4LQGQFOc=
 modernc.org/gc/v2 v2.6.5 h1:nyqdV8q46KvTpZlsw66kWqwXRHdjIlJOhG6kxiV/9xI=
 modernc.org/gc/v2 v2.6.5/go.mod h1:YgIahr1ypgfe7chRuJi2gD7DBQiKSLMPgBQe9oIiito=
-modernc.org/libc v1.65.7 h1:Ia9Z4yzZtWNtUIuiPuQ7Qf7kxYrxP1/jeHZzG8bFu00=
-modernc.org/libc v1.65.7/go.mod h1:011EQibzzio/VX3ygj1qGFt5kMjP0lHb0qCW5/D/pQU=
 modernc.org/libc v1.65.8 h1:7PXRJai0TXZ8uNA3srsmYzmTyrLoHImV5QxHeni108Q=
 modernc.org/libc v1.65.8/go.mod h1:011EQibzzio/VX3ygj1qGFt5kMjP0lHb0qCW5/D/pQU=
 modernc.org/mathutil v1.7.1 h1:GCZVGXdaN8gTqB1Mf/usp1Y/hSqgI2vAGGP4jZMCxOU=
@@ -232,8 +226,6 @@ modernc.org/opt v0.1.4 h1:2kNGMRiUjrp4LcaPuLY2PzUfqM/w9N23quVwhKt5Qm8=
 modernc.org/opt v0.1.4/go.mod h1:03fq9lsNfvkYSfxrfUhZCWPk1lm4cq4N+Bh//bEtgns=
 modernc.org/sortutil v1.2.1 h1:+xyoGf15mM3NMlPDnFqrteY07klSFxLElE2PVuWIJ7w=
 modernc.org/sortutil v1.2.1/go.mod h1:7ZI3a3REbai7gzCLcotuw9AC4VZVpYMjDzETGsSMqJE=
-modernc.org/sqlite v1.37.0 h1:s1TMe7T3Q3ovQiK2Ouz4Jwh7dw4ZDqbebSDTlSJdfjI=
-modernc.org/sqlite v1.37.0/go.mod h1:5YiWv+YviqGMuGw4V+PNplcyaJ5v+vQd7TQOgkACoJM=
 modernc.org/sqlite v1.37.1 h1:EgHJK/FPoqC+q2YBXg7fUmES37pCHFc97sI7zSayBEs=
 modernc.org/sqlite v1.37.1/go.mod h1:XwdRtsE1MpiBcL54+MbKcaDvcuej+IYSMfLN6gSKV8g=
 modernc.org/strutil v1.2.1 h1:UneZBkQA+DX2Rp35KcM69cSsNES9ly8mQWD71HKlOA0=
@@ -243,7 +235,5 @@ modernc.org/token v1.1.0/go.mod h1:UGzOrNV1mAFSEB63lOFHIpNRUVMvYTc6yu1SMY/XTDM=
 moul.io/http2curl/v2 v2.3.0 h1:9r3JfDzWPcbIklMOs2TnIFzDYvfAZvjeavG6EzP7jYs=
 moul.io/http2curl/v2 v2.3.0/go.mod h1:RW4hyBjTWSYDOxapodpNEtX0g5Eb16sxklBqmd2RHcE=
 nullprogram.com/x/optparse v1.0.0/go.mod h1:KdyPE+Igbe0jQUrVfMqDMeJQIJZEuyV7pjYmp6pbG50=
-zombiezen.com/go/sqlite v1.4.0 h1:N1s3RIljwtp4541Y8rM880qgGIgq3fTD2yks1xftnKU=
-zombiezen.com/go/sqlite v1.4.0/go.mod h1:0w9F1DN9IZj9AcLS9YDKMboubCACkwYCGkzoy3eG5ik=
 zombiezen.com/go/sqlite v1.4.2 h1:KZXLrBuJ7tKNEm+VJcApLMeQbhmAUOKA5VWS93DfFRo=
 zombiezen.com/go/sqlite v1.4.2/go.mod h1:5Kd4taTAD4MkBzT25mQ9uaAlLjyR0rFhsR6iINO70jc=

backend/main.go

@@ -5,14 +5,15 @@ import (
 	"embed"
 	"errors"
 	"fmt"
-	"gitea.seeseepuff.be/seeseemelk/mysqlite"
-	"github.com/adhocore/gronx"
 	"log"
 	"net"
 	"net/http"
 	"os"
 	"strconv"
 
+	"gitea.seeseepuff.be/seeseemelk/mysqlite"
+	"github.com/adhocore/gronx"
+
 	"github.com/gin-contrib/cors"
 	"github.com/gin-gonic/gin"
 )