Create expense-tracker.go

Author: Dang Linh Anh

expense-tracker.go

@@ -0,0 +1,102 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strconv"
+	"time"
+	"io/ioutil"
+)
+
+type Expense struct {
+	Amount   float64   `json:"amount"`
+	Category string    `json:"category"`
+	Date     time.Time `json:"date"`
+}
+
+const dataFile = "expenses.json"
+
+func loadExpenses() ([]Expense, error) {
+	data, err := ioutil.ReadFile(dataFile)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return []Expense{}, nil
+		}
+		return nil, err
+	}
+	var expenses []Expense
+	err = json.Unmarshal(data, &expenses)
+	return expenses, err
+}
+
+func saveExpenses(expenses []Expense) error {
+	data, err := json.MarshalIndent(expenses, "", "  ")
+	if err != nil {
+		return err
+	}
+	return ioutil.WriteFile(dataFile, data, 0644)
+}
+
+func addExpense(args []string) {
+	if len(args) < 2 {
+		fmt.Println("Usage: add <amount> <category>")
+		return
+	}
+	amount, err := strconv.ParseFloat(args[0], 64)
+	if err != nil {
+		fmt.Println("Invalid amount.")
+		return
+	}
+	category := args[1]
+	expenses, err := loadExpenses()
+	if err != nil {
+		fmt.Println("Error loading expenses:", err)
+		return
+	}
+	expense := Expense{
+		Amount:   amount,
+		Category: category,
+		Date:     time.Now(),
+	}
+	expenses = append(expenses, expense)
+	if err := saveExpenses(expenses); err != nil {
+		fmt.Println("Error saving expense:", err)
+	} else {
+		fmt.Println("Expense added.")
+	}
+}
+
+func listExpenses() {
+	expenses, err := loadExpenses()
+	if err != nil {
+		fmt.Println("Error loading expenses:", err)
+		return
+	}
+	if len(expenses) == 0 {
+		fmt.Println("No expenses recorded.")
+		return
+	}
+	var total float64
+	for _, e := range expenses {
+		fmt.Printf("- $%.2f [%s] (%s)\n", e.Amount, e.Category, e.Date.Format("2006-01-02"))
+		total += e.Amount
+	}
+	fmt.Printf("Total: $%.2f\n", total)
+}
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Println("Commands: add <amount> <category> | list")
+		return
+	}
+	cmd := os.Args[1]
+	switch cmd {
+	case "add":
+		addExpense(os.Args[2:])
+	case "list":
+		listExpenses()
+	default:
+		fmt.Println("Unknown command.")
+	}
+}