feat: added basic backend features to it

  - Set up API framework (Gin Gonic)
  - Set up ORM/DB library (GORM)
  - Design database schema (Users, Accounts, Transactions, Loans, Goals)
  - Set up database connection and migrations

1 files changed, 248 insertions, 0 deletions

diff --git a/backend/internal/api/v1/loans/loans.go b/backend/internal/api/v1/loans/loans.go
new file mode 100644
index 0000000..06d96b0
--- /dev/null
+++ b/backend/internal/api/v1/loans/loans.go
@@ -0,0 +1,248 @@
+package loans
+
+import (
+	"net/http"
+	"strconv"
+	"time"
+
+	"finance/backend/internal/database"
+	"finance/backend/internal/models"
+
+	"github.com/gin-gonic/gin"
+	"gorm.io/gorm"
+)
+
+// GetLoans returns all loans for the authenticated user
+func GetLoans() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		// Get user from context (set by auth middleware)
+		user, exists := c.Get("user")
+		if !exists {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Unauthorized"})
+			return
+		}
+
+		userObj := user.(*models.User)
+		var loans []models.Loan
+
+		// Fetch all loans for the user
+		if err := database.DB.Where("user_id = ?", userObj.ID).Find(&loans).Error; err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to fetch loans"})
+			return
+		}
+
+		c.JSON(http.StatusOK, gin.H{"loans": loans})
+	}
+}
+
+// GetLoanByID returns a specific loan by ID
+func GetLoanByID() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		// Get user from context (set by auth middleware)
+		user, exists := c.Get("user")
+		if !exists {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Unauthorized"})
+			return
+		}
+		userObj := user.(*models.User)
+
+		// Get loan ID from URL parameter
+		loanID, err := strconv.ParseUint(c.Param("id"), 10, 32)
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid loan ID format"})
+			return
+		}
+
+		var loan models.Loan
+
+		// Fetch the loan and ensure it belongs to the authenticated user
+		if err := database.DB.Where("id = ? AND user_id = ?", loanID, userObj.ID).First(&loan).Error; err != nil {
+			if err == gorm.ErrRecordNotFound {
+				c.JSON(http.StatusNotFound, gin.H{"error": "Loan not found"})
+			} else {
+				c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to fetch loan"})
+			}
+			return
+		}
+
+		c.JSON(http.StatusOK, gin.H{"loan": loan})
+	}
+}
+
+// CreateLoan creates a new loan
+func CreateLoan() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		// Get user from context (set by auth middleware)
+		user, exists := c.Get("user")
+		if !exists {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Unauthorized"})
+			return
+		}
+		userObj := user.(*models.User)
+
+		// Define a struct to bind the request JSON
+		var input struct {
+			Name           string  `json:"name" binding:"required"`
+			OriginalAmount int64   `json:"originalAmount" binding:"required"`
+			CurrentBalance int64   `json:"currentBalance" binding:"required"`
+			InterestRate   float64 `json:"interestRate"`
+			StartDate      string  `json:"startDate" binding:"required"`
+			EndDate        string  `json:"endDate" binding:"required"`
+			AccountID      *uint   `json:"accountId"`
+		}
+
+		// Bind JSON to struct
+		if err := c.ShouldBindJSON(&input); err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+			return
+		}
+
+		// Parse dates
+		startDate, err := time.Parse("2006-01-02", input.StartDate)
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid start date format"})
+			return
+		}
+
+		endDate, err := time.Parse("2006-01-02", input.EndDate)
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid end date format"})
+			return
+		}
+
+		// Create loan object
+		loan := models.Loan{
+			UserID:         userObj.ID,
+			Name:           input.Name,
+			OriginalAmount: input.OriginalAmount,
+			CurrentBalance: input.CurrentBalance,
+			InterestRate:   input.InterestRate,
+			StartDate:      startDate,
+			EndDate:        endDate,
+			AccountID:      input.AccountID,
+		}
+
+		// Save to database
+		if err := database.DB.Create(&loan).Error; err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to create loan"})
+			return
+		}
+
+		c.JSON(http.StatusCreated, gin.H{"loan": loan})
+	}
+}
+
+// UpdateLoan updates an existing loan
+func UpdateLoan() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		// Get user from context (set by auth middleware)
+		user, exists := c.Get("user")
+		if !exists {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Unauthorized"})
+			return
+		}
+		userObj := user.(*models.User)
+
+		// Get loan ID from URL parameter
+		loanID, err := strconv.ParseUint(c.Param("id"), 10, 32)
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid loan ID format"})
+			return
+		}
+
+		// Check if the loan exists and belongs to the user
+		var loan models.Loan
+		if err := database.DB.Where("id = ? AND user_id = ?", loanID, userObj.ID).First(&loan).Error; err != nil {
+			if err == gorm.ErrRecordNotFound {
+				c.JSON(http.StatusNotFound, gin.H{"error": "Loan not found"})
+			} else {
+				c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to fetch loan"})
+			}
+			return
+		}
+
+		// Define a struct to bind the request JSON
+		var input struct {
+			Name           string  `json:"name"`
+			CurrentBalance int64   `json:"currentBalance"`
+			InterestRate   float64 `json:"interestRate"`
+			EndDate        string  `json:"endDate"`
+			AccountID      *uint   `json:"accountId"`
+		}
+
+		// Bind JSON to struct
+		if err := c.ShouldBindJSON(&input); err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+			return
+		}
+
+		// Update fields if provided
+		if input.Name != "" {
+			loan.Name = input.Name
+		}
+		if input.CurrentBalance != 0 {
+			loan.CurrentBalance = input.CurrentBalance
+		}
+		if input.InterestRate != 0 {
+			loan.InterestRate = input.InterestRate
+		}
+		if input.EndDate != "" {
+			endDate, err := time.Parse("2006-01-02", input.EndDate)
+			if err != nil {
+				c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid end date format"})
+				return
+			}
+			loan.EndDate = endDate
+		}
+		if input.AccountID != nil {
+			loan.AccountID = input.AccountID
+		}
+
+		// Save updates to database
+		if err := database.DB.Save(&loan).Error; err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to update loan"})
+			return
+		}
+
+		c.JSON(http.StatusOK, gin.H{"loan": loan})
+	}
+}
+
+// DeleteLoan deletes a loan
+func DeleteLoan() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		// Get user from context (set by auth middleware)
+		user, exists := c.Get("user")
+		if !exists {
+			c.JSON(http.StatusUnauthorized, gin.H{"error": "Unauthorized"})
+			return
+		}
+		userObj := user.(*models.User)
+
+		// Get loan ID from URL parameter
+		loanID, err := strconv.ParseUint(c.Param("id"), 10, 32)
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid loan ID format"})
+			return
+		}
+
+		// Check if the loan exists and belongs to the user
+		var loan models.Loan
+		if err := database.DB.Where("id = ? AND user_id = ?", loanID, userObj.ID).First(&loan).Error; err != nil {
+			if err == gorm.ErrRecordNotFound {
+				c.JSON(http.StatusNotFound, gin.H{"error": "Loan not found"})
+			} else {
+				c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to fetch loan"})
+			}
+			return
+		}
+
+		// Delete the loan
+		if err := database.DB.Delete(&loan).Error; err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to delete loan"})
+			return
+		}
+
+		c.JSON(http.StatusOK, gin.H{"message": "Loan deleted successfully"})
+	}
+}