1 files changed, 239 insertions, 0 deletions
diff --git a/backend/internal/api/handlers/loan_handler.go b/backend/internal/api/handlers/loan_handler.go
new file mode 100644
index 0000000..3edb559
--- /dev/null
+++ b/backend/internal/api/handlers/loan_handler.go
@@ -0,0 +1,239 @@
+package handlers
+
+import (
+	"log"
+	"net/http"
+	"strconv"
+	"time"
+
+	"finance/backend/internal/database"
+	"finance/backend/internal/models"
+
+	"github.com/gin-gonic/gin"
+)
+
+// LoanHandler handles loan-related operations
+type LoanHandler struct {
+}
+
+// NewLoanHandler creates and returns a new LoanHandler instance
+func NewLoanHandler() *LoanHandler {
+	return &LoanHandler{}
+}
+
+// GetLoans retrieves all loans for the authenticated user
+func (h *LoanHandler) GetLoans(c *gin.Context) {
+	userID := c.MustGet("userID").(uint)
+	var loans []models.Loan
+
+	if err := database.DB.Where("user_id = ?", userID).Find(&loans).Error; err != nil {
+		log.Printf("Error fetching loans for user %d: %v", userID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to get loans"})
+		return
+	}
+
+	c.JSON(http.StatusOK, loans)
+}
+
+// GetLoanByID retrieves a specific loan by ID for the authenticated user
+func (h *LoanHandler) GetLoanByID(c *gin.Context) {
+	userID := c.MustGet("userID").(uint)
+	loanID, err := strconv.ParseUint(c.Param("id"), 10, 32)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid loan ID"})
+		return
+	}
+
+	var loan models.Loan
+	if err := database.DB.Where("id = ? AND user_id = ?", loanID, userID).First(&loan).Error; err != nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": "Loan not found"})
+		return
+	}
+
+	c.JSON(http.StatusOK, loan)
+}
+
+// CreateLoan creates a new loan for the authenticated user
+func (h *LoanHandler) CreateLoan(c *gin.Context) {
+	userID := c.MustGet("userID").(uint)
+
+	// Define input structure
+	type CreateLoanInput 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"`
+		EndDate        string  `json:"endDate"`
+		AccountID      *uint   `json:"accountId"`
+	}
+
+	var input CreateLoanInput
+	if err := c.ShouldBindJSON(&input); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	// Parse dates if provided
+	var startDate, endDate time.Time
+	var err error
+
+	if input.StartDate != "" {
+		startDate, err = time.Parse("2006-01-02", input.StartDate)
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid start date format. Use YYYY-MM-DD"})
+			return
+		}
+	}
+
+	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. Use YYYY-MM-DD"})
+			return
+		}
+	}
+
+	// Validate account if provided
+	if input.AccountID != nil {
+		var account models.Account
+		if err := database.DB.Where("id = ? AND user_id = ?", *input.AccountID, userID).First(&account).Error; err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "Associated account not found or doesn't belong to user"})
+			return
+		}
+	}
+
+	// Create loan
+	loan := models.Loan{
+		UserID:         userID,
+		AccountID:      input.AccountID,
+		Name:           input.Name,
+		OriginalAmount: input.OriginalAmount,
+		CurrentBalance: input.CurrentBalance,
+		InterestRate:   input.InterestRate,
+	}
+
+	// Only set dates if they were provided
+	if !startDate.IsZero() {
+		loan.StartDate = startDate
+	}
+	if !endDate.IsZero() {
+		loan.EndDate = endDate
+	}
+
+	if err := database.DB.Create(&loan).Error; err != nil {
+		log.Printf("Error creating loan for user %d: %v", userID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to create loan"})
+		return
+	}
+
+	c.JSON(http.StatusCreated, loan)
+}
+
+// UpdateLoan updates an existing loan for the authenticated user
+func (h *LoanHandler) UpdateLoan(c *gin.Context) {
+	userID := c.MustGet("userID").(uint)
+	loanID, err := strconv.ParseUint(c.Param("id"), 10, 32)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid loan ID"})
+		return
+	}
+
+	// Find loan
+	var loan models.Loan
+	if err := database.DB.Where("id = ? AND user_id = ?", loanID, userID).First(&loan).Error; err != nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": "Loan not found"})
+		return
+	}
+
+	// Define update structure
+	type UpdateLoanInput struct {
+		Name           string  `json:"name"`
+		OriginalAmount int64   `json:"originalAmount"`
+		CurrentBalance int64   `json:"currentBalance"`
+		InterestRate   float64 `json:"interestRate"`
+		StartDate      string  `json:"startDate"`
+		EndDate        string  `json:"endDate"`
+		AccountID      *uint   `json:"accountId"`
+	}
+
+	var input UpdateLoanInput
+	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.OriginalAmount != 0 {
+		loan.OriginalAmount = input.OriginalAmount
+	}
+	if input.CurrentBalance != 0 {
+		loan.CurrentBalance = input.CurrentBalance
+	}
+	if input.InterestRate != 0 {
+		loan.InterestRate = input.InterestRate
+	}
+	if input.StartDate != "" {
+		startDate, err := time.Parse("2006-01-02", input.StartDate)
+		if err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid start date format. Use YYYY-MM-DD"})
+			return
+		}
+		loan.StartDate = startDate
+	}
+	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. Use YYYY-MM-DD"})
+			return
+		}
+		loan.EndDate = endDate
+	}
+	if input.AccountID != nil {
+		// Validate account if provided
+		var account models.Account
+		if err := database.DB.Where("id = ? AND user_id = ?", *input.AccountID, userID).First(&account).Error; err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": "Associated account not found or doesn't belong to user"})
+			return
+		}
+		loan.AccountID = input.AccountID
+	}
+
+	// Save changes
+	if err := database.DB.Save(&loan).Error; err != nil {
+		log.Printf("Error updating loan ID %d for user %d: %v", loanID, userID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to update loan"})
+		return
+	}
+
+	c.JSON(http.StatusOK, loan)
+}
+
+// DeleteLoan deletes a loan belonging to the authenticated user
+func (h *LoanHandler) DeleteLoan(c *gin.Context) {
+	userID := c.MustGet("userID").(uint)
+	loanID, err := strconv.ParseUint(c.Param("id"), 10, 32)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid loan ID"})
+		return
+	}
+
+	// Check if loan exists and belongs to user
+	var loan models.Loan
+	if err := database.DB.Where("id = ? AND user_id = ?", loanID, userID).First(&loan).Error; err != nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": "Loan not found"})
+		return
+	}
+
+	// Delete loan
+	if err := database.DB.Delete(&loan).Error; err != nil {
+		log.Printf("Error deleting loan ID %d for user %d: %v", loanID, userID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to delete loan"})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{"message": "Loan deleted successfully"})
+}