added api for handling transfer

Signed-off-by: GitHub <[email protected]>

api/server.go

@@ -18,6 +18,8 @@ func NewServer(store db.Store) *Server {
 	router.GET("/accounts/:id", server.getAccount)
 	router.GET("/accounts", server.listAccount)
 
+	router.POST("/transfers", server.createTransfer)
+
 	server.router = router
 	return server
 }

api/transfer.go

@@ -0,0 +1,71 @@
+package api
+
+import (
+	"database/sql"
+	"fmt"
+	"net/http"
+
+	db "github.com/1shubham7/bank/db/sqlc"
+	"github.com/gin-gonic/gin"
+)
+
+type transferRequest struct {
+	FromAccountID int64  `json:"from_account_id" binding:"required,min=1"`
+	ToAccountID int64 `json:"to_account_id" binding:"required,min=1"`
+	Amount int64 `json:"amount" binding:"required,gt=0"`
+	Currency string `json:"currency" binding:"required,oneof=USD INR EUR CAD YUAN"`
+}
+
+func (server *Server) createTransfer(ctx *gin.Context) {
+	var req transferRequest
+
+	err := ctx.ShouldBindJSON(&req)
+	if err != nil {
+		ctx.JSON(http.StatusBadRequest, errorResponse(err))
+		return
+	}
+
+	if !server.validAccount(ctx, req.FromAccountID, req.Currency){
+		return
+	}
+
+	if !server.validAccount(ctx, req.ToAccountID, req.Currency){
+		return
+	}
+
+	arg := db.TransferTransectionParams{
+		FromAccountID: req.FromAccountID,
+		ToAccountID: req.ToAccountID,
+		Amount: req.Amount,
+	}
+
+	transferTransectionResult, err := server.store.TransferTransection(ctx, arg)
+
+	if err != nil {
+		ctx.JSON(http.StatusInternalServerError, errorResponse(err))
+		return
+	}
+
+	ctx.JSON(http.StatusOK, transferTransectionResult)
+}
+
+func (server *Server) validAccount(ctx *gin.Context, accountID int64, currency string) (bool) {
+	account, err := server.store.GetAccount(ctx, accountID)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			ctx.JSON(http.StatusNotFound, errorResponse(err))
+			return false
+		}
+
+		ctx.JSON(http.StatusInternalServerError, errorResponse(err))
+		return false
+	}
+
+	if account.Currency != currency {
+		err := fmt.Errorf("account [%d] currency mismatch: %s vs %s", account.ID, account.Currency, currency)
+		ctx.JSON(http.StatusBadRequest, errorResponse(err))
+		return false
+	}
+
+	return true
+}