byom-golang-lib/pkg/server/middleware.go

package server

import (
	"net/http"
	"runtime/debug"
	"time"

	"git.linuxforward.com/byom/byom-golang-lib/pkg/validation"
	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
)

func (s *Server) corsMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		origin := c.Request.Header.Get("Origin")
		if len(s.config.AllowedOrigins) == 0 {
			s.logger.Warn("no allowed origins configured")
		}

		allowed := false
		for _, allowedOrigin := range s.config.AllowedOrigins {
			if origin == allowedOrigin {
				c.Writer.Header().Set("Access-Control-Allow-Origin", origin)
				allowed = true
				break
			}
		}

		if !allowed && origin != "" {
			s.logger.WithField("origin", origin).Warn("blocked request from unauthorized origin")
			c.AbortWithError(http.StatusForbidden, NewCORSError(origin, ErrUnauthorizedOrigin, "origin not allowed"))
			return
		}

		c.Writer.Header().Set("Access-Control-Allow-Credentials", "true")
		c.Writer.Header().Set("Access-Control-Allow-Headers", "Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization, X-Request-ID")
		c.Writer.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")

		if c.Request.Method == "OPTIONS" {
			c.AbortWithStatus(http.StatusNoContent)
			return
		}

		c.Next()
	}
}

func (s *Server) requestIDMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		requestID := c.GetHeader("X-Request-ID")
		if requestID == "" {
			requestID = uuid.New().String()
		}

		c.Set("RequestID", requestID)
		c.Header("X-Request-ID", requestID)

		c.Next()
	}
}

func (s *Server) loggerMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		start := time.Now()
		path := c.Request.URL.Path
		query := c.Request.URL.RawQuery

		c.Next()

		s.logger.WithFields(map[string]interface{}{
			"status_code": c.Writer.Status(),
			"method":      c.Request.Method,
			"path":        path,
			"query":       query,
			"ip":          c.ClientIP(),
			"latency":     time.Since(start),
			"request_id":  c.GetString("RequestID"),
			"user_agent":  c.Request.UserAgent(),
		}).Info("request completed")
	}
}

func (s *Server) recoveryMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		defer func() {
			if err := recover(); err != nil {
				requestID := c.GetString("RequestID")
				s.logger.WithFields(map[string]interface{}{
					"error":      err,
					"request_id": requestID,
					"stack":      string(debug.Stack()),
				}).Error("panic recovered")

				c.AbortWithStatusJSON(http.StatusInternalServerError, gin.H{
					"error":      ErrInternalServer.Error(),
					"request_id": requestID,
				})
			}
		}()
		c.Next()
	}
}

func (s *Server) errorHandlerMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		c.Next()

		if len(c.Errors) > 0 {
			err := c.Errors.Last().Err
			requestID := c.GetString("RequestID")

			// Log the error with appropriate level and details
			s.logger.WithFields(map[string]interface{}{
				"error":      err.Error(),
				"request_id": requestID,
			}).Error("request error")

			// Create a server error with request context
			serverErr := NewRequestError(
				"handle_request",
				c.Request.Method,
				c.Request.URL.Path,
				StatusCode(err),
				err,
				"request processing failed",
			)

			response := gin.H{
				"error":      serverErr.Error(),
				"request_id": requestID,
			}

			c.JSON(serverErr.StatusCode, response)
		}
	}
}

// ValidateRequest returns a middleware function that validates request bodies against
// the specified request type. It integrates with the gin context for error handling and logging.
func ValidateRequest(validateFn func(interface{}) []validation.ValidationError) gin.HandlerFunc {
	return func(c *gin.Context) {
		requestID := c.GetString("RequestID")
		var req interface{}

		// Bind JSON request body
		if err := c.ShouldBindJSON(&req); err != nil {
			bindErr := NewRequestError(
				"validate_request",
				c.Request.Method,
				c.Request.URL.Path,
				http.StatusBadRequest,
				err,
				"invalid request format",
			)

			c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{
				"error":      bindErr.Error(),
				"request_id": requestID,
				"errors":     []validation.ValidationError{{Field: "body", Message: err.Error()}},
			})
			return
		}

		// Validate request struct
		if errors := validateFn(req); len(errors) > 0 {
			validationErr := NewRequestError(
				"validate_request",
				c.Request.Method,
				c.Request.URL.Path,
				http.StatusBadRequest,
				ErrValidationFailed,
				"validation failed",
			)

			c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{
				"error":      validationErr.Error(),
				"request_id": requestID,
				"errors":     errors,
			})
			return
		}

		// Store validated request in context
		c.Set("ValidatedRequest", req)
		c.Next()
	}
}

// GetValidatedRequest retrieves the validated request from the gin context.
// Returns the request and true if found and type matches, nil and false otherwise.
func GetValidatedRequest[T any](c *gin.Context) (*T, bool) {
	if req, exists := c.Get("ValidatedRequest"); exists {
		if typed, ok := req.(*T); ok {
			return typed, true
		}
	}
	return nil, false
}