backend-service/internal/middleware/auth.go

package middleware

import (
	"net/http"
	"strings"

	"attune-heart-therapy/internal/services"

	"github.com/gin-gonic/gin"
)

// AuthMiddleware creates a middleware for JWT authentication
func AuthMiddleware(jwtService services.JWTService) gin.HandlerFunc {
	return func(c *gin.Context) {
		// Get token from Authorization header
		authHeader := c.GetHeader("Authorization")
		if authHeader == "" {
			c.JSON(http.StatusUnauthorized, gin.H{
				"error": "Authorization header is required",
			})
			c.Abort()
			return
		}

		// Check if header starts with "Bearer "
		tokenParts := strings.SplitN(authHeader, " ", 2)
		if len(tokenParts) != 2 || tokenParts[0] != "Bearer" {
			c.JSON(http.StatusUnauthorized, gin.H{
				"error": "Invalid authorization header format. Expected: Bearer <token>",
			})
			c.Abort()
			return
		}

		tokenString := tokenParts[1]
		if tokenString == "" {
			c.JSON(http.StatusUnauthorized, gin.H{
				"error": "Token is required",
			})
			c.Abort()
			return
		}

		// Validate the token
		claims, err := jwtService.ValidateToken(tokenString)
		if err != nil {
			c.JSON(http.StatusUnauthorized, gin.H{
				"error": "Invalid or expired token",
			})
			c.Abort()
			return
		}

		// Set user information in context for use in handlers
		c.Set("user_id", claims.UserID)
		c.Set("user_email", claims.Email)
		c.Set("is_admin", claims.IsAdmin)
		c.Set("jwt_claims", claims)

		c.Next()
	}
}

// GetUserIDFromContext extracts user ID from Gin context
func GetUserIDFromContext(c *gin.Context) (uint, bool) {
	userID, exists := c.Get("user_id")
	if !exists {
		return 0, false
	}

	id, ok := userID.(uint)
	return id, ok
}

// GetUserEmailFromContext extracts user email from Gin context
func GetUserEmailFromContext(c *gin.Context) (string, bool) {
	email, exists := c.Get("user_email")
	if !exists {
		return "", false
	}

	emailStr, ok := email.(string)
	return emailStr, ok
}

// IsAdminFromContext checks if user is admin from Gin context
func IsAdminFromContext(c *gin.Context) bool {
	isAdmin, exists := c.Get("is_admin")
	if !exists {
		return false
	}

	admin, ok := isAdmin.(bool)
	return ok && admin
}

// GetJWTClaimsFromContext extracts JWT claims from Gin context
func GetJWTClaimsFromContext(c *gin.Context) (*services.JWTClaims, bool) {
	claims, exists := c.Get("jwt_claims")
	if !exists {
		return nil, false
	}

	jwtClaims, ok := claims.(*services.JWTClaims)
	return jwtClaims, ok
}

// AdminMiddleware creates a middleware for admin authorization
// This middleware should be used after AuthMiddleware to ensure user is authenticated first
func AdminMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		// Check if user is authenticated (should be set by AuthMiddleware)
		userID, exists := GetUserIDFromContext(c)
		if !exists || userID == 0 {
			c.JSON(http.StatusUnauthorized, gin.H{
				"error": "Authentication required",
			})
			c.Abort()
			return
		}

		// Check if user has admin privileges
		if !IsAdminFromContext(c) {
			c.JSON(http.StatusForbidden, gin.H{
				"error": "Admin privileges required",
			})
			c.Abort()
			return
		}

		c.Next()
	}
}

// RequireAdmin is a convenience function that combines auth and admin middleware
func RequireAdmin(jwtService services.JWTService) gin.HandlerFunc {
	return gin.HandlerFunc(func(c *gin.Context) {
		// First authenticate the user
		AuthMiddleware(jwtService)(c)
		if c.IsAborted() {
			return
		}

		// Then check admin privileges
		AdminMiddleware()(c)
	})
}