wails/v3/examples/gin-service/services/gin_service.go

package services

import (
	"context"
	"net/http"
	"strconv"
	"sync"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/wailsapp/wails/v3/pkg/application"
)

// User represents a user in the system
type User struct {
	ID        int       `json:"id"`
	Name      string    `json:"name"`
	Email     string    `json:"email"`
	CreatedAt time.Time `json:"createdAt"`
}

// GinService implements a Wails service that uses Gin for HTTP handling
type GinService struct {
	ginEngine *gin.Engine
	users     []User
	nextID    int
	mu        sync.RWMutex
	app       *application.App
}

type EventData struct {
	Message   string `json:"message"`
	Timestamp string `json:"timestamp"`
}

// NewGinService creates a new GinService instance
func NewGinService() *GinService {
	// Create a new Gin router
	ginEngine := gin.New()

	// Add middlewares
	ginEngine.Use(gin.Recovery())
	ginEngine.Use(LoggingMiddleware())

	service := &GinService{
		ginEngine: ginEngine,
		users: []User{
			{ID: 1, Name: "Alice", Email: "alice@example.com", CreatedAt: time.Now().Add(-72 * time.Hour)},
			{ID: 2, Name: "Bob", Email: "bob@example.com", CreatedAt: time.Now().Add(-48 * time.Hour)},
			{ID: 3, Name: "Charlie", Email: "charlie@example.com", CreatedAt: time.Now().Add(-24 * time.Hour)},
		},
		nextID: 4,
	}

	// Define routes
	service.setupRoutes()

	return service
}

// ServiceName returns the name of the service
func (s *GinService) ServiceName() string {
	return "Gin API Service"
}

// ServiceStartup is called when the service starts
func (s *GinService) ServiceStartup(ctx context.Context, options application.ServiceOptions) error {
	// You can access the application instance via ctx
	s.app = application.Get()

	// Register an event handler that can be triggered from the frontend
	s.app.OnEvent("gin-api-event", func(event *application.CustomEvent) {
		// Log the event data
		// Parse the event data
		s.app.Logger.Info("Received event from frontend", "data", event.Data)

		// You could also emit an event back to the frontend
		s.app.EmitEvent("gin-api-response", map[string]interface{}{
			"message": "Response from Gin API Service",
			"time":    time.Now().Format(time.RFC3339),
		})
	})

	return nil
}

// ServiceShutdown is called when the service shuts down
func (s *GinService) ServiceShutdown(ctx context.Context) error {
	return nil
}

// ServeHTTP implements the http.Handler interface
func (s *GinService) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	// All other requests go to the Gin router
	s.ginEngine.ServeHTTP(w, r)
}

// setupRoutes configures the API routes
func (s *GinService) setupRoutes() {
	// Basic info endpoint
	s.ginEngine.GET("/info", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{
			"service": "Gin API Service",
			"version": "1.0.0",
			"time":    time.Now().Format(time.RFC3339),
		})
	})

	// Users group
	users := s.ginEngine.Group("/users")
	{
		// Get all users
		users.GET("", func(c *gin.Context) {
			s.mu.RLock()
			defer s.mu.RUnlock()
			c.JSON(http.StatusOK, s.users)
		})

		// Get user by ID
		users.GET("/:id", func(c *gin.Context) {
			id, err := strconv.Atoi(c.Param("id"))
			if err != nil {
				c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid user ID"})
				return
			}

			s.mu.RLock()
			defer s.mu.RUnlock()

			for _, user := range s.users {
				if user.ID == id {
					c.JSON(http.StatusOK, user)
					return
				}
			}

			c.JSON(http.StatusNotFound, gin.H{"error": "User not found"})
		})

// import block (ensure this exists in your file)
import (
	"context"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"time"
)

// ...

// Create a new user
users.POST("", func(c *gin.Context) {
	var newUser User
	if err := c.ShouldBindJSON(&newUser); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	// Validate required fields
	if newUser.Name == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Name is required"})
		return
	}
	if newUser.Email == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Email is required"})
		return
	}
	// Basic email validation (consider using a proper validator library in production)
	if !strings.Contains(newUser.Email, "@") {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid email format"})
		return
	}

	s.mu.Lock()
	defer s.mu.Unlock()

	// Set the ID and creation time
	newUser.ID = s.nextID
	newUser.CreatedAt = time.Now()
	s.nextID++

	// Add to the users slice
	s.users = append(s.users, newUser)

	c.JSON(http.StatusCreated, newUser)

	// Emit an event to notify about the new user
	s.app.EmitEvent("user-created", newUser)
})

		// Delete a user
		users.DELETE("/:id", func(c *gin.Context) {
			id, err := strconv.Atoi(c.Param("id"))
			if err != nil {
				c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid user ID"})
				return
			}

			s.mu.Lock()
			defer s.mu.Unlock()

			for i, user := range s.users {
				if user.ID == id {
					// Remove the user from the slice
					s.users = append(s.users[:i], s.users[i+1:]...)
					c.JSON(http.StatusOK, gin.H{"message": "User deleted"})
					return
				}
			}

			c.JSON(http.StatusNotFound, gin.H{"error": "User not found"})
		})
	}
}

// LoggingMiddleware is a Gin middleware that logs request details
func LoggingMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		// Start timer
		start := time.Now()

		// Process request
		c.Next()

		// Calculate latency
		latency := time.Since(start)

		// Log request details
		statusCode := c.Writer.Status()
		clientIP := c.ClientIP()
		method := c.Request.Method
		path := c.Request.URL.Path

		// Get the application instance
		app := application.Get()
		if app != nil {
			app.Logger.Info("HTTP Request",
				"status", statusCode,
				"method", method,
				"path", path,
				"ip", clientIP,
				"latency", latency,
			)
		}
	}
}