package handlers

import (
	"fmt"
	"net"
	"net/http"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
	"gorm.io/gorm"

	"github.com/Wikid82/CaddyProxyManagerPlus/backend/internal/models"
	"github.com/Wikid82/CaddyProxyManagerPlus/backend/internal/services"
)

// RemoteServerHandler handles HTTP requests for remote server management.
type RemoteServerHandler struct {
	service *services.RemoteServerService
}

// NewRemoteServerHandler creates a new remote server handler.
func NewRemoteServerHandler(db *gorm.DB) *RemoteServerHandler {
	return &RemoteServerHandler{
		service: services.NewRemoteServerService(db),
	}
}

// RegisterRoutes registers remote server routes.
func (h *RemoteServerHandler) RegisterRoutes(router *gin.RouterGroup) {
	router.GET("/remote-servers", h.List)
	router.POST("/remote-servers", h.Create)
	router.GET("/remote-servers/:uuid", h.Get)
	router.PUT("/remote-servers/:uuid", h.Update)
	router.DELETE("/remote-servers/:uuid", h.Delete)
	router.POST("/remote-servers/:uuid/test", h.TestConnection)
}

// List retrieves all remote servers.
func (h *RemoteServerHandler) List(c *gin.Context) {
	enabledOnly := c.Query("enabled") == "true"

	servers, err := h.service.List(enabledOnly)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, servers)
}

// Create creates a new remote server.
func (h *RemoteServerHandler) Create(c *gin.Context) {
	var server models.RemoteServer
	if err := c.ShouldBindJSON(&server); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	server.UUID = uuid.NewString()

	if err := h.service.Create(&server); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusCreated, server)
}

// Get retrieves a remote server by UUID.
func (h *RemoteServerHandler) Get(c *gin.Context) {
	uuid := c.Param("uuid")

	server, err := h.service.GetByUUID(uuid)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "server not found"})
		return
	}

	c.JSON(http.StatusOK, server)
}

// Update updates an existing remote server.
func (h *RemoteServerHandler) Update(c *gin.Context) {
	uuid := c.Param("uuid")

	server, err := h.service.GetByUUID(uuid)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "server not found"})
		return
	}

	if err := c.ShouldBindJSON(server); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	if err := h.service.Update(server); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, server)
}

// Delete removes a remote server.
func (h *RemoteServerHandler) Delete(c *gin.Context) {
	uuid := c.Param("uuid")

	server, err := h.service.GetByUUID(uuid)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "server not found"})
		return
	}

	if err := h.service.Delete(server.ID); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusNoContent, nil)
}

// TestConnection tests the TCP connection to a remote server.
func (h *RemoteServerHandler) TestConnection(c *gin.Context) {
	uuid := c.Param("uuid")

	server, err := h.service.GetByUUID(uuid)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "server not found"})
		return
	}

	// Test TCP connection with 5 second timeout
	address := net.JoinHostPort(server.Host, fmt.Sprintf("%d", server.Port))
	conn, err := net.DialTimeout("tcp", address, 5*time.Second)

	result := gin.H{
		"server_uuid": server.UUID,
		"address":     address,
		"timestamp":   time.Now().UTC(),
	}

	if err != nil {
		result["reachable"] = false
		result["error"] = err.Error()

		// Update server reachability status
		server.Reachable = false
		now := time.Now().UTC()
		server.LastChecked = &now
		h.service.Update(server)

		c.JSON(http.StatusOK, result)
		return
	}
	defer conn.Close()

	// Connection successful
	result["reachable"] = true
	result["latency_ms"] = time.Since(time.Now()).Milliseconds()

	// Update server reachability status
	server.Reachable = true
	now := time.Now().UTC()
	server.LastChecked = &now
	h.service.Update(server)

	c.JSON(http.StatusOK, result)
}