package server

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/yourusername/repo-diagram/backend/internal/analyzer"
	"github.com/yourusername/repo-diagram/backend/internal/diagram"
	"github.com/yourusername/repo-diagram/backend/pkg/models"
	"github.com/yourusername/repo-diagram/backend/pkg/utils"
)

type Server struct {
	router     *gin.Engine
	analyzer   *analyzer.Service
	diagramSvc *diagram.Service
	port       string
}

func NewServer() *Server {
	// Initialize services
	analyzerSvc := analyzer.NewService()
	diagramSvc := diagram.NewService()

	// Setup router
	router := gin.Default()

	// Setup CORS
	router.Use(func(c *gin.Context) {
		c.Header("Access-Control-Allow-Origin", "*")
		c.Header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
		c.Header("Access-Control-Allow-Headers", "Content-Type, Authorization")
		if c.Request.Method == "OPTIONS" {
			c.AbortWithStatus(204)
			return
		}
		c.Next()
	})

	// Initialize server
	server := &Server{
		router:     router,
		analyzer:   analyzerSvc,
		diagramSvc: diagramSvc,
		port:       getEnv("PORT", "8080"),
	}

	// Setup routes
	server.setupRoutes()

	return server
}

func (s *Server) setupRoutes() {
	api := s.router.Group("/api")
	{
		api.POST("/analyze", s.handleAnalyze)
		api.GET("/diagram/:id", s.handleGetDiagram)
		api.GET("/status/:id", s.handleGetStatus)
		api.GET("/export/:id", s.handleExport)
		api.GET("/health", s.handleHealth)
	}
}

func (s *Server) handleAnalyze(c *gin.Context) {
	var req models.AnalysisRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, models.ErrorResponse{Error: err.Error()})
		return
	}

	// Validate repository URL
	if !utils.IsValidGitHubURL(req.RepoURL) {
		c.JSON(http.StatusBadRequest, models.ErrorResponse{Error: "Invalid GitHub repository URL"})
		return
	}

	// Start analysis in background
	go func() {
		ctx := context.Background()
		result, err := s.analyzer.AnalyzeRepository(ctx, req)
		if err != nil {
			log.Printf("Analysis failed: %v", err)
			return
		}

		// Generate diagram
		diagram, err := s.diagramSvc.Generate(ctx, result)
		if err != nil {
			log.Printf("Diagram generation failed: %v", err)
			return
		}

		// Store result (in production, use database)
		utils.SaveResult(result.ID, diagram)
	}()

	c.JSON(http.StatusAccepted, models.AnalysisResponse{
		ID:     utils.GenerateID(),
		Status: "processing",
		Message: "Analysis started",
	})
}

func (s *Server) handleGetDiagram(c *gin.Context) {
	id := c.Param("id")
	diagram := utils.GetDiagram(id)
	if diagram == nil {
		c.JSON(http.StatusNotFound, models.ErrorResponse{Error: "Diagram not found"})
		return
	}
	c.JSON(http.StatusOK, diagram)
}

func (s *Server) handleGetStatus(c *gin.Context) {
	id := c.Param("id")
	status := utils.GetStatus(id)
	if status == nil {
		c.JSON(http.StatusNotFound, models.ErrorResponse{Error: "Analysis not found"})
		return
	}
	c.JSON(http.StatusOK, status)
}

func (s *Server) handleExport(c *gin.Context) {
	id := c.Param("id")
	format := c.DefaultQuery("format", "svg")
	
	diagram := utils.GetDiagram(id)
	if diagram == nil {
		c.JSON(http.StatusNotFound, models.ErrorResponse{Error: "Diagram not found"})
		return
	}

	switch format {
	case "svg":
		c.Data(http.StatusOK, "image/svg+xml", diagram.SVG)
	case "json":
		c.JSON(http.StatusOK, diagram)
	default:
		c.JSON(http.StatusBadRequest, models.ErrorResponse{Error: "Unsupported format"})
	}
}

func (s *Server) handleHealth(c *gin.Context) {
	c.JSON(http.StatusOK, gin.H{
		"status": "healthy",
		"time":   time.Now().Unix(),
	})
}

func (s *Server) Start() error {
	return s.router.Run(":" + s.port)
}

func (s *Server) Shutdown(ctx context.Context) error {
	// Graceful shutdown logic here
	return nil
}

func getEnv(key, defaultValue string) string {
	if value, exists := os.LookupEnv(key); exists {
		return value
	}
	return defaultValue
}

func main() {
	server := NewServer()

	// Setup signal handling for graceful shutdown
	quit := make(chan os.Signal, 1)
	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)

	go func() {
		<-quit
		log.Println("Shutting down server...")
		// Add cleanup logic here
		os.Exit(0)
	}()

	log.Printf("Server starting on port %s", server.port)
	if err := server.Start(); err != nil {
		log.Fatalf("Failed to start server: %v", err)
	}
}