package util

import (
	"context"
	"log"
	"net"
	"net/http"
	"os"
	"os/signal"

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

// Copied from: https://github.com/gin-gonic/gin/blob/59ab588bf597f9f41faee4f217b5659893c2e925/utils.go#L137
func resolveAddress(addr []string) string {
	switch len(addr) {
	case 0:
		if port := os.Getenv("PORT"); port != "" {
			log.Printf("Environment variable PORT=\"%s\"", port)
			return ":" + port
		}
		log.Printf("Environment variable PORT is undefined. Using port :8080 by default")
		return ":8080"
	case 1:
		return addr[0]
	default:
		panic("too many parameters")
	}
}

// Runs a gin.Engine instance in a way that can be canceled by an SIGINT
func GinRun(e *gin.Engine, debug bool, a ...string) {
	if debug {
		gin.SetMode(gin.DebugMode)
	} else {
		gin.SetMode(gin.ReleaseMode)
	}

	srv := &http.Server{
		Addr:    resolveAddress(a),
		Handler: e,
	}

	idleConnsClosed := make(chan struct{})

	go func() {
		sigint := make(chan os.Signal, 1)
		signal.Notify(sigint, os.Interrupt)
		<-sigint

		log.Println("Caught SIGINT, shutting down")
		if err := srv.Shutdown(context.Background()); err != nil {
			log.Printf("HTTP server Shutdown: %v", err)
		}

		close(idleConnsClosed)
	}()

	log.Printf("Listening and serving HTTP on %s\n", srv.Addr)
	if err := srv.ListenAndServe(); err != http.ErrServerClosed {
		log.Fatalf("HTTP server ListenAndServe: %v", err)
	}

	<-idleConnsClosed
}

func GetRequestIP(c *gin.Context) net.IP {
	if xff := c.Request.Header.Get("X-Forwarded-For"); xff != "" {
		return ParseIP(xff)
	}
	return ParseIP(c.Request.RemoteAddr)
}