// source:https://github.com/afoley587/go-rev-proxy/tree/main
package server

import (
    "errors"
    "fmt"
    "github.com/Akilan1999/p2p-rendering-computation/config"
    "github.com/gin-gonic/gin"
    "log"
    "net/http"
    "net/http/httputil"
    "net/url"
)

var (
    //RunPort              = 2002                                           // The server port to run on
    //ReverseServerAddr    = fmt.Sprint("0.0.0.0:", RunPort)                // this is our reverse server ip address
    //InsideProxyHostname  = fmt.Sprint("proxy:", RunPort)                  // Requests from private network
    //OutsideProxyHostname = fmt.Sprint("registration.localhost:", RunPort) // Requests from public network
    KnownAddresses = map[string]string{} // Known Addresses
)

type RegistrationRequest struct {
    OutsideHost string // Outside host address. The hostname or IP on the public network. For example foo.bar.com or foo.localhost
    InsideHost  string // Inside host address. The hostname or IP on the internal network. For example 192.168.10.5
}

// This function checks if TLS was enabled on the request
// and translates it to the proper scheme (http or https)
func GetScheme(c *gin.Context) string {
    if c.Request.TLS != nil {
        return "https"
    } else {
        return "http"
    }
}

// IsRegistrationRequest checks if an incoming request is meant to register
// a new inside/outside hostname pair by checking if the hostname and
// path match a specific combination.
// If the host is our registration.localhost or proxy hostname
// AND if the path is /register, we will register a new endpoint
//func IsRegistrationRequest(c *gin.Context) bool {
//	isRR := ((c.Request.Host == InsideProxyHostname || c.Request.Host == OutsideProxyHostname) &&
//		c.Request.URL.String() == "/register")
//	return isRR
//}
//
//// SaveRegistrationRequest saves an inside/outside hostname pairing
//// to our KnownAddresses map so we can use it later. Effectively
//// registering a new endpoint for us
//func SaveRegistrationRequest(c *gin.Context) error {
//	var rr RegistrationRequest
//	log.Println(c.Request.Body)
//	err := c.BindJSON(&rr)
//
//	if err != nil {
//		return err
//	}
//
//	log.Println("Registering", rr.OutsideHost, "to", rr.InsideHost)
//	KnownAddresses[rr.OutsideHost] = rr.InsideHost
//	return nil
//}

// SaveRegistration Creates registration of proxy node
func SaveRegistration(OutsideHost string, InsideHost string) error {
    _, ok := KnownAddresses[OutsideHost]
    if !ok {
        return errors.New("domain name provided already exists")
    }
    KnownAddresses[OutsideHost] = InsideHost

    fmt.Println(OutsideHost)
    fmt.Println(InsideHost)
    fmt.Println(KnownAddresses[OutsideHost])

    return nil
}

// Proxy runs the actual proxy and will look at the
// hostnames requested from the received request. It will
// then translate that to the inside hostname and forward the
// request
func Proxy(c *gin.Context) {

    // Get if HTTP or HTTPS
    scheme := GetScheme(c)

    log.Println(scheme, c.Request.Host, c.Request.URL.String())

    // Translate the outside hostname to the inside hostname
    forwardTo, _ := KnownAddresses[c.Request.Host]

    //if !ok {
    //	log.Printf("Unkown Host: %v", c.Request.Host)
    //	c.String(400, "Unkown Host")
    //	return
    //}

    rUrl := fmt.Sprintf("%v://%v%v", scheme, forwardTo, c.Request.URL)

    remote, err := url.Parse(rUrl)

    if err != nil {
        log.Println(err)
        c.String(500, "Error Proxying Host")
        return
    }

    log.Println("Forwarding request to", remote)

    // Forward the request to the inside remote server
    // https://pkg.go.dev/net/http/httputil#NewSingleHostReverseProxy
    proxy := httputil.NewSingleHostReverseProxy(remote)

    // Director is a function which modifies
    // the request into a new request to be sent
    // https://pkg.go.dev/net/http/httputil#ReverseProxy
    proxy.Director = func(req *http.Request) {
        req.Header = c.Request.Header
        req.Host = remote.Host
        req.URL.Scheme = remote.Scheme
        req.URL.Host = remote.Host
        req.URL.Path = c.Param("path")
    }

    proxy.ServeHTTP(c.Writer, c.Request)
}

func ProxyRun(port string) {
    r := gin.Default()

    KnownAddresses = make(map[string]string)

    // Get config information
    Config, err := config.ConfigInit(nil, nil)
    if err != nil {
        log.Printf("Error: %v", err)
    }

    // all paths should be handled by Proxy()
    r.Any("/*path", Proxy)

    if err := r.RunTLS(fmt.Sprint("0.0.0.0:", port), Config.PemFile, Config.KeyFile); err != nil {
        log.Printf("Error: %v", err)
    }
}