package main

import (
    "io"
    "net/http"

    "github.com/alexedwards/scs"
)

// Initialize a new encrypted-cookie based session manager and store it in a global
// variable. In a real application, you might inject the session manager as a
// dependency to your handlers instead. The parameter to the NewCookieManager()
// function is a 32 character long random key, which is used to encrypt and
// authenticate the session cookies.
var sessionManager = scs.NewCookieManager("u46IpCV9y5Vlur8YvODJEhgOY8m9JVE4")

func main() {
    // Set up your HTTP handlers in the normal way.
    mux := http.NewServeMux()
    mux.HandleFunc("/put", putHandler)
    mux.HandleFunc("/get", getHandler)

    // Wrap your handlers with the session manager middleware.
    http.ListenAndServe(":4000", sessionManager.Use(mux))
}

func putHandler(w http.ResponseWriter, r *http.Request) {
    // Load the session data for the current request. Any errors are deferred
    // until you actually use the session data.
    session := sessionManager.Load(r)

    // Use the PutString() method to add a new key and associated string value
    // to the session data. Methods for many other common data types are also
    // provided. The session data is automatically saved.
    err := session.PutString(w, "message", "Hello world!")
    if err != nil {
        http.Error(w, err.Error(), 500)
    }
}

func getHandler(w http.ResponseWriter, r *http.Request) {
    // Load the session data for the current request.
    session := sessionManager.Load(r)

    // Use the GetString() helper to retrieve the string value for the "message"
    // key from the session data. The zero value for a string is returned if the
    // key does not exist.
    message, err := session.GetString("message")
    if err != nil {
        http.Error(w, err.Error(), 500)
    }

    io.WriteString(w, message)
}

sessionManager = scs.NewCookieManager("u46IpCV9y5Vlur8YvODJEhgOY8m9JVE4")
sessionManager.Lifetime(time.Hour) // Set the maximum session lifetime to 1 hour.
sessionManager.Persist(true) // Persist the session after a user has closed their browser.
sessionManager.Secure(true) // Set the Secure flag on the session cookie.