Refactor the lib and break to v3 (#35)

* Refactor the session `AutoCreate` behaviour. This is a breaking change.
* feat: refactor tests
* fix: update code comments
* refactor: remove Commit() pattern and introduce setMulti to store interface
- remove Commit() pattern, Set and SetMulti should immediately set the
  values to backend.
- rename LoadValues() to CacheAll() and update cache on Set, SetMulti,
  Delete and Clear calls.
* fix: update goredis package to implement latest store interface
* feat: v3 refactor
- Update store interface to take session ID instead of returning on
  Create()
- Introduce hooks to generate and validate session ID in manager. By
  default use alpha-numeric 32 length ID.
- Rename get and set cookie register method to `SetCookieHooks`.
- Ditch ErrFieldNotFound error and get/set supposed to return Nil
  instead.
* refactor: conv package to v3 spec
* feat: migrate memory store to v3 spec
* refactor: redis package to v3 spec
* refactor: securecookie package to v3 spec
* refactor: postgres package to v3 spec
* fix: Clear() should only clear the values and not session
* feat: add Destroy() which deletes the dession from backend
* chore: update README and lib comments
* fix: incorrect store Delete() method implementation
* fix: update store version to v3
* fix: update examples to v3
* fix: refactor examples module structure

---------

Co-authored-by: Kailash Nadh <kailash@nadh.in>

README.md

@@ -9,39 +9,41 @@ Most session libraries are highly opinionated and hard-wired to work with `net/h
 ## Features
 1. Framework/network library agnostic.
 2. Simple API and with support for primitive data types. Complex types can be stored using own encoding/decoding.
-3. Pre-built redis/postgres/in-memory stores that can be separately installed.
+3. Pre-built redis/postgres/in-memory/securecookie stores that can be separately installed.
 4. Multiple session instances with custom handlers and different backend stores.
 
 ## Installation
 Install `simplesessions` and all [available stores](/stores).
 
 ```shell
-go get -u github.com/vividvilla/simplesessions
+go get -u github.com/vividvilla/simplesessions/v3
 
-# Install the requrired store: memory|goredis|redis|postgres
-go get -u github.com/vividvilla/simplesessions/stores/goredis
+# Install the requrired store: memory|redis|postgres|securecookie
+go get -u github.com/vividvilla/simplesessions/v3/stores/redis
+go get -u github.com/vividvilla/simplesessions/v3/stores/postgres
 ```
 
 # Stores
 Sessions can be stored to any backend by implementing the [store](/store.go) interface. The following stores are bundled.
 
-* [in-memory](/stores/memory)
 * [redis](/stores/redis)
+* [postgres](/stores/postgres)
+* [in-memory](/stores/memory)
 * [secure cookie](/stores/securecookie)
 
 # Usage
 Check the [examples](/examples) directory for complete examples.
 
 ## Connecting a store
-Stores can be registered to a session instance by using `Use` method.
+Stores can be registered to a session instance by using `Use` method. Check individual [Stores](#stores) docs for more details.
 
 ```go
 sess := simplesessions.New(simplesessions.Options{})
-sess.UseStore(memory.New())
+sess.UseStore(store.New())
 ```
 
 ## Connecting an HTTP handler
-Any HTTP library can be connected to simplesessions by registering the `RegisterGetCookie()` and `RegisterSetCookie()` callbacks. The below example shows a simple `net/http` usecase. Another example showing `fasthttp` can be found [here](/examples).
+Any HTTP library can be connected to simplesessions by registering the get and set cookie hooks using `SetCookieHooks()`. The below example shows a simple `net/http` usecase. Another example showing `fasthttp` can be found [here](/examples).
 
 ```go
 var sessMan *simplesessions.Manager
@@ -81,61 +83,104 @@ func setCookie(cookie *http.Cookie, w interface{}) error {
 func handler(w http.ResponseWriter, r *http.Request) {
 	// Use method `Acquire` to acquire a session before you access the session.
 	// Acquire takes read, write interface and context respectively.
-	// Read interface sent to callback registered with `RegisterGetCookie`
-	// and write interface is sent to callback registered with `RegisterWriteCookie`
+	// Read interface sent to callback registered with get cookie hook
+	// and write interface is sent to callback registered with write cookie hook
+	// set using `SetCookieHooks()` method.
+	//
 	// Optionally `context` can be sent which is usually request context where acquire
 	// session will get previously loaded session. This is useful if you have multiple
 	// middlewares accessing sessions. New sessions will be created in first middleware which
 	// does `Acquire` and will be reused in other places.
-	sess, err := sessMan.Acquire(r, w, nil)
-
-	// Use 'Set` and `Commit` to set a field for session.
-	// 'Set` ideally doesn't persist the value to store unless method `Commit` is called.
-	// But note that its up to the store you are using to decide to
-	// persist data only on `commit` or persist on `Set` itself.
-	// Stores like redis, db etc should persist on `Commit` while in-memory does on `Set`.
-	// No matter what store you use its better to explicitly
-	// call `Commit` method when you set all the values.
+	//
+	// If `Options.EnableAutoCreate` is set to True then if session doesn't exist it will
+	// be immediately created and returned. Bydefault its set to False so if session doesn't
+	// exist then `ErrInvalidSession` error is returned.
+	sess, err := sessMan.Acquire(nil, r, w)
+
+	// If session doesn't exist then create new session.
+	// In a traditional login flow you can create a new session once user completes the login flow.
+	if err == simplesessions.ErrInvalidSession {
+		sess, err = sessMan.NewSession(r, w)
+	}
+
+	// Use 'Set` or `SetMulti` to set a field for session.
 	err = sess.Set("somekey", "somevalue")
-	err = sess.Set("someotherkey", 10)
-	err = sess.Commit()
+	err = sess.SetMulti(map[string]interface{}{
+		"k1": "v1",
+		"k2": "v2",
+	})
 
 	// Use `Get` method to get a field from current session. The result will be an interface
 	// so you can use helper methods like
 	// `String', `Int`, `Int64`, `UInt64`, `Float64`, `Bytes`, `Bool`.
 	val, err := sess.String(sess.Get("somekey"))
+	fmt.Println("val=", val)
 
 	// Use `GetAll` to get map of all fields from session.
 	// The result is map of string and interface you can use helper methods to type cast it.
-	val, err := sess.GetAll()
+	all, err := sess.GetAll()
+	fmt.Println("all=", all)
 
 	// Use `GetMulti` to get values for given fields from session.
 	// The result is map of string and interface you can use helper methods to type cast it.
 	// If key is not there then store should ideally send `nil` value for given key.
-	val, err := sess.GetMulti("somekey", "someotherkey")
+	vals, err := sess.GetMulti("somekey", "someotherkey")
+	fmt.Println("vals=", vals)
 
 	// Use `Delete` to delete a field from session.
-	err := sess.Delete("somekey")
+	err = sess.Delete("somekey")
+
+	// Use `Clear` to empty the session but to keep the session alive.
+	err = sess.Clear()
 
-	// Use `Clear` to clear session from store.
-	err := sess.Clear()
+	// Use `Destroy` to clear session from store and cookie.
+	err = sess.Destroy()
 
 	fmt.Fprintf(w, "success")
 }
 
 func main() {
 	// Create a session manager with custom options like cookie name,
 	// cookie domain, is secure cookie etc. Check `Options` struct for more options.
-	sessMan := simplesessions.New(simplesessions.Options{})
+	sessMan := simplesessions.New(simplesessions.Options{
+		// If set to true then `Acquire()` method will create new session instead of throwing
+		// `ErrInvalidSession` when the session doesn't exist. By default its set to false.
+		EnableAutoCreate: false,
+		Cookie: simplesessions.CookieOptions{
+			// Name sets http cookie name. This is also sent as cookie name in `GetCookie` callback.
+			Name: "session",
+			// Domain sets hostname for the cookie. Domain specifies allowed hosts to receive the cookie.
+			Domain: "example.com",
+			// Path sets path for the cookie. Path indicates a URL path that must exist in the requested URL in order to send the cookie header.
+			Path: "/",
+			// IsSecure marks the cookie as secure cookie (only sent in HTTPS).
+			IsSecure: true,
+			// IsHTTPOnly marks the cookie as http only cookie. JS won't be able to access the cookie so prevents XSS attacks.
+			IsHTTPOnly: true,
+			// SameSite sets allows you to declare if your cookie should be restricted to a first-party or same-site context.
+			SameSite: http.SameSiteDefaultMode,
+			// Expires sets absolute expiration date and time for the cookie.
+			// If both Expires and MaxAge are sent then MaxAge takes precedence over Expires.
+			// Cookies without a Max-age or Expires attribute – are deleted when the current session ends
+			// and some browsers use session restoring when restarting. This can cause session cookies to last indefinitely.
+			Expires: time.Now().Add(time.Hour * 24),
+			// Sets the cookie's expiration in seconds from the current time, internally its rounder off to nearest seconds.
+			// If both Expires and MaxAge are sent then MaxAge takes precedence over Expires.
+			// Cookies without a Max-age or Expires attribute – are deleted when the current session ends
+			// and some browsers use session restoring when restarting. This can cause session cookies to last indefinitely.
+			MaxAge: time.Hour * 24,
+		},
+	})
+
 	// Create a new store instance and attach to session manager
 	sessMan.UseStore(memory.New())
-	// Register callbacks for read and write cookie
+	// Register callbacks for read and write cookie.
 	// Get cookie callback should get cookie based on cookie name and
 	// sent back in net/http cookie format.
-	sessMan.RegisterGetCookie(getCookie)
 	// Set cookie callback should set cookie it received for received cookie name.
-	sessMan.RegisterSetCookie(setCookie)
+	sessMan.SetCookieHooks(getCookie, setCookie)
 
-	http.HandleFunc("/set", handler)
+	// Initialize the handler.
+	http.HandleFunc("/", handler)
 }
 ```