iris/context.go

package iris

import (
	"bytes"
	"encoding/json"
	"encoding/xml"
	"fmt"
	"io"
	"io/ioutil"
	"mime/multipart"
	"net"
	"net/http"
	"os"
	"path"
	"reflect"
	"regexp"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/iris-contrib/formBinder"
	"github.com/kataras/go-errors"
)

const (
	// ContentType represents the header["Content-Type"]
	contentType = "Content-Type"
	// ContentLength represents the header["Content-Length"]
	contentLength = "Content-Length"
	// contentEncodingHeader represents the header["Content-Encoding"]
	contentEncodingHeader = "Content-Encoding"
	// varyHeader represents the header "Vary"
	varyHeader = "Vary"
	// acceptEncodingHeader represents the header key & value "Accept-Encoding"
	acceptEncodingHeader = "Accept-Encoding"
	// ContentHTML is the  string of text/html response headers
	contentHTML = "text/html"
	// ContentBinary header value for binary data.
	contentBinary = "application/octet-stream"
	// ContentJSON header value for JSON data.
	contentJSON = "application/json"
	// ContentJSONP header value for JSONP & Javascript data.
	contentJSONP = "application/javascript"
	// ContentJavascript header value for Javascript/JSONP
	// conversional
	contentJavascript = "application/javascript"
	// ContentText header value for Text data.
	contentText = "text/plain"
	// ContentXML header value for XML data.
	contentXML = "text/xml"

	// contentMarkdown custom key/content type, the real is the text/html
	contentMarkdown = "text/markdown"

	// LastModified "Last-Modified"
	lastModified = "Last-Modified"
	// IfModifiedSince "If-Modified-Since"
	ifModifiedSince = "If-Modified-Since"
	// ContentDisposition "Content-Disposition"
	contentDisposition = "Content-Disposition"
	// CacheControl "Cache-Control"
	cacheControl = "Cache-Control"

	// stopExecutionPosition used inside the Context, is the number which shows us that the context's middleware manually stop the execution
	stopExecutionPosition = 255
)

type (
	requestValue struct {
		key   []byte
		value interface{}
	}
	requestValues []requestValue
)

func (r *requestValues) Set(key string, value interface{}) {
	args := *r
	n := len(args)
	for i := 0; i < n; i++ {
		kv := &args[i]
		if string(kv.key) == key {
			kv.value = value
			return
		}
	}

	c := cap(args)
	if c > n {
		args = args[:n+1]
		kv := &args[n]
		kv.key = append(kv.key[:0], key...)
		kv.value = value
		*r = args
		return
	}

	kv := requestValue{}
	kv.key = append(kv.key[:0], key...)
	kv.value = value
	*r = append(args, kv)
}

func (r *requestValues) Get(key string) interface{} {
	args := *r
	n := len(args)
	for i := 0; i < n; i++ {
		kv := &args[i]
		if string(kv.key) == key {
			return kv.value
		}
	}
	return nil
}

func (r *requestValues) Reset() {
	*r = (*r)[:0]
}

type (
	// ContextPool is a set of temporary *Context that may be individually saved and
	// retrieved.
	//
	// Any item stored in the Pool may be removed automatically at any time without
	// notification. If the Pool holds the only reference when this happens, the
	// item might be deallocated.
	//
	// The ContextPool is safe for use by multiple goroutines simultaneously.
	//
	// ContextPool's purpose is to cache allocated but unused Contexts for later reuse,
	// relieving pressure on the garbage collector.
	ContextPool interface {
		// Acquire returns a Context from pool.
		// See Release.
		Acquire(w http.ResponseWriter, r *http.Request) *Context

		// Release puts a Context back to its pull, this function releases its resources.
		// See Acquire.
		Release(ctx *Context)

		// Framework is never used, except when you're in a place where you don't have access to the *iris.Framework station
		// but you need to fire a func or check its Config.
		//
		// Used mostly inside external routers to take the .Config.VHost
		// without the need of other param receivers and refactors when changes
		//
		// note: we could make a variable inside contextPool which would be received by newContextPool
		// but really doesn't need, we just need to borrow a context: we are in pre-build state
		// so the server is not actually running yet, no runtime performance cost.
		Framework() *Framework

		// Run is a combination of Acquire and Release , between these two the `runner` runs,
		// when `runner` finishes its job then the Context is being released.
		Run(w http.ResponseWriter, r *http.Request, runner func(ctx *Context))
	}

	contextPool struct {
		pool sync.Pool
	}
)

var _ ContextPool = &contextPool{}

func (c *contextPool) Acquire(w http.ResponseWriter, r *http.Request) *Context {
	ctx := c.pool.Get().(*Context)
	ctx.ResponseWriter = acquireResponseWriter(w)
	ctx.Request = r
	return ctx
}

func (c *contextPool) Release(ctx *Context) {
	// flush the body (on recorder) or just the status code (on basic response writer)
	// when all finished
	ctx.ResponseWriter.flushResponse()

	ctx.Middleware = nil
	ctx.session = nil
	ctx.Request = nil
	///TODO:
	ctx.ResponseWriter.releaseMe()
	ctx.values.Reset()

	c.pool.Put(ctx)
}

func (c *contextPool) Framework() *Framework {
	ctx := c.pool.Get().(*Context)
	s := ctx.framework
	c.pool.Put(ctx)
	return s
}

func (c *contextPool) Run(w http.ResponseWriter, r *http.Request, runner func(*Context)) {
	ctx := c.Acquire(w, r)
	runner(ctx)
	c.Release(ctx)
}

type (

	// Map is just a conversion for a map[string]interface{}
	// should not be used inside Render when PongoEngine is used.
	Map map[string]interface{}

	// Context is resetting every time a request is coming to the server
	// it is not good practice to use this object in goroutines, for these cases use the .Clone()
	Context struct {
		ResponseWriter // *responseWriter by default, when record is on then *ResponseRecorder
		Request        *http.Request
		values         requestValues
		framework      *Framework
		//keep track all registered middleware (handlers)
		Middleware Middleware //  exported because is useful for debugging
		session    Session
		// Pos is the position number of the Context, look .Next to understand
		Pos int // exported because is useful for debugging
	}
)

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// -----------------------------Handler(s) Execution------------------------------------
// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------

// Do calls the first handler only, it's like Next with negative pos, used only on Router&MemoryRouter
func (ctx *Context) Do() {
	ctx.Pos = 0
	ctx.Middleware[0].Serve(ctx)
}

// Next calls all the next handler from the middleware stack, it used inside a middleware
func (ctx *Context) Next() {
	//set position to the next
	ctx.Pos++
	//run the next
	if ctx.Pos < len(ctx.Middleware) {
		ctx.Middleware[ctx.Pos].Serve(ctx)
	}
}

// NextHandler returns the next handler in the chain (ctx.Middleware)
// otherwise nil.
// Notes:
//  If the result of NextHandler() will be executed then
//  the ctx.Pos (which is exported for these reasons) should be manually increment(++)
//  otherwise your app will visit twice the same handler.
func (ctx *Context) NextHandler() Handler {
	nextPos := ctx.Pos + 1
	// check if it has a next middleware
	if nextPos < len(ctx.Middleware) {
		return ctx.Middleware[nextPos]
	}
	return nil
}

// StopExecution just sets the .pos to 255 in order to  not move to the next middlewares(if any)
func (ctx *Context) StopExecution() {
	ctx.Pos = stopExecutionPosition
}

// IsStopped checks and returns true if the current position of the Context is 255, means that the StopExecution has called
func (ctx *Context) IsStopped() bool {
	return ctx.Pos == stopExecutionPosition
}

// GetHandlerName as requested returns the stack-name of the function which the Middleware is setted from
func (ctx *Context) GetHandlerName() string {
	return runtime.FuncForPC(reflect.ValueOf(ctx.Middleware[len(ctx.Middleware)-1]).Pointer()).Name()
}

// ExecRoute calls any route (mostly  "offline" route) like it was requested by the user, but it is not.
// Offline means that the route is registered to the iris and have all features that a normal route has
// BUT it isn't available by browsing, its handlers executed only when other handler's context call them
// it can validate paths, has sessions, path parameters and all.
//
// You can find the Route by iris.Default.Routes().Lookup("theRouteName")
// you can set a route name as: myRoute := iris.Default.Get("/mypath", handler)("theRouteName")
// that will set a name to the route and returns its iris.Route instance for further usage.
//
// It doesn't changes the global state, if a route was "offline" it remains offline.
//
// see ExecRouteAgainst(routeName, againstRequestPath string),
// iris.Default.None(...) and iris.Default.SetRouteOnline/SetRouteOffline
// For more details look: https://github.com/kataras/iris/issues/585
//
// Example: https://github.com/iris-contrib/examples/tree/master/route_state
func (ctx *Context) ExecRoute(r RouteInfo) {
	ctx.ExecRouteAgainst(r, ctx.Path())
}

// ExecRouteAgainst calls any iris.Route against a 'virtually' request path
// like it was requested by the user, but it is not.
// Offline means that the route is registered to the iris and have all features that a normal route has
// BUT it isn't available by browsing, its handlers executed only when other handler's context call them
// it can validate paths, has sessions, path parameters and all.
//
// You can find the Route by iris.Default.Routes().Lookup("theRouteName")
// you can set a route name as: myRoute := iris.Default.Get("/mypath", handler)("theRouteName")
// that will set a name to the route and returns its iris.Route instance for further usage.
//
// It doesn't changes the global state, if a route was "offline" it remains offline.
//
// see ExecRoute(routeName),
// iris.Default.None(...) and iris.Default.SetRouteOnline/SetRouteOffline
// For more details look: https://github.com/kataras/iris/issues/585
//
// Example: https://github.com/iris-contrib/examples/tree/master/route_state
//
// User can get the response by simple using rec := ctx.Recorder(); rec.Body()/rec.StatusCode()/rec.Header()
// The route will be executed via the Router, as it would requested by client.
func (ctx *Context) ExecRouteAgainst(r RouteInfo, againstRequestPath string) {
	if r != nil && againstRequestPath != "" {
		// ok no need to clone the whole context, let's be dirty here for the sake of performance.
		backupMidldeware := ctx.Middleware[0:]
		backupPath := ctx.Path()
		bakcupMethod := ctx.Method()
		backupValues := ctx.values
		backupPos := ctx.Pos
		// sessions stays.

		ctx.values.Reset()
		ctx.Middleware = ctx.Middleware[0:0]
		ctx.Request.RequestURI = againstRequestPath
		ctx.Request.URL.Path = againstRequestPath
		ctx.Request.Method = r.Method()

		ctx.framework.Router.ServeHTTP(ctx.ResponseWriter, ctx.Request)

		ctx.Middleware = backupMidldeware
		ctx.Request.RequestURI = backupPath
		ctx.Request.URL.Path = backupPath
		ctx.Request.Method = bakcupMethod
		ctx.values = backupValues
		ctx.Pos = backupPos
	}
}

// Prioritize is a middleware which executes a route against this path
// when the request's Path has a prefix of the route's STATIC PART
// is not executing ExecRoute to determinate if it's valid, for performance reasons
// if this function is not enough for you and you want to test more than one parameterized path
// then use the:  if c := ExecRoute(r); c == nil { /*  move to the next, the route is not valid */ }
//
// You can find the Route by iris.Default.Routes().Lookup("theRouteName")
// you can set a route name as: myRoute := iris.Default.Get("/mypath", handler)("theRouteName")
// that will set a name to the route and returns its iris.Route instance for further usage.
//
// if the route found then it executes that and don't continue to the next handler
// if not found then continue to the next handler
func Prioritize(r RouteInfo) HandlerFunc {
	if r != nil {
		return func(ctx *Context) {
			reqPath := ctx.Path()
			staticPath := ctx.framework.policies.RouterReversionPolicy.StaticPath(r.Path())
			if strings.HasPrefix(reqPath, staticPath) {
				ctx.ExecRouteAgainst(r, reqPath) // returns 404 page from EmitErrors, these things depends on router adaptors
				// we are done here.
				return
			}
			// execute the next handler if no prefix
			// here look, the only error we catch is the 404,
			//  we can't go ctx.Next() and believe that the next handler will manage the error
			// because it will not, we are not on the router.
			ctx.Next()
		}
	}
	return func(ctx *Context) { ctx.Next() }
}

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// -----------------------------Request URL, Method, IP & Headers getters---------------
// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------

// Method returns the http request method
// same as *http.Request.Method
func (ctx *Context) Method() string {
	return ctx.Request.Method
}

// Host returns the host part of the current url
func (ctx *Context) Host() string {
	h := ctx.Request.URL.Host
	if h == "" {
		h = ctx.Request.Host
	}
	return h
}

// ServerHost returns the server host taken by *http.Request.Host
func (ctx *Context) ServerHost() string {
	return ctx.Request.Host
}

// Subdomain returns the subdomain (string) of this request, if any
func (ctx *Context) Subdomain() (subdomain string) {
	host := ctx.Host()
	if index := strings.IndexByte(host, '.'); index > 0 {
		subdomain = host[0:index]
	}

	return
}

// VirtualHostname returns the hostname that user registers,
// host path maybe differs from the real which is the Host(), which taken from a net.listener
func (ctx *Context) VirtualHostname() string {
	realhost := ctx.Host()
	hostname := realhost
	virtualhost := ctx.framework.Config.VHost

	if portIdx := strings.IndexByte(hostname, ':'); portIdx > 0 {
		hostname = hostname[0:portIdx]
	}
	if idxDotAnd := strings.LastIndexByte(hostname, '.'); idxDotAnd > 0 {
		s := hostname[idxDotAnd:]
		// means that we have the request's host mymachine.com or 127.0.0.1/0.0.0.0, but for the second option we will need to replace it with the hostname that the dev was registered
		// this needed to parse correct the {{ url }} iris global template engine's function
		if s == ".1" {
			hostname = strings.Replace(hostname, "127.0.0.1", virtualhost, 1)
		} else if s == ".0" {
			hostname = strings.Replace(hostname, "0.0.0.0", virtualhost, 1)
		}
		//
	} else {
		hostname = strings.Replace(hostname, "localhost", virtualhost, 1)
	}

	return hostname
}

// Path returns the full escaped path as string
// for unescaped use: ctx.RequestCtx.RequestURI() or RequestPath(escape bool)
func (ctx *Context) Path() string {
	return ctx.RequestPath(ctx.framework.Config.EnablePathEscape)
}

// RequestPath returns the requested path
func (ctx *Context) RequestPath(escape bool) string {
	if escape {
		// NOTE: for example:
		// DecodeURI decodes %2F to '/'
		// DecodeQuery decodes any %20 to whitespace
		// here we choose to be query-decoded only
		// and with context.ParamDecoded the user receives a URI decoded path parameter.
		// see https://github.com/iris-contrib/examples/tree/master/named_parameters_pathescape
		// and https://github.com/iris-contrib/examples/tree/master/pathescape

		return DecodeQuery(ctx.Request.URL.EscapedPath())
	}
	return ctx.Request.URL.Path
}

// RemoteAddr tries to return the real client's request IP
func (ctx *Context) RemoteAddr() string {
	header := ctx.RequestHeader("X-Real-Ip")
	realIP := strings.TrimSpace(header)
	if realIP != "" {
		return realIP
	}
	realIP = ctx.RequestHeader("X-Forwarded-For")
	idx := strings.IndexByte(realIP, ',')
	if idx >= 0 {
		realIP = realIP[0:idx]
	}
	realIP = strings.TrimSpace(realIP)
	if realIP != "" {
		return realIP
	}
	addr := strings.TrimSpace(ctx.Request.RemoteAddr)
	if len(addr) == 0 {
		return ""
	}
	// if addr has port use the net.SplitHostPort otherwise(error occurs) take as it is
	if ip, _, err := net.SplitHostPort(addr); err == nil {
		return ip
	}
	return addr
}

// RequestHeader returns the request header's value
// accepts one parameter, the key of the header (string)
// returns string
func (ctx *Context) RequestHeader(k string) string {
	return ctx.Request.Header.Get(k)
}

// IsAjax returns true if this request is an 'ajax request'( XMLHttpRequest)
//
// Read more at: http://www.w3schools.com/ajax/
func (ctx *Context) IsAjax() bool {
	return ctx.RequestHeader("HTTP_X_REQUESTED_WITH") == "XMLHttpRequest"
}

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// -----------------------------GET & POST arguments------------------------------------
// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------

// URLParam returns the get parameter from a request , if any
func (ctx *Context) URLParam(key string) string {
	return ctx.Request.URL.Query().Get(key)
}

// URLParams returns a map of GET query parameters separated by comma if more than one
// it returns an empty map if nothing founds
func (ctx *Context) URLParams() map[string]string {
	values := map[string]string{}

	q := ctx.URLParamsAsMulti()
	if q != nil {
		for k, v := range q {
			values[k] = strings.Join(v, ",")
		}
	}

	return values
}

// URLParamsAsMulti returns a map of list contains the url get parameters
func (ctx *Context) URLParamsAsMulti() map[string][]string {
	return ctx.Request.URL.Query()
}

// URLParamInt returns the url query parameter as int value from a request ,  returns error on parse fail
func (ctx *Context) URLParamInt(key string) (int, error) {
	return strconv.Atoi(ctx.URLParam(key))
}

// URLParamInt64 returns the url query parameter as int64 value from a request ,  returns error on parse fail
func (ctx *Context) URLParamInt64(key string) (int64, error) {
	return strconv.ParseInt(ctx.URLParam(key), 10, 64)
}

func (ctx *Context) askParseForm() error {
	if ctx.Request.Form == nil {
		if err := ctx.Request.ParseForm(); err != nil {
			return err
		}
	}
	return nil
}

// FormValues returns all post data values with their keys
// form data, get, post & put query arguments
//
// NOTE: A check for nil is necessary for zero results
func (ctx *Context) FormValues() map[string][]string {
	//  we skip the check of multipart form, takes too much memory, if user wants it can do manually now.
	if err := ctx.askParseForm(); err != nil {
		return nil
	}
	return ctx.Request.Form // nothing more to do, it's already contains both query and post & put args.
}

// FormValue returns a single form value by its name/key
func (ctx *Context) FormValue(name string) string {
	return ctx.Request.FormValue(name)
}

// PostValue returns a form's only-post value by its name
// same as Request.PostFormValue
func (ctx *Context) PostValue(name string) string {
	return ctx.Request.PostFormValue(name)
}

// FormFile returns the first file for the provided form key.
// FormFile calls ctx.Request.ParseMultipartForm and ParseForm if necessary.
//
// same as Request.FormFile
func (ctx *Context) FormFile(key string) (multipart.File, *multipart.FileHeader, error) {
	return ctx.Request.FormFile(key)
}

var (
	errTemplateExecute = errors.New("Unable to execute a template. Trace: %s")
	errReadBody        = errors.New("While trying to read %s from the request body. Trace %s")
	errServeContent    = errors.New("While trying to serve content to the client. Trace %s")
)

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// -----------------------------Request Body Binders/Readers----------------------------
// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------

// NOTE: No default max body size http package has some built'n protection for DoS attacks
// See iris.Default.Config.MaxBytesReader, https://github.com/golang/go/issues/2093#issuecomment-66057813
// and https://github.com/golang/go/issues/2093#issuecomment-66057824

// LimitRequestBodySize is a middleware which sets a request body size limit for all next handlers
// should be registered before all other handlers
var LimitRequestBodySize = func(maxRequestBodySizeBytes int64) HandlerFunc {
	return func(ctx *Context) {
		ctx.SetMaxRequestBodySize(maxRequestBodySizeBytes)
		ctx.Next()
	}
}

// SetMaxRequestBodySize sets a limit to the request body size
// should be called before reading the request body from the client
func (ctx *Context) SetMaxRequestBodySize(limitOverBytes int64) {
	ctx.Request.Body = http.MaxBytesReader(ctx.ResponseWriter, ctx.Request.Body, limitOverBytes)
}

// BodyDecoder is an interface which any struct can implement in order to customize the decode action
// from ReadJSON and ReadXML
//
// Trivial example of this could be:
// type User struct { Username string }
//
// func (u *User) Decode(data []byte) error {
//	  return json.Unmarshal(data, u)
// }
//
// the 'context.ReadJSON/ReadXML(&User{})' will call the User's
// Decode option to decode the request body
//
// Note: This is totally optionally, the default decoders
// for ReadJSON is the encoding/json and for ReadXML is the encoding/xml
type BodyDecoder interface {
	Decode(data []byte) error
}

// Unmarshaler is the interface implemented by types that can unmarshal any raw data
// TIP INFO: Any v object which implements the BodyDecoder can be override the unmarshaler
type Unmarshaler interface {
	Unmarshal(data []byte, v interface{}) error
}

// UnmarshalerFunc a shortcut for the Unmarshaler interface
//
// See 'Unmarshaler' and 'BodyDecoder' for more
type UnmarshalerFunc func(data []byte, v interface{}) error

// Unmarshal parses the X-encoded data and stores the result in the value pointed to by v.
// Unmarshal uses the inverse of the encodings that Marshal uses, allocating maps,
// slices, and pointers as necessary.
func (u UnmarshalerFunc) Unmarshal(data []byte, v interface{}) error {
	return u(data, v)
}

// UnmarshalBody reads the request's body and binds it to a value or pointer of any type
// Examples of usage: context.ReadJSON, context.ReadXML
func (ctx *Context) UnmarshalBody(v interface{}, unmarshaler Unmarshaler) error {
	if ctx.Request.Body == nil {
		return errors.New("unmarshal: empty body")
	}

	rawData, err := ioutil.ReadAll(ctx.Request.Body)
	if err != nil {
		return err
	}

	if ctx.framework.Config.DisableBodyConsumptionOnUnmarshal {
		// * remember, Request.Body has no Bytes(), we have to consume them first
		// and after re-set them to the body, this is the only solution.
		ctx.Request.Body = ioutil.NopCloser(bytes.NewBuffer(rawData))
	}

	// check if the v contains its own decode
	// in this case the v should be a pointer also,
	// but this is up to the user's custom Decode implementation*
	//
	// See 'BodyDecoder' for more
	if decoder, isDecoder := v.(BodyDecoder); isDecoder {
		return decoder.Decode(rawData)
	}

	// check if v is already a pointer, if yes then pass as it's
	if reflect.TypeOf(v).Kind() == reflect.Ptr {
		return unmarshaler.Unmarshal(rawData, v)
	}
	// finally, if the v doesn't contains a self-body decoder and it's not a pointer
	// use the custom unmarshaler to bind the body
	return unmarshaler.Unmarshal(rawData, &v)
}

// ReadJSON reads JSON from request's body and binds it to a value of any json-valid type
func (ctx *Context) ReadJSON(jsonObject interface{}) error {
	return ctx.UnmarshalBody(jsonObject, UnmarshalerFunc(json.Unmarshal))
}

// ReadXML reads XML from request's body and binds it to a value of any xml-valid type
func (ctx *Context) ReadXML(xmlObject interface{}) error {
	return ctx.UnmarshalBody(xmlObject, UnmarshalerFunc(xml.Unmarshal))
}

// ReadForm binds the formObject  with the form data
// it supports any kind of struct
func (ctx *Context) ReadForm(formObject interface{}) error {
	values := ctx.FormValues()
	if values == nil {
		return errors.New("An empty form passed on context.ReadForm")
	}
	return errReadBody.With(formBinder.Decode(values, formObject))
}

/* Response */

// SetContentType sets the response writer's header key 'Content-Type' to a given value(s)
func (ctx *Context) SetContentType(s string) {
	ctx.ResponseWriter.Header().Set(contentType, s)
}

// SetHeader write to the response writer's header to a given key the given value
func (ctx *Context) SetHeader(k string, v string) {
	ctx.ResponseWriter.Header().Add(k, v)
}

// SetStatusCode sets the status code header to the response
//
// same as .WriteHeader, iris takes cares of your status code seriously
func (ctx *Context) SetStatusCode(statusCode int) {
	ctx.ResponseWriter.WriteHeader(statusCode)
}

// Redirect redirect sends a redirect response the client
// accepts 2 parameters string and an optional int
// first parameter is the url to redirect
// second parameter is the http status should send, default is 302 (StatusFound),
// you can set it to 301 (Permant redirect), if that's nessecery
func (ctx *Context) Redirect(urlToRedirect string, statusHeader ...int) {
	ctx.StopExecution()

	httpStatus := StatusFound // a 'temporary-redirect-like' which works better than for our purpose
	if len(statusHeader) > 0 && statusHeader[0] > 0 {
		httpStatus = statusHeader[0]
	}

	// we don't know the Method of the url to redirect,
	// sure we can find it by reverse routing as we already implemented
	// but it will take too much time for a simple redirect, it doesn't worth it.
	// So we are checking the CURRENT Method for GET, HEAD,  CONNECT and TRACE.
	// the
	// Fixes: http: //support.iris-go.com/d/21-wrong-warning-message-while-redirecting
	shouldCheckForCycle := urlToRedirect == ctx.Path() && ctx.Method() == MethodGet
	// from POST to GET on the same path will give a warning message but developers don't use the iris.DevLogger
	// for production, so I assume it's OK to let it logs it
	// (it can solve issues when developer redirects to the same handler over and over again)
	// Note: it doesn't stops the redirect, the developer gets what he/she expected.
	if shouldCheckForCycle {
		ctx.Log(DevMode, "warning: redirect from: '%s' to: '%s',\ncurrent method: '%s'", ctx.Path(), urlToRedirect, ctx.Method())
	}

	http.Redirect(ctx.ResponseWriter, ctx.Request, urlToRedirect, httpStatus)
}

// RedirectTo does the same thing as Redirect but instead of receiving a uri or path it receives a route name
func (ctx *Context) RedirectTo(routeName string, args ...interface{}) {
	s := ctx.framework.URL(routeName, args...)
	if s != "" {
		ctx.Redirect(s, StatusFound)
	}
}

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// -----------------------------(Custom) Errors-----------------------------------------
// ----------------------Look iris.OnError/EmitError for more---------------------------
// -------------------------------------------------------------------------------------

// NotFound emits an error 404 to the client, using the custom http errors
// if no custom errors provided then it sends the default error message
func (ctx *Context) NotFound() {
	ctx.framework.EmitError(StatusNotFound, ctx)
}

// Panic emits an error 500 to the client, using the custom http errors
// if no custom errors rpovided then it sends the default error message
func (ctx *Context) Panic() {
	ctx.framework.EmitError(StatusInternalServerError, ctx)
}

// EmitError executes the custom error by the http status code passed to the function
func (ctx *Context) EmitError(statusCode int) {
	ctx.framework.EmitError(statusCode, ctx)
	ctx.StopExecution()
}

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// -------------------------Context's gzip inline response writer ----------------------
// ---------------------Look adaptors/view & iris.go for more options-------------------
// -------------------------------------------------------------------------------------

var (
	errClientDoesNotSupportGzip = errors.New("Client doesn't supports gzip compression")
)

func (ctx *Context) clientAllowsGzip() bool {
	if h := ctx.RequestHeader(acceptEncodingHeader); h != "" {
		for _, v := range strings.Split(h, ";") {
			if strings.Contains(v, "gzip") { // we do Contains because sometimes browsers has the q=, we don't use it atm. || strings.Contains(v,"deflate"){
				return true
			}
		}
	}
	return false
}

// WriteGzip accepts bytes, which are compressed to gzip format and sent to the client.
// returns the number of bytes written and an error ( if the client doesn' supports gzip compression)
func (ctx *Context) WriteGzip(b []byte) (int, error) {
	if ctx.clientAllowsGzip() {
		ctx.ResponseWriter.Header().Add(varyHeader, acceptEncodingHeader)

		gzipWriter := acquireGzipWriter(ctx.ResponseWriter)
		n, err := gzipWriter.Write(b)
		releaseGzipWriter(gzipWriter)

		if err == nil {
			ctx.SetHeader(contentEncodingHeader, "gzip")
		} // else write the contents as it is? no let's create a new func for this
		return n, err
	}

	return 0, errClientDoesNotSupportGzip
}

// TryWriteGzip accepts bytes, which are compressed to gzip format and sent to the client.
// If client does not supprots gzip then the contents are written as they are, uncompressed.
func (ctx *Context) TryWriteGzip(b []byte) (int, error) {
	n, err := ctx.WriteGzip(b)
	if err != nil {
		// check if the error came from gzip not allowed and not the writer itself
		if _, ok := err.(*errors.Error); ok {
			// client didn't supported gzip, write them uncompressed:
			return ctx.ResponseWriter.Write(b)
		}
	}
	return n, err
}

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// -----------------------------Render and powerful content negotiation-----------------
// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------

const (
	// NoLayout to disable layout for a particular template file
	NoLayout = "@.|.@no_layout@.|.@"
	// TemplateLayoutContextKey is the name of the user values which can be used to set a template layout from a middleware and override the parent's
	TemplateLayoutContextKey = "templateLayout"
)

// getGzipOption receives a default value and the render options map and returns if gzip is enabled for this render action
func getGzipOption(defaultValue bool, options map[string]interface{}) bool {
	gzipOpt := options["gzip"] // we only need that, so don't create new map to keep the options.
	if b, isBool := gzipOpt.(bool); isBool {
		return b
	}
	return defaultValue
}

// gtCharsetOption receives a default value and the render options  map and returns the correct charset for this render action
func getCharsetOption(defaultValue string, options map[string]interface{}) string {
	charsetOpt := options["charset"]
	if s, isString := charsetOpt.(string); isString {
		return s
	}
	return defaultValue
}

func (ctx *Context) fastRenderWithStatus(status int, cType string, data []byte) (err error) {
	if _, shouldFirstStatusCode := ctx.ResponseWriter.(*responseWriter); shouldFirstStatusCode {
		ctx.SetStatusCode(status)
	}
	gzipEnabled := ctx.framework.Config.Gzip
	charset := ctx.framework.Config.Charset

	if cType != contentBinary {
		cType += "; charset=" + charset
	}

	// add the content type to the response
	ctx.SetContentType(cType)

	var out io.Writer
	if gzipEnabled && ctx.clientAllowsGzip() {
		ctx.ResponseWriter.Header().Add(varyHeader, acceptEncodingHeader)
		ctx.SetHeader(contentEncodingHeader, "gzip")

		gzipWriter := acquireGzipWriter(ctx.ResponseWriter)
		defer releaseGzipWriter(gzipWriter)
		out = gzipWriter
	} else {
		out = ctx.ResponseWriter
	}

	// no need to loop through the RenderPolicy, these types must be fast as possible
	// with the features like gzip and custom charset too.
	_, err = out.Write(data)

	// we don't care for the last one it will not be written more than one if we have the *responseWriter
	///TODO:
	// if we have ResponseRecorder order doesn't matters but I think the transactions have bugs,
	// temporary let's keep it here because it 'fixes' one of them...
	ctx.SetStatusCode(status)

	return
}

// RenderWithStatus builds up the response from the specified template or a serialize engine.
// Note: the options: "gzip" and "charset" are built'n support by Iris, so you can pass these on any template engine or serialize engines
func (ctx *Context) RenderWithStatus(status int, name string, binding interface{}, options ...map[string]interface{}) (err error) {
	if _, shouldFirstStatusCode := ctx.ResponseWriter.(*responseWriter); shouldFirstStatusCode {
		ctx.SetStatusCode(status)
	}

	// we do all these because we don't want to initialize a new map for each execution...
	gzipEnabled := ctx.framework.Config.Gzip
	charset := ctx.framework.Config.Charset
	if len(options) > 0 {
		gzipEnabled = getGzipOption(gzipEnabled, options[0])
		charset = getCharsetOption(charset, options[0])
	}

	ctxLayout := ctx.GetString(TemplateLayoutContextKey)
	if ctxLayout != "" {
		if len(options) > 0 {
			options[0]["layout"] = ctxLayout
		} else {
			options = []map[string]interface{}{{"layout": ctxLayout}}
		}
	}

	// Find Content type
	// if it the name is not a template file, then take that as the content type.
	cType := contentHTML
	if !strings.Contains(name, ".") {
		// remember the text/markdown is just a custom internal
		// iris content type, which in reallity renders html
		if name != contentMarkdown {
			cType = name
		}

	}
	if cType != contentBinary {
		cType += "; charset=" + charset
	}

	// add the content type to the response
	ctx.SetContentType(cType)

	var out io.Writer
	if gzipEnabled && ctx.clientAllowsGzip() {
		ctx.ResponseWriter.Header().Add(varyHeader, acceptEncodingHeader)
		ctx.SetHeader(contentEncodingHeader, "gzip")

		gzipWriter := acquireGzipWriter(ctx.ResponseWriter)
		defer releaseGzipWriter(gzipWriter)
		out = gzipWriter
	} else {
		out = ctx.ResponseWriter
	}

	err = ctx.framework.Render(out, name, binding, options...)

	// we don't care for the last one it will not be written more than one if we have the *responseWriter
	///TODO:
	// if we have ResponseRecorder order doesn't matters but I think the transactions have bugs , for now let's keep it here because it 'fixes' one of them...
	ctx.SetStatusCode(status)

	return
}

// Render same as .RenderWithStatus but with status to iris.StatusOK (200) if no previous status exists
// builds up the response from the specified template or a serialize engine.
// Note: the options: "gzip" and "charset" are built'n support by Iris, so you can pass these on any template engine or serialize engine
func (ctx *Context) Render(name string, binding interface{}, options ...map[string]interface{}) error {
	errCode := ctx.ResponseWriter.StatusCode()
	if errCode <= 0 {
		errCode = StatusOK
	}
	return ctx.RenderWithStatus(errCode, name, binding, options...)
}

// MustRender same as .Render but returns 503 service unavailable http status with a (html) message if render failed
// Note: the options: "gzip" and "charset" are built'n support by Iris, so you can pass these on any template engine or serialize engine
func (ctx *Context) MustRender(name string, binding interface{}, options ...map[string]interface{}) {
	if err := ctx.Render(name, binding, options...); err != nil {
		htmlErr := ctx.HTML(StatusServiceUnavailable,
			fmt.Sprintf("<h2>Template: %s</h2><b>%s</b>", name, err.Error()))

		ctx.Log(DevMode, "MustRender failed to render '%s', trace: %s\n",
			name, err)

		if htmlErr != nil {
			ctx.Log(DevMode, "MustRender also failed to render the html fallback: %s",
				htmlErr.Error())
		}

	}
}

// Data writes out the raw bytes as binary data.
//
// RenderPolicy does NOT apply to context.HTML, context.Text and context.Data
// To change their default behavior users should use
// the context.RenderWithStatus(statusCode, contentType, content, options...) instead.
func (ctx *Context) Data(status int, data []byte) error {
	return ctx.fastRenderWithStatus(status, contentBinary, data)
}

// Text writes out a string as plain text.
//
// RenderPolicy does NOT apply to context.HTML, context.Text and context.Data
// To change their default behavior users should use
// the context.RenderWithStatus(statusCode, contentType, content, options...) instead.
func (ctx *Context) Text(status int, text string) error {
	return ctx.fastRenderWithStatus(status, contentText, []byte(text))
}

// HTML writes html string with a http status
//
// RenderPolicy does NOT apply to context.HTML, context.Text and context.Data
// To change their default behavior users should use
// the context.RenderWithStatus(statusCode, contentType, content, options...) instead.
func (ctx *Context) HTML(status int, htmlContents string) error {
	return ctx.fastRenderWithStatus(status, contentHTML, []byte(htmlContents))
}

// JSON marshals the given interface object and writes the JSON response.
func (ctx *Context) JSON(status int, v interface{}) error {
	return ctx.RenderWithStatus(status, contentJSON, v)
}

// JSONP marshals the given interface object and writes the JSON response.
func (ctx *Context) JSONP(status int, callback string, v interface{}) error {
	return ctx.RenderWithStatus(status, contentJSONP, v, map[string]interface{}{"callback": callback})
}

// XML marshals the given interface object and writes the XML response.
func (ctx *Context) XML(status int, v interface{}) error {
	return ctx.RenderWithStatus(status, contentXML, v)
}

// MarkdownString parses the (dynamic) markdown string and returns the converted html string
func (ctx *Context) MarkdownString(markdownText string) string {
	out := &bytes.Buffer{}
	ok, _ := ctx.framework.policies.RenderPolicy(out, contentMarkdown, markdownText)
	if ok {
		return out.String()
	}
	return ""
}

// Markdown parses and renders to the client a particular (dynamic) markdown string
// accepts two parameters
// first is the http status code
// second is the markdown string
func (ctx *Context) Markdown(status int, markdown string) error {
	return ctx.HTML(status, ctx.MarkdownString(markdown))
}

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// --------------------Static content serve by context implementation-------------------
// --------------------Look iris.go for more useful Static web system methods-----------
// -------------------------------------------------------------------------------------

// staticCachePassed checks the IfModifiedSince header and
// returns true if (client-side) duration has expired
func (ctx *Context) staticCachePassed(modtime time.Time) bool {
	if t, err := time.Parse(ctx.framework.Config.TimeFormat, ctx.RequestHeader(ifModifiedSince)); err == nil && modtime.Before(t.Add(StaticCacheDuration)) {
		ctx.ResponseWriter.Header().Del(contentType)
		ctx.ResponseWriter.Header().Del(contentLength)
		ctx.SetStatusCode(StatusNotModified)
		return true
	}
	return false
}

// SetClientCachedBody like SetBody but it sends with an expiration datetime
// which is managed by the client-side (all major browsers supports this feature)
func (ctx *Context) SetClientCachedBody(status int, bodyContent []byte, cType string, modtime time.Time) error {
	if ctx.staticCachePassed(modtime) {
		return nil
	}

	modtimeFormatted := modtime.UTC().Format(ctx.framework.Config.TimeFormat)

	ctx.ResponseWriter.Header().Set(contentType, cType)
	ctx.ResponseWriter.Header().Set(lastModified, modtimeFormatted)
	ctx.SetStatusCode(status)

	_, err := ctx.ResponseWriter.Write(bodyContent)
	return err
}

// ServeContent serves content, headers are autoset
// receives three parameters, it's low-level function, instead you can use .ServeFile(string,bool)/SendFile(string,string)
//
// You can define your own "Content-Type" header also, after this function call
// Doesn't implements resuming (by range), use ctx.SendFile instead
func (ctx *Context) ServeContent(content io.ReadSeeker, filename string, modtime time.Time, gzipCompression bool) error {
	if t, err := time.Parse(ctx.framework.Config.TimeFormat, ctx.RequestHeader(ifModifiedSince)); err == nil && modtime.Before(t.Add(1*time.Second)) {
		ctx.ResponseWriter.Header().Del(contentType)
		ctx.ResponseWriter.Header().Del(contentLength)
		ctx.SetStatusCode(StatusNotModified)
		return nil
	}

	ctx.ResponseWriter.Header().Set(contentType, typeByExtension(filename))
	ctx.ResponseWriter.Header().Set(lastModified, modtime.UTC().Format(ctx.framework.Config.TimeFormat))
	ctx.SetStatusCode(StatusOK)
	var out io.Writer
	if gzipCompression && ctx.clientAllowsGzip() {
		ctx.ResponseWriter.Header().Add(varyHeader, acceptEncodingHeader)
		ctx.SetHeader(contentEncodingHeader, "gzip")

		gzipWriter := acquireGzipWriter(ctx.ResponseWriter)
		defer releaseGzipWriter(gzipWriter)
		out = gzipWriter
	} else {
		out = ctx.ResponseWriter
	}
	_, err := io.Copy(out, content)
	return errServeContent.With(err)
}

// ServeFile serves a view file, to send a file ( zip for example) to the client you should use the SendFile(serverfilename,clientfilename)
// receives two parameters
// filename/path (string)
// gzipCompression (bool)
//
// You can define your own "Content-Type" header also, after this function call
// This function doesn't implement resuming (by range), use ctx.SendFile instead
//
// Use it when you want to serve css/js/... files to the client, for bigger files and 'force-download' use the SendFile
func (ctx *Context) ServeFile(filename string, gzipCompression bool) error {
	f, err := os.Open(filename)
	if err != nil {
		return fmt.Errorf("%d", 404)
	}
	defer f.Close()
	fi, _ := f.Stat()
	if fi.IsDir() {
		filename = path.Join(filename, "index.html")
		f, err = os.Open(filename)
		if err != nil {
			return fmt.Errorf("%d", 404)
		}
		fi, _ = f.Stat()
	}
	return ctx.ServeContent(f, fi.Name(), fi.ModTime(), gzipCompression)
}

// SendFile sends file for force-download to the client
//
// Use this instead of ServeFile to 'force-download' bigger files to the client
func (ctx *Context) SendFile(filename string, destinationName string) error {
	ctx.ResponseWriter.Header().Set(contentDisposition, "attachment;filename="+destinationName)
	return ctx.ServeFile(filename, false)
}

// StreamWriter registers the given stream writer for populating
// response body.
//
// Access to context's and/or its' members is forbidden from writer.
//
// This function may be used in the following cases:
//
//     * if response body is too big (more than iris.LimitRequestBodySize(if setted)).
//     * if response body is streamed from slow external sources.
//     * if response body must be streamed to the client in chunks.
//     (aka `http server push`).
//
// receives a function which receives the response writer
// and returns false when it should stop writing, otherwise true in order to continue
func (ctx *Context) StreamWriter(writer func(w io.Writer) bool) {
	w := ctx.ResponseWriter
	notifyClosed := w.CloseNotify()
	for {
		select {
		// response writer forced to close, exit.
		case <-notifyClosed:
			return
		default:
			shouldContinue := writer(w)
			w.Flush()
			if !shouldContinue {
				return
			}
		}
	}
}

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// --------------------------------Storage----------------------------------------------
// -----------------------User Values &  Path parameters--------------------------------
// -------------------------------------------------------------------------------------

// ValuesLen returns the total length of the user values storage, some of them maybe path parameters
func (ctx *Context) ValuesLen() (n int) {
	return len(ctx.values)
}

// Get returns the user's value from a key
// if doesn't exists returns nil
func (ctx *Context) Get(key string) interface{} {
	return ctx.values.Get(key)
}

// GetFmt returns a value which has this format: func(format string, args ...interface{}) string
// if doesn't exists returns a function which returns an empty string.
//
// "translate" is the key of the i18n middlweare
// for more plaese look: https://github.com/iris-contrib/examples/tree/master/middleware_internationalization_i18n
func (ctx *Context) getFmt(key string) func(format string, args ...interface{}) string {
	if v, ok := ctx.Get(key).(func(format string, args ...interface{}) string); ok {
		return v
	}
	return func(format string, args ...interface{}) string { return "" }
}

// TranslateLanguageContextKey & TranslateFunctionContextKey are used by i18n handlers/middleware
// currently we have only one: https://github.com/iris-contrib/middleware/tree/master/i18n
// but you can use these keys to override the i18n's cookie name (TranslateLanguageContextKey)
// or to store new translate function  by using the ctx.Set(iris.TranslateFunctionContextKey, theTrFunc)
var (
	TranslateLanguageContextKey = "language"
	TranslateFunctionContextKey = "translate"
)

// Translate is the i18n (localization) middleware's function, it just
// calls the ctx.getFmt("translate").
// "translate" is the key of the i18n middlweare
// for more plaese look: https://github.com/iris-contrib/examples/tree/master/middleware_internationalization_i18n
func (ctx *Context) Translate(format string, args ...interface{}) string {
	return ctx.getFmt(TranslateFunctionContextKey)(format, args...)
}

// GetString same as Get but returns the value as string
// if nothing founds returns empty string ""
func (ctx *Context) GetString(key string) string {
	if v, ok := ctx.Get(key).(string); ok {
		return v
	}

	return ""
}

var errIntParse = errors.New("Unable to find or parse the integer, found: %#v")

// GetInt same as Get but tries to convert the return value as integer
// if nothing found or canno be parsed to integer it returns an error
func (ctx *Context) GetInt(key string) (int, error) {
	v := ctx.Get(key)
	if vint, ok := v.(int); ok {
		return vint, nil
	} else if vstring, sok := v.(string); sok {
		return strconv.Atoi(vstring)
	}

	return -1, errIntParse.Format(v)
}

// Set sets a value to a key in the values map
func (ctx *Context) Set(key string, value interface{}) {
	ctx.values.Set(key, value)
}

// VisitValues calls visitor for each existing context's temp values.
//
// visitor must not retain references to key and value after returning.
// Make key and/or value copies if you need storing them after returning.
func (ctx *Context) VisitValues(visitor func(string, interface{})) {
	for i, n := 0, len(ctx.values); i < n; i++ {
		kv := &ctx.values[i]
		visitor(string(kv.key), kv.value)
	}
}

// ParamsLen tries to return all the stored values which values are string, probably most of them will be the path parameters
func (ctx *Context) ParamsLen() (n int) {
	ctx.VisitValues(func(kb string, vg interface{}) {
		if _, ok := vg.(string); ok {
			n++
		}

	})
	return
}

// Param returns the string representation of the key's path named parameter's value
// same as GetString
func (ctx *Context) Param(key string) string {
	return ctx.GetString(key)
}

// ParamDecoded returns a url-query-decoded path parameter's value
func (ctx *Context) ParamDecoded(key string) string {
	return DecodeQuery(DecodeQuery(ctx.Param(key)))
}

// ParamInt returns the int representation of the key's path named parameter's value
// same as GetInt
func (ctx *Context) ParamInt(key string) (int, error) {
	return ctx.GetInt(key)
}

// ParamInt64 returns the int64 representation of the key's path named parameter's value
func (ctx *Context) ParamInt64(key string) (int64, error) {
	return strconv.ParseInt(ctx.Param(key), 10, 64)
}

// ParamsSentence returns a string implementation of all parameters that this context  keeps
// hasthe form of key1=value1,key2=value2...
func (ctx *Context) ParamsSentence() string {
	var buff bytes.Buffer
	ctx.VisitValues(func(k string, vi interface{}) {
		v, ok := vi.(string)
		if !ok {
			return
		}
		buff.WriteString(k)
		buff.WriteString("=")
		buff.WriteString(v)
		// we don't know where that (yet) stops so...
		buff.WriteString(",")

	})
	result := buff.String()
	if len(result) < 2 {
		return ""
	}

	return result[0 : len(result)-1]

}

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// -----------https://github.com/golang/net/blob/master/context/context.go--------------
// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------

// Deadline returns the time when work done on behalf of this context
// should be canceled.  Deadline returns ok==false when no deadline is
// set.  Successive calls to Deadline return the same results.
func (ctx *Context) Deadline() (deadline time.Time, ok bool) {
	return
}

// Done returns a channel that's closed when work done on behalf of this
// context should be canceled.  Done may return nil if this context can
// never be canceled.  Successive calls to Done return the same value.
//
// WithCancel arranges for Done to be closed when cancel is called;
// WithDeadline arranges for Done to be closed when the deadline
// expires; WithTimeout arranges for Done to be closed when the timeout
// elapses.
//
// Done is provided for use in select statements:
//
//  // Stream generates values with DoSomething and sends them to out
//  // until DoSomething returns an error or ctx.Done is closed.
//  func Stream(ctx context.Context, out chan<- Value) error {
//  	for {
//  		v, err := DoSomething(ctx)
//  		if err != nil {
//  			return err
//  		}
//  		select {
//  		case <-ctx.Done():
//  			return ctx.Err()
//  		case out <- v:
//  		}
//  	}
//  }
//
// See http://blog.golang.org/pipelines for more examples of how to use
// a Done channel for cancelation.
func (ctx *Context) Done() <-chan struct{} {
	return nil
}

// Err returns a non-nil error value after Done is closed.  Err returns
// Canceled if the context was canceled or DeadlineExceeded if the
// context's deadline passed.  No other values for Err are defined.
// After Done is closed, successive calls to Err return the same value.
func (ctx *Context) Err() error {
	return nil
}

// Value returns the value associated with this context for key, or nil
// if no value is associated with key.  Successive calls to Value with
// the same key returns the same result.
//
// Use context values only for request-scoped data that transits
// processes and API boundaries, not for passing optional parameters to
// functions.
//
// A key identifies a specific value in a Context.  Functions that wish
// to store values in Context typically allocate a key in a global
// variable then use that key as the argument to context.WithValue and
// Context.Value.  A key can be any type that supports equality;
// packages should define keys as an unexported type to avoid
// collisions.
//
// Packages that define a Context key should provide type-safe accessors
// for the values stores using that key:
//
// 	// Package user defines a User type that's stored in Contexts.
// 	package user
//
// 	import "golang.org/x/net/context"
//
// 	// User is the type of value stored in the Contexts.
// 	type User struct {...}
//
// 	// key is an unexported type for keys defined in this package.
// 	// This prevents collisions with keys defined in other packages.
// 	type key int
//
// 	// userKey is the key for user.User values in Contexts.  It is
// 	// unexported; clients use user.NewContext and user.FromContext
// 	// instead of using this key directly.
// 	var userKey key = 0
//
// 	// NewContext returns a new Context that carries value u.
// 	func NewContext(ctx context.Context, u *User) context.Context {
// 		return context.WithValue(ctx, userKey, u)
// 	}
//
// 	// FromContext returns the User value stored in ctx, if any.
// 	func FromContext(ctx context.Context) (*User, bool) {
// 		u, ok := ctx.Value(userKey).(*User)
// 		return u, ok
// 	}
func (ctx *Context) Value(key interface{}) interface{} {
	if key == 0 {
		return ctx.Request
	}
	if k, ok := key.(string); ok {
		return ctx.GetString(k)
	}
	return nil
}

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// --------------------------------Session & Cookies------------------------------------
// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------

// VisitAllCookies takes a visitor which loops on each (request's) cookie key and value
func (ctx *Context) VisitAllCookies(visitor func(key string, value string)) {
	for _, cookie := range ctx.Request.Cookies() {
		visitor(cookie.Name, cookie.Value)
	}
}

// GetCookie returns cookie's value by it's name
// returns empty string if nothing was found
func (ctx *Context) GetCookie(name string) string {
	cookie, err := ctx.Request.Cookie(name)
	if err != nil {
		return ""
	}
	return cookie.Value
}

// SetCookie adds a cookie
func (ctx *Context) SetCookie(cookie *http.Cookie) {
	http.SetCookie(ctx.ResponseWriter, cookie)
}

// SetCookieKV adds a cookie, receives just a key(string) and a value(string)
//
// Expires on 2 hours by default(unchable)
// use ctx.SetCookie or http.SetCookie instead for more control.
func (ctx *Context) SetCookieKV(name, value string) {
	c := &http.Cookie{}
	c.Name = name
	c.Value = value
	c.HttpOnly = true
	c.Expires = time.Now().Add(time.Duration(120) * time.Minute)
	ctx.SetCookie(c)
}

// RemoveCookie deletes a cookie by it's name/key
func (ctx *Context) RemoveCookie(name string) {
	c := &http.Cookie{}
	c.Name = name
	c.Value = ""
	c.Path = "/"
	c.HttpOnly = true
	exp := time.Now().Add(-time.Duration(1) * time.Minute) //RFC says 1 second, but let's do it 1 minute to make sure is working...
	c.Expires = exp
	c.MaxAge = -1
	ctx.SetCookie(c)
	// delete request's cookie also, which is temporary available
	ctx.Request.Header.Set("Cookie", "")
}

var errSessionsPolicyIsMissing = errors.New(
	`
manually call of context.Session() for client IP: '%s' without specified SessionsPolicy!
Please .Adapt one of the available session managers inside 'kataras/iris/adaptors'.

Edit your main .go source file to adapt one of these and restart your app.
	i.e: lines (<---) were missing.
	-------------------------------------------------------------------
	import (
		"gopkg.in/kataras/iris.v6"
		"gopkg.in/kataras/iris.v6/adaptors/httprouter" // or gorillamux
		"gopkg.in/kataras/iris.v6/adaptors/sessions" // <--- this line
	)

	func main(){
		app := iris.New()
		// right below the iris.New()
		app.Adapt(httprouter.New()) // or gorillamux.New()

		mySessions := sessions.New(sessions.Config{
			// Cookie string, the session's client cookie name, for example: "mysessionid"
			//
			// Defaults to "gosessionid"
			Cookie: "mysessionid",
			// base64 urlencoding,
			// if you have strange name cookie name enable this
			DecodeCookie: false,
			// it's time.Duration, from the time cookie is created, how long it can be alive?
			// 0 means no expire.
			Expires: 0,
			// the length of the sessionid's cookie's value
			CookieLength: 32,
			// if you want to invalid cookies on different subdomains
			// of the same host, then enable it
			DisableSubdomainPersistence: false,
		})

		// OPTIONALLY:
		// import "gopkg.in/kataras/iris.v6/adaptors/sessions/sessiondb/redis"
		// or import "github.com/kataras/go-sessions/sessiondb/$any_available_community_database"
		// mySessions.UseDatabase(redis.New(...))

		app.Adapt(mySessions) // <--- and this line were missing.

		// the rest of your source code...
		// ...

		app.Listen("%s")
	}
	-------------------------------------------------------------------
 `)

// Session returns the current Session.
//
// if SessionsPolicy is missing then a detailed how-to-fix message
// will be visible to the user (DevMode)
// and the return value will be NILL.
func (ctx *Context) Session() Session {
	policy := ctx.framework.policies.SessionsPolicy
	if policy.Start == nil {
		ctx.framework.Log(DevMode,
			errSessionsPolicyIsMissing.Format(ctx.RemoteAddr(), ctx.framework.Config.VHost).Error())
		return nil
	}

	if ctx.session == nil {
		ctx.session = policy.Start(ctx.ResponseWriter, ctx.Request)
	}

	return ctx.session
}

// SessionDestroy destroys the whole session, calls the provider's destroy and remove the cookie
func (ctx *Context) SessionDestroy() {
	if sess := ctx.Session(); sess != nil {
		ctx.framework.policies.SessionsPolicy.Destroy(ctx.ResponseWriter, ctx.Request)
	}
}

var maxAgeExp = regexp.MustCompile(`maxage=(\d+)`)

// MaxAge returns the "cache-control" request header's value
// seconds as int64
// if header not found or parse failed then it returns -1
func (ctx *Context) MaxAge() int64 {
	header := ctx.RequestHeader(cacheControl)
	if header == "" {
		return -1
	}
	m := maxAgeExp.FindStringSubmatch(header)
	if len(m) == 2 {
		if v, err := strconv.Atoi(m[1]); err == nil {
			return int64(v)
		}
	}
	return -1
}

// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------
// ---------------------------Transactions & Response Writer Recording------------------
// -------------------------------------------------------------------------------------
// -------------------------------------------------------------------------------------

// Record transforms the context's basic and direct responseWriter to a ResponseRecorder
// which can be used to reset the body, reset headers, get the body,
// get & set the status code at any time and more
func (ctx *Context) Record() {
	if w, ok := ctx.ResponseWriter.(*responseWriter); ok {
		ctx.ResponseWriter = acquireResponseRecorder(w)
	}
}

// Recorder returns the context's ResponseRecorder
// if not recording then it starts recording and returns the new context's ResponseRecorder
func (ctx *Context) Recorder() *ResponseRecorder {
	ctx.Record()
	return ctx.ResponseWriter.(*ResponseRecorder)
}

// IsRecording returns the response recorder and a true value
// when the response writer is recording the status code, body, headers and so on,
// else returns nil and false
func (ctx *Context) IsRecording() (*ResponseRecorder, bool) {
	//NOTE:
	// two return values in order to minimize the if statement:
	// if (Recording) then writer = Recorder()
	// instead we do: recorder,ok = Recording()
	rr, ok := ctx.ResponseWriter.(*ResponseRecorder)
	return rr, ok
}

// skipTransactionsContextKey set this to any value to stop executing next transactions
// it's a context-key in order to be used from anywhere, set it by calling the SkipTransactions()
const skipTransactionsContextKey = "__IRIS_TRANSACTIONS_SKIP___"

// SkipTransactions if called then skip the rest of the transactions
// or all of them if called before the first transaction
func (ctx *Context) SkipTransactions() {
	ctx.Set(skipTransactionsContextKey, 1)
}

// TransactionsSkipped returns true if the transactions skipped or canceled at all.
func (ctx *Context) TransactionsSkipped() bool {
	if n, err := ctx.GetInt(skipTransactionsContextKey); err == nil && n == 1 {
		return true
	}
	return false
}

// non-detailed error log for transacton unexpected panic
var errTransactionInterrupted = errors.New("Transaction Interrupted, recovery from panic:\n%s")

// BeginTransaction starts a scoped transaction.
//
// Can't say a lot here because it will take more than 200 lines to write about.
// You can search third-party articles or books on how Business Transaction works (it's quite simple, especially here).
//
// Note that this is unique and new
// (=I haver never seen any other examples or code in Golang on this subject, so far, as with the most of iris features...)
// it's not covers all paths,
// such as databases, this should be managed by the libraries you use to make your database connection,
// this transaction scope is only for context's response.
// Transactions have their own middleware ecosystem also, look iris.go:UseTransaction.
//
// See https://github.com/iris-contrib/examples/tree/master/transactions for more
func (ctx *Context) BeginTransaction(pipe func(transaction *Transaction)) {
	// SILLY NOTE: use of manual pipe type in order of TransactionFunc
	// in order to help editors complete the sentence here...

	// do NOT begin a transaction when the previous transaction has been failed
	// and it was requested scoped or SkipTransactions called manually.
	if ctx.TransactionsSkipped() {
		return
	}

	// start recording in order to be able to control the full response writer
	ctx.Record()

	// get a transaction scope from the pool by passing the temp context/
	t := newTransaction(ctx)
	defer func() {
		if err := recover(); err != nil {
			ctx.Log(DevMode, errTransactionInterrupted.Format(err).Error())
			// complete (again or not , doesn't matters) the scope without loud
			t.Complete(nil)
			// we continue as normal, no need to return here*
		}

		// write the temp contents to the original writer
		t.Context.ResponseWriter.writeTo(ctx.ResponseWriter)

		// give back to the transaction the original writer (SetBeforeFlush works this way and only this way)
		// this is tricky but nessecery if we want ctx.EmitError to work inside transactions
		t.Context.ResponseWriter = ctx.ResponseWriter
	}()

	// run the worker with its context clone inside.
	pipe(t)
}

// Log logs to the iris defined logger
func (ctx *Context) Log(mode LogMode, format string, a ...interface{}) {
	ctx.framework.Log(mode, fmt.Sprintf(format, a...))
}

// Framework returns the Iris instance, containing the configuration and all other fields
func (ctx *Context) Framework() *Framework {
	return ctx.framework
}