go.sdls.io/sin@v0.0.9/pkg/sin/context.go

// Copyright 2014 Manu Martinez-Almeida.  All rights reserved.
// Use of this source code is governed by a MIT style
// license that can be found in the LICENSE file.

package sin

import (
	"io"
	"math"
	"mime/multipart"
	"net/http"
	"net/url"
	"strings"
	"sync"
	"time"

	"go.sdls.io/sin/pkg/render"
)

const abortIndex int8 = math.MaxInt8 / 2

// Context is the most important part of gin. It allows us to pass variables between middleware,
// manage the flow, validate the JSON of a request and render a JSON response for example.
type Context struct {
	Writer     ResponseWriter
	engine     *Engine
	Request    *http.Request
	queryCache url.Values
	Keys       map[ // queryCache use url.ParseQuery cached the param query result from c.Request.URL.Query()
	// Keys is a key/value pair exclusively for the context of each request.
	string]interface{}
	params    *Params
	fullPath  string
	writermem responseWriter
	handlers  HandlersChain
	Errors    errorMsgs

	Params   Params
	sameSite http.SameSite
	mu       sync.RWMutex
	index    int8 // SameSite allows a server to define a cookie attribute making it impossible for
	// the browser to send this cookie along with cross-site requests.
	// This mutex protect Keys map
}

/************************************/
/********** CONTEXT CREATION ********/
/************************************/

func (c *Context) reset() {
	c.Writer = &c.writermem
	c.Params = c.Params[0:0]
	c.handlers = nil
	c.index = -1

	c.fullPath = ""
	c.Keys = nil
	c.Errors = c.Errors[0:0]
	c.queryCache = nil
	*c.params = (*c.params)[0:0]
}

// Copy returns a copy of the current context that can be safely used outside the request's scope.
// This has to be used when the context has to be passed to a goroutine.
func (c *Context) Copy() *Context {
	cp := Context{
		writermem: c.writermem,
		Request:   c.Request,
		Params:    c.Params,
		engine:    c.engine,
	}
	cp.writermem.ResponseWriter = nil
	cp.Writer = &cp.writermem
	cp.index = abortIndex
	cp.handlers = nil
	cp.Keys = map[string]interface{}{}
	for k, v := range c.Keys {
		cp.Keys[k] = v
	}
	paramCopy := make([]Param, len(cp.Params))
	copy(paramCopy, cp.Params)
	cp.Params = paramCopy
	return &cp
}

// HandlerName returns the main handler's name. For example if the handler is "handleGetUsers()",
// this function will return "main.handleGetUsers".
func (c *Context) HandlerName() string {
	return nameOfFunction(c.handlers.Last())
}

// HandlerNames returns a list of all registered handlers for this context in descending order,
// following the semantics of HandlerName()
func (c *Context) HandlerNames() []string {
	hn := make([]string, 0, len(c.handlers))
	for _, val := range c.handlers {
		hn = append(hn, nameOfFunction(val))
	}
	return hn
}

// Handler returns the main handler.
func (c *Context) Handler() HandlerFunc {
	return c.handlers.Last()
}

// FullPath returns a matched route full path. For not found routes
// returns an empty string.
//     router.GET("/user/:id", func(c *gin.Context) {
//         c.FullPath() == "/user/:id" // true
//     })
func (c *Context) FullPath() string {
	return c.fullPath
}

/************************************/
/*********** FLOW CONTROL ***********/
/************************************/

// Next should be used only inside middleware.
// It executes the pending handlers in the chain inside the calling handler.
// See example in GitHub.
func (c *Context) Next() {
	c.index++
	for c.index < int8(len(c.handlers)) {
		c.handlers[c.index](c)
		c.index++
	}
}

// IsAborted returns true if the current context was aborted.
func (c *Context) IsAborted() bool {
	return c.index >= abortIndex
}

// Abort prevents pending handlers from being called. Note that this will not stop the current handler.
// Let's say you have an authorization middleware that validates that the current request is authorized.
// If the authorization fails (ex: the password does not match), call Abort to ensure the remaining handlers
// for this request are not called.
func (c *Context) Abort() {
	c.index = abortIndex
}

// AbortWithStatus calls `Abort()` and writes the headers with the specified status code.
// For example, a failed attempt to authenticate a request could use: context.AbortWithStatus(401).
func (c *Context) AbortWithStatus(code int) {
	c.Status(code)
	c.Writer.WriteHeaderNow()
	c.Abort()
}

// AbortWithStatusJSON calls `Abort()` and then `JSON` internally.
// This method stops the chain, writes the status code and return a JSON body.
// It also sets the Content-Type as "application/json".
func (c *Context) AbortWithStatusJSON(code int, jsonObj interface{}) {
	c.Abort()
	c.JSON(code, jsonObj)
}

// AbortWithError calls `AbortWithStatus()` and `Error()` internally.
// This method stops the chain, writes the status code and pushes the specified error to `c.Errors`.
// See Context.Error() for more details.
func (c *Context) AbortWithError(code int, err error) *Error {
	c.AbortWithStatus(code)
	return c.Error(err)
}

/************************************/
/********* ERROR MANAGEMENT *********/
/************************************/

// Error attaches an error to the current context. The error is pushed to a list of errors.
// It's a good idea to call Error for each error that occurred during the resolution of a request.
// A middleware can be used to collect all the errors and push them to a database together,
// print a log, or append it in the HTTP response.
// Error will panic if err is nil.
func (c *Context) Error(err error) *Error {
	if err == nil {
		panic("err is nil")
	}

	parsedError, ok := err.(*Error)
	if !ok {
		parsedError = &Error{
			Err:  err,
			Type: ErrorTypePrivate,
		}
	}

	c.Errors = append(c.Errors, parsedError)
	return parsedError
}

/************************************/
/******** METADATA MANAGEMENT********/
/************************************/

// Set is used to store a new key/value pair exclusively for this context.
// It also lazy initializes  c.Keys if it was not used previously.
func (c *Context) Set(key string, value interface{}) {
	c.mu.Lock()
	if c.Keys == nil {
		c.Keys = make(map[string]interface{})
	}

	c.Keys[key] = value
	c.mu.Unlock()
}

// Get returns the value for the given key, ie: (value, true).
// If the value does not exists it returns (nil, false)
func (c *Context) Get(key string) (value interface{}, exists bool) {
	c.mu.RLock()
	value, exists = c.Keys[key]
	c.mu.RUnlock()
	return
}

// MustGet returns the value for the given key if it exists, otherwise it panics.
func (c *Context) MustGet(key string) interface{} {
	if value, exists := c.Get(key); exists {
		return value
	}
	panic("Key \"" + key + "\" does not exist")
}

// GetString returns the value associated with the key as a string.
func (c *Context) GetString(key string) (s string) {
	if val, ok := c.Get(key); ok && val != nil {
		s, _ = val.(string)
	}
	return
}

// GetBool returns the value associated with the key as a boolean.
func (c *Context) GetBool(key string) (b bool) {
	if val, ok := c.Get(key); ok && val != nil {
		b, _ = val.(bool)
	}
	return
}

// GetInt returns the value associated with the key as an integer.
func (c *Context) GetInt(key string) (i int) {
	if val, ok := c.Get(key); ok && val != nil {
		i, _ = val.(int)
	}
	return
}

// GetInt64 returns the value associated with the key as an integer.
func (c *Context) GetInt64(key string) (i64 int64) {
	if val, ok := c.Get(key); ok && val != nil {
		i64, _ = val.(int64)
	}
	return
}

// GetUint returns the value associated with the key as an unsigned integer.
func (c *Context) GetUint(key string) (ui uint) {
	if val, ok := c.Get(key); ok && val != nil {
		ui, _ = val.(uint)
	}
	return
}

// GetUint64 returns the value associated with the key as an unsigned integer.
func (c *Context) GetUint64(key string) (ui64 uint64) {
	if val, ok := c.Get(key); ok && val != nil {
		ui64, _ = val.(uint64)
	}
	return
}

// GetFloat64 returns the value associated with the key as a float64.
func (c *Context) GetFloat64(key string) (f64 float64) {
	if val, ok := c.Get(key); ok && val != nil {
		f64, _ = val.(float64)
	}
	return
}

// GetTime returns the value associated with the key as time.
func (c *Context) GetTime(key string) (t time.Time) {
	if val, ok := c.Get(key); ok && val != nil {
		t, _ = val.(time.Time)
	}
	return
}

// GetDuration returns the value associated with the key as a duration.
func (c *Context) GetDuration(key string) (d time.Duration) {
	if val, ok := c.Get(key); ok && val != nil {
		d, _ = val.(time.Duration)
	}
	return
}

// GetStringSlice returns the value associated with the key as a slice of strings.
func (c *Context) GetStringSlice(key string) (ss []string) {
	if val, ok := c.Get(key); ok && val != nil {
		ss, _ = val.([]string)
	}
	return
}

// GetStringMap returns the value associated with the key as a map of interfaces.
func (c *Context) GetStringMap(key string) (sm map[string]interface{}) {
	if val, ok := c.Get(key); ok && val != nil {
		sm, _ = val.(map[string]interface{})
	}
	return
}

// GetStringMapString returns the value associated with the key as a map of strings.
func (c *Context) GetStringMapString(key string) (sms map[string]string) {
	if val, ok := c.Get(key); ok && val != nil {
		sms, _ = val.(map[string]string)
	}
	return
}

// GetStringMapStringSlice returns the value associated with the key as a map to a slice of strings.
func (c *Context) GetStringMapStringSlice(key string) (smss map[string][]string) {
	if val, ok := c.Get(key); ok && val != nil {
		smss, _ = val.(map[string][]string)
	}
	return
}

/************************************/
/************ INPUT DATA ************/
/************************************/

// Param returns the value of the URL param.
// It is a shortcut for c.Params.ByName(key)
//     router.GET("/user/:id", func(c *gin.Context) {
//         // a GET request to /user/john
//         id := c.Param("id") // id == "john"
//     })
func (c *Context) Param(key string) string {
	return c.Params.ByName(key)
}

// Query returns the keyed url query value if it exists,
// otherwise it returns an empty string `("")`.
// It is shortcut for `c.Request.URL.Query().Get(key)`
//     GET /path?id=1234&name=Manu&value=
// 	   c.Query("id") == "1234"
// 	   c.Query("name") == "Manu"
// 	   c.Query("value") == ""
// 	   c.Query("wtf") == ""
func (c *Context) Query(key string) string {
	value, _ := c.GetQuery(key)
	return value
}

// DefaultQuery returns the keyed url query value if it exists,
// otherwise it returns the specified defaultValue string.
// See: Query() and GetQuery() for further information.
//     GET /?name=Manu&lastname=
//     c.DefaultQuery("name", "unknown") == "Manu"
//     c.DefaultQuery("id", "none") == "none"
//     c.DefaultQuery("lastname", "none") == ""
func (c *Context) DefaultQuery(key, defaultValue string) string {
	if value, ok := c.GetQuery(key); ok {
		return value
	}
	return defaultValue
}

// GetQuery is like Query(), it returns the keyed url query value
// if it exists `(value, true)` (even when the value is an empty string),
// otherwise it returns `("", false)`.
// It is shortcut for `c.Request.URL.Query().Get(key)`
//     GET /?name=Manu&lastname=
//     ("Manu", true) == c.GetQuery("name")
//     ("", false) == c.GetQuery("id")
//     ("", true) == c.GetQuery("lastname")
func (c *Context) GetQuery(key string) (string, bool) {
	if values, ok := c.GetQueryArray(key); ok {
		return values[0], ok
	}
	return "", false
}

// QueryArray returns a slice of strings for a given query key.
// The length of the slice depends on the number of params with the given key.
func (c *Context) QueryArray(key string) []string {
	values, _ := c.GetQueryArray(key)
	return values
}

func (c *Context) initQueryCache() {
	if c.queryCache == nil {
		if c.Request != nil {
			c.queryCache = c.Request.URL.Query()
		} else {
			c.queryCache = url.Values{}
		}
	}
}

// GetQueryArray returns a slice of strings for a given query key, plus
// a boolean value whether at least one value exists for the given key.
func (c *Context) GetQueryArray(key string) ([]string, bool) {
	c.initQueryCache()
	if values, ok := c.queryCache[key]; ok && len(values) > 0 {
		return values, true
	}
	return nil, false
}

// QueryMap returns a map for a given query key.
func (c *Context) QueryMap(key string) map[string]string {
	dicts, _ := c.GetQueryMap(key)
	return dicts
}

// GetQueryMap returns a map for a given query key, plus a boolean value
// whether at least one value exists for the given key.
func (c *Context) GetQueryMap(key string) (map[string]string, bool) {
	c.initQueryCache()
	return c.get(c.queryCache, key)
}

// get is an internal method and returns a map which satisfy conditions.
func (c *Context) get(m map[string][]string, key string) (map[string]string, bool) {
	dicts := make(map[string]string)
	exist := false
	for k, v := range m {
		if i := strings.IndexByte(k, '['); i >= 1 && k[0:i] == key {
			if j := strings.IndexByte(k[i+1:], ']'); j >= 1 {
				exist = true
				dicts[k[i+1:][:j]] = v[0]
			}
		}
	}
	return dicts, exist
}

// FormFile returns the first file for the provided form key.
func (c *Context) FormFile(name string) (*multipart.FileHeader, error) {
	if c.Request.MultipartForm == nil {
		if err := c.Request.ParseMultipartForm(c.engine.MaxMultipartMemory); err != nil {
			return nil, err
		}
	}
	f, fh, err := c.Request.FormFile(name)
	if err != nil {
		return nil, err
	}
	_ = f.Close()
	return fh, err
}

// MultipartForm is the parsed multipart form, including file uploads.
func (c *Context) MultipartForm() (*multipart.Form, error) {
	err := c.Request.ParseMultipartForm(c.engine.MaxMultipartMemory)
	return c.Request.MultipartForm, err
}

// ContentType returns the Content-Type header of the request.
func (c *Context) ContentType() string {
	return filterFlags(c.requestHeader("Content-Type"))
}

// IsWebsocket returns true if the request headers indicate that a websocket
// handshake is being initiated by the client.
func (c *Context) IsWebsocket() bool {
	if strings.Contains(strings.ToLower(c.requestHeader("Connection")), "upgrade") &&
		strings.EqualFold(c.requestHeader("Upgrade"), "websocket") {
		return true
	}
	return false
}

func (c *Context) requestHeader(key string) string {
	return c.Request.Header.Get(key)
}

/************************************/
/******** RESPONSE RENDERING ********/
/************************************/

// bodyAllowedForStatus is a copy of http.bodyAllowedForStatus non-exported function.
func bodyAllowedForStatus(status int) bool {
	switch {
	case status >= 100 && status <= 199:
		return false
	case status == http.StatusNoContent:
		return false
	case status == http.StatusNotModified:
		return false
	}
	return true
}

// Status sets the HTTP response code.
func (c *Context) Status(code int) {
	c.Writer.WriteHeader(code)
}

// Header is a intelligent shortcut for c.Writer.Header().Set(key, value).
// It writes a header in the response.
// If value == "", this method removes the header `c.Writer.Header().Del(key)`
func (c *Context) Header(key, value string) {
	if value == "" {
		c.Writer.Header().Del(key)
		return
	}
	c.Writer.Header().Set(key, value)
}

// GetHeader returns value from request headers.
func (c *Context) GetHeader(key string) string {
	return c.requestHeader(key)
}

// SetSameSite with cookie
func (c *Context) SetSameSite(samesite http.SameSite) {
	c.sameSite = samesite
}

// SetCookie adds a Set-Cookie header to the ResponseWriter's headers.
// The provided cookie must have a valid Name. Invalid cookies may be
// silently dropped.
func (c *Context) SetCookie(name, value string, maxAge int, path, domain string, secure, httpOnly bool) {
	if path == "" {
		path = "/"
	}
	http.SetCookie(c.Writer, &http.Cookie{
		Name:     name,
		Value:    url.QueryEscape(value),
		MaxAge:   maxAge,
		Path:     path,
		Domain:   domain,
		SameSite: c.sameSite,
		Secure:   secure,
		HttpOnly: httpOnly,
	})
}

// Cookie returns the named cookie provided in the request or
// ErrNoCookie if not found. And return the named cookie is unescaped.
// If multiple cookies match the given name, only one cookie will
// be returned.
func (c *Context) Cookie(name string) (string, error) {
	cookie, err := c.Request.Cookie(name)
	if err != nil {
		return "", err
	}
	val, _ := url.QueryUnescape(cookie.Value)
	return val, nil
}

// Render writes the response headers and calls render.Render to render data.
func (c *Context) Render(code int, r render.Render) {
	c.Status(code)

	if !bodyAllowedForStatus(code) {
		r.WriteContentType(c.Writer)
		c.Writer.WriteHeaderNow()
		return
	}

	if err := r.Render(c.Writer); err != nil {
		_ = c.Error(err)
		c.Abort()
	}
}

// IndentedJSON serializes the given struct as pretty JSON (indented + endlines) into the response body.
// It also sets the Content-Type as "application/json".
// WARNING: we recommend to use this only for development purposes since printing pretty JSON is
// more CPU and bandwidth consuming. Use Context.JSON() instead.
func (c *Context) IndentedJSON(code int, obj interface{}) {
	c.Render(code, render.IndentedJSON{Data: obj})
}

// JSON serializes the given struct as JSON into the response body.
// It also sets the Content-Type as "application/json".
func (c *Context) JSON(code int, obj interface{}) {
	c.Render(code, render.JSON{Data: obj})
}

// XML serializes the given struct as XML into the response body.
// It also sets the Content-Type as "application/xml".
func (c *Context) XML(code int, obj interface{}) {
	c.Render(code, render.XML{Data: obj})
}

// String writes the given string into the response body.
func (c *Context) String(code int, format string, values ...interface{}) {
	c.Render(code, render.String{Format: format, Data: values})
}

// Redirect returns a HTTP redirect to the specific location.
func (c *Context) Redirect(code int, location string) {
	c.Render(-1, render.Redirect{
		Code:     code,
		Location: location,
		Request:  c.Request,
	})
}

// Data writes some data into the body stream and updates the HTTP code.
func (c *Context) Data(code int, contentType string, data []byte) {
	c.Render(code, render.Data{
		ContentType: contentType,
		Data:        data,
	})
}

// DataFromReader writes the specified reader into the body stream and updates the HTTP code.
func (c *Context) DataFromReader(code int, contentLength int64, contentType string, reader io.Reader, extraHeaders map[string]string) {
	c.Render(code, render.Reader{
		Headers:       extraHeaders,
		ContentType:   contentType,
		ContentLength: contentLength,
		Reader:        reader,
	})
}

/************************************/
/***** GOLANG.ORG/X/NET/CONTEXT *****/
/************************************/

// Deadline always returns that there is no deadline (ok==false),
// maybe you want to use Request.Context().Deadline() instead.
func (c *Context) Deadline() (deadline time.Time, ok bool) {
	if c.Request == nil || c.Request.Context() == nil {
		return
	}
	return c.Request.Context().Deadline()
}

// Done always returns nil (chan which will wait forever),
// if you want to abort your work when the connection was closed
// you should use Request.Context().Done() instead.
func (c *Context) Done() <-chan struct{} {
	if c.Request == nil || c.Request.Context() == nil {
		return nil
	}
	return c.Request.Context().Done()
}

// Err always returns nil, maybe you want to use Request.Context().Err() instead.
func (c *Context) Err() error {
	if c.Request == nil || c.Request.Context() == nil {
		return nil
	}
	return c.Request.Context().Err()
}

// 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.
func (c *Context) Value(key interface{}) interface{} {
	if key == 0 {
		return c.Request
	}
	if keyAsString, ok := key.(string); ok {
		if val, exists := c.Get(keyAsString); exists {
			return val
		}
	}
	if c.Request == nil || c.Request.Context() == nil {
		return nil
	}
	return c.Request.Context().Value(key)
}