/*
 * @Author: hongyu guo
 * @Description:
 * @Version: 1.0.0
 * @Date: 11:34 2021/06/15
 * @Copyright: MIN-Group；国家重大科技基础设施——未来网络北大实验室；深圳市信息论与未来网络重点实验室
 */

package minhttp

import (
	"bufio"
	"net"
)

// A ResponseWriter interface is used by an HTTP handler to
// construct an HTTP response.
//
// A ResponseWriter may not be used after the Handler.ServeHTTP method
// has returned.
type ResponseWriter interface {
	// Header returns the header map that will be sent by
	// WriteHeader. The Header map also is the mechanism with which
	// Handlers can set HTTP trailers.
	//
	// Changing the header map after a call to WriteHeader (or
	// Write) has no effect unless the modified headers are
	// trailers.
	//
	// There are two ways to set Trailers. The preferred way is to
	// predeclare in the headers which trailers you will later
	// send by setting the "Trailer" header to the names of the
	// trailer keys which will come later. In this case, those
	// keys of the Header map are treated as if they were
	// trailers. See the example. The second way, for trailer
	// keys not known to the Handler until after the first Write,
	// is to prefix the Header map keys with the TrailerPrefix
	// constant value. See TrailerPrefix.
	//
	// To suppress automatic response headers (such as "Date"), set
	// their value to nil.
	Header() Header

	// Write writes the data to the connection as part of an HTTP reply.
	//
	// If WriteHeader has not yet been called, Write calls
	// WriteHeader(http.StatusOK) before writing the data. If the Header
	// does not contain a Content-Type line, Write adds a Content-Type set
	// to the result of passing the initial 512 bytes of written data to
	// DetectContentType. Additionally, if the total size of all written
	// data is under a few KB and there are no Flush calls, the
	// Content-Length header is added automatically.
	//
	// Depending on the HTTP protocol version and the client, calling
	// Write or WriteHeader may prevent future reads on the
	// Request.Body. For HTTP/1.x requests, handlers should read any
	// needed request body data before writing the response. Once the
	// headers have been flushed (due to either an explicit Flusher.Flush
	// call or writing enough data to trigger a flush), the request body
	// may be unavailable. For HTTP/2 requests, the Go HTTP server permits
	// handlers to continue to read the request body while concurrently
	// writing the response. However, such behavior may not be supported
	// by all HTTP/2 clients. Handlers should read before writing if
	// possible to maximize compatibility.
	Write([]byte) (int, error)

	// WriteHeader sends an HTTP response header with the provided
	// status code.
	//
	// If WriteHeader is not called explicitly, the first call to Write
	// will trigger an implicit WriteHeader(http.StatusOK).
	// Thus explicit calls to WriteHeader are mainly used to
	// send error codes.
	//
	// The provided code must be a valid HTTP 1xx-5xx status code.
	// Only one header may be written. Go does not currently
	// support sending user-defined 1xx informational headers,
	// with the exception of 100-continue response header that the
	// Server sends automatically when the Request.Body is read.
	WriteHeader(statusCode int)
}


// The Flusher interface is implemented by ResponseWriters that allow
// an HTTP handler to flush buffered data to the client.
//
// The default HTTP/1.x and HTTP/2 ResponseWriter implementations
// support Flusher, but ResponseWriter wrappers may not. Handlers
// should always test for this ability at runtime.
//
// Note that even for ResponseWriters that support Flush,
// if the client is connected through an HTTP proxy,
// the buffered data may not reach the client until the response
// completes.
type Flusher interface {
	// Flush sends any buffered data to the client.
	Flush()
}

// The Hijacker interface is implemented by ResponseWriters that allow
// an HTTP handler to take over the connection.
//
// The default ResponseWriter for HTTP/1.x connections supports
// Hijacker, but HTTP/2 connections intentionally do not.
// ResponseWriter wrappers may also not support Hijacker. Handlers
// should always test for this ability at runtime.
type Hijacker interface {
	// Hijack lets the caller take over the connection.
	// After a call to Hijack the HTTP server library
	// will not do anything else with the connection.
	//
	// It becomes the caller's responsibility to manage
	// and close the connection.
	//
	// The returned net.Conn may have read or write deadlines
	// already set, depending on the configuration of the
	// Server. It is the caller's responsibility to set
	// or clear those deadlines as needed.
	//
	// The returned bufio.Reader may contain unprocessed buffered
	// data from the client.
	//
	// After a call to Hijack, the original Request.Body must not
	// be used. The original Request's Context remains valid and
	// is not canceled until the Request's ServeHTTP method
	// returns.
	Hijack() (net.Conn, *bufio.ReadWriter, error)
}

type closeWriter interface {
	CloseWrite() error
}