package http

import (
	"bufio"
	"bytes"
	"crypto/tls"
	"errors"
	"fmt"
	"io"
	"net/textproto"
	"net/url"
	"strconv"
	"strings"

	"golang.org/x/net/http/httpguts"
)

var respExcludeHeader = map[string]bool{
	"Content-Length":    true,
	"Transfer-Encoding": true,
	"Trailer":           true,
}

type Response struct {
	Status     string // e.g. "200 OK"
	StatusCode int    // e.g. 200
	Proto      string // e.g. "HTTP/1.0"
	ProtoMajor int    // e.g. 1
	ProtoMinor int    // e.g. 0

	Header Header

	Body io.ReadCloser

	ContentLength int64

	TransferEncoding []string

	Close bool

	Uncompressed bool

	Trailer Header

	Request *Request

	TLS *tls.ConnectionState
}

func (r *Response) Cookies() []*Cookie {
	return readSetCookies(r.Header)
}

var ErrNoLocation = errors.New("http: no Location header in response")

func (r *Response) Location() (*url.URL, error) {
	lv := r.Header.Get("Location")
	if lv == "" {
		return nil, ErrNoLocation
	}
	if r.Request != nil && r.Request.URL != nil {
		return r.Request.URL.Parse(lv)
	}
	return url.Parse(lv)
}

func ReadResponse(r *bufio.Reader, req *Request) (*Response, error) {
	tp := textproto.NewReader(r)
	resp := &Response{
		Request: req,
	}

	line, err := tp.ReadLine()
	if err != nil {
		if err == io.EOF {
			err = io.ErrUnexpectedEOF
		}
		return nil, err
	}
	if i := strings.IndexByte(line, ' '); i == -1 {
		return nil, badStringError("malformed HTTP response", line)
	} else {
		resp.Proto = line[:i]
		resp.Status = strings.TrimLeft(line[i+1:], " ")
	}
	statusCode := resp.Status
	if i := strings.IndexByte(resp.Status, ' '); i != -1 {
		statusCode = resp.Status[:i]
	}
	if len(statusCode) != 3 {
		return nil, badStringError("malformed HTTP status code", statusCode)
	}
	resp.StatusCode, err = strconv.Atoi(statusCode)
	if err != nil || resp.StatusCode < 0 {
		return nil, badStringError("malformed HTTP status code", statusCode)
	}
	var ok bool
	if resp.ProtoMajor, resp.ProtoMinor, ok = ParseHTTPVersion(resp.Proto); !ok {
		return nil, badStringError("malformed HTTP version", resp.Proto)
	}

	mimeHeader, err := tp.ReadMIMEHeader()
	if err != nil {
		if err == io.EOF {
			err = io.ErrUnexpectedEOF
		}
		return nil, err
	}
	resp.Header = Header(mimeHeader)

	fixPragmaCacheControl(resp.Header)

	err = readTransfer(resp, r)
	if err != nil {
		return nil, err
	}

	return resp, nil
}

func fixPragmaCacheControl(header Header) {
	if hp, ok := header["Pragma"]; ok && len(hp) > 0 && hp[0] == "no-cache" {
		if _, presentcc := header["Cache-Control"]; !presentcc {
			header["Cache-Control"] = []string{"no-cache"}
		}
	}
}

func (r *Response) ProtoAtLeast(major, minor int) bool {
	return r.ProtoMajor > major ||
		r.ProtoMajor == major && r.ProtoMinor >= minor
}

	text := r.Status
	if text == "" {
		var ok bool
		text, ok = statusText[r.StatusCode]
		if !ok {
			text = "status code " + strconv.Itoa(r.StatusCode)
		}

		text = strings.TrimPrefix(text, strconv.Itoa(r.StatusCode)+" ")
	}

	if _, err := fmt.Fprintf(w, "HTTP/%d.%d %03d %s\r\n", r.ProtoMajor, r.ProtoMinor, r.StatusCode, text); err != nil {
		return err
	}

	r1 := new(Response)
	*r1 = *r

		var buf [1]byte
		n, err := r1.Body.Read(buf[:])
		if err != nil && err != io.EOF {
			return err
		}

			r1.Body = NoBody
		} else {
			r1.ContentLength = -1
			r1.Body = struct {
				io.Reader
				io.Closer
			}{
				io.MultiReader(bytes.NewReader(buf[:1]), r.Body),
				r.Body,
			}
		}

	if r1.ContentLength == -1 && !r1.Close && r1.ProtoAtLeast(1, 1) && !chunked(r1.TransferEncoding) && !r1.Uncompressed {
		r1.Close = true
	}

	tw, err := newTransferWriter(r1)
	if err != nil {
		return err
	}
	err = tw.writeHeader(w, nil)
	if err != nil {
		return err
	}

	err = r.Header.WriteSubset(w, respExcludeHeader)
	if err != nil {
		return err
	}

	contentLengthAlreadySent := tw.shouldSendContentLength()
	if r1.ContentLength == 0 && !chunked(r1.TransferEncoding) && !contentLengthAlreadySent && bodyAllowedForStatus(r.StatusCode) {
		if _, err := io.WriteString(w, "Content-Length: 0\r\n"); err != nil {
			return err
		}
	}

	if _, err := io.WriteString(w, "\r\n"); err != nil {
		return err
	}

	err = tw.writeBody(w)
	if err != nil {
		return err
	}

	return nil
}

func (r *Response) closeBody() {
	if r.Body != nil {
		r.Body.Close()
	}
}

func (r *Response) bodyIsWritable() bool {
	_, ok := r.Body.(io.Writer)
	return ok
}

func (r *Response) isProtocolSwitch() bool {
	return isProtocolSwitchResponse(r.StatusCode, r.Header)
}

func isProtocolSwitchResponse(code int, h Header) bool {
	return code == StatusSwitchingProtocols && isProtocolSwitchHeader(h)
}

func isProtocolSwitchHeader(h Header) bool {
	return h.Get("Upgrade") != "" &&
		httpguts.HeaderValuesContainsToken(h["Connection"], "Upgrade")