package hw3test

import (
	"fmt"
	"net"
	"net/http"
	"strings"
	"time"
)

// validateResponseFraming checks headers before reading the response body.
func validateResponseFraming(resp *http.Response) error {
	// net/http removes Connection: close from Header and records it in Close.
	// With HTTP/1.1 and explicit framing, Close reflects that header.
	closeFound := resp.ProtoMajor == 1 && resp.ProtoMinor == 1 && resp.Close
	for _, value := range resp.Header.Values("Connection") {
		for _, token := range strings.Split(value, ",") {
			closeFound = closeFound || strings.EqualFold(strings.TrimSpace(token), "close")
		}
	}
	if !closeFound {
		return fmt.Errorf("expected Connection: close")
	}
	if len(resp.TransferEncoding) != 0 || len(resp.Header.Values("Transfer-Encoding")) != 0 {
		return fmt.Errorf("Transfer-Encoding is not supported")
	}
	lengths := resp.Header.Values("Content-Length")
	if resp.StatusCode == http.StatusNoContent {
		if len(lengths) != 0 {
			return fmt.Errorf("204 must not contain Content-Length")
		}
	} else if len(lengths) != 1 || resp.ContentLength < 0 {
		return fmt.Errorf("expected exactly one valid Content-Length")
	}
	return nil
}

// Bound a stalled peer, without imposing a total duration on large transfers.
type idleDeadlineReader struct {
	net.Conn
	Timeout time.Duration
}

func (r *idleDeadlineReader) Read(p []byte) (int, error) {
	if err := r.Conn.SetReadDeadline(time.Now().Add(r.Timeout)); err != nil {
		return 0, err
	}
	return r.Conn.Read(p)
}