package anubis

import (
	"bytes"
	"io"
	"net/http"
	"net/url"
	"strings"
)

// resolveRef resolves a (possibly relative) URL reference against a base URL,
// preserving the base's scheme and host. Anubis's preact redir is host-relative
// (e.g. "/.within.website/...").
func resolveRef(base *url.URL, ref string) *url.URL {
	u, err := url.Parse(ref)
	if err != nil {
		// Fall back to a copy of base; the caller's cookie check will catch it.
		c := *base
		return &c
	}
	return base.ResolveReference(u)
}

// maybeHTML reports whether a response could be an HTML page (and thus possibly
// an Anubis interstitial). Non-HTML responses are passed through untouched.
func maybeHTML(resp *http.Response) bool {
	ct := resp.Header.Get("Content-Type")
	if ct == "" {
		return true // unknown; be safe and inspect
	}
	return strings.Contains(strings.ToLower(ct), "text/html")
}

// withBody returns resp with its body replaced by an in-memory reader over b,
// so the (already consumed) body can be read again by the caller.
func withBody(resp *http.Response, b []byte) *http.Response {
	resp.Body = io.NopCloser(bytes.NewReader(b))
	resp.ContentLength = int64(len(b))
	resp.Header.Del("Content-Length")
	return resp
}

// applyCookies replaces the request's Cookie header with the cookies the shared
// jar holds for the request URL. The replayed request goes through the base
// transport directly (bypassing the client jar), so we must attach the freshly
// obtained auth cookie ourselves.
func (t *Transport) applyCookies(req *http.Request) {
	req.Header.Del("Cookie")
	for _, c := range t.Jar.Cookies(req.URL) {
		req.AddCookie(c)
	}
}