package oidcrp

import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strconv"
)

type inProcess struct {
	host string
	h    http.Handler
}

func InProcess(host string, h http.Handler) http.RoundTripper {
	return inProcess{host: host, h: h}
}

func (t inProcess) RoundTrip(req *http.Request) (*http.Response, error) {
	if req.URL.Host != t.host {
		if req.Body != nil {
			req.Body.Close()
		}
		return nil, fmt.Errorf("oidcrp: %s is not served in process", req.URL.Host)
	}
	body := req.Body
	if body == nil {
		body = http.NoBody
	}
	defer body.Close()
	sreq := req.Clone(req.Context())
	sreq.Host = req.URL.Host
	sreq.URL = &url.URL{Path: req.URL.Path, RawPath: req.URL.RawPath, RawQuery: req.URL.RawQuery}
	sreq.RequestURI = req.URL.RequestURI()
	sreq.Proto, sreq.ProtoMajor, sreq.ProtoMinor = "HTTP/1.1", 1, 1
	sreq.Body = body
	rec := &recorder{header: http.Header{}}
	t.h.ServeHTTP(rec, sreq)
	return rec.response(req), nil
}

type recorder struct {
	header  http.Header
	written http.Header
	status  int
	body    bytes.Buffer
}

func (r *recorder) Header() http.Header { return r.header }

func (r *recorder) WriteHeader(status int) {
	if r.status != 0 {
		return
	}
	r.status = status
	r.written = r.header.Clone()
}

func (r *recorder) Write(b []byte) (int, error) {
	if r.status == 0 {
		r.WriteHeader(http.StatusOK)
	}
	return r.body.Write(b)
}

func (r *recorder) response(req *http.Request) *http.Response {
	if r.status == 0 {
		r.WriteHeader(http.StatusOK)
	}
	h := r.written
	h.Del("Content-Length")
	h.Set("Content-Length", strconv.Itoa(r.body.Len()))
	return &http.Response{
		Status:        strconv.Itoa(r.status) + " " + http.StatusText(r.status),
		StatusCode:    r.status,
		Proto:         "HTTP/1.1",
		ProtoMajor:    1,
		ProtoMinor:    1,
		Header:        h,
		Body:          io.NopCloser(bytes.NewReader(r.body.Bytes())),
		ContentLength: int64(r.body.Len()),
		Request:       req,
	}
}