dropbox.go

package backend

import (
	"encoding/json"
	"fmt"
	"mime"
	"net/http"
	"path"
	"time"

	"github.com/pkg/errors"
	"github.com/superfly/go-proxy/log"
	proxy "github.com/superfly/go-proxy/proxy/context"
)

// DropboxBackend is a Backend implementation for Dropbox
type DropboxBackend struct {
	*GenericBackend
}

const (
	dropboxEndpoint = "https://content.dropboxapi.com/2/files/"
)

// ProxyRequest proxies the Request to the DropboxBackend and returns a Response
func (b *DropboxBackend) ProxyRequest(ctx *proxy.Context, rw http.ResponseWriter, req *http.Request) (res *http.Response, err error) {
	directory, err := b.GetSettingString("directory")
	if err != nil {
		return nil, errors.Wrap(err, "failed to get directory")
	}
	accessToken, err := b.GetSettingString("access_token")
	if err != nil {
		return nil, errors.Wrap(err, "failed to get access_token")
	}

	//curl -X POST https://content.dropboxapi.com/2/files/download \
	//--header "Authorization: Bearer <token>" \
	//--header "Dropbox-API-Arg: {\"path\": \"/Homework/math/Prime_Numbers.txt\"}"

	if req.Method != "HEAD" && req.Method != "GET" {
		h := make(http.Header)
		h.Set("Allow", "GET, HEAD")
		return &http.Response{
			StatusCode: http.StatusMethodNotAllowed,
			Body:       http.NoBody,
			Header:     h,
		}, nil
	}
	url := dropboxEndpoint + "download"
	dpath := path.Join(directory, req.URL.Path)

	log.Debugf("requesting %s from Dropbox endpoint %s", dpath, url)
	// this seems heavy for one string
	payload := map[string]interface{}{
		"path": dpath,
	}
	jsonPayload, err := json.Marshal(payload)
	if err != nil {
		return nil, err
	}
	client := &http.Client{
		Timeout: time.Second * 10,
	}
	dreq, err := http.NewRequest("POST", url, nil)
	dreq.Header.Set("Authorization", fmt.Sprintf("Bearer %s", accessToken))
	dreq.Header.Set("Dropbox-API-Arg", string(jsonPayload))

	dresp, err := client.Do(dreq)

	if err != nil {
		return nil, err
	}

	resp := &http.Response{
		StatusCode: dresp.StatusCode,
		Header:     make(http.Header),
	}
	if req.Method == "GET" {
		resp.Body = dresp.Body
	} else {
		dresp.Body.Close()
		resp.Body = http.NoBody
	}

	if dresp.StatusCode == http.StatusOK {
		setDropboxResponseHeaders(dresp, resp, dpath)
	} else if dresp.StatusCode == http.StatusConflict { // should be a 404
		resp.StatusCode = http.StatusNotFound
	}

	return resp, nil

}

func setDropboxResponseHeaders(dres *http.Response, resp *http.Response, dpath string) {
	// HTTP/1.1 200 OK
	// Server: nginx
	//Date: Sat, 02 Sep 2017 00:17:08 GMT
	//Content-Type: application/octet-stream
	//Content-Length: 181778
	//Connection: keep-alive
	//accept-ranges: bytes
	//etag: W/"25bcdd45a"
	//pragma: no-cache
	//cache-control: no-cache
	//original-content-length: 181778
	//dropbox-api-result: {"name": "hero.png", "path_lower": "/hero.png", "path_display": "/hero.png", "id": "id:xkk7UhkHpRAAAAAAAAAABw", "client_modified": "2017-08-28T20:47:08Z", "server_modified": "2017-08-28T20:47:08Z", "rev": "25bcdd45a", "size": 181778, "content_hash": "b98e5dce5349af9b3a882956997dd7322ba47cc544593b239f49f05559f29120"}
	//X-Server-Response-Time: 431
	//X-Dropbox-Request-Id: e9f9bc1ebf173060842175b2130c0a77
	//X-Robots-Tag: noindex, nofollow, noimageindex
	resp.Header.Set("Content-Length", dres.Header.Get("Content-Length"))
	resp.Header.Set("etag", dres.Header.Get("etag"))
	resp.Header.Set("Transfer-Encoding", dres.Header.Get("Transfer-Encoding"))

	ext := path.Ext(dpath)
	ctype := dres.Header.Get("Content-Type")
	if ext != "" {
		detected := mime.TypeByExtension(ext)
		if detected != "" {
			ctype = detected
		}
	}
	resp.Header.Set("Content-Type", ctype)
}