perkeep/pkg/server/ui.go

/*
Copyright 2011 Google Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package server

import (
	"errors"
	"fmt"
	"log"
	"net/http"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"time"

	"camlistore.org/pkg/blob"
	"camlistore.org/pkg/blobserver"
	"camlistore.org/pkg/constants"
	"camlistore.org/pkg/fileembed"
	"camlistore.org/pkg/httputil"
	"camlistore.org/pkg/jsonconfig"
	"camlistore.org/pkg/jsonsign/signhandler"
	"camlistore.org/pkg/misc/closure"
	"camlistore.org/pkg/search"
	"camlistore.org/pkg/sorted"
	"camlistore.org/pkg/syncutil"
	uistatic "camlistore.org/server/camlistored/ui"
	closurestatic "camlistore.org/server/camlistored/ui/closure"
	"camlistore.org/third_party/code.google.com/p/rsc/qr"
	fontawesomestatic "camlistore.org/third_party/fontawesome"
	glitchstatic "camlistore.org/third_party/glitch"
	reactstatic "camlistore.org/third_party/react"
)

var (
	staticFilePattern = regexp.MustCompile(`^([a-zA-Z0-9\-\_]+\.(html|js|css|png|jpg|gif|svg))$`)
	identOrDotPattern = regexp.MustCompile(`^[a-zA-Z\_]+(\.[a-zA-Z\_]+)*$`)

	// Download URL suffix:
	//   $1: blobref (checked in download handler)
	//   $2: optional "/filename" to be sent as recommended download name,
	//       if sane looking
	downloadPattern = regexp.MustCompile(`^download/([^/]+)(/.*)?$`)

	thumbnailPattern   = regexp.MustCompile(`^thumbnail/([^/]+)(/.*)?$`)
	treePattern        = regexp.MustCompile(`^tree/([^/]+)(/.*)?$`)
	closurePattern     = regexp.MustCompile(`^closure/(([^/]+)(/.*)?)$`)
	reactPattern       = regexp.MustCompile(`^react/(.+)$`)
	fontawesomePattern = regexp.MustCompile(`^fontawesome/(.+)$`)
	glitchPattern      = regexp.MustCompile(`^glitch/(.+)$`)

	disableThumbCache, _ = strconv.ParseBool(os.Getenv("CAMLI_DISABLE_THUMB_CACHE"))
)

// UIHandler handles serving the UI and discovery JSON.
type UIHandler struct {
	// JSONSignRoot is the optional path or full URL to the JSON
	// Signing helper. Only used by the UI and thus necessary if
	// UI is true.
	// TODO(bradfitz): also move this up to the root handler,
	// if we start having clients (like phones) that we want to upload
	// but don't trust to have private signing keys?
	JSONSignRoot string

	publishRoots map[string]*PublishHandler

	prefix string // of the UI handler itself
	root   *RootHandler
	sigh   *signhandler.Handler // or nil

	// Cache optionally specifies a cache blob server, used for
	// caching image thumbnails and other emphemeral data.
	Cache blobserver.Storage // or nil

	// Limit peak RAM used by concurrent image thumbnail calls.
	resizeSem *syncutil.Sem
	thumbMeta *thumbMeta // optional thumbnail key->blob.Ref cache

	// sourceRoot optionally specifies the path to root of Camlistore's
	// source. If empty, the UI files must be compiled in to the
	// binary (with go run make.go).  This comes from the "sourceRoot"
	// ui handler config option.
	sourceRoot string

	uiDir string // if sourceRoot != "", this is sourceRoot+"/server/camlistored/ui"

	closureHandler         http.Handler
	fileReactHandler       http.Handler
	fileFontawesomeHandler http.Handler
	fileGlitchHandler      http.Handler
}

func init() {
	blobserver.RegisterHandlerConstructor("ui", uiFromConfig)
}

// newKVOrNil wraps sorted.NewKeyValue and adds the ability
// to pass a nil conf to get a (nil, nil) response.
func newKVOrNil(conf jsonconfig.Obj) (sorted.KeyValue, error) {
	if len(conf) == 0 {
		return nil, nil
	}
	return sorted.NewKeyValue(conf)
}

func uiFromConfig(ld blobserver.Loader, conf jsonconfig.Obj) (h http.Handler, err error) {
	ui := &UIHandler{
		prefix:       ld.MyPrefix(),
		JSONSignRoot: conf.OptionalString("jsonSignRoot", ""),
		sourceRoot:   conf.OptionalString("sourceRoot", ""),
		resizeSem: syncutil.NewSem(int64(conf.OptionalInt("maxResizeBytes",
			constants.DefaultMaxResizeMem))),
	}
	pubRoots := conf.OptionalList("publishRoots")
	cachePrefix := conf.OptionalString("cache", "")
	scaledImageConf := conf.OptionalObject("scaledImage")
	if err = conf.Validate(); err != nil {
		return
	}

	if ui.JSONSignRoot != "" {
		h, _ := ld.GetHandler(ui.JSONSignRoot)
		if sigh, ok := h.(*signhandler.Handler); ok {
			ui.sigh = sigh
		}
	}

	if os.Getenv("CAMLI_PUBLISH_ENABLED") == "false" {
		// Hack for dev server, to simplify its config with devcam server --publish=false.
		pubRoots = nil
	}

	ui.publishRoots = make(map[string]*PublishHandler)
	for _, pubRoot := range pubRoots {
		h, err := ld.GetHandler(pubRoot)
		if err != nil {
			return nil, fmt.Errorf("UI handler's publishRoots references invalid %q", pubRoot)
		}
		pubh, ok := h.(*PublishHandler)
		if !ok {
			return nil, fmt.Errorf("UI handler's publishRoots references invalid %q; not a PublishHandler", pubRoot)
		}
		ui.publishRoots[pubRoot] = pubh
	}

	checkType := func(key string, htype string) {
		v := conf.OptionalString(key, "")
		if v == "" {
			return
		}
		ct := ld.GetHandlerType(v)
		if ct == "" {
			err = fmt.Errorf("UI handler's %q references non-existant %q", key, v)
		} else if ct != htype {
			err = fmt.Errorf("UI handler's %q references %q of type %q; expected type %q", key, v, ct, htype)
		}
	}
	checkType("searchRoot", "search")
	checkType("jsonSignRoot", "jsonsign")
	if err != nil {
		return
	}

	scaledImageKV, err := newKVOrNil(scaledImageConf)
	if err != nil {
		return nil, fmt.Errorf("in UI handler's scaledImage: %v", err)
	}
	if scaledImageKV != nil && cachePrefix == "" {
		return nil, fmt.Errorf("in UI handler, can't specify scaledImage without cache")
	}
	if cachePrefix != "" {
		bs, err := ld.GetStorage(cachePrefix)
		if err != nil {
			return nil, fmt.Errorf("UI handler's cache of %q error: %v", cachePrefix, err)
		}
		ui.Cache = bs
		ui.thumbMeta = newThumbMeta(scaledImageKV)
	}

	if ui.sourceRoot == "" {
		ui.sourceRoot = os.Getenv("CAMLI_DEV_CAMLI_ROOT")
		if uistatic.IsAppEngine {
			if _, err = os.Stat(filepath.Join(uistatic.GaeSourceRoot,
				filepath.FromSlash("server/camlistored/ui/index.html"))); err != nil {
				hint := fmt.Sprintf("\"sourceRoot\" was not specified in the config,"+
					" and the default sourceRoot dir %v does not exist or does not contain"+
					" \"server/camlistored/ui/index.html\". devcam appengine can do that for you.",
					uistatic.GaeSourceRoot)
				log.Print(hint)
				return nil, errors.New("No sourceRoot found; UI not available.")
			}
			log.Printf("Using the default \"%v\" as the sourceRoot for AppEngine", uistatic.GaeSourceRoot)
			ui.sourceRoot = uistatic.GaeSourceRoot
		}
	}
	if ui.sourceRoot != "" {
		ui.uiDir = filepath.Join(ui.sourceRoot, filepath.FromSlash("server/camlistored/ui"))
		// Ignore any fileembed files:
		Files = &fileembed.Files{
			DirFallback: filepath.Join(ui.sourceRoot, filepath.FromSlash("pkg/server")),
		}
		uistatic.Files = &fileembed.Files{
			DirFallback: ui.uiDir,
			Listable:    true,
			// In dev_appserver, allow edit-and-reload without
			// restarting. In production, though, it's faster to just
			// slurp it in.
			SlurpToMemory: uistatic.IsProdAppEngine,
		}
	}

	ui.closureHandler, err = ui.makeClosureHandler(ui.sourceRoot)
	if err != nil {
		return nil, fmt.Errorf(`Invalid "sourceRoot" value of %q: %v"`, ui.sourceRoot, err)
	}

	if ui.sourceRoot != "" {
		ui.fileReactHandler, err = makeFileServer(ui.sourceRoot, filepath.Join("third_party", "react"), "react.js")
		if err != nil {
			return nil, fmt.Errorf("Could not make react handler: %s", err)
		}
		ui.fileGlitchHandler, err = makeFileServer(ui.sourceRoot, filepath.Join("third_party", "glitch"), "npc_piggy__x1_walk_png_1354829432.png")
		if err != nil {
			return nil, fmt.Errorf("Could not make glitch handler: %s", err)
		}
		ui.fileFontawesomeHandler, err = makeFileServer(ui.sourceRoot, filepath.Join("third_party", "fontawesome"), "css/font-awesome.css")
		if err != nil {
			return nil, fmt.Errorf("Could not make fontawesome handler: %s", err)
		}
	}

	rootPrefix, _, err := ld.FindHandlerByType("root")
	if err != nil {
		return nil, errors.New("No root handler configured, which is necessary for the ui handler")
	}
	if h, err := ld.GetHandler(rootPrefix); err == nil {
		ui.root = h.(*RootHandler)
		ui.root.registerUIHandler(ui)
	} else {
		return nil, errors.New("failed to find the 'root' handler")
	}

	return ui, nil
}

func (ui *UIHandler) makeClosureHandler(root string) (http.Handler, error) {
	return makeClosureHandler(root, "ui")
}

// makeClosureHandler returns a handler to serve Closure files.
// root is either:
// 1) empty: use the Closure files compiled in to the binary (if
//    available), else redirect to the Internet.
// 2) a URL prefix: base of Camlistore to get Closure to redirect to
// 3) a path on disk to the root of camlistore's source (which
//    contains the necessary subset of Closure files)
func makeClosureHandler(root, handlerName string) (http.Handler, error) {
	// devcam server environment variable takes precedence:
	if d := os.Getenv("CAMLI_DEV_CLOSURE_DIR"); d != "" {
		log.Printf("%v: serving Closure from devcam server's $CAMLI_DEV_CLOSURE_DIR: %v", handlerName, d)
		return http.FileServer(http.Dir(d)), nil
	}
	if root == "" {
		fs, err := closurestatic.FileSystem()
		if err == os.ErrNotExist {
			log.Printf("%v: no configured setting or embedded resources; serving Closure via %v", handlerName, closureBaseURL)
			return closureBaseURL, nil
		}
		if err != nil {
			return nil, fmt.Errorf("error loading embedded Closure zip file: %v", err)
		}
		log.Printf("%v: serving Closure from embedded resources", handlerName)
		return http.FileServer(fs), nil
	}
	if strings.HasPrefix(root, "http") {
		log.Printf("%v: serving Closure using redirects to %v", handlerName, root)
		return closureRedirector(root), nil
	}

	path := filepath.Join("third_party", "closure", "lib", "closure")
	return makeFileServer(root, path, filepath.Join("goog", "base.js"))
}

func makeFileServer(sourceRoot string, pathToServe string, expectedContentPath string) (http.Handler, error) {
	fi, err := os.Stat(sourceRoot)
	if err != nil {
		return nil, err
	}
	if !fi.IsDir() {
		return nil, errors.New("not a directory")
	}
	dirToServe := filepath.Join(sourceRoot, pathToServe)
	_, err = os.Stat(filepath.Join(dirToServe, expectedContentPath))
	if err != nil {
		return nil, fmt.Errorf("directory doesn't contain %s; wrong directory?", expectedContentPath)
	}
	return http.FileServer(http.Dir(dirToServe)), nil
}

const closureBaseURL closureRedirector = "https://closure-library.googlecode.com/git"

// closureRedirector is a hack to redirect requests for Closure's million *.js files
// to https://closure-library.googlecode.com/git.
// TODO: this doesn't work when offline. We need to run genjsdeps over all of the Camlistore
// UI to figure out which Closure *.js files to fileembed and generate zembed. Then this
// type can be deleted.
type closureRedirector string

func (base closureRedirector) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
	newURL := string(base) + "/" + path.Clean(httputil.PathSuffix(req))
	http.Redirect(rw, req, newURL, http.StatusTemporaryRedirect)
}

func camliMode(req *http.Request) string {
	return req.URL.Query().Get("camli.mode")
}

func wantsDiscovery(req *http.Request) bool {
	return httputil.IsGet(req) &&
		(req.Header.Get("Accept") == "text/x-camli-configuration" ||
			camliMode(req) == "config")
}

func wantsUploadHelper(req *http.Request) bool {
	return req.Method == "POST" && camliMode(req) == "uploadhelper"
}

func wantsPermanode(req *http.Request) bool {
	if httputil.IsGet(req) && blob.ValidRefString(req.FormValue("p")) {
		// The new UI is handled by index.html.
		if req.FormValue("newui") != "1" {
			return true
		}
	}
	return false
}

func wantsBlobInfo(req *http.Request) bool {
	return httputil.IsGet(req) && blob.ValidRefString(req.FormValue("b"))
}

func wantsFileTreePage(req *http.Request) bool {
	return httputil.IsGet(req) && blob.ValidRefString(req.FormValue("d"))
}

func getSuffixMatches(req *http.Request, pattern *regexp.Regexp) bool {
	if httputil.IsGet(req) {
		suffix := httputil.PathSuffix(req)
		return pattern.MatchString(suffix)
	}
	return false
}

func (ui *UIHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
	suffix := httputil.PathSuffix(req)

	rw.Header().Set("Vary", "Accept")
	switch {
	case wantsDiscovery(req):
		ui.root.serveDiscovery(rw, req)
	case wantsUploadHelper(req):
		ui.serveUploadHelper(rw, req)
	case strings.HasPrefix(suffix, "download/"):
		ui.serveDownload(rw, req)
	case strings.HasPrefix(suffix, "thumbnail/"):
		ui.serveThumbnail(rw, req)
	case strings.HasPrefix(suffix, "tree/"):
		ui.serveFileTree(rw, req)
	case strings.HasPrefix(suffix, "qr/"):
		ui.serveQR(rw, req)
	case getSuffixMatches(req, closurePattern):
		ui.serveClosure(rw, req)
	case getSuffixMatches(req, reactPattern):
		ui.serveFromDiskOrStatic(rw, req, reactPattern, ui.fileReactHandler, reactstatic.Files)
	case getSuffixMatches(req, glitchPattern):
		ui.serveFromDiskOrStatic(rw, req, glitchPattern, ui.fileGlitchHandler, glitchstatic.Files)
	case getSuffixMatches(req, fontawesomePattern):
		ui.serveFromDiskOrStatic(rw, req, fontawesomePattern, ui.fileFontawesomeHandler, fontawesomestatic.Files)
	default:
		file := ""
		if m := staticFilePattern.FindStringSubmatch(suffix); m != nil {
			file = m[1]
		} else {
			switch {
			case wantsPermanode(req):
				file = "permanode.html"
			case wantsBlobInfo(req):
				file = "blobinfo.html"
			case wantsFileTreePage(req):
				file = "filetree.html"
			case req.URL.Path == httputil.PathBase(req):
				file = "index.html"
			default:
				http.Error(rw, "Illegal URL.", http.StatusNotFound)
				return
			}
		}
		if file == "deps.js" {
			serveDepsJS(rw, req, ui.uiDir)
			return
		}
		serveStaticFile(rw, req, uistatic.Files, file)
	}
}

func serveStaticFile(rw http.ResponseWriter, req *http.Request, root http.FileSystem, file string) {
	f, err := root.Open("/" + file)
	if err != nil {
		http.NotFound(rw, req)
		log.Printf("Failed to open file %q from embedded resources: %v", file, err)
		return
	}
	defer f.Close()
	var modTime time.Time
	if fi, err := f.Stat(); err == nil {
		modTime = fi.ModTime()
	}
	// TODO(wathiede): should pkg/magic be leveraged here somehow?  It has a
	// slightly different purpose.
	if strings.HasSuffix(file, ".svg") {
		rw.Header().Set("Content-Type", "image/svg+xml")
	}
	http.ServeContent(rw, req, file, modTime, f)
}

func (ui *UIHandler) populateDiscoveryMap(m map[string]interface{}) {
	pubRoots := map[string]interface{}{}
	for key, pubh := range ui.publishRoots {
		m := map[string]interface{}{
			"name":   pubh.RootName,
			"prefix": []string{key},
			// TODO: include gpg key id
		}
		if sh, ok := ui.root.SearchHandler(); ok {
			pn, err := sh.Index().PermanodeOfSignerAttrValue(sh.Owner(), "camliRoot", pubh.RootName)
			if err == nil {
				m["currentPermanode"] = pn.String()
			}
		}
		pubRoots[pubh.RootName] = m
	}

	uiDisco := map[string]interface{}{
		"jsonSignRoot":    ui.JSONSignRoot,
		"uiRoot":          ui.prefix,
		"uploadHelper":    ui.prefix + "?camli.mode=uploadhelper", // hack; remove with better javascript
		"downloadHelper":  path.Join(ui.prefix, "download") + "/",
		"directoryHelper": path.Join(ui.prefix, "tree") + "/",
		"publishRoots":    pubRoots,
	}
	// TODO(mpl): decouple discovery of the sig handler from the
	// existence of a ui handler.
	if ui.sigh != nil {
		uiDisco["signing"] = ui.sigh.DiscoveryMap(ui.JSONSignRoot)
	}
	for k, v := range uiDisco {
		if _, ok := m[k]; ok {
			log.Fatalf("Duplicate discovery key %q", k)
		}
		m[k] = v
	}
}

func (ui *UIHandler) serveDownload(rw http.ResponseWriter, req *http.Request) {
	if ui.root.Storage == nil {
		http.Error(rw, "No BlobRoot configured", 500)
		return
	}

	suffix := httputil.PathSuffix(req)
	m := downloadPattern.FindStringSubmatch(suffix)
	if m == nil {
		httputil.ErrorRouting(rw, req)
		return
	}

	fbr, ok := blob.Parse(m[1])
	if !ok {
		http.Error(rw, "Invalid blobref", 400)
		return
	}

	dh := &DownloadHandler{
		Fetcher: ui.root.Storage,
		Cache:   ui.Cache,
	}
	dh.ServeHTTP(rw, req, fbr)
}

func (ui *UIHandler) serveThumbnail(rw http.ResponseWriter, req *http.Request) {
	if ui.root.Storage == nil {
		http.Error(rw, "No BlobRoot configured", 500)
		return
	}

	suffix := httputil.PathSuffix(req)
	m := thumbnailPattern.FindStringSubmatch(suffix)
	if m == nil {
		httputil.ErrorRouting(rw, req)
		return
	}

	query := req.URL.Query()
	width, _ := strconv.Atoi(query.Get("mw"))
	height, _ := strconv.Atoi(query.Get("mh"))
	blobref, ok := blob.Parse(m[1])
	if !ok {
		http.Error(rw, "Invalid blobref", 400)
		return
	}

	if width == 0 {
		width = search.MaxImageSize
	}
	if height == 0 {
		height = search.MaxImageSize
	}

	th := &ImageHandler{
		Fetcher:   ui.root.Storage,
		Cache:     ui.Cache,
		MaxWidth:  width,
		MaxHeight: height,
		thumbMeta: ui.thumbMeta,
		resizeSem: ui.resizeSem,
	}
	th.ServeHTTP(rw, req, blobref)
}

func (ui *UIHandler) serveFileTree(rw http.ResponseWriter, req *http.Request) {
	if ui.root.Storage == nil {
		http.Error(rw, "No BlobRoot configured", 500)
		return
	}

	suffix := httputil.PathSuffix(req)
	m := treePattern.FindStringSubmatch(suffix)
	if m == nil {
		httputil.ErrorRouting(rw, req)
		return
	}

	blobref, ok := blob.Parse(m[1])
	if !ok {
		http.Error(rw, "Invalid blobref", 400)
		return
	}

	fth := &FileTreeHandler{
		Fetcher: ui.root.Storage,
		file:    blobref,
	}
	fth.ServeHTTP(rw, req)
}

func (ui *UIHandler) serveClosure(rw http.ResponseWriter, req *http.Request) {
	suffix := httputil.PathSuffix(req)
	if ui.closureHandler == nil {
		log.Printf("%v not served: closure handler is nil", suffix)
		http.NotFound(rw, req)
		return
	}
	m := closurePattern.FindStringSubmatch(suffix)
	if m == nil {
		httputil.ErrorRouting(rw, req)
		return
	}
	req.URL.Path = "/" + m[1]
	ui.closureHandler.ServeHTTP(rw, req)
}

// serveFromDiskOrStatic matches rx against req's path and serves the match either from disk (if non-nil) or from static (embedded in the binary).
func (ui *UIHandler) serveFromDiskOrStatic(rw http.ResponseWriter, req *http.Request, rx *regexp.Regexp, disk http.Handler, static *fileembed.Files) {
	suffix := httputil.PathSuffix(req)
	m := rx.FindStringSubmatch(suffix)
	if m == nil {
		panic("Caller should verify that rx matches")
	}
	file := m[1]
	if disk != nil {
		req.URL.Path = "/" + file
		disk.ServeHTTP(rw, req)
	} else {
		serveStaticFile(rw, req, static, file)
	}

}

func (ui *UIHandler) serveQR(rw http.ResponseWriter, req *http.Request) {
	url := req.URL.Query().Get("url")
	if url == "" {
		http.Error(rw, "Missing url parameter.", http.StatusBadRequest)
		return
	}
	code, err := qr.Encode(url, qr.L)
	if err != nil {
		http.Error(rw, err.Error(), http.StatusInternalServerError)
		return
	}
	rw.Header().Set("Content-Type", "image/png")
	rw.Write(code.PNG())
}

// serveDepsJS serves an auto-generated Closure deps.js file.
func serveDepsJS(rw http.ResponseWriter, req *http.Request, dir string) {
	var root http.FileSystem
	if dir == "" {
		root = uistatic.Files
	} else {
		root = http.Dir(dir)
	}

	b, err := closure.GenDeps(root)
	if err != nil {
		log.Print(err)
		http.Error(rw, "Server error", 500)
		return
	}
	rw.Header().Set("Content-Type", "text/javascript; charset=utf-8")
	rw.Write([]byte("// auto-generated from camlistored\n"))
	rw.Write(b)
}