/*
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"
	"path"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"time"

	"camlistore.org/pkg/blobref"
	"camlistore.org/pkg/blobserver"
	"camlistore.org/pkg/httputil"
	"camlistore.org/pkg/jsonconfig"
	newuistatic "camlistore.org/server/camlistored/newui"
	uistatic "camlistore.org/server/camlistored/ui"
)

var _ = log.Printf

var (
	staticFilePattern  = regexp.MustCompile(`^([a-zA-Z0-9\-\_]+\.(html|js|css|png|jpg|gif))$`)
	static2FilePattern = regexp.MustCompile(`^(new/)([a-zA-Z0-9\-\_]+\.(html|js|css|png|jpg|gif))$`)
	identPattern       = regexp.MustCompile(`^[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(`^(new/closure/)([^/]+)(/.*)?$`)
)

var uiFiles = uistatic.Files
var newuiFiles = newuistatic.Files

// 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

	Cache blobserver.Storage // or nil
	sc    ScaledImage        // cache for scaled images, optional

	newUIStaticHandler http.Handler // for the new ui
	closureHandler     http.Handler
}

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

func newUIFromConfig(ld blobserver.Loader, conf jsonconfig.Obj) (h http.Handler, err error) {
	ui := &UIHandler{
		prefix:       ld.MyPrefix(),
		JSONSignRoot: conf.OptionalString("jsonSignRoot", ""),
	}
	pubRoots := conf.OptionalList("publishRoots")
	cachePrefix := conf.OptionalString("cache", "")
	scType := conf.OptionalString("scaledImage", "")
	if err = conf.Validate(); err != nil {
		return
	}

	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
	}

	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
		switch scType {
		case "lrucache":
			ui.sc = NewScaledImageLru()
		default:
			return nil, fmt.Errorf("unsupported ui handler's scType: %q ", scType)
		}
	}

	ui.newUIStaticHandler = http.FileServer(newuiFiles)
	// TODO(mpl): figure out camliroot and use an abs path
	closureDir := filepath.Join("tmp", "closure")
	ui.closureHandler = http.FileServer(http.Dir(closureDir))

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

func wantsDiscovery(req *http.Request) bool {
	return req.Method == "GET" &&
		(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 wantsRecentPermanodes(req *http.Request) bool {
	return req.Method == "GET" && req.FormValue("mode") == "thumbnails"
}

func wantsPermanode(req *http.Request) bool {
	return req.Method == "GET" && blobref.Parse(req.FormValue("p")) != nil
}

func wantsGallery(req *http.Request) bool {
	return req.Method == "GET" && blobref.Parse(req.FormValue("g")) != nil
}

func wantsBlobInfo(req *http.Request) bool {
	return req.Method == "GET" && blobref.Parse(req.FormValue("b")) != nil
}

func wantsFileTreePage(req *http.Request) bool {
	return req.Method == "GET" && blobref.Parse(req.FormValue("d")) != nil
}

func (ui *UIHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
	base := req.Header.Get("X-PrefixHandler-PathBase")
	suffix := req.Header.Get("X-PrefixHandler-PathSuffix")

	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)
	default:
		file := ""
		if m := staticFilePattern.FindStringSubmatch(suffix); m != nil {
			file = m[1]
			// TODO(mpl): change the regexp to make it not match the stripped part
		} else if m := static2FilePattern.FindStringSubmatch(suffix); m != nil {
			file = strings.Replace(suffix, m[1], "", 1)
			req.URL.Path = "/" + file
			ui.newUIStaticHandler.ServeHTTP(rw, req)
			break
		} else if m := closurePattern.FindStringSubmatch(suffix); m != nil {
			file = strings.Replace(suffix, m[1], "", 1)
			req.URL.Path = "/" + file
			ui.closureHandler.ServeHTTP(rw, req)
			break
		} else {
			switch {
			case wantsPermanode(req):
				file = "permanode.html"
			case wantsGallery(req):
				file = "gallery.html"
			case wantsBlobInfo(req):
				file = "blobinfo.html"
			case wantsFileTreePage(req):
				file = "filetree.html"
			case req.URL.Path == base:
				file = "index.html"
			default:
				http.Error(rw, "Illegal URL.", 404)
				return
			}
		}
		serveStaticFile(rw, req, uiFiles, 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 uiFiles: %v", file, err)
		return
	}
	defer f.Close()
	var modTime time.Time
	if fi, err := f.Stat(); err == nil {
		modTime = fi.ModTime()
	}
	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 ui.root.Search != nil {
			pn, err := ui.root.Search.Index().PermanodeOfSignerAttrValue(ui.root.Search.Owner(), "camliRoot", pubh.RootName)
			if err == nil {
				m["currentPermanode"] = pn.String()
			}
		}
		pubRoots[pubh.RootName] = m
	}

	uiDisco := map[string]interface{}{
		"jsonSignRoot":    ui.JSONSignRoot,
		"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,
	}
	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 := req.Header.Get("X-PrefixHandler-PathSuffix")
	m := downloadPattern.FindStringSubmatch(suffix)
	if m == nil {
		httputil.ErrorRouting(rw, req)
		return
	}

	fbr := blobref.Parse(m[1])
	if fbr == nil {
		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 := req.Header.Get("X-PrefixHandler-PathSuffix")
	m := thumbnailPattern.FindStringSubmatch(suffix)
	if m == nil {
		httputil.ErrorRouting(rw, req)
		return
	}

	query := req.URL.Query()
	width, err := strconv.Atoi(query.Get("mw"))
	if err != nil {
		http.Error(rw, "Invalid specified max width 'mw'", 500)
		return
	}
	height, err := strconv.Atoi(query.Get("mh"))
	if err != nil {
		http.Error(rw, "Invalid specified height 'mh'", 500)
		return
	}

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

	th := &ImageHandler{
		Fetcher:   ui.root.Storage,
		Cache:     ui.Cache,
		MaxWidth:  width,
		MaxHeight: height,
		sc:        ui.sc,
	}
	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 := req.Header.Get("X-PrefixHandler-PathSuffix")
	m := treePattern.FindStringSubmatch(suffix)
	if m == nil {
		httputil.ErrorRouting(rw, req)
		return
	}

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

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