/*
Copyright 2012 The Camlistore Authors.

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 (
	"crypto/rand"
	"encoding/json"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"os"
	"reflect"
	"strconv"
	"strings"

	"camlistore.org/pkg/auth"
	"camlistore.org/pkg/blobserver"
	"camlistore.org/pkg/httputil"
	"camlistore.org/pkg/jsonconfig"
	"camlistore.org/pkg/osutil"

	"camlistore.org/third_party/code.google.com/p/xsrftoken"
)

var ignoredFields = map[string]bool{
	"gallery":     true,
	"blog":        true,
	"replicateTo": true,
}

// SetupHandler handles serving the wizard setup page.
type SetupHandler struct {
	config jsonconfig.Obj
}

func init() {
	blobserver.RegisterHandlerConstructor("setup", newSetupFromConfig)
}

func newSetupFromConfig(ld blobserver.Loader, conf jsonconfig.Obj) (h http.Handler, err error) {
	wizard := &SetupHandler{config: conf}
	return wizard, nil
}

func printWizard(i interface{}) (s string) {
	switch ei := i.(type) {
	case []string:
		for _, v := range ei {
			s += printWizard(v) + ","
		}
		s = strings.TrimRight(s, ",")
	case []interface{}:
		for _, v := range ei {
			s += printWizard(v) + ","
		}
		s = strings.TrimRight(s, ",")
	default:
		return fmt.Sprintf("%v", i)
	}
	return s
}

// TODO(mpl): probably not needed anymore. check later and remove.
// Flatten all published entities as lists and move them at the root
// of the conf, to have them displayed individually by the template
func flattenPublish(config jsonconfig.Obj) error {
	gallery := []string{}
	blog := []string{}
	config["gallery"] = gallery
	config["blog"] = blog
	published, ok := config["publish"]
	if !ok {
		delete(config, "publish")
		return nil
	}
	pubObj, ok := published.(map[string]interface{})
	if !ok {
		return fmt.Errorf("Was expecting a map[string]interface{} for \"publish\", got %T", published)
	}
	for k, v := range pubObj {
		pub, ok := v.(map[string]interface{})
		if !ok {
			return fmt.Errorf("Was expecting a map[string]interface{} for %s, got %T", k, pub)
		}
		template, rootPermanode, style := "", "", ""
		for pk, pv := range pub {
			val, ok := pv.(string)
			if !ok {
				return fmt.Errorf("Was expecting a string for %s, got %T", pk, pv)
			}
			switch pk {
			case "template":
				template = val
			case "rootPermanode":
				rootPermanode = val
			case "style":
				style = val
			default:
				return fmt.Errorf("Unknown key %q in %s", pk, k)
			}
		}
		if template == "" || rootPermanode == "" {
			return fmt.Errorf("missing \"template\" key or \"rootPermanode\" key in %s", k)
		}
		obj := []string{k, rootPermanode, style}
		config[template] = obj
	}

	delete(config, "publish")
	return nil
}

var serverKey = func() string {
	var b [20]byte
	rand.Read(b[:])
	return string(b[:])
}()

func sendWizard(rw http.ResponseWriter, req *http.Request, hasChanged bool) {
	config, err := jsonconfig.ReadFile(osutil.UserServerConfigPath())
	if err != nil {
		httputil.ServeError(rw, req, err)
		return
	}

	err = flattenPublish(config)
	if err != nil {
		httputil.ServeError(rw, req, err)
		return
	}

	funcMap := template.FuncMap{
		"printWizard": printWizard,
		"showField": func(inputName string) bool {
			if _, ok := ignoredFields[inputName]; ok {
				return false
			}
			return true
		},
		"genXSRF": func() string {
			return xsrftoken.Generate(serverKey, "user", "wizardSave")
		},
	}

	body := `
	<form id="WizardForm" method="POST" enctype="multipart/form-data">
	<table>
	{{range $k,$v := .}}{{if showField $k}}<tr><td>{{printf "%v" $k}}</td><td><input type="text" size="30" name ="{{printf "%v" $k}}" value="{{printWizard $v}}" ></td></tr>{{end}}{{end}}
	</table>
	<input type="hidden" name="token" value="{{genXSRF}}">
	<input type="submit" form="WizardForm" value="Save"> (Will restart server.)</form>`

	if hasChanged {
		body += `<p> Configuration succesfully rewritten </p>`
	}

	tmpl, err := template.New("wizard").Funcs(funcMap).Parse(topWizard + body + bottomWizard)
	if err != nil {
		httputil.ServeError(rw, req, err)
		return
	}
	err = tmpl.Execute(rw, config)
	if err != nil {
		httputil.ServeError(rw, req, err)
		return
	}
}

func rewriteConfig(config *jsonconfig.Obj, configfile string) error {
	b, err := json.MarshalIndent(*config, "", "	")
	if err != nil {
		return err
	}
	s := string(b)
	f, err := os.Create(configfile)
	if err != nil {
		return err
	}
	defer f.Close()
	_, err = f.WriteString(s)
	return err
}

func handleSetupChange(rw http.ResponseWriter, req *http.Request) {
	hilevelConf, err := jsonconfig.ReadFile(osutil.UserServerConfigPath())
	if err != nil {
		httputil.ServeError(rw, req, err)
		return
	}
	if !xsrftoken.Valid(req.FormValue("token"), serverKey, "user", "wizardSave") {
		http.Error(rw, "Form expired. Press back and reload form.", http.StatusBadRequest)
		log.Printf("invalid xsrf token=%q", req.FormValue("token"))
		return
	}

	hasChanged := false
	var el interface{}
	publish := jsonconfig.Obj{}
	for k, v := range req.Form {
		if _, ok := hilevelConf[k]; !ok {
			if k != "gallery" && k != "blog" {
				continue
			}
		}

		switch k {
		case "https", "shareHandler":
			b, err := strconv.ParseBool(v[0])
			if err != nil {
				httputil.ServeError(rw, req, fmt.Errorf("%v field expects a boolean value", k))
			}
			el = b
		default:
			el = v[0]
		}
		if reflect.DeepEqual(hilevelConf[k], el) {
			continue
		}
		hasChanged = true
		hilevelConf[k] = el
	}
	// "publish" wasn't checked yet
	if !reflect.DeepEqual(hilevelConf["publish"], publish) {
		hilevelConf["publish"] = publish
		hasChanged = true
	}

	if hasChanged {
		err = rewriteConfig(&hilevelConf, osutil.UserServerConfigPath())
		if err != nil {
			httputil.ServeError(rw, req, err)
			return
		}
		err = osutil.RestartProcess()
		if err != nil {
			log.Fatal("Failed to restart: " + err.Error())
			http.Error(rw, "Failed to restart process", 500)
			return
		}
	}
	sendWizard(rw, req, hasChanged)
}

func (sh *SetupHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
	if !auth.IsLocalhost(req) {
		fmt.Fprintf(rw,
			"<html><body>Setup only allowed from localhost"+
				"<p><a href='/'>Back</a></p>"+
				"</body></html>\n")
		return
	}
	if req.Method == "POST" {
		err := req.ParseMultipartForm(10e6)
		if err != nil {
			httputil.ServeError(rw, req, err)
			return
		}
		if len(req.Form) > 0 {
			handleSetupChange(rw, req)
		}
		return
	}

	sendWizard(rw, req, false)
}