// Copyright (C) 2020 Storj Labs, Inc.
// See LICENSE for copying information.

// Package admin implements administrative endpoints for satellite.
package admin

import (
	"context"
	"crypto/subtle"
	"errors"
	"fmt"
	"net"
	"net/http"
	"strings"
	"time"

	"github.com/gorilla/mux"
	"go.uber.org/zap"
	"golang.org/x/sync/errgroup"

	"storj.io/common/errs2"
	"storj.io/storj/satellite/accounting"
	backoffice "storj.io/storj/satellite/admin/back-office"
	adminui "storj.io/storj/satellite/admin/ui"
	"storj.io/storj/satellite/analytics"
	"storj.io/storj/satellite/attribution"
	"storj.io/storj/satellite/buckets"
	"storj.io/storj/satellite/console"
	"storj.io/storj/satellite/console/consoleweb"
	"storj.io/storj/satellite/console/restkeys"
	"storj.io/storj/satellite/oidc"
	"storj.io/storj/satellite/payments"
	"storj.io/storj/satellite/payments/stripe"
)

const (
	// UnauthorizedNotInGroup - message for when api user is not part of a required access group.
	UnauthorizedNotInGroup = "User must be a member of one of these groups to conduct this operation: %s"
	// AuthorizationNotEnabled - message for when authorization is disabled.
	AuthorizationNotEnabled = "Authorization not enabled."

	// BackOfficePathPrefix is the path prefix used for the back office router.
	BackOfficePathPrefix = "/back-office"
)

// Config defines configuration for debug server.
type Config struct {
	Address          string `help:"admin peer http listening address"                                                                              releaseDefault:"" devDefault:""`
	StaticDir        string `help:"an alternate directory path which contains the static assets to serve. When empty, it uses the embedded assets" releaseDefault:"" devDefault:""`
	AllowedOauthHost string `help:"the oauth host allowed to bypass token authentication."`
	Groups           Groups

	AuthorizationToken string `internal:"true"`
	BackOffice         backoffice.Config
}

// Groups defines permission groups.
type Groups struct {
	LimitUpdate string `help:"the group which is only allowed to update user and project limits and freeze and unfreeze accounts."`
}

// DB is databases needed for the admin server.
type DB interface {
	// ProjectAccounting returns database for storing information about project data use
	ProjectAccounting() accounting.ProjectAccounting
	// Console returns database for satellite console
	Console() console.DB
	// OIDC returns the database for OIDC and OAuth information.
	OIDC() oidc.DB
	// StripeCoinPayments returns database for satellite stripe coin payments
	StripeCoinPayments() stripe.DB
	// Buckets returns database for buckets metainfo.
	Buckets() buckets.DB
	// Attribution returns database for value attribution.
	Attribution() attribution.DB
}

// Server provides endpoints for administrative tasks.
type Server struct {
	log *zap.Logger

	listener net.Listener
	server   http.Server

	db             DB
	payments       payments.Accounts
	buckets        *buckets.Service
	restKeys       *restkeys.Service
	analytics      *analytics.Service
	freezeAccounts *console.AccountFreezeService

	nowFn func() time.Time

	console consoleweb.Config
	config  Config
}

// NewServer returns a new administration Server.
func NewServer(
	log *zap.Logger,
	listener net.Listener,
	db DB,
	buckets *buckets.Service,
	restKeys *restkeys.Service,
	freezeAccounts *console.AccountFreezeService,
	analyticsService *analytics.Service,
	accounts payments.Accounts,
	backOfficeService *backoffice.Service,
	console consoleweb.Config,
	config Config,
) *Server {
	server := &Server{
		log: log,

		listener: listener,

		db:             db,
		payments:       accounts,
		buckets:        buckets,
		restKeys:       restKeys,
		analytics:      analyticsService,
		freezeAccounts: freezeAccounts,

		nowFn: time.Now,

		console: console,
		config:  config,
	}

	root := mux.NewRouter()

	api := root.PathPrefix("/api/").Subrouter()

	// When adding new options, also update README.md

	// prod owners only
	fullAccessAPI := api.NewRoute().Subrouter()
	fullAccessAPI.Use(server.withAuth([]string{config.Groups.LimitUpdate}, true))
	fullAccessAPI.HandleFunc("/users", server.addUser).Methods("POST")
	fullAccessAPI.HandleFunc("/users/{useremail}", server.updateUser).Methods("PUT")
	fullAccessAPI.HandleFunc("/users/{useremail}", server.deleteUser).Methods("DELETE")
	fullAccessAPI.HandleFunc("/users/{useremail}/mfa", server.disableUserMFA).Methods("DELETE")
	fullAccessAPI.HandleFunc("/users/{useremail}/activate-account/disable-bot-restriction", server.disableBotRestriction).Methods("PATCH")
	fullAccessAPI.HandleFunc("/users/{useremail}/useragent", server.updateUsersUserAgent).Methods("PATCH")
	fullAccessAPI.HandleFunc("/users/{useremail}/geofence", server.createGeofenceForAccount).Methods("PATCH")
	fullAccessAPI.HandleFunc("/users/{useremail}/geofence", server.deleteGeofenceForAccount).Methods("DELETE")
	fullAccessAPI.HandleFunc("/oauth/clients", server.createOAuthClient).Methods("POST")
	fullAccessAPI.HandleFunc("/oauth/clients/{id}", server.updateOAuthClient).Methods("PUT")
	fullAccessAPI.HandleFunc("/oauth/clients/{id}", server.deleteOAuthClient).Methods("DELETE")
	fullAccessAPI.HandleFunc("/projects", server.addProject).Methods("POST")
	fullAccessAPI.HandleFunc("/projects/{project}", server.renameProject).Methods("PUT")
	fullAccessAPI.HandleFunc("/projects/{project}", server.deleteProject).Methods("DELETE")
	fullAccessAPI.HandleFunc("/projects/{project}", server.getProject).Methods("GET")
	fullAccessAPI.HandleFunc("/projects/{project}/apikeys", server.addAPIKey).Methods("POST")
	fullAccessAPI.HandleFunc("/projects/{project}/apikeys", server.listAPIKeys).Methods("GET")
	fullAccessAPI.HandleFunc("/projects/{project}/apikeys", server.deleteAPIKeyByName).Methods("DELETE").Queries("name", "")
	fullAccessAPI.HandleFunc("/projects/{project}/buckets/{bucket}", server.getBucketInfo).Methods("GET")
	fullAccessAPI.HandleFunc("/projects/{project}/buckets/{bucket}/geofence", server.createGeofenceForBucket).Methods("POST")
	fullAccessAPI.HandleFunc("/projects/{project}/buckets/{bucket}/geofence", server.deleteGeofenceForBucket).Methods("DELETE")
	fullAccessAPI.HandleFunc("/projects/{project}/usage", server.checkProjectUsage).Methods("GET")
	fullAccessAPI.HandleFunc("/projects/{project}/useragent", server.updateProjectsUserAgent).Methods("PATCH")
	fullAccessAPI.HandleFunc("/projects/{project}/geofence", server.createGeofenceForProject).Methods("POST")
	fullAccessAPI.HandleFunc("/projects/{project}/geofence", server.deleteGeofenceForProject).Methods("DELETE")
	fullAccessAPI.HandleFunc("/apikeys/{apikey}", server.getAPIKey).Methods("GET")
	fullAccessAPI.HandleFunc("/apikeys/{apikey}", server.deleteAPIKey).Methods("DELETE")
	fullAccessAPI.HandleFunc("/restkeys/{useremail}", server.addRESTKey).Methods("POST")
	fullAccessAPI.HandleFunc("/restkeys/{apikey}/revoke", server.revokeRESTKey).Methods("PUT")

	// limit update access required
	limitUpdateAPI := api.NewRoute().Subrouter()
	limitUpdateAPI.Use(server.withAuth([]string{config.Groups.LimitUpdate}, false))
	limitUpdateAPI.HandleFunc("/users/{useremail}", server.userInfo).Methods("GET")
	limitUpdateAPI.HandleFunc("/users/{useremail}/limits", server.userLimits).Methods("GET")
	limitUpdateAPI.HandleFunc("/users/{useremail}/limits", server.updateLimits).Methods("PUT")
	limitUpdateAPI.HandleFunc("/users/{useremail}/billing-freeze", server.billingFreezeUser).Methods("PUT")
	limitUpdateAPI.HandleFunc("/users/{useremail}/billing-freeze", server.billingUnfreezeUser).Methods("DELETE")
	limitUpdateAPI.HandleFunc("/users/{useremail}/billing-warning", server.billingUnWarnUser).Methods("DELETE")
	limitUpdateAPI.HandleFunc("/users/{useremail}/violation-freeze", server.violationFreezeUser).Methods("PUT")
	limitUpdateAPI.HandleFunc("/users/{useremail}/violation-freeze", server.violationUnfreezeUser).Methods("DELETE")
	limitUpdateAPI.HandleFunc("/users/{useremail}/legal-freeze", server.legalFreezeUser).Methods("PUT")
	limitUpdateAPI.HandleFunc("/users/{useremail}/legal-freeze", server.legalUnfreezeUser).Methods("DELETE")
	limitUpdateAPI.HandleFunc("/users/pending-deletion", server.usersPendingDeletion).Methods("GET")
	limitUpdateAPI.HandleFunc("/projects/{project}/limit", server.getProjectLimit).Methods("GET")
	limitUpdateAPI.HandleFunc("/projects/{project}/limit", server.putProjectLimit).Methods("PUT", "POST")

	// NewServer adds the backoffice.PahtPrefix for the static assets, but not for the API because the
	// generator already add the PathPrefix to router when the API handlers are hooked.
	_ = backoffice.NewServer(
		log.Named("back-office"),
		nil,
		backOfficeService,
		root,
		config.BackOffice,
	)

	// This handler must be the last one because it uses the root as prefix,
	// otherwise will try to serve all the handlers set after this one.
	if config.StaticDir == "" {
		root.PathPrefix("/").Handler(http.FileServer(http.FS(adminui.Assets))).Methods("GET")
	} else {
		root.PathPrefix("/").Handler(http.FileServer(http.Dir(config.StaticDir))).Methods("GET")
	}

	server.server.Handler = root
	return server
}

// Run starts the admin endpoint.
func (server *Server) Run(ctx context.Context) error {
	if server.listener == nil {
		return nil
	}
	ctx, cancel := context.WithCancel(ctx)
	var group errgroup.Group
	group.Go(func() error {
		<-ctx.Done()
		return Error.Wrap(server.server.Shutdown(context.Background()))
	})
	group.Go(func() error {
		defer cancel()
		err := server.server.Serve(server.listener)
		if errs2.IsCanceled(err) || errors.Is(err, http.ErrServerClosed) {
			err = nil
		}
		return Error.Wrap(err)
	})
	return group.Wait()
}

// SetNow allows tests to have the server act as if the current time is whatever they want.
func (server *Server) SetNow(nowFn func() time.Time) {
	server.nowFn = nowFn
}

// Close closes server and underlying listener.
func (server *Server) Close() error {
	return Error.Wrap(server.server.Close())
}

// SetAllowedOauthHost allows tests to set which address to recognize as belonging to the OAuth proxy.
func (server *Server) SetAllowedOauthHost(host string) {
	server.config.AllowedOauthHost = host
}

// withAuth checks if the requester is authorized to perform an operation. If the request did not come from the oauth proxy, verify the auth token.
// Otherwise, check that the user has the required permissions to conduct the operation. `allowedGroups` is a list of groups that are authorized.
// If it is nil, then the api method is not accessible from the oauth proxy.
func (server *Server) withAuth(allowedGroups []string, requireAPIKey bool) func(next http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			if server.config.AuthorizationToken == "" {
				sendJSONError(w, AuthorizationNotEnabled, "", http.StatusForbidden)
				return
			}

			if r.Host != server.config.AllowedOauthHost {
				// not behind the proxy; use old authentication method.
				if !validateAPIKey(server.config.AuthorizationToken, r.Header.Get("Authorization")) {
					sendJSONError(w, "Forbidden", "required a valid authorization token", http.StatusForbidden)
					return
				}
			} else {
				var allowed bool
				userGroupsString := r.Header.Get("X-Forwarded-Groups")
				userGroups := strings.Split(userGroupsString, ",")

			AUTHENTICATED:
				for _, userGroup := range userGroups {
					if userGroup == "" {
						continue
					}
					for _, permGroup := range allowedGroups {
						if userGroup == permGroup {
							allowed = true
							break AUTHENTICATED
						}
					}
				}

				if !allowed {
					sendJSONError(w, "Forbidden", fmt.Sprintf(UnauthorizedNotInGroup, allowedGroups), http.StatusForbidden)
					return
				}

				// The operation requires to provide a valid authorization token.
				if requireAPIKey && !validateAPIKey(server.config.AuthorizationToken, r.Header.Get("Authorization")) {
					sendJSONError(
						w, "Forbidden",
						"you are part of one of the authorized groups, but this operation requires a valid authorization token",
						http.StatusForbidden,
					)
					return
				}
			}

			server.log.Info(
				"admin action",
				zap.String("host", r.Host),
				zap.String("user", r.Header.Get("X-Forwarded-Email")),
				zap.String("action", fmt.Sprintf("%s-%s", r.Method, r.RequestURI)),
				zap.String("queries", r.URL.Query().Encode()),
			)

			r.Header.Set("Cache-Control", "must-revalidate")
			next.ServeHTTP(w, r)
		})
	}
}

func validateAPIKey(configured, sent string) bool {
	equality := subtle.ConstantTimeCompare([]byte(sent), []byte(configured))
	return equality == 1
}