// Copyright (c) 2016-present Mattermost, Inc. All Rights Reserved.
// See License.txt for license information.

package app

import (
	"crypto/ecdsa"
	"html/template"
	"net"
	"net/http"
	"reflect"
	"strings"
	"sync"
	"sync/atomic"

	l4g "github.com/alecthomas/log4go"
	"github.com/gorilla/mux"
	"github.com/pkg/errors"

	"github.com/mattermost/mattermost-server/einterfaces"
	ejobs "github.com/mattermost/mattermost-server/einterfaces/jobs"
	"github.com/mattermost/mattermost-server/jobs"
	"github.com/mattermost/mattermost-server/model"
	"github.com/mattermost/mattermost-server/plugin/pluginenv"
	"github.com/mattermost/mattermost-server/store"
	"github.com/mattermost/mattermost-server/store/sqlstore"
	"github.com/mattermost/mattermost-server/utils"
)

const ADVANCED_PERMISSIONS_MIGRATION_KEY = "AdvancedPermissionsMigrationComplete"

type App struct {
	goroutineCount      int32
	goroutineExitSignal chan struct{}

	Srv *Server

	PluginEnv              *pluginenv.Environment
	PluginConfigListenerId string

	EmailBatching *EmailBatchingJob

	Hubs                        []*Hub
	HubsStopCheckingForDeadlock chan bool

	Jobs *jobs.JobServer

	AccountMigration einterfaces.AccountMigrationInterface
	Brand            einterfaces.BrandInterface
	Cluster          einterfaces.ClusterInterface
	Compliance       einterfaces.ComplianceInterface
	DataRetention    einterfaces.DataRetentionInterface
	Elasticsearch    einterfaces.ElasticsearchInterface
	Emoji            einterfaces.EmojiInterface
	Ldap             einterfaces.LdapInterface
	MessageExport    einterfaces.MessageExportInterface
	Metrics          einterfaces.MetricsInterface
	Mfa              einterfaces.MfaInterface
	Saml             einterfaces.SamlInterface

	config          atomic.Value
	configFile      string
	configListeners map[string]func(*model.Config, *model.Config)

	licenseValue       atomic.Value
	clientLicenseValue atomic.Value
	licenseListeners   map[string]func()

	siteURL string

	newStore func() store.Store

	htmlTemplateWatcher  *utils.HTMLTemplateWatcher
	sessionCache         *utils.Cache
	configListenerId     string
	licenseListenerId    string
	disableConfigWatch   bool
	configWatcher        *utils.ConfigWatcher
	asymmetricSigningKey *ecdsa.PrivateKey

	pluginCommands     []*PluginCommand
	pluginCommandsLock sync.RWMutex

	clientConfig     map[string]string
	clientConfigHash string
	diagnosticId     string
}

var appCount = 0

// New creates a new App. You must call Shutdown when you're done with it.
// XXX: For now, only one at a time is allowed as some resources are still shared.
func New(options ...Option) (outApp *App, outErr error) {
	appCount++
	if appCount > 1 {
		panic("Only one App should exist at a time. Did you forget to call Shutdown()?")
	}

	app := &App{
		goroutineExitSignal: make(chan struct{}, 1),
		Srv: &Server{
			Router: mux.NewRouter(),
		},
		sessionCache:     utils.NewLru(model.SESSION_CACHE_SIZE),
		configFile:       "config.json",
		configListeners:  make(map[string]func(*model.Config, *model.Config)),
		clientConfig:     make(map[string]string),
		licenseListeners: map[string]func(){},
	}
	defer func() {
		if outErr != nil {
			app.Shutdown()
		}
	}()

	for _, option := range options {
		option(app)
	}

	if utils.T == nil {
		if err := utils.TranslationsPreInit(); err != nil {
			return nil, errors.Wrapf(err, "unable to load Mattermost translation files")
		}
	}
	model.AppErrorInit(utils.T)
	if err := app.LoadConfig(app.configFile); err != nil {
		return nil, err
	}
	app.EnableConfigWatch()
	if err := utils.InitTranslations(app.Config().LocalizationSettings); err != nil {
		return nil, errors.Wrapf(err, "unable to load Mattermost translation files")
	}

	app.configListenerId = app.AddConfigListener(func(_, _ *model.Config) {
		app.configOrLicenseListener()
	})
	app.licenseListenerId = app.AddLicenseListener(app.configOrLicenseListener)
	app.regenerateClientConfig()

	l4g.Info(utils.T("api.server.new_server.init.info"))

	app.initEnterprise()

	if app.newStore == nil {
		app.newStore = func() store.Store {
			return store.NewLayeredStore(sqlstore.NewSqlSupplier(app.Config().SqlSettings, app.Metrics), app.Metrics, app.Cluster)
		}
	}

	if htmlTemplateWatcher, err := utils.NewHTMLTemplateWatcher("templates"); err != nil {
		l4g.Error(utils.T("api.api.init.parsing_templates.error"), err)
	} else {
		app.htmlTemplateWatcher = htmlTemplateWatcher
	}

	app.Srv.Store = app.newStore()
	if err := app.ensureAsymmetricSigningKey(); err != nil {
		return nil, errors.Wrapf(err, "unable to ensure asymmetric signing key")
	}

	app.initJobs()

	app.initBuiltInPlugins()
	app.Srv.Router.HandleFunc("/plugins/{plugin_id:[A-Za-z0-9\\_\\-\\.]+}", app.ServePluginRequest)
	app.Srv.Router.HandleFunc("/plugins/{plugin_id:[A-Za-z0-9\\_\\-\\.]+}/{anything:.*}", app.ServePluginRequest)

	app.Srv.Router.NotFoundHandler = http.HandlerFunc(app.Handle404)

	app.Srv.WebSocketRouter = &WebSocketRouter{
		app:      app,
		handlers: make(map[string]webSocketHandler),
	}

	return app, nil
}

func (a *App) configOrLicenseListener() {
	a.regenerateClientConfig()
}

func (a *App) Shutdown() {
	appCount--

	l4g.Info(utils.T("api.server.stop_server.stopping.info"))

	a.StopServer()
	a.HubStop()

	a.ShutDownPlugins()
	a.WaitForGoroutines()

	if a.Srv.Store != nil {
		a.Srv.Store.Close()
	}
	a.Srv = nil

	if a.htmlTemplateWatcher != nil {
		a.htmlTemplateWatcher.Close()
	}

	a.RemoveConfigListener(a.configListenerId)
	a.RemoveLicenseListener(a.licenseListenerId)
	l4g.Info(utils.T("api.server.stop_server.stopped.info"))

	a.DisableConfigWatch()
}

var accountMigrationInterface func(*App) einterfaces.AccountMigrationInterface

func RegisterAccountMigrationInterface(f func(*App) einterfaces.AccountMigrationInterface) {
	accountMigrationInterface = f
}

var brandInterface func(*App) einterfaces.BrandInterface

func RegisterBrandInterface(f func(*App) einterfaces.BrandInterface) {
	brandInterface = f
}

var clusterInterface func(*App) einterfaces.ClusterInterface

func RegisterClusterInterface(f func(*App) einterfaces.ClusterInterface) {
	clusterInterface = f
}

var complianceInterface func(*App) einterfaces.ComplianceInterface

func RegisterComplianceInterface(f func(*App) einterfaces.ComplianceInterface) {
	complianceInterface = f
}

var dataRetentionInterface func(*App) einterfaces.DataRetentionInterface

func RegisterDataRetentionInterface(f func(*App) einterfaces.DataRetentionInterface) {
	dataRetentionInterface = f
}

var elasticsearchInterface func(*App) einterfaces.ElasticsearchInterface

func RegisterElasticsearchInterface(f func(*App) einterfaces.ElasticsearchInterface) {
	elasticsearchInterface = f
}

var emojiInterface func(*App) einterfaces.EmojiInterface

func RegisterEmojiInterface(f func(*App) einterfaces.EmojiInterface) {
	emojiInterface = f
}

var jobsDataRetentionJobInterface func(*App) ejobs.DataRetentionJobInterface

func RegisterJobsDataRetentionJobInterface(f func(*App) ejobs.DataRetentionJobInterface) {
	jobsDataRetentionJobInterface = f
}

var jobsMessageExportJobInterface func(*App) ejobs.MessageExportJobInterface

func RegisterJobsMessageExportJobInterface(f func(*App) ejobs.MessageExportJobInterface) {
	jobsMessageExportJobInterface = f
}

var jobsElasticsearchAggregatorInterface func(*App) ejobs.ElasticsearchAggregatorInterface

func RegisterJobsElasticsearchAggregatorInterface(f func(*App) ejobs.ElasticsearchAggregatorInterface) {
	jobsElasticsearchAggregatorInterface = f
}

var jobsElasticsearchIndexerInterface func(*App) ejobs.ElasticsearchIndexerInterface

func RegisterJobsElasticsearchIndexerInterface(f func(*App) ejobs.ElasticsearchIndexerInterface) {
	jobsElasticsearchIndexerInterface = f
}

var jobsLdapSyncInterface func(*App) ejobs.LdapSyncInterface

func RegisterJobsLdapSyncInterface(f func(*App) ejobs.LdapSyncInterface) {
	jobsLdapSyncInterface = f
}

var ldapInterface func(*App) einterfaces.LdapInterface

func RegisterLdapInterface(f func(*App) einterfaces.LdapInterface) {
	ldapInterface = f
}

var messageExportInterface func(*App) einterfaces.MessageExportInterface

func RegisterMessageExportInterface(f func(*App) einterfaces.MessageExportInterface) {
	messageExportInterface = f
}

var metricsInterface func(*App) einterfaces.MetricsInterface

func RegisterMetricsInterface(f func(*App) einterfaces.MetricsInterface) {
	metricsInterface = f
}

var mfaInterface func(*App) einterfaces.MfaInterface

func RegisterMfaInterface(f func(*App) einterfaces.MfaInterface) {
	mfaInterface = f
}

var samlInterface func(*App) einterfaces.SamlInterface

func RegisterSamlInterface(f func(*App) einterfaces.SamlInterface) {
	samlInterface = f
}

func (a *App) initEnterprise() {
	if accountMigrationInterface != nil {
		a.AccountMigration = accountMigrationInterface(a)
	}
	if brandInterface != nil {
		a.Brand = brandInterface(a)
	}
	if clusterInterface != nil {
		a.Cluster = clusterInterface(a)
	}
	if complianceInterface != nil {
		a.Compliance = complianceInterface(a)
	}
	if elasticsearchInterface != nil {
		a.Elasticsearch = elasticsearchInterface(a)
	}
	if emojiInterface != nil {
		a.Emoji = emojiInterface(a)
	}
	if ldapInterface != nil {
		a.Ldap = ldapInterface(a)
		a.AddConfigListener(func(_, cfg *model.Config) {
			if err := utils.ValidateLdapFilter(cfg, a.Ldap); err != nil {
				panic(utils.T(err.Id))
			}
		})
	}
	if messageExportInterface != nil {
		a.MessageExport = messageExportInterface(a)
	}
	if metricsInterface != nil {
		a.Metrics = metricsInterface(a)
	}
	if mfaInterface != nil {
		a.Mfa = mfaInterface(a)
	}
	if samlInterface != nil {
		a.Saml = samlInterface(a)
		a.AddConfigListener(func(_, cfg *model.Config) {
			a.Saml.ConfigureSP()
		})
	}
	if dataRetentionInterface != nil {
		a.DataRetention = dataRetentionInterface(a)
	}
}

func (a *App) initJobs() {
	a.Jobs = jobs.NewJobServer(a, a.Srv.Store)
	if jobsDataRetentionJobInterface != nil {
		a.Jobs.DataRetentionJob = jobsDataRetentionJobInterface(a)
	}
	if jobsMessageExportJobInterface != nil {
		a.Jobs.MessageExportJob = jobsMessageExportJobInterface(a)
	}
	if jobsElasticsearchAggregatorInterface != nil {
		a.Jobs.ElasticsearchAggregator = jobsElasticsearchAggregatorInterface(a)
	}
	if jobsElasticsearchIndexerInterface != nil {
		a.Jobs.ElasticsearchIndexer = jobsElasticsearchIndexerInterface(a)
	}
	if jobsLdapSyncInterface != nil {
		a.Jobs.LdapSync = jobsLdapSyncInterface(a)
	}
}

func (a *App) DiagnosticId() string {
	return a.diagnosticId
}

func (a *App) SetDiagnosticId(id string) {
	a.diagnosticId = id
}

func (a *App) EnsureDiagnosticId() {
	if a.diagnosticId != "" {
		return
	}
	if result := <-a.Srv.Store.System().Get(); result.Err == nil {
		props := result.Data.(model.StringMap)

		id := props[model.SYSTEM_DIAGNOSTIC_ID]
		if len(id) == 0 {
			id = model.NewId()
			systemId := &model.System{Name: model.SYSTEM_DIAGNOSTIC_ID, Value: id}
			<-a.Srv.Store.System().Save(systemId)
		}

		a.diagnosticId = id
	}
}

// Go creates a goroutine, but maintains a record of it to ensure that execution completes before
// the app is destroyed.
func (a *App) Go(f func()) {
	atomic.AddInt32(&a.goroutineCount, 1)

	go func() {
		f()

		atomic.AddInt32(&a.goroutineCount, -1)
		select {
		case a.goroutineExitSignal <- struct{}{}:
		default:
		}
	}()
}

// WaitForGoroutines blocks until all goroutines created by App.Go exit.
func (a *App) WaitForGoroutines() {
	for atomic.LoadInt32(&a.goroutineCount) != 0 {
		<-a.goroutineExitSignal
	}
}

func (a *App) HTMLTemplates() *template.Template {
	return a.htmlTemplateWatcher.Templates()
}

func (a *App) HTTPClient(trustURLs bool) *http.Client {
	insecure := a.Config().ServiceSettings.EnableInsecureOutgoingConnections != nil && *a.Config().ServiceSettings.EnableInsecureOutgoingConnections

	if trustURLs {
		return utils.NewHTTPClient(insecure, nil, nil)
	}

	allowHost := func(host string) bool {
		if a.Config().ServiceSettings.AllowedUntrustedInternalConnections == nil {
			return false
		}
		for _, allowed := range strings.Fields(*a.Config().ServiceSettings.AllowedUntrustedInternalConnections) {
			if host == allowed {
				return true
			}
		}
		return false
	}

	allowIP := func(ip net.IP) bool {
		if !utils.IsReservedIP(ip) {
			return true
		}
		if a.Config().ServiceSettings.AllowedUntrustedInternalConnections == nil {
			return false
		}
		for _, allowed := range strings.Fields(*a.Config().ServiceSettings.AllowedUntrustedInternalConnections) {
			if _, ipRange, err := net.ParseCIDR(allowed); err == nil && ipRange.Contains(ip) {
				return true
			}
		}
		return false
	}

	return utils.NewHTTPClient(insecure, allowHost, allowIP)
}

func (a *App) Handle404(w http.ResponseWriter, r *http.Request) {
	err := model.NewAppError("Handle404", "api.context.404.app_error", nil, "", http.StatusNotFound)

	l4g.Debug("%v: code=404 ip=%v", r.URL.Path, utils.GetIpAddress(r))

	utils.RenderWebAppError(w, r, err, a.AsymmetricSigningKey())
}

// This function migrates the default built in roles from code/config to the database.
func (a *App) DoAdvancedPermissionsMigration() {
	// If the migration is already marked as completed, don't do it again.
	if result := <-a.Srv.Store.System().GetByName(ADVANCED_PERMISSIONS_MIGRATION_KEY); result.Err == nil {
		return
	}

	l4g.Info("Migrating roles to database.")
	roles := model.MakeDefaultRoles()
	roles = utils.SetRolePermissionsFromConfig(roles, a.Config(), a.License() != nil)

	allSucceeded := true

	for _, role := range roles {
		if result := <-a.Srv.Store.Role().Save(role); result.Err != nil {
			// If this failed for reasons other than the role already existing, don't mark the migration as done.
			if result2 := <-a.Srv.Store.Role().GetByName(role.Name); result2.Err != nil {
				l4g.Critical("Failed to migrate role to database.")
				l4g.Critical(result.Err)
				allSucceeded = false
			} else {
				// If the role already existed, check it is the same and update if not.
				fetchedRole := result.Data.(*model.Role)
				if !reflect.DeepEqual(fetchedRole.Permissions, role.Permissions) ||
					fetchedRole.DisplayName != role.DisplayName ||
					fetchedRole.Description != role.Description ||
					fetchedRole.SchemeManaged != role.SchemeManaged {
					role.Id = fetchedRole.Id
					if result := <-a.Srv.Store.Role().Save(role); result.Err != nil {
						// Role is not the same, but failed to update.
						l4g.Critical("Failed to migrate role to database.")
						l4g.Critical(result.Err)
						allSucceeded = false
					}
				}
			}
		}
	}

	if !allSucceeded {
		return
	}

	system := model.System{
		Name:  ADVANCED_PERMISSIONS_MIGRATION_KEY,
		Value: "true",
	}

	if result := <-a.Srv.Store.System().Save(&system); result.Err != nil {
		l4g.Critical("Failed to mark advanced permissions migration as completed.")
		l4g.Critical(result.Err)
	}
}