bloat/service/service.go

package service

import (
	"crypto/sha256"
	"encoding/base64"
	"errors"
	"fmt"
	"mime/multipart"
	"net/url"
	"strings"

	"bloat/mastodon"
	"bloat/model"
	"bloat/renderer"
	"bloat/util"
)

var (
	errInvalidArgument  = errors.New("invalid argument")
	errInvalidSession   = errors.New("invalid session")
	errInvalidCSRFToken = errors.New("invalid csrf token")
)

type service struct {
	cname       string
	cscope      string
	cwebsite    string
	css         string
	instance    string
	postFormats []model.PostFormat
	renderer    renderer.Renderer
}

func NewService(cname string, cscope string, cwebsite string,
	css string, instance string, postFormats []model.PostFormat,
	renderer renderer.Renderer) *service {
	return &service{
		cname:       cname,
		cscope:      cscope,
		cwebsite:    cwebsite,
		css:         css,
		instance:    instance,
		postFormats: postFormats,
		renderer:    renderer,
	}
}

func (s *service) cdata(c *client, title string, count int, rinterval int,
	target string) (data *renderer.CommonData) {
	if title == "" {
		title = s.cname
	} else {
		title += " - " + s.cname
	}
	data = &renderer.CommonData{
		Title:           title,
		CustomCSS:       s.css,
		Count:           count,
		RefreshInterval: rinterval,
		Target:          target,
	}
	if c != nil && c.s.IsLoggedIn() {
		data.CSRFToken = c.s.CSRFToken
		data.Title += " - " + c.s.Instance
	}
	return
}

func (s *service) ErrorPage(c *client, err error, retry bool) error {
	var errStr string
	var sessionErr bool
	if err != nil {
		errStr = err.Error()
		if me, ok := err.(mastodon.Error); ok && me.IsAuthError() ||
			err == errInvalidSession || err == errInvalidCSRFToken {
			sessionErr = true
		}
	}
	cdata := s.cdata(nil, "error", 0, 0, "")
	data := &renderer.ErrorData{
		CommonData: cdata,
		Err:        errStr,
		Retry:      retry,
		SessionErr: sessionErr,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.ErrorPage, data)
}

func (s *service) SigninPage(c *client) (err error) {
	cdata := s.cdata(nil, "Signin", 0, 0, "")
	data := &renderer.SigninData{
		CommonData: cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.SigninPage, data)
}

func (s *service) RootPage(c *client) (err error) {
	cdata := s.cdata(c, "", 0, 0, "")
	data := &renderer.RootData{
		CommonData: cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.RootPage, data)
}

func (s *service) NavPage(c *client) (err error) {
	u, err := c.GetAccountCurrentUser(c.ctx)
	if err != nil {
		return
	}
	pctx := model.PostContext{
		DefaultVisibility: c.s.Settings.DefaultVisibility,
		DefaultFormat:     c.s.Settings.DefaultFormat,
		Formats:           s.postFormats,
	}
	cdata := s.cdata(c, "Nav", 0, 0, "main")
	data := &renderer.NavData{
		User:        u,
		CommonData:  cdata,
		PostContext: pctx,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.NavPage, data)
}

func (s *service) TimelinePage(c *client, tType, q, listId, maxID,
	minID string) (err error) {

	var nextLink, prevLink, title string
	var statuses []*mastodon.Status
	var pg = mastodon.Pagination{
		MaxID: maxID,
		MinID: minID,
		Limit: 20,
	}
	var refreshLink = "/timeline/" + tType

	switch tType {
	default:
		return errInvalidArgument
	case "home":
		statuses, err = c.GetTimelineHome(c.ctx, &pg)
		if err != nil {
			return err
		}
		title = "Timeline"
	case "direct":
		statuses, err = c.GetTimelineDirect(c.ctx, &pg)
		if err != nil {
			return err
		}
		title = "Direct Timeline"
	case "local":
		statuses, err = c.GetTimelinePublic(c.ctx, true, "", &pg)
		if err != nil {
			return err
		}
		title = "Local Timeline"
	case "remote":
		if len(q) > 0 {
			statuses, err = c.GetTimelinePublic(c.ctx, false, q, &pg)
			if err != nil {
				return err
			}
			refreshLink += "?q=" + url.QueryEscape(q)
		}
		title = "Remote Timeline"
	case "twkn":
		statuses, err = c.GetTimelinePublic(c.ctx, false, "", &pg)
		if err != nil {
			return err
		}
		title = "The Whole Known Network"
	case "list":
		statuses, err = c.GetTimelineList(c.ctx, listId, &pg)
		if err != nil {
			return err
		}
		list, err := c.GetList(c.ctx, listId)
		if err != nil {
			return err
		}
		title = "List Timeline - " + list.Title
		refreshLink += "?list=" + listId
	case "hashtag":
		q = strings.TrimPrefix(q, "#")
		if len(q) > 0 {
			statuses, err = c.GetTimelineHashtag(c.ctx, q, false, &pg)
			if err != nil {
				return err
			}
			refreshLink += "?q=" + url.QueryEscape(q)
		}
		title = "Hashtag Timeline"
	}

	for i := range statuses {
		if statuses[i].Reblog != nil {
			statuses[i].Reblog.RetweetedByID = statuses[i].ID
		}
	}

	if (len(maxID) > 0 || len(minID) > 0) && len(statuses) > 0 {
		v := make(url.Values)
		v.Set("min_id", statuses[0].ID)
		if len(q) > 0 {
			v.Set("q", q)
		}
		if len(listId) > 0 {
			v.Set("list", listId)
		}
		prevLink = "/timeline/" + tType + "?" + v.Encode()
	}

	if len(minID) > 0 || (len(pg.MaxID) > 0 && len(statuses) == 20) {
		v := make(url.Values)
		v.Set("max_id", pg.MaxID)
		if len(q) > 0 {
			v.Set("q", q)
		}
		if len(listId) > 0 {
			v.Set("list", listId)
		}
		nextLink = "/timeline/" + tType + "?" + v.Encode()
	}

	cdata := s.cdata(c, title, 0, 0, "")
	data := &renderer.TimelineData{
		Title:       title,
		Type:        tType,
		Q:           q,
		Statuses:    statuses,
		NextLink:    nextLink,
		PrevLink:    prevLink,
		RefreshLink: refreshLink,
		CommonData:  cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.TimelinePage, data)
}

func addToReplyMap(m map[string][]mastodon.ReplyInfo, key interface{},
	val string, number int) {
	if key == nil {
		return
	}
	keyStr, ok := key.(string)
	if !ok {
		return
	}
	_, ok = m[keyStr]
	if !ok {
		m[keyStr] = []mastodon.ReplyInfo{}
	}
	m[keyStr] = append(m[keyStr], mastodon.ReplyInfo{val, number})
}

func (s *service) ListsPage(c *client) (err error) {
	lists, err := c.GetLists(c.ctx)
	if err != nil {
		return
	}

	cdata := s.cdata(c, "Lists", 0, 0, "")
	data := renderer.ListsData{
		Lists:      lists,
		CommonData: cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.ListsPage, data)
}

func (s *service) AddList(c *client, title string) (err error) {
	_, err = c.CreateList(c.ctx, title)
	return err
}

func (s *service) RemoveList(c *client, id string) (err error) {
	return c.DeleteList(c.ctx, id)
}

func (s *service) RenameList(c *client, id, title string) (err error) {
	_, err = c.RenameList(c.ctx, id, title)
	return err
}

func (s *service) ListPage(c *client, id string, q string) (err error) {
	list, err := c.GetList(c.ctx, id)
	if err != nil {
		return
	}
	accounts, err := c.GetListAccounts(c.ctx, id)
	if err != nil {
		return
	}
	var searchAccounts []*mastodon.Account
	if len(q) > 0 {
		result, err := c.Search(c.ctx, q, "accounts", 20, true, 0, id, false)
		if err != nil {
			return err
		}
		searchAccounts = result.Accounts
	}
	cdata := s.cdata(c, "List "+list.Title, 0, 0, "")
	data := renderer.ListData{
		List:           list,
		Accounts:       accounts,
		Q:              q,
		SearchAccounts: searchAccounts,
		CommonData:     cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.ListPage, data)
}

func (s *service) ListAddUser(c *client, id string, uid string) (err error) {
	return c.AddToList(c.ctx, id, uid)
}

func (s *service) ListRemoveUser(c *client, id string, uid string) (err error) {
	return c.RemoveFromList(c.ctx, id, uid)
}

func (s *service) ThreadPage(c *client, id string, reply bool) (err error) {
	var pctx model.PostContext

	status, err := c.GetStatus(c.ctx, id)
	if err != nil {
		return
	}

	if reply {
		var content string
		var visibility string
		if c.s.UserID != status.Account.ID {
			content += "@" + status.Account.Acct + " "
		}
		for i := range status.Mentions {
			if status.Mentions[i].ID != c.s.UserID &&
				status.Mentions[i].ID != status.Account.ID {
				content += "@" + status.Mentions[i].Acct + " "
			}
		}

		isDirect := status.Visibility == "direct"
		if isDirect || c.s.Settings.CopyScope {
			visibility = status.Visibility
		} else {
			visibility = c.s.Settings.DefaultVisibility
		}

		pctx = model.PostContext{
			DefaultVisibility: visibility,
			DefaultFormat:     c.s.Settings.DefaultFormat,
			Formats:           s.postFormats,
			ReplyContext: &model.ReplyContext{
				InReplyToID:     id,
				InReplyToName:   status.Account.Acct,
				ReplyContent:    content,
				ForceVisibility: isDirect,
			},
		}
	}

	context, err := c.GetStatusContext(c.ctx, id)
	if err != nil {
		return
	}

	statuses := append(append(context.Ancestors, status), context.Descendants...)
	replies := make(map[string][]mastodon.ReplyInfo)
	idNumbers := make(map[string]int)

	for i := range statuses {
		statuses[i].ShowReplies = true

		statuses[i].IDNumbers = idNumbers
		idNumbers[statuses[i].ID] = i + 1

		statuses[i].IDReplies = replies
		addToReplyMap(replies, statuses[i].InReplyToID, statuses[i].ID, i+1)
	}

	cdata := s.cdata(c, "Post by "+status.Account.DisplayName, 0, 0, "")
	data := &renderer.ThreadData{
		Statuses:    statuses,
		PostContext: pctx,
		ReplyMap:    replies,
		CommonData:  cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.ThreadPage, data)
}

func (s *service) QuickReplyPage(c *client, id string) (err error) {
	status, err := c.GetStatus(c.ctx, id)
	if err != nil {
		return
	}

	var ancestor *mastodon.Status
	if status.InReplyToID != nil {
		ancestor, err = c.GetStatus(c.ctx, status.InReplyToID.(string))
		if err != nil {
			return
		}
	}

	var content string
	if c.s.UserID != status.Account.ID {
		content += "@" + status.Account.Acct + " "
	}
	for i := range status.Mentions {
		if status.Mentions[i].ID != c.s.UserID &&
			status.Mentions[i].ID != status.Account.ID {
			content += "@" + status.Mentions[i].Acct + " "
		}
	}

	var visibility string
	isDirect := status.Visibility == "direct"
	if isDirect || c.s.Settings.CopyScope {
		visibility = status.Visibility
	} else {
		visibility = c.s.Settings.DefaultVisibility
	}

	pctx := model.PostContext{
		DefaultVisibility: visibility,
		DefaultFormat:     c.s.Settings.DefaultFormat,
		Formats:           s.postFormats,
		ReplyContext: &model.ReplyContext{
			InReplyToID:     id,
			InReplyToName:   status.Account.Acct,
			QuickReply:      true,
			ReplyContent:    content,
			ForceVisibility: isDirect,
		},
	}

	cdata := s.cdata(c, "Post by "+status.Account.DisplayName, 0, 0, "")
	data := &renderer.QuickReplyData{
		Ancestor:    ancestor,
		Status:      status,
		PostContext: pctx,
		CommonData:  cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.QuickReplyPage, data)
}

func (s *service) LikedByPage(c *client, id string) (err error) {
	likers, err := c.GetFavouritedBy(c.ctx, id, nil)
	if err != nil {
		return
	}
	cdata := s.cdata(c, "Likes", 0, 0, "")
	data := &renderer.LikedByData{
		CommonData: cdata,
		Users:      likers,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.LikedByPage, data)
}

func (s *service) RetweetedByPage(c *client, id string) (err error) {
	retweeters, err := c.GetRebloggedBy(c.ctx, id, nil)
	if err != nil {
		return
	}
	cdata := s.cdata(c, "Retweets", 0, 0, "")
	data := &renderer.RetweetedByData{
		CommonData: cdata,
		Users:      retweeters,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.RetweetedByPage, data)
}

func (s *service) NotificationPage(c *client, maxID string,
	minID string) (err error) {

	var nextLink string
	var unreadCount int
	var readID string
	var includes, excludes []string
	var pg = mastodon.Pagination{
		MaxID: maxID,
		MinID: minID,
		Limit: 20,
	}

	if c.s.Settings.HideUnsupportedNotifs {
		// Explicitly include the supported types.
		// For now, only Pleroma supports this option, Mastadon
		// will simply ignore the unknown params.
		includes = []string{"follow", "follow_request", "mention", "reblog", "favourite"}
	}
	if c.s.Settings.AntiDopamineMode {
		excludes = append(excludes, "follow", "favourite", "reblog")
	}

	notifications, err := c.GetNotifications(c.ctx, &pg, includes, excludes)
	if err != nil {
		return
	}

	for i := range notifications {
		if notifications[i].Pleroma != nil && !notifications[i].Pleroma.IsSeen {
			unreadCount++
		}
	}

	if unreadCount > 0 {
		readID = notifications[0].ID
	}
	if len(notifications) == 20 && len(pg.MaxID) > 0 {
		nextLink = "/notifications?max_id=" + pg.MaxID
	}

	cdata := s.cdata(c, "Notifications", unreadCount,
		c.s.Settings.NotificationInterval, "main")
	data := &renderer.NotificationData{
		Notifications: notifications,
		UnreadCount:   unreadCount,
		ReadID:        readID,
		NextLink:      nextLink,
		CommonData:    cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.NotificationPage, data)
}

func (s *service) UserPage(c *client, id string, pageType string,
	maxID string, minID string) (err error) {

	var nextLink string
	var statuses []*mastodon.Status
	var users []*mastodon.Account
	var pg = mastodon.Pagination{
		MaxID: maxID,
		MinID: minID,
		Limit: 20,
	}
	isCurrent := c.s.UserID == id

	// Some fields like AccountSource are only available in the
	// CurrentUser API
	var user *mastodon.Account
	if isCurrent {
		user, err = c.GetAccountCurrentUser(c.ctx)
	} else {
		user, err = c.GetAccount(c.ctx, id)
	}
	if err != nil {
		return
	}

	switch pageType {
	case "":
		statuses, err = c.GetAccountStatuses(c.ctx, id, false, &pg)
		if err != nil {
			return
		}
		if len(statuses) == 20 && len(pg.MaxID) > 0 {
			nextLink = fmt.Sprintf("/user/%s?max_id=%s", id,
				pg.MaxID)
		}
	case "following":
		users, err = c.GetAccountFollowing(c.ctx, id, &pg)
		if err != nil {
			return
		}
		if len(users) == 20 && len(pg.MaxID) > 0 {
			nextLink = fmt.Sprintf("/user/%s/following?max_id=%s",
				id, pg.MaxID)
		}
	case "followers":
		users, err = c.GetAccountFollowers(c.ctx, id, &pg)
		if err != nil {
			return
		}
		if len(users) == 20 && len(pg.MaxID) > 0 {
			nextLink = fmt.Sprintf("/user/%s/followers?max_id=%s",
				id, pg.MaxID)
		}
	case "media":
		statuses, err = c.GetAccountStatuses(c.ctx, id, true, &pg)
		if err != nil {
			return
		}
		if len(statuses) == 20 && len(pg.MaxID) > 0 {
			nextLink = fmt.Sprintf("/user/%s/media?max_id=%s",
				id, pg.MaxID)
		}
	case "bookmarks":
		if !isCurrent {
			return errInvalidArgument
		}
		statuses, err = c.GetBookmarks(c.ctx, &pg)
		if err != nil {
			return
		}
		if len(statuses) == 20 && len(pg.MaxID) > 0 {
			nextLink = fmt.Sprintf("/user/%s/bookmarks?max_id=%s",
				id, pg.MaxID)
		}
	case "mutes":
		if !isCurrent {
			return errInvalidArgument
		}
		users, err = c.GetMutes(c.ctx, &pg)
		if err != nil {
			return
		}
		if len(users) == 20 && len(pg.MaxID) > 0 {
			nextLink = fmt.Sprintf("/user/%s/mutes?max_id=%s",
				id, pg.MaxID)
		}
	case "blocks":
		if !isCurrent {
			return errInvalidArgument
		}
		users, err = c.GetBlocks(c.ctx, &pg)
		if err != nil {
			return
		}
		if len(users) == 20 && len(pg.MaxID) > 0 {
			nextLink = fmt.Sprintf("/user/%s/blocks?max_id=%s",
				id, pg.MaxID)
		}
	case "likes":
		if !isCurrent {
			return errInvalidArgument
		}
		statuses, err = c.GetFavourites(c.ctx, &pg)
		if err != nil {
			return
		}
		if len(statuses) == 20 && len(pg.MaxID) > 0 {
			nextLink = fmt.Sprintf("/user/%s/likes?max_id=%s",
				id, pg.MaxID)
		}
	case "requests":
		if !isCurrent {
			return errInvalidArgument
		}
		users, err = c.GetFollowRequests(c.ctx, &pg)
		if err != nil {
			return
		}
		if len(users) == 20 && len(pg.MaxID) > 0 {
			nextLink = fmt.Sprintf("/user/%s/requests?max_id=%s",
				id, pg.MaxID)
		}
	default:
		return errInvalidArgument
	}

	for i := range statuses {
		if statuses[i].Reblog != nil {
			statuses[i].Reblog.RetweetedByID = statuses[i].ID
		}
	}

	cdata := s.cdata(c, user.DisplayName+" @"+user.Acct, 0, 0, "")
	data := &renderer.UserData{
		User:       user,
		Type:       pageType,
		Users:      users,
		Statuses:   statuses,
		NextLink:   nextLink,
		CommonData: cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.UserPage, data)
}

func (s *service) UserSearchPage(c *client,
	id string, q string, offset int) (err error) {

	var nextLink string
	var title = "Search"

	user, err := c.GetAccount(c.ctx, id)
	if err != nil {
		return
	}

	var results *mastodon.Results
	if len(q) > 0 {
		results, err = c.Search(c.ctx, q, "statuses", 20, true, offset, id, false)
		if err != nil {
			return err
		}
	} else {
		results = &mastodon.Results{}
	}

	if len(results.Statuses) == 20 {
		offset += 20
		nextLink = fmt.Sprintf("/usersearch/%s?q=%s&offset=%d", id,
			url.QueryEscape(q), offset)
	}

	if len(q) > 0 {
		title += " \"" + q + "\""
	}

	cdata := s.cdata(c, title, 0, 0, "")
	data := &renderer.UserSearchData{
		CommonData: cdata,
		User:       user,
		Q:          q,
		Statuses:   results.Statuses,
		NextLink:   nextLink,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.UserSearchPage, data)
}

func (s *service) MutePage(c *client, id string) (err error) {
	user, err := c.GetAccount(c.ctx, id)
	if err != nil {
		return
	}
	cdata := s.cdata(c, "Mute "+user.DisplayName+" @"+user.Acct, 0, 0, "")
	data := &renderer.UserData{
		User:       user,
		CommonData: cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.MutePage, data)
}

func (s *service) AboutPage(c *client) (err error) {
	cdata := s.cdata(c, "About", 0, 0, "")
	data := &renderer.AboutData{
		CommonData: cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.AboutPage, data)
}

func (s *service) EmojiPage(c *client) (err error) {
	emojis, err := c.GetInstanceEmojis(c.ctx)
	if err != nil {
		return
	}
	cdata := s.cdata(c, "Emojis", 0, 0, "")
	data := &renderer.EmojiData{
		Emojis:     emojis,
		CommonData: cdata,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.EmojiPage, data)
}

func (s *service) SearchPage(c *client, q string, qType string, offset int) (
	rurl string, err error) {

	var nextLink string
	var title = "Search"

	var results *mastodon.Results
	if len(q) > 0 {
		if qType == "hashtags" {
			rurl = "/timeline/hashtag?q=" + url.QueryEscape(q)
			return
		}
		results, err = c.Search(c.ctx, q, qType, 20, true, offset, "", false)
		if err != nil {
			return "", err
		}
	} else {
		results = &mastodon.Results{}
	}

	if (qType == "accounts" && len(results.Accounts) == 20) ||
		(qType == "statuses" && len(results.Statuses) == 20) {
		offset += 20
		nextLink = fmt.Sprintf("/search?q=%s&type=%s&offset=%d",
			url.QueryEscape(q), qType, offset)
	}

	if len(q) > 0 {
		title += " \"" + q + "\""
	}

	cdata := s.cdata(c, title, 0, 0, "")
	data := &renderer.SearchData{
		CommonData: cdata,
		Q:          q,
		Type:       qType,
		Users:      results.Accounts,
		Statuses:   results.Statuses,
		NextLink:   nextLink,
	}
	return "", s.renderer.Render(c.rctx, c.w, renderer.SearchPage, data)
}

func (s *service) SettingsPage(c *client) (err error) {
	cdata := s.cdata(c, "Settings", 0, 0, "")
	data := &renderer.SettingsData{
		CommonData:  cdata,
		Settings:    &c.s.Settings,
		PostFormats: s.postFormats,
	}
	return s.renderer.Render(c.rctx, c.w, renderer.SettingsPage, data)
}

func (svc *service) FiltersPage(c *client) (err error) {
	filters, err := c.GetFilters(c.ctx)
	if err != nil {
		return
	}
	cdata := svc.cdata(c, "Filters", 0, 0, "")
	data := &renderer.FiltersData{
		CommonData: cdata,
		Filters:    filters,
	}
	return svc.renderer.Render(c.rctx, c.w, renderer.FiltersPage, data)
}

func (svc *service) ProfilePage(c *client) (err error) {
	u, err := c.GetAccountCurrentUser(c.ctx)
	if err != nil {
		return
	}
	// Some instances allow more than 4 fields, but make sure that there are
	// at least 4 fields in the slice because the template depends on it.
	if u.Source.Fields == nil {
		u.Source.Fields = new([]mastodon.Field)
	}
	for len(*u.Source.Fields) < 4 {
		*u.Source.Fields = append(*u.Source.Fields, mastodon.Field{})
	}
	cdata := svc.cdata(c, "Edit profile", 0, 0, "")
	data := &renderer.ProfileData{
		CommonData: cdata,
		User:       u,
	}
	return svc.renderer.Render(c.rctx, c.w, renderer.ProfilePage, data)
}

func (s *service) ProfileUpdate(c *client, name, bio string, avatar, banner *multipart.FileHeader,
	fields []mastodon.Field, locked bool) (err error) {
	// Need to pass empty data to clear fields
	if len(fields) == 0 {
		fields = append(fields, mastodon.Field{})
	}
	p := &mastodon.Profile{
		DisplayName: &name,
		Note:        &bio,
		Avatar:      avatar,
		Header:      banner,
		Fields:      &fields,
		Locked:      &locked,
	}
	_, err = c.AccountUpdate(c.ctx, p)
	return err
}

func (s *service) ProfileDelAvatar(c *client) (err error) {
	_, err = c.AccountDeleteAvatar(c.ctx)
	return
}

func (s *service) ProfileDelBanner(c *client) (err error) {
	_, err = c.AccountDeleteHeader(c.ctx)
	return err
}

func (s *service) SingleInstance() (instance string, ok bool) {
	if len(s.instance) > 0 {
		instance = s.instance
		ok = true
	}
	return
}

func (s *service) NewSession(c *client, instance string) (rurl string, sess *model.Session, err error) {
	var instanceURL string
	if strings.HasPrefix(instance, "https://") {
		instanceURL = instance
		instance = strings.TrimPrefix(instance, "https://")
	} else {
		instanceURL = "https://" + instance
	}

	csrf, err := util.NewCSRFToken()
	if err != nil {
		return
	}

	app, err := mastodon.RegisterApp(c.ctx, &mastodon.AppConfig{
		Server:       instanceURL,
		ClientName:   s.cname,
		Scopes:       s.cscope,
		Website:      s.cwebsite,
		RedirectURIs: s.cwebsite + "/oauth_callback",
	})
	if err != nil {
		return
	}
	rurl = app.AuthURI
	sess = &model.Session{
		Instance:     instance,
		ClientID:     app.ClientID,
		ClientSecret: app.ClientSecret,
		CSRFToken:    csrf,
		Settings:     *model.NewSettings(),
	}
	return
}

func (s *service) Signin(c *client, code string) (err error) {
	if len(code) < 1 {
		err = errInvalidArgument
		return
	}
	err = c.AuthenticateToken(c.ctx, code, s.cwebsite+"/oauth_callback")
	if err != nil {
		return
	}
	u, err := c.GetAccountCurrentUser(c.ctx)
	if err != nil {
		return
	}
	c.s.AccessToken = c.GetAccessToken(c.ctx)
	c.s.UserID = u.ID
	return c.setSession(c.s)
}

func (s *service) Signout(c *client) (err error) {
	return c.RevokeToken(c.ctx)
}

func (s *service) Post(c *client, content string, replyToID string,
	format string, visibility string, isNSFW bool,
	files []*multipart.FileHeader) (id string, err error) {

	var mediaIDs []string
	for _, f := range files {
		a, err := c.UploadMediaFromMultipartFileHeader(c.ctx, f)
		if err != nil {
			return "", err
		}
		mediaIDs = append(mediaIDs, a.ID)
	}

	tweet := &mastodon.Toot{
		Status:      content,
		InReplyToID: replyToID,
		MediaIDs:    mediaIDs,
		ContentType: format,
		Visibility:  visibility,
		Sensitive:   isNSFW,
	}
	st, err := c.PostStatus(c.ctx, tweet)
	if err != nil {
		return
	}
	return st.ID, nil
}

func (s *service) Like(c *client, id string) (count int64, err error) {
	st, err := c.Favourite(c.ctx, id)
	if err != nil {
		return
	}
	count = st.FavouritesCount
	return
}

func (s *service) UnLike(c *client, id string) (count int64, err error) {
	st, err := c.Unfavourite(c.ctx, id)
	if err != nil {
		return
	}
	count = st.FavouritesCount
	return
}

func (s *service) Retweet(c *client, id string) (count int64, err error) {
	st, err := c.Reblog(c.ctx, id)
	if err != nil {
		return
	}
	if st.Reblog != nil {
		count = st.Reblog.ReblogsCount
	}
	return
}

func (s *service) UnRetweet(c *client, id string) (
	count int64, err error) {
	st, err := c.Unreblog(c.ctx, id)
	if err != nil {
		return
	}
	count = st.ReblogsCount
	return
}

func (s *service) Vote(c *client, id string, choices []string) (err error) {
	_, err = c.Vote(c.ctx, id, choices)
	return
}

func (s *service) Follow(c *client, id string, reblogs *bool) (err error) {
	_, err = c.AccountFollow(c.ctx, id, reblogs)
	return
}

func (s *service) UnFollow(c *client, id string) (err error) {
	_, err = c.AccountUnfollow(c.ctx, id)
	return
}

func (s *service) Accept(c *client, id string) (err error) {
	return c.FollowRequestAuthorize(c.ctx, id)
}

func (s *service) Reject(c *client, id string) (err error) {
	return c.FollowRequestReject(c.ctx, id)
}

func (s *service) Mute(c *client, id string, notifications bool, duration int) (err error) {
	_, err = c.AccountMute(c.ctx, id, notifications, duration)
	return
}

func (s *service) UnMute(c *client, id string) (err error) {
	_, err = c.AccountUnmute(c.ctx, id)
	return
}

func (s *service) Block(c *client, id string) (err error) {
	_, err = c.AccountBlock(c.ctx, id)
	return
}

func (s *service) UnBlock(c *client, id string) (err error) {
	_, err = c.AccountUnblock(c.ctx, id)
	return
}

func (s *service) Subscribe(c *client, id string) (err error) {
	_, err = c.Subscribe(c.ctx, id)
	return
}

func (s *service) UnSubscribe(c *client, id string) (err error) {
	_, err = c.UnSubscribe(c.ctx, id)
	return
}

func (s *service) SaveSettings(c *client, settings *model.Settings) (err error) {
	switch settings.NotificationInterval {
	case 0, 30, 60, 120, 300, 600:
	default:
		return errInvalidArgument
	}
	if len(settings.CSS) > 0 {
		if len(settings.CSS) > 1<<20 {
			return errInvalidArgument
		}
		// For some reason, browsers convert CRLF to LF before calculating
		// the hash of the inline resources.
		settings.CSS = strings.Replace(settings.CSS, "\x0d\x0a", "\x0a", -1)

		h := sha256.Sum256([]byte(settings.CSS))
		settings.CSSHash = base64.StdEncoding.EncodeToString(h[:])
	} else {
		settings.CSSHash = ""
	}
	c.s.Settings = *settings
	return c.setSession(c.s)
}

func (s *service) MuteConversation(c *client, id string) (err error) {
	_, err = c.MuteConversation(c.ctx, id)
	return
}

func (s *service) UnMuteConversation(c *client, id string) (err error) {
	_, err = c.UnmuteConversation(c.ctx, id)
	return
}

func (s *service) Delete(c *client, id string) (err error) {
	return c.DeleteStatus(c.ctx, id)
}

func (s *service) ReadNotifications(c *client, maxID string) (err error) {
	return c.ReadNotifications(c.ctx, maxID)
}

func (s *service) Bookmark(c *client, id string) (err error) {
	_, err = c.Bookmark(c.ctx, id)
	return
}

func (s *service) UnBookmark(c *client, id string) (err error) {
	_, err = c.Unbookmark(c.ctx, id)
	return
}

func (svc *service) Filter(c *client, phrase string, wholeWord bool) (err error) {
	fctx := []string{"home", "notifications", "public", "thread"}
	return c.AddFilter(c.ctx, phrase, fctx, false, wholeWord, nil)
}

func (svc *service) UnFilter(c *client, id string) (err error) {
	return c.RemoveFilter(c.ctx, id)
}