import { useEffect, useMemo, useRef, useState } from "react";
import { Activity, Check, ChevronRight, Database, Home, Mail, MailOpen, Paperclip, RefreshCw, Search, UserPlus, X } from "lucide-react";
import { useLocation } from "react-router";
import { ActionToolbar,
  ActionBlockerHint,
  Button,
  CountBadge,
  DataGridPaginationBar,
  DocumentationHelpLink,
  Dialog,
  DismissibleAlert,
  ExplorerTree,
  FormField,
  FormSection,
  IconButton,
  LoadingIndicator,
  MessageDisplayPanel,
  WorkspaceActionBar,
  WorkspaceFrame,
  hasAnyScope,
  formatDateTime,
  i18nMessage,
  useGuardedNavigate,
  type ApiSettings,
  type AuthInfo
} from "@govoplan/core-webui";
import {
  bootstrapMailbox,
  createMailAddressContact,
  getMailboxMessage,
  listMailAddressWriteTargets,
  listMailboxMessages,
  listMailboxFolders,
  listMailServerProfiles,
  type MailAddressWriteTarget,
  type MailImapFolderResponse,
  type MailMailboxMessageDetail,
  type MailMailboxMessageSummary,
  type MailMailboxProtocol,
  type MailServerProfile } from
"../../api/mail";
import { buildMailboxFolderTree, findFolderNodeId, folderAncestorIds, type MailFolderNode } from "./mailboxFolders";
import { isMailboxMessageRead, mailboxSyncState, type MailboxSyncProvenance } from "./mailboxDisplay";
import { mailboxLaunchFolder, parseMailboxLaunch, type MailboxLaunch } from "./mailboxLaunch";
import { mailboxHeaderAddresses } from "./mailAddressIntegration";

const MAILBOX_DOCUMENTATION = {
  topicId: "mail.workflow.read-mailbox",
  documentationType: "user"
} as const;

// Each context read revalidates the current principal and explicit Reload must
// not reuse Core's short-lived GET response/in-flight promise cache. Mail's
// bounded provider index remains available unless the refresh flag is set.
const MAILBOX_READ_OPTIONS = { cache: "no-store" } as const;

export default function MailboxPage({ settings, auth }: { settings: ApiSettings; auth: AuthInfo }) {
  const navigate = useGuardedNavigate();
  const location = useLocation();
  const [profiles, setProfiles] = useState<MailServerProfile[]>([]);
  const [selectedProfileId, setSelectedProfileId] = useState("");
  const [folders, setFolders] = useState<MailImapFolderResponse[]>([]);
  const [selectedFolder, setSelectedFolder] = useState("INBOX");
  const [selectedFolderGroup, setSelectedFolderGroup] = useState<Pick<MailFolderNode, "id" | "label"> | null>(null);
  const [foldersLoadedForProfile, setFoldersLoadedForProfile] = useState("");
  const [expandedFolders, setExpandedFolders] = useState<Set<string>>(() => new Set());
  const [messages, setMessages] = useState<MailMailboxMessageSummary[]>([]);
  const [messageTotalCount, setMessageTotalCount] = useState<number | null>(null);
  const [messageProvenance, setMessageProvenance] = useState<MailboxSyncProvenance | null>(null);
  const [messagePage, setMessagePage] = useState(1);
  const [messagePageSize, setMessagePageSize] = useState(10);
  const [messageQuery, setMessageQuery] = useState("");
  const [selectedMessage, setSelectedMessage] = useState<MailMailboxMessageDetail | null>(null);
  const [selectedMessageKeyState, setSelectedMessageKeyState] = useState("");
  const [pendingMessageKey, setPendingMessageKey] = useState("");
  const [loadingProfiles, setLoadingProfiles] = useState(true);
  const [loadingFolders, setLoadingFolders] = useState(false);
  const [loadingMessages, setLoadingMessages] = useState(false);
  const [loadingMessage, setLoadingMessage] = useState(false);
  const [error, setError] = useState("");
  const [folderError, setFolderError] = useState("");
  const [messageError, setMessageError] = useState("");
  const [detailError, setDetailError] = useState("");
  const [mailToolsOpen, setMailToolsOpen] = useState(false);
  const [reloadingMailbox, setReloadingMailbox] = useState(false);
  const profileRequestRef = useRef(0);
  const mailboxReloadRequestRef = useRef(0);
  const selectedProfileIdRef = useRef(selectedProfileId);
  selectedProfileIdRef.current = selectedProfileId;
  const authorityKey = JSON.stringify([settings.apiBaseUrl, settings.apiKey, settings.accessToken, auth.user.id, auth.active_tenant?.id ?? auth.tenant.id]);
  const authorityRef = useRef(authorityKey);
  authorityRef.current = authorityKey;
  const revealedFolderRef = useRef("");
  const selectedMessageKeyRef = useRef("");
  const folderRequestRef = useRef(0);
  const messageListRequestRef = useRef(0);
  const messageDetailRequestRef = useRef(0);
  const loadedMessagePageRef = useRef<{ profileId: string; folder: string; page: number; pageSize: number } | null>(null);
  const mailboxPageCursorsRef = useRef<Record<string, string | null>>({});
  const skipNextMessageLoadRef = useRef(false);
  const launchRequestRef = useRef<MailboxLaunch | null>(parseMailboxLaunch(location.search));

  const selectedProfile = profiles.find((profile) => profile.id === selectedProfileId) ?? null;
  const mailboxProfiles = useMemo(() => profiles.filter((profile) => profile.is_active && mailboxProtocolForProfile(profile)), [profiles]);
  const selectedMailboxProtocol = mailboxProtocolForProfile(selectedProfile) ?? "imap";
  const folderTree = useMemo(() => buildMailboxFolderTree(folders), [folders]);
  const selectedFolderNodeId = useMemo(() => selectedFolderGroup?.id ?? findFolderNodeId(folderTree, selectedFolder) ?? "", [folderTree, selectedFolder, selectedFolderGroup]);
  const filteredMessages = useMemo(() => filterMessages(messages, messageQuery), [messageQuery, messages]);
  const messagePageCount = Math.max(1, Math.ceil((messageTotalCount ?? 0) / messagePageSize));
  const shellBusy = loadingProfiles || loadingFolders || loadingMessages || reloadingMailbox;
  const noMailboxProfiles = !loadingProfiles && mailboxProfiles.length === 0;
  const foldersReady = Boolean(selectedProfileId) && foldersLoadedForProfile === selectedProfileId;
  const selectedMessageKey = pendingMessageKey || selectedMessageKeyState || (selectedMessage ? mailboxMessageKey(selectedMessage.folder || selectedFolder, selectedMessage.uid) : "");
  const messageCountLabel = messageListCountLabel(messages.length, messageTotalCount, loadingMessages, foldersReady);
  const syncState = mailboxSyncState(messageProvenance);
  const folderEmptyText = folderError || (noMailboxProfiles ? "No IMAP- or JMAP-enabled Mail profiles are available." : loadingFolders ? "i18n:govoplan-mail.loading_folders.17f9f0e2" : "i18n:govoplan-mail.no_folders_available.14133b26");
  const messageEmptyText = messageError || (selectedFolderGroup ? "i18n:govoplan-mail.folder_group_selection" : !selectedProfileId ? "i18n:govoplan-mail.select_an_imap_profile.5445648c" : !foldersReady || loadingMessages ? "i18n:govoplan-mail.loading_messages.77b62232" : messages.length > 0 && filteredMessages.length === 0 ? "i18n:govoplan-mail.no_messages_match_the_current_filter_on_this_pag.9dda6916" : "i18n:govoplan-mail.no_messages_in_this_folder.5c7fa25d");
  const previewEmptyText = detailError || (loadingMessage ? "i18n:govoplan-mail.loading_message.815c2094" : "i18n:govoplan-mail.select_a_message_to_inspect_its_content.5f3d1342");
  const loadingLabel = loadingProfiles ? "i18n:govoplan-mail.loading_mail_profiles.87de3560" : loadingFolders ? "i18n:govoplan-mail.loading_folders.17f9f0e2" : loadingMessages ? "i18n:govoplan-mail.loading_messages.77b62232" : "i18n:govoplan-mail.loading_message.815c2094";
  const profileReloadBlocker = shellBusy ? "i18n:govoplan-mail.mailbox_refresh_in_progress" : "";
  const folderReloadBlocker = !selectedProfileId
    ? "Select an IMAP- or JMAP-enabled Mail profile before refreshing folders."
    : shellBusy
      ? "Wait for the current mailbox refresh to finish."
      : "";
  const messageReloadBlocker = !selectedProfileId
    ? "Select an IMAP- or JMAP-enabled Mail profile before refreshing messages."
    : !selectedFolder || !foldersReady
      ? "Select a loaded mailbox folder before refreshing messages."
      : shellBusy
        ? "Messages are already loading."
        : "";

  useEffect(() => {
    selectProfile("");
    setProfiles([]);
    setMailToolsOpen(false);
    void loadProfiles();
    return () => {
      profileRequestRef.current += 1;
      folderRequestRef.current += 1;
      messageListRequestRef.current += 1;
      messageDetailRequestRef.current += 1;
      mailboxReloadRequestRef.current += 1;
    };
  }, [authorityKey]);
  useEffect(() => {
    const request = parseMailboxLaunch(location.search);
    launchRequestRef.current = request;
    if (!profiles.length || (!request.profileId && !request.folder && !request.folderRole && !request.messageUid)) return;
    const usable = profiles.filter((profile) => profile.is_active && mailboxProtocolForProfile(profile));
    const targetProfileId = request.profileId && usable.some((profile) => profile.id === request.profileId)
      ? request.profileId
      : selectedProfileId || usable[0]?.id || "";
    if (!targetProfileId) return;
    if (targetProfileId !== selectedProfileId) {
      selectProfile(targetProfileId);
      return;
    }
    void loadMailboxBootstrap(targetProfileId);
  }, [location.search]);
  useEffect(() => {selectedMessageKeyRef.current = selectedMessageKeyState;}, [selectedMessageKeyState]);
  useEffect(() => {if (messagePage > messagePageCount) setMessagePage(messagePageCount);}, [messagePage, messagePageCount]);
  useEffect(() => {if (selectedProfileId) void loadMailboxBootstrap(selectedProfileId);}, [selectedProfileId]);
  useEffect(() => {
    if (!selectedProfileId || !selectedFolder || !foldersReady) return;
    if (skipNextMessageLoadRef.current) {
      skipNextMessageLoadRef.current = false;
      return;
    }
    void loadMessages(selectedProfileId, selectedFolder, messagePage, messagePageSize);
  }, [foldersReady, messagePage, messagePageSize, selectedProfileId, selectedFolder]);
  useEffect(() => {
    if (selectedMailboxProtocol !== "jmap" || !selectedProfileId || !selectedFolder || !foldersReady) return;
    const requestAuthority = authorityKey;
    const profileId = selectedProfileId;
    const listRequest = messageListRequestRef.current;
    const handle = window.setTimeout(() => {
      if (requestAuthority !== authorityRef.current || profileId !== selectedProfileIdRef.current || listRequest !== messageListRequestRef.current) return;
      setMessagePage(1);
      mailboxPageCursorsRef.current = {};
      void loadMessages(selectedProfileId, selectedFolder, 1, messagePageSize);
    }, 250);
    return () => window.clearTimeout(handle);
  }, [messageQuery, selectedFolderGroup]);

  useEffect(() => {
    const request = launchRequestRef.current;
    if (!request || !foldersReady || loadingMessages) return;
    const targetProfileMatches = !request.profileId || request.profileId === selectedProfileId;
    const targetFolder = mailboxLaunchFolder(request, selectedProfile);
    if (!targetProfileMatches || (targetFolder && targetFolder !== selectedFolder)) return;
    const target = request.messageUid
      ? messages.find((message) => message.uid === request.messageUid)
      : null;
    launchRequestRef.current = null;
    if (target) void openMessage(target);
  }, [foldersReady, loadingMessages, messages, selectedFolder, selectedProfile, selectedProfileId]);

  useEffect(() => {
    const handlePreviewShortcut = (event: KeyboardEvent) => {
      if (mailToolsOpen || isEditableTarget(event.target)) return;
      if (event.key === "Escape") {
        if (selectedMessage || selectedMessageKey || pendingMessageKey || detailError) {
          event.preventDefault();
          messageDetailRequestRef.current += 1;
          setLoadingMessage(false);
          setSelectedMessage(null);
          setSelectedMessageKeyState("");
          selectedMessageKeyRef.current = "";
          setPendingMessageKey("");
          setDetailError("");
        }
        return;
      }
      if (shellBusy || loadingMessage || filteredMessages.length === 0) return;
      const selectedIndex = filteredMessages.findIndex((message) => mailboxMessageKey(message.folder || selectedFolder, message.uid) === selectedMessageKey);
      let nextIndex: number | null = null;
      if (event.key === "ArrowLeft") nextIndex = selectedIndex > 0 ? selectedIndex - 1 : 0;else
      if (event.key === "ArrowRight") nextIndex = selectedIndex >= 0 ? Math.min(filteredMessages.length - 1, selectedIndex + 1) : 0;else
      if (event.key === "Home") nextIndex = 0;else
      if (event.key === "End") nextIndex = filteredMessages.length - 1;
      if (nextIndex === null) return;
      event.preventDefault();
      const nextMessage = filteredMessages[nextIndex];
      if (nextMessage) void openMessage(nextMessage);
    };

    window.addEventListener("keydown", handlePreviewShortcut);
    return () => window.removeEventListener("keydown", handlePreviewShortcut);
  }, [detailError, filteredMessages, loadingMessage, mailToolsOpen, pendingMessageKey, selectedFolder, selectedMessage, selectedMessageKey, shellBusy]);

  useEffect(() => {
    const revealKey = `${selectedProfileId}:${selectedFolder}`;
    if (revealedFolderRef.current === revealKey) return;
    const ancestorIds = folderAncestorIds(folderTree, selectedFolder);
    if (ancestorIds.length === 0) return;
    revealedFolderRef.current = revealKey;
    setExpandedFolders((current) => {
      const next = new Set(current);
      ancestorIds.forEach((id) => next.add(id));
      return next;
    });
  }, [folderTree, selectedFolder, selectedProfileId]);

  async function loadProfiles() {
    const requestId = ++profileRequestRef.current;
    const requestAuthority = authorityRef.current;
    setLoadingProfiles(true);
    setError("");
    try {
      const loaded = await listMailServerProfiles(settings, false, undefined, MAILBOX_READ_OPTIONS);
      if (requestId !== profileRequestRef.current || requestAuthority !== authorityRef.current) return null;
      const usable = loaded.filter((profile) => profile.is_active && mailboxProtocolForProfile(profile));
      const requestedProfileId = parseMailboxLaunch(location.search).profileId;
      setProfiles(loaded);
      const currentId = selectedProfileIdRef.current;
      const next = usable.find((profile) => profile.id === currentId)
        ?? usable.find((profile) => profile.id === requestedProfileId)
        ?? usable[0] ?? null;
      const changed = (next?.id ?? "") !== currentId;
      if (changed) selectProfile(next?.id ?? "");
      return { selected: next, changed };
    } catch (err) {
      if (requestId !== profileRequestRef.current || requestAuthority !== authorityRef.current) return null;
      setError(errorText(err));
      return null;
    } finally {
      if (requestId === profileRequestRef.current && requestAuthority === authorityRef.current) setLoadingProfiles(false);
    }
  }

  async function reloadMailbox() {
    const requestId = ++mailboxReloadRequestRef.current;
    setReloadingMailbox(true);
    try {
      const result = await loadProfiles();
      if (!result || requestId !== mailboxReloadRequestRef.current || result.changed || !result.selected) return;
      if (selectedFolderGroup) await refreshFolderCatalogue(result.selected);
      else await loadMailboxBootstrap(result.selected.id, true, result.selected);
    } finally {
      if (requestId === mailboxReloadRequestRef.current) setReloadingMailbox(false);
    }
  }

  async function refreshFolderCatalogue(profile = selectedProfile) {
    if (!profile) return;
    const requestId = ++folderRequestRef.current;
    const requestAuthority = authorityRef.current;
    setLoadingFolders(true);
    setFolderError("");
    setError("");
    try {
      const response = await listMailboxFolders(settings, profile.id, true, true, mailboxProtocolForProfile(profile) ?? "imap", MAILBOX_READ_OPTIONS);
      if (requestId !== folderRequestRef.current || requestAuthority !== authorityRef.current || profile.id !== selectedProfileIdRef.current) return;
      if (!response.ok) throw new Error(response.message || "i18n:govoplan-mail.mailbox_folders_could_not_be_loaded.c3e3880e");
      setFolders(response.folders ?? []);
      setFoldersLoadedForProfile(profile.id);
    } catch (err) {
      if (requestId !== folderRequestRef.current || requestAuthority !== authorityRef.current || profile.id !== selectedProfileIdRef.current) return;
      setFolderError(errorText(err));
      setError(errorText(err));
    } finally {
      if (requestId === folderRequestRef.current && requestAuthority === authorityRef.current) setLoadingFolders(false);
    }
  }

  async function loadMailboxBootstrap(profileId = selectedProfileId, refresh = false, profileOverride?: MailServerProfile) {
    if (!profileId) return;
    const targetProfile = profileOverride ?? profiles.find((profile) => profile.id === profileId) ?? null;
    const mailboxProtocol = mailboxProtocolForProfile(targetProfile) ?? "imap";
    const profileInbox = mailboxProtocol === "imap" ? targetProfile?.imap?.folder_mappings?.inbox || "" : "";
    const requestedLaunch = launchRequestRef.current;
    const requestedLaunchFolder = requestedLaunch && (!requestedLaunch.profileId || requestedLaunch.profileId === profileId)
      ? mailboxLaunchFolder(requestedLaunch, profiles.find((profile) => profile.id === profileId) ?? null)
      : null;
    const requestedFolder = requestedLaunchFolder || (foldersLoadedForProfile === profileId && selectedFolder
      ? selectedFolder
      : profileInbox || "INBOX");
    const folderRequestId = ++folderRequestRef.current;
    const messageRequestId = ++messageListRequestRef.current;
    const requestAuthority = authorityRef.current;
    const isCurrent = () => folderRequestId === folderRequestRef.current
      && messageRequestId === messageListRequestRef.current
      && requestAuthority === authorityRef.current && profileId === selectedProfileIdRef.current;
    const preserve = refresh && foldersLoadedForProfile === profileId;
    // A refreshed JMAP query starts a new cursor chain; IMAP offsets can retain
    // the current page without silently losing the user's mailbox context.
    const requestedPage = preserve && mailboxProtocol !== "jmap" ? messagePage : 1;
    const rememberedMessageKey = preserve ? selectedMessageKeyRef.current : "";
    const detailRequestId = ++messageDetailRequestRef.current;
    setLoadingMessage(false);
    setPendingMessageKey("");
    setLoadingFolders(true);
    setLoadingMessages(true);
    if (!preserve) {
      setFoldersLoadedForProfile("");
      setMessageTotalCount(null);
      setMessageProvenance(null);
      setMessagePage(1);
      setSelectedMessage(null);
      setSelectedMessageKeyState("");
      selectedMessageKeyRef.current = "";
    }
    setFolderError("");
    setMessageError("");
    setDetailError("");
    setError("");
    try {
      const response = await bootstrapMailbox(settings, profileId, requestedFolder, messagePageSize, (requestedPage - 1) * messagePageSize, refresh, mailboxProtocol, MAILBOX_READ_OPTIONS);
      if (!isCurrent()) return;
      if (!response.folders.ok) throw new Error(response.folders.message || "i18n:govoplan-mail.mailbox_folders_could_not_be_loaded.c3e3880e");
      const loadedFolders = response.folders.folders?.length ? response.folders.folders : [{ name: "INBOX", flags: [] }];
      let nextFolder = response.folder || response.messages.folder || selectedFolder || "INBOX";
      if (!loadedFolders.some((folder) => folder.name === nextFolder)) {
        const detectedInbox = response.folders.detected_folder_mappings?.inbox;
        nextFolder = detectedInbox && loadedFolders.some((folder) => folder.name === detectedInbox)
          ? detectedInbox
          : loadedFolders.some((folder) => folder.name === "INBOX") ? "INBOX" : response.folders.detected_sent_folder || loadedFolders[0]?.name || "INBOX";
      }
      let messageResponse = mailboxProtocol === "jmap" && messageQuery.trim()
        ? await listMailboxMessages(settings, profileId, nextFolder, messagePageSize, 0, null, refresh, mailboxProtocol, messageQuery, MAILBOX_READ_OPTIONS)
        : response.messages;
      if (!isCurrent()) return;
      const total = messageResponse.total_count ?? messageResponse.messages?.length ?? 0;
      const nextPage = Math.min(requestedPage, Math.max(1, Math.ceil(total / messagePageSize)));
      if (nextPage !== requestedPage) {
        messageResponse = await listMailboxMessages(settings, profileId, nextFolder, messagePageSize, (nextPage - 1) * messagePageSize, null, refresh, mailboxProtocol, null, MAILBOX_READ_OPTIONS);
        if (!isCurrent()) return;
      }
      const loadedMessages = messageResponse.messages ?? [];
      const foldersWithCounts = loadedFolders.map((folder) => folder.name === nextFolder ? { ...folder, message_count: total } : folder);
      const cursorKey = mailboxCursorKey(profileId, nextFolder, messagePageSize, mailboxProtocol === "jmap" ? messageQuery : "");
      mailboxPageCursorsRef.current = {
        [`${cursorKey}:${nextPage}`]: null,
        [`${cursorKey}:${nextPage + 1}`]: messageResponse.next_cursor ?? null
      };
      skipNextMessageLoadRef.current = foldersLoadedForProfile !== profileId || nextFolder !== selectedFolder || messagePage !== nextPage;
      loadedMessagePageRef.current = { profileId, folder: nextFolder, page: nextPage, pageSize: messagePageSize };
      setFolders(foldersWithCounts);
      if (!preserve) setExpandedFolders(new Set());
      setSelectedFolderGroup(null);
      setSelectedFolder(nextFolder);
      setMessagePage(nextPage);
      setFoldersLoadedForProfile(profileId);
      setMessages(loadedMessages);
      setMessageTotalCount(total);
      setMessageProvenance(mailboxProvenance(messageResponse));
      const retainedMessage = loadedMessages.find((message) => mailboxMessageKey(message.folder || nextFolder, message.uid) === rememberedMessageKey);
      // Explicit preview navigation or Escape during a refresh wins over the
      // remembered selection; completing a read must not undo the user's action.
      if (detailRequestId === messageDetailRequestRef.current && selectedMessageKeyRef.current === rememberedMessageKey) {
        if (retainedMessage) await openMessage(retainedMessage, profileId, mailboxProtocol, true);
        else if (rememberedMessageKey) {
          setSelectedMessage(null);
          setSelectedMessageKeyState("");
          selectedMessageKeyRef.current = "";
        }
      }
    } catch (err) {
      if (!isCurrent()) return;
      const message = errorText(err);
      skipNextMessageLoadRef.current = false;
      setFolderError(message);
      setMessageError(message);
      setError(message);
      if (!preserve) {
        loadedMessagePageRef.current = null;
        setFolders([]);
        setFoldersLoadedForProfile("");
        setMessages([]);
        setMessageTotalCount(null);
        setMessageProvenance(null);
        setSelectedMessage(null);
        setSelectedMessageKeyState("");
        selectedMessageKeyRef.current = "";
        setPendingMessageKey("");
      }
    } finally {
      if (folderRequestId === folderRequestRef.current && requestAuthority === authorityRef.current) setLoadingFolders(false);
      if (messageRequestId === messageListRequestRef.current && requestAuthority === authorityRef.current) setLoadingMessages(false);
    }
  }

  async function loadMessages(profileId = selectedProfileId, folder = selectedFolder, page = messagePage, pageSize = messagePageSize, refresh = false) {
    if (!profileId || !folder) return;
    const mailboxProtocol = mailboxProtocolForProfile(profiles.find((profile) => profile.id === profileId) ?? null) ?? "imap";
    const requestId = ++messageListRequestRef.current;
    const requestAuthority = authorityRef.current;
    const isCurrent = () => requestId === messageListRequestRef.current && requestAuthority === authorityRef.current && profileId === selectedProfileIdRef.current;
    const offset = (Math.max(1, page) - 1) * pageSize;
    const cursorKey = mailboxCursorKey(profileId, folder, pageSize, mailboxProtocol === "jmap" ? messageQuery : "");
    const cursor = page <= 1 ? null : mailboxPageCursorsRef.current[`${cursorKey}:${page}`] || null;
    setLoadingMessages(true);
    if (!refresh) setMessageProvenance(null);
    setMessageError("");
    setDetailError("");
    setError("");
    try {
      const response = await listMailboxMessages(
        settings,
        profileId,
        folder,
        pageSize,
        offset,
        cursor,
        refresh,
        mailboxProtocol,
        mailboxProtocol === "jmap" ? messageQuery : null,
        MAILBOX_READ_OPTIONS
      );
      if (!isCurrent()) return;
      const loaded = response.messages ?? [];
      const total = response.total_count ?? loaded.length;
      loadedMessagePageRef.current = { profileId, folder, page, pageSize };
      if (page <= 1) mailboxPageCursorsRef.current[`${cursorKey}:1`] = null;
      mailboxPageCursorsRef.current[`${cursorKey}:${page + 1}`] = response.next_cursor ?? null;
      setMessages(loaded);
      setMessageTotalCount(total);
      setMessageProvenance(mailboxProvenance(response));
      setFolderMessageCount(folder, total);
      const rememberedKey = selectedMessageKeyRef.current;
      if (rememberedKey && !loaded.some((message) => mailboxMessageKey(message.folder || folder, message.uid) === rememberedKey)) {
        messageDetailRequestRef.current += 1;
        setLoadingMessage(false);
        setSelectedMessage(null);
        setSelectedMessageKeyState("");
        setPendingMessageKey("");
        selectedMessageKeyRef.current = "";
      }
    } catch (err) {
      if (!isCurrent()) return;
      const message = errorText(err);
      setMessageError(message);
      setError(message);
      const committed = loadedMessagePageRef.current;
      if (committed?.profileId === profileId && committed.folder === folder && (committed.page !== page || committed.pageSize !== pageSize)) {
        // Retained rows must keep their actual page/size labels after a failed
        // pagination read; restoring controls is not a second provider request.
        skipNextMessageLoadRef.current = true;
        setMessagePage(committed.page);
        setMessagePageSize(committed.pageSize);
      }
      // A failed read is not an empty mailbox. Keep the last loaded index and
      // selection visible until a successful refresh or an explicit switch.
    } finally {
      if (isCurrent()) setLoadingMessages(false);
    }
  }

  async function openMessage(message: MailMailboxMessageSummary, profileId = selectedProfileId, protocol = selectedMailboxProtocol, preservePreview = false) {
    if (!profileId) return;
    const folderName = message.folder || selectedFolder;
    const requestId = ++messageDetailRequestRef.current;
    const requestAuthority = authorityRef.current;
    const isCurrent = () => requestId === messageDetailRequestRef.current && requestAuthority === authorityRef.current && profileId === selectedProfileIdRef.current;
    const nextKey = mailboxMessageKey(folderName, message.uid);
    setSelectedMessageKeyState(nextKey);
    selectedMessageKeyRef.current = nextKey;
    setPendingMessageKey(nextKey);
    if (!preservePreview) setSelectedMessage(null);
    setDetailError("");
    setLoadingMessage(true);
    setError("");
    try {
      const response = await getMailboxMessage(settings, profileId, folderName, message.uid, protocol, MAILBOX_READ_OPTIONS);
      if (!isCurrent()) return;
      setSelectedMessage(response.message);
      setSelectedMessageKeyState(mailboxMessageKey(response.message.folder || folderName, response.message.uid));
      setPendingMessageKey("");
    } catch (err) {
      if (!isCurrent()) return;
      const messageText = errorText(err);
      setDetailError(messageText);
      setError(messageText);
      setPendingMessageKey("");
    } finally {
      if (isCurrent()) setLoadingMessage(false);
    }
  }

  function selectProfile(profileId: string) {
    loadedMessagePageRef.current = null;
    mailboxReloadRequestRef.current += 1;
    folderRequestRef.current += 1;
    messageListRequestRef.current += 1;
    messageDetailRequestRef.current += 1;
    setSelectedProfileId(profileId);
    selectedProfileIdRef.current = profileId;
    setReloadingMailbox(false);
    setSelectedFolderGroup(null);
    setFolders([]);
    setFoldersLoadedForProfile("");
    setMessages([]);
    setMessageTotalCount(null);
    setMessageProvenance(null);
    setMessagePage(1);
    setSelectedFolder("INBOX");
    setMessageQuery("");
    setError("");
    setFolderError("");
    setMessageError("");
    setDetailError("");
    revealedFolderRef.current = "";
    setSelectedMessage(null);
    setSelectedMessageKeyState("");
    selectedMessageKeyRef.current = "";
    setPendingMessageKey("");
    setExpandedFolders(new Set());
    setLoadingFolders(false);
    setLoadingMessages(false);
    setLoadingMessage(false);
    mailboxPageCursorsRef.current = {};
    skipNextMessageLoadRef.current = false;
  }

  function openFolderNode(node: MailFolderNode) {
    if (node.folderName) {
      setSelectedFolderGroup(null);
      if (node.folderName === selectedFolder && foldersReady) void loadMessages(selectedProfileId, node.folderName, messagePage, messagePageSize);else
      {
        loadedMessagePageRef.current = null;
        messageListRequestRef.current += 1;
        messageDetailRequestRef.current += 1;
        setLoadingMessage(false);
        setMessages([]);
        setMessageTotalCount(null);
        setMessageProvenance(null);
        setSelectedFolder(node.folderName);
        setMessagePage(1);
        setSelectedMessage(null);
        setSelectedMessageKeyState("");
        selectedMessageKeyRef.current = "";
        setPendingMessageKey("");
        setDetailError("");
      }
      return;
    }
    // Synthetic parent folders have no provider mailbox to open. Selecting
    // their label must not toggle expansion or fetch an invented folder name.
    loadedMessagePageRef.current = null;
    messageListRequestRef.current += 1;
    messageDetailRequestRef.current += 1;
    setSelectedFolderGroup({ id: node.id, label: node.label });
    setSelectedFolder("");
    setMessages([]);
    setMessageTotalCount(0);
    setMessageProvenance(null);
    setMessagePage(1);
    setSelectedMessage(null);
    setSelectedMessageKeyState("");
    selectedMessageKeyRef.current = "";
    setPendingMessageKey("");
    setLoadingMessage(false);
    setLoadingMessages(false);
    setMessageError("");
    setDetailError("");
    skipNextMessageLoadRef.current = false;
  }

  function toggleFolderNode(node: MailFolderNode) {
    setExpandedFolders((current) => {
      const next = new Set(current);
      if (next.has(node.id)) next.delete(node.id);else
      next.add(node.id);
      return next;
    });
  }

  function setFolderMessageCount(folderName: string, count: number) {
    setFolders((current) => current.map((folder) => folder.name === folderName ? { ...folder, message_count: count } : folder));
  }

  function changeMessagePage(page: number) {
    const nextPage = Math.min(messagePageCount, Math.max(1, page));
    if (nextPage !== messagePage) setMessagePage(nextPage);
  }

  function changeMessagePageSize(pageSize: number) {
    setMessagePageSize(pageSize);
    setMessagePage(1);
  }

  return (
    <WorkspaceFrame as="main" height="viewport" surface="plain" label="i18n:govoplan-mail.mailbox_workspace" className="mailbox-page" helpContextId="mail.mailbox" helpModuleId="mail" helpTopicId="mail.workflow.read-mailbox">
      {error && <DismissibleAlert tone="danger" resetKey={error} floating>{error}</DismissibleAlert>}

      <WorkspaceActionBar
        title="i18n:govoplan-mail.mailbox_workspace"
        titleHelp={<DocumentationHelpLink reference={MAILBOX_DOCUMENTATION} />}
        variant="workspace"
        scope="workspace"
        label="i18n:govoplan-mail.mail_actions.c08b5f08"
        refreshable
        reloadAction={{
          onReload: () => void reloadMailbox(),
          loading: shellBusy,
          state: error ? "reload-failed" : "current",
          helpContextId: "mail.mailbox.reload",
          helpModuleId: "mail",
          helpTopicId: "mail.workflow.read-mailbox"
        }}
        contextActions={<>
          <FormField label="i18n:govoplan-mail.mailbox_profile" className="mailbox-profile-field">
            <select value={selectedProfileId} disabled={loadingProfiles || mailboxProfiles.length === 0} onChange={(event) => selectProfile(event.target.value)}>
              {mailboxProfiles.length === 0 && <option value="">i18n:govoplan-mail.no_mailbox_profiles</option>}
              {mailboxProfiles.map((profile) => <option key={profile.id} value={profile.id}>{profile.name}</option>)}
            </select>
          </FormField>
          <Button type="button" onClick={() => setMailToolsOpen(true)} helpContextId="mail.mailbox.tools" helpModuleId="mail" helpTopicId="mail.workflow.read-mailbox">i18n:govoplan-mail.mailbox_tools</Button>
        </>}
      />

      <div className={`file-manager-shell mailbox-shell ${shellBusy ? "is-loading" : ""}`}>
        <aside className="file-tree-panel" aria-label="i18n:govoplan-mail.mailbox_folders.c92f6de4">
          <div className="file-tree-heading">i18n:govoplan-mail.folders.19adc47b</div>
          <div className="file-tree-list">
            {folderTree.length === 0 && <p className="muted small-text mailbox-tree-empty">{folderEmptyText}</p>}
            <ExplorerTree
              nodes={folderTree}
              getNodeId={(node) => node.id}
              getNodeLabel={(node) => node.label}
              getNodeChildren={(node) => node.children}
              activeId={selectedFolderNodeId}
              expandedIds={expandedFolders}
              onOpen={openFolderNode}
              onToggle={toggleFolderNode}
              disabled={shellBusy}
              renderNodeContent={(node) => {
                const flagText = folderFlagLabel(node.flags);
                const showCount = foldersReady && node.messageCount !== null;
                return (
                  <span className="mailbox-tree-node-label">
                    <span className="mailbox-tree-node-main">
                      <span>{node.label}</span>
                      {showCount && <CountBadge tone="neutral" size="compact" className="mailbox-folder-count">{node.messageCount}</CountBadge>}
                    </span>
                    {flagText && <small>{flagText}</small>}
                  </span>);

              }} />

          </div>
        </aside>

        <section className="file-list-panel mailbox-message-list-panel" aria-label="i18n:govoplan-mail.mailbox_messages.5c06afaf">
          <div className="file-list-sticky">
            {noMailboxProfiles &&
            <ActionBlockerHint
              className="mailbox-profile-blocker"
              reason={{
                summary: "No mailbox-enabled Mail profile is available.",
                details: "The mailbox workspace is read-only and needs an active profile with an authorized IMAP or JMAP server and credential.",
                requiredAction: "Ask a Mail administrator to configure and authorize an IMAP- or JMAP-enabled profile.",
                actor: "Mail profile administrator",
                target: "Settings or Administration > Mail profiles"
              }}
              documentation={MAILBOX_DOCUMENTATION} />
            }

            <nav className="file-breadcrumbs" aria-label="i18n:govoplan-mail.current_mailbox_folder.55e2aea5">
              <span className="file-breadcrumb mailbox-breadcrumb-static"><Home size={15} aria-hidden="true" /> {selectedProfile?.name || "i18n:govoplan-mail.mail.92379cbb"}</span>
              <span className="file-breadcrumb-segment"><ChevronRight size={14} aria-hidden="true" /><span className="file-breadcrumb mailbox-breadcrumb-static">{selectedFolderGroup?.label ?? selectedFolder}</span></span>
            </nav>

            <div className="mailbox-filter-row">
              <label className="mailbox-search-field">
                <Search size={15} aria-hidden="true" />
                <input value={messageQuery} onChange={(event) => setMessageQuery(event.target.value)} placeholder="i18n:govoplan-mail.search_messages.abea65ae" />
                {messageQuery && <IconButton label="i18n:govoplan-mail.clear_message_search.cc9f2800" icon={<X />} variant="ghost" onClick={() => setMessageQuery("")} />}
              </label>
            </div>

            <div className="file-list-meta">
              <span>{messageCountLabel}</span>
              <span>{selectedFolder}</span>
              {messageQuery && <span>{filteredMessages.length} match{filteredMessages.length === 1 ? "" : "es"} i18n:govoplan-mail.on_page.ca7166f4</span>}
              {syncState &&
              <span className={`mailbox-sync-provenance is-${syncState}`} aria-live="polite">
                  <Database size={13} aria-hidden="true" />
                  {syncState === "refreshing" ? "i18n:govoplan-mail.cached_index_refreshing.75f18a6c" : syncState === "cached" ? "i18n:govoplan-mail.cached_mailbox_index.16fe75d1" : "i18n:govoplan-mail.live_provider_response.39c46538"}
                  {messageProvenance?.indexedAt && <span> · {formatDateTime(messageProvenance.indexedAt, { fallback: "-" })}</span>}
                </span>
              }
              {shellBusy && <span>i18n:govoplan-mail.working.049ac820</span>}
              {loadingMessage && <span>{i18nMessage("i18n:govoplan-mail.loading_preview.ebd86225")}</span>}
            </div>

            <div className="file-list-table-head mailbox-message-head" role="row">
              <span>i18n:govoplan-mail.subject.8d183dbd</span>
              <span>i18n:govoplan-mail.date.eb9a4bc1</span>
              <span>i18n:govoplan-mail.size.b7152342</span>
            </div>
          </div>

          <div className="file-list-drop-target mailbox-message-scroll">
            <div className="file-list-table mailbox-message-table" role="table" aria-label="i18n:govoplan-mail.mailbox_messages.5c06afaf">
              {filteredMessages.length === 0 && <div className={`file-list-empty${messageError ? " mailbox-error-state" : ""}`}>{messageEmptyText}</div>}
              {filteredMessages.map((message) => {
                const key = mailboxMessageKey(message.folder || selectedFolder, message.uid);
                const selected = key === selectedMessageKey;
                const loadingSelected = loadingMessage && key === pendingMessageKey;
                const read = isMailboxMessageRead(message.flags);
                return (
                  <div
                    key={message.uid}
                    className={`file-list-row file-row mailbox-message-row ${read ? "is-read" : "is-unread"} ${selected ? "is-selected" : ""} ${loadingSelected ? "is-loading-message" : ""}`}
                    role="row"
                    tabIndex={0}
                    onClick={() => void openMessage(message)}
                    onKeyDown={(event) => {
                      if (event.key === "Enter" || event.key === " ") {
                        event.preventDefault();
                        void openMessage(message);
                      }
                    }}>

                    <div className="file-list-name-cell">
                      <div className="file-list-name">
                        {read ? <MailOpen className="file-row-icon" size={20} aria-hidden="true" /> : <Mail className="file-row-icon" size={20} aria-hidden="true" />}
                        <span>
                          <strong>{message.subject || "i18n:govoplan-mail.no_subject.49b20da0"}</strong>
                          <small>{message.from_header || "-"}</small>
                        </span>
                      </div>
                    </div>
                    <span className="mailbox-message-date">{formatDateTime(message.date, { fallback: "-" })}</span>
                    <span className="file-row-tail mailbox-message-tail">
                      <span className="mailbox-read-state" title={read ? "i18n:govoplan-mail.read.80ca1564" : "i18n:govoplan-mail.unread.66c78634"}>
                        <span className="visually-hidden">{read ? "i18n:govoplan-mail.read.80ca1564" : "i18n:govoplan-mail.unread.66c78634"}</span>
                        <span aria-hidden="true">{read ? "i18n:govoplan-mail.read.80ca1564" : "i18n:govoplan-mail.unread.66c78634"}</span>
                      </span>
                      {message.attachment_count ? <span><Paperclip size={14} aria-hidden="true" /> {message.attachment_count}</span> : null}
                      <span>{formatBytes(message.size_bytes)}</span>
                    </span>
                  </div>);

              })}
            </div>
          </div>
          <DataGridPaginationBar
            page={messagePage}
            pageSize={messagePageSize}
            totalRows={messageTotalCount ?? 0}
            className="mailbox-pagination"
            ariaLabel="i18n:govoplan-mail.mailbox_message_pagination.965407bf"
            disabled={loadingMessages || !foldersReady}
            onPageChange={changeMessagePage}
            onPageSizeChange={changeMessagePageSize} />

        </section>

        <section className="mailbox-preview-panel" aria-label="i18n:govoplan-mail.message_preview.58de1450">
          <div className="file-tree-heading">i18n:govoplan-mail.preview.f1fbb2b4</div>
          <div className="mailbox-preview-scroll">
            <MessageDisplayPanel
              title={selectedMessage?.subject}
              fields={selectedMessage ? [
              { label: "i18n:govoplan-mail.from.3f66052a", value: selectedMessage.from_header || "-" },
              { label: "i18n:govoplan-mail.to.ae79ea1e", value: selectedMessage.to_header || "-" },
              { label: "i18n:govoplan-mail.cc.1fd6a880", value: selectedMessage.cc_header || null },
              { label: "i18n:govoplan-mail.bcc.8431acad", value: selectedMessage.bcc_header || null },
              { label: "i18n:govoplan-mail.date.eb9a4bc1", value: formatDateTime(selectedMessage.date, { fallback: "-" }) }] :
              []}
              bodyText={selectedMessage?.body_text}
              bodyHtml={selectedMessage?.body_html}
              bodyPreview={selectedMessage?.body_preview}
              headers={selectedMessage?.headers}
              attachments={selectedMessage?.attachments?.map((attachment) => ({
                filename: attachment.filename,
                contentType: attachment.content_type,
                sizeBytes: attachment.size_bytes
              }))}
              emptyText={previewEmptyText} />

            <MailboxContactActions settings={settings} message={selectedMessage} />

          </div>
        </section>

        {shellBusy &&
        <div className="file-manager-loading-overlay" aria-live="polite" aria-busy="true">
            <div className="loading-frame-panel"><LoadingIndicator label={loadingLabel} /> <span>{i18nMessage(loadingLabel)}</span></div>
          </div>
        }
      </div>
      <Dialog open={mailToolsOpen} title="i18n:govoplan-mail.mailbox_tools" description={selectedProfile ? `${selectedProfile.name} · ${transportLabel(selectedProfile)}` : "i18n:govoplan-mail.no_mailbox_profiles"} onClose={() => setMailToolsOpen(false)}
        footer={<Button type="button" onClick={() => setMailToolsOpen(false)}>i18n:govoplan-core.close.bbfa773e</Button>}>
        <FormSection title="i18n:govoplan-mail.mailbox_refresh_tools" description="i18n:govoplan-mail.mailbox_refresh_tools_help">
          <ActionToolbar surface="plain">
            <Button type="button" onClick={() => { setMailToolsOpen(false); void loadProfiles(); }} disabledReason={profileReloadBlocker}><RefreshCw size={16} aria-hidden="true" /> i18n:govoplan-mail.refresh_mailbox_profiles</Button>
            <Button type="button" onClick={() => { setMailToolsOpen(false); void refreshFolderCatalogue(); }} disabledReason={folderReloadBlocker}><RefreshCw size={16} aria-hidden="true" /> i18n:govoplan-mail.refresh_mailbox_folder_catalogue</Button>
            <Button type="button" onClick={() => { setMailToolsOpen(false); void loadMessages(selectedProfileId, selectedFolder, messagePage, messagePageSize, true); }} disabledReason={messageReloadBlocker}><RefreshCw size={16} aria-hidden="true" /> i18n:govoplan-mail.refresh_mailbox_message_index</Button>
          </ActionToolbar>
        </FormSection>
        <FormSection variant="separated" title="i18n:govoplan-mail.mailbox_related_tools">
          <ActionToolbar surface="plain"><Button type="button" onClick={() => { setMailToolsOpen(false); navigate("/mail/bounces"); }} disabledReason={!hasAnyScope(auth, ["mail:bounce:read", "mail:bounce:manage"]) ? "i18n:govoplan-mail.mailbox_bounce_permission" : ""}><Activity size={16} aria-hidden="true" /> i18n:govoplan-mail.mailbox_bounce_status</Button></ActionToolbar>
        </FormSection>
      </Dialog>
    </WorkspaceFrame>);

}

function MailboxContactActions({
  settings,
  message
}: {
  settings: ApiSettings;
  message: MailMailboxMessageDetail | null;
}) {
  const [available, setAvailable] = useState(false);
  const [loaded, setLoaded] = useState(false);
  const [targets, setTargets] = useState<MailAddressWriteTarget[]>([]);
  const [selectedTargetId, setSelectedTargetId] = useState("");
  const [creatingEmail, setCreatingEmail] = useState("");
  const [addedEmails, setAddedEmails] = useState<Set<string>>(() => new Set());
  const [error, setError] = useState("");
  const [success, setSuccess] = useState("");

  useEffect(() => {
    let active = true;
    setLoaded(false);
    void listMailAddressWriteTargets(settings)
      .then((response) => {
        if (!active) return;
        const writable = response.targets.filter((target) => target.allowed);
        setAvailable(response.available);
        setTargets(response.targets);
        setSelectedTargetId((current) => writable.some((target) => target.address_book_id === current)
          ? current
          : writable[0]?.address_book_id || "");
        setError("");
      })
      .catch((loadError) => {
        if (!active) return;
        setAvailable(false);
        setTargets([]);
        setError(loadError instanceof Error ? loadError.message : String(loadError));
      })
      .finally(() => {
        if (active) setLoaded(true);
      });
    return () => { active = false; };
  }, [settings.apiBaseUrl, settings.apiKey, settings.accessToken]);

  useEffect(() => {
    setAddedEmails(new Set());
    setError("");
    setSuccess("");
  }, [message?.folder, message?.uid]);

  if (!message || !loaded || !available) return null;

  const writableTargets = targets.filter((target) => target.allowed);
  const blockedTargets = targets.filter((target) => !target.allowed);
  const addresses = uniqueMailboxAddresses([
    ...mailboxHeaderAddresses(message.from_header),
    ...mailboxHeaderAddresses(message.to_header),
    ...mailboxHeaderAddresses(message.cc_header)
  ]);

  async function addContact(address: { name?: string | null; email: string }) {
    if (!selectedTargetId || creatingEmail) return;
    setCreatingEmail(address.email);
    setError("");
    setSuccess("");
    try {
      const result = await createMailAddressContact(settings, {
        address_book_id: selectedTargetId,
        display_name: address.name || address.email,
        email: address.email
      });
      setAddedEmails((current) => new Set(current).add(address.email));
      setSuccess(i18nMessage("i18n:govoplan-mail.contact_added", { value0: result.display_name }));
    } catch (createError) {
      setError(createError instanceof Error ? createError.message : String(createError));
    } finally {
      setCreatingEmail("");
    }
  }

  return (
    <section className="mailbox-contact-actions" aria-label="i18n:govoplan-mail.address_book_actions">
      <h4>i18n:govoplan-mail.address_book_actions</h4>
      {error ? <DismissibleAlert tone="warning" resetKey={error}>{error}</DismissibleAlert> : null}
      {success ? <DismissibleAlert tone="success" resetKey={success}>{success}</DismissibleAlert> : null}
      {writableTargets.length > 0 ? (
        <label className="mailbox-contact-target">
          <span>i18n:govoplan-mail.save_contacts_to</span>
          <select value={selectedTargetId} onChange={(event) => setSelectedTargetId(event.target.value)}>
            {writableTargets.map((target) => (
              <option key={target.address_book_id} value={target.address_book_id}>
                {target.address_book_label || target.address_book_id}
              </option>
            ))}
          </select>
        </label>
      ) : (
        <p className="form-help">i18n:govoplan-mail.no_writable_address_book</p>
      )}
      <div className="mailbox-contact-candidates">
        {addresses.map((address) => {
          const added = addedEmails.has(address.email);
          return (
            <Button
              key={address.email}
              className="compact"
              disabled={!selectedTargetId || Boolean(creatingEmail) || added}
              disabledReason={!selectedTargetId ? blockedTargets[0]?.message || "i18n:govoplan-mail.no_writable_address_book" : undefined}
              onClick={() => void addContact(address)}
            >
              {added ? <Check size={15} aria-hidden="true" /> : <UserPlus size={15} aria-hidden="true" />}
              {added ? "i18n:govoplan-mail.contact_added_short" : i18nMessage("i18n:govoplan-mail.add_value_to_contacts", { value0: address.name || address.email })}
            </Button>
          );
        })}
      </div>
      {blockedTargets.length > 0 ? (
        <details className="mailbox-contact-policy">
          <summary>i18n:govoplan-mail.unavailable_address_books</summary>
          <ul>
            {blockedTargets.map((target) => (
              <li key={target.address_book_id}>
                <strong>{target.address_book_label || target.address_book_id}</strong>: {target.message}
              </li>
            ))}
          </ul>
        </details>
      ) : null}
    </section>
  );
}

function uniqueMailboxAddresses<T extends { email: string }>(addresses: T[]): T[] {
  const seen = new Set<string>();
  return addresses.filter((address) => {
    const email = address.email.toLocaleLowerCase();
    if (seen.has(email)) return false;
    seen.add(email);
    return true;
  });
}


function mailboxMessageKey(folder: string, uid: string): string {
  return `${folder || "INBOX"}::${uid}`;
}

function mailboxCursorKey(profileId: string, folder: string, pageSize: number, query: string): string {
  return `${profileId}::${folder || "INBOX"}::${pageSize}::${query.trim()}`;
}

function mailboxProvenance(response: { from_cache?: boolean; refreshing?: boolean; indexed_at?: string | null }): MailboxSyncProvenance {
  return {
    fromCache: response.from_cache === true,
    refreshing: response.refreshing === true,
    indexedAt: response.indexed_at ?? null
  };
}

function filterMessages(messages: MailMailboxMessageSummary[], query: string): MailMailboxMessageSummary[] {
  const normalized = query.trim().toLocaleLowerCase();
  if (!normalized) return messages;
  return messages.filter((message) => [
  message.subject,
  message.from_header,
  message.to_header,
  message.cc_header,
  message.date,
  message.body_preview].
  some((value) => String(value ?? "").toLocaleLowerCase().includes(normalized)));
}

function messageListCountLabel(visibleCount: number, totalCount: number | null, loading: boolean, ready: boolean): string {
  if (!ready) return "i18n:govoplan-mail.no_folder_loaded.889bdb1b";
  if (loading) return "i18n:govoplan-mail.loading_messages.4294022c";
  if (totalCount !== null && totalCount > visibleCount) return i18nMessage("i18n:govoplan-mail.value_of_value_messages.981a1618", { value0: visibleCount, value1: totalCount });
  const count = totalCount ?? visibleCount;
  return i18nMessage(count === 1 ? "i18n:govoplan-mail.value_message" : "i18n:govoplan-mail.value_messages", { value0: count });
}

function folderFlagLabel(flags: string[]): string {
  const labels = flags.map(displayFolderFlag).filter((label): label is string => Boolean(label));
  return Array.from(new Set(labels)).join(" ");
}

function displayFolderFlag(flag: string): string | null {
  const normalized = flag.replace(/^\\/, "").toLowerCase();
  switch (normalized) {
    case "sent":
      return "i18n:govoplan-mail.sent.35f49dcf";
    case "drafts":
      return "i18n:govoplan-mail.drafts.22a31d86";
    case "trash":
      return "i18n:govoplan-mail.trash.e3bf62bb";
    case "archive":
      return "i18n:govoplan-mail.archive.2621c6fd";
    case "junk":
      return "i18n:govoplan-mail.junk.86c7d94c";
    case "flagged":
      return "i18n:govoplan-mail.flagged.f8db8a17";
    case "haschildren":
    case "hasnochildren":
    case "noselect":
      return null;
    default:
      return null;
  }
}

function transportLabel(profile: MailServerProfile): string {
  const jmap = preferredJmapServer(profile);
  if (jmap) {
    const sessionUrl = "session_url" in jmap.config ? jmap.config.session_url : null;
    return `JMAP · ${String(sessionUrl || "configured endpoint")}`;
  }
  const imap = profile.imap;
  if (!imap?.host) return "i18n:govoplan-mail.imap_not_configured.b2892af3";
  return `${imap.host}:${imap.port ?? "?"} ${imap.security ?? ""}`.trim();
}

function preferredJmapServer(profile: MailServerProfile | null): NonNullable<MailServerProfile["servers"]>[number] | null {
  if (!profile) return null;
  const servers = (profile.servers ?? []).filter((server) => server.protocol === "jmap" && server.is_active);
  return servers.find((server) => server.is_default) ?? servers[0] ?? null;
}

function mailboxProtocolForProfile(profile: MailServerProfile | null): MailMailboxProtocol | null {
  if (!profile) return null;
  if (preferredJmapServer(profile)) return "jmap";
  if (profile.imap || (profile.servers ?? []).some((server) => server.protocol === "imap" && server.is_active)) return "imap";
  return null;
}

function formatBytes(value?: number | null): string {
  if (!value) return "-";
  if (value < 1024) return i18nMessage("i18n:govoplan-mail.bytes_b", { value0: value });
  if (value < 1024 * 1024) return i18nMessage("i18n:govoplan-mail.bytes_kb", { value0: (value / 1024).toFixed(1) });
  return i18nMessage("i18n:govoplan-mail.bytes_mb", { value0: (value / 1024 / 1024).toFixed(1) });
}

function errorText(error: unknown): string {
  return error instanceof Error ? error.message : String(error);
}

function isEditableTarget(target: EventTarget | null): boolean {
  if (!(target instanceof HTMLElement)) return false;
  return target.isContentEditable || ["INPUT", "SELECT", "TEXTAREA"].includes(target.tagName);
}