import { useEffect, useMemo, useState } from "react";
import { Mail, Save } from "lucide-react";
import { FormGrid, ContentGrid,
  ActionBlockerHint,
  Button,
  Card,
  DismissibleAlert,
  DocumentationHelpLink,
  FormField,
  ReferenceMultiSelect,
  ToggleSwitch,
  hasScope,
  i18nMessage,
  isViewSurfaceVisible,
  moduleViewSurfaceId,
  platformModuleReferenceProvider,
  useEffectiveView,
  usePlatformLanguage,
  usePlatformModules,
  useUnsavedDraftGuard,
  useViewSurfaces,
  type ApiSettings,
  type AuthInfo,
  type ReferenceOption
} from "@govoplan/core-webui";
import { getNotificationPreferences, updateNotificationPreferences, type NotificationPreferences } from "../../api/notifications";
import {
  NOTIFICATIONS_BLOCKER_LABELS,
  NOTIFICATIONS_DELIVERY_DOCUMENTATION,
  NOTIFICATIONS_DOCUMENTATION,
  NOTIFICATIONS_I18N
} from "./interfacePatterns";

type Draft = Pick<NotificationPreferences, "show_unread_badge" | "email_enabled" | "email_digest_enabled"> & {
  muted_source_modules: string[];
};

const DEFAULT_DRAFT: Draft = {
  show_unread_badge: true,
  email_enabled: false,
  email_digest_enabled: false,
  muted_source_modules: []
};

export default function NotificationSettingsPanel({ settings, auth }: { settings: ApiSettings; auth: AuthInfo }) {
  const modules = usePlatformModules();
  const effectiveView = useEffectiveView();
  const viewSurfaces = useViewSurfaces();
  const { translateText } = usePlatformLanguage();
  const [loaded, setLoaded] = useState<NotificationPreferences | null>(null);
  const [draft, setDraft] = useState<Draft>(DEFAULT_DRAFT);
  const [loading, setLoading] = useState(true);
  const [saving, setSaving] = useState(false);
  const [message, setMessage] = useState("");
  const [messageTone, setMessageTone] = useState<"success" | "warning">("success");
  const canWrite = hasScope(auth, "notifications:notification:write");
  const mailAvailable = modules.some((module) => module.id === "mail");

  const dirty = useMemo(() => {
    if (!loaded) return false;
    return (
      draft.show_unread_badge !== loaded.show_unread_badge ||
      draft.email_enabled !== loaded.email_enabled ||
      draft.email_digest_enabled !== loaded.email_digest_enabled ||
      draft.muted_source_modules.join(",") !== loaded.muted_source_modules.join(",")
    );
  }, [draft, loaded]);
  const moduleOptions = useMemo<ReferenceOption[]>(
    () => modules.map((module) => {
      const visible = isViewSurfaceVisible(
        effectiveView,
        moduleViewSurfaceId(module.id),
        viewSurfaces
      );
      return {
        value: module.id,
        label: translateText(module.label),
        description: [
          module.id,
          i18nMessage("i18n:govoplan-notifications.version_value", { value0: module.version }),
          visible ? null : translateText("i18n:govoplan-notifications.hidden_by_view")
        ].filter(Boolean).join(" · "),
        kind: "module",
        availability: visible ? "available" : "unavailable",
        disabled: !visible,
        sourceModule: "core",
        provenance: {
          version: module.version,
          visibleInActiveView: visible
        }
      };
    }),
    [effectiveView, modules, translateText, viewSurfaces]
  );
  const moduleProvider = useMemo(
    () => platformModuleReferenceProvider(settings, moduleOptions),
    [moduleOptions, settings]
  );

  function resetDraft() {
    if (!loaded) return;
    setDraft({
      show_unread_badge: loaded.show_unread_badge,
      email_enabled: loaded.email_enabled,
      email_digest_enabled: loaded.email_digest_enabled,
      muted_source_modules: loaded.muted_source_modules
    });
  }

  useUnsavedDraftGuard({
    dirty,
    onSave: savePreferences,
    onDiscard: resetDraft
  });

  useEffect(() => {
    void loadPreferences();
  }, [auth.user.id, settings.accessToken, settings.apiBaseUrl, settings.apiKey]);

  async function loadPreferences() {
    setLoading(true);
    setMessage("");
    try {
      const preferences = await getNotificationPreferences(settings);
      setLoaded(preferences);
      setDraft({
        show_unread_badge: preferences.show_unread_badge,
        email_enabled: preferences.email_enabled,
        email_digest_enabled: preferences.email_digest_enabled,
        muted_source_modules: preferences.muted_source_modules
      });
    } catch (error) {
      setMessageTone("warning");
      setMessage(error instanceof Error ? error.message : translateText("i18n:govoplan-notifications.preferences_load_failed"));
    } finally {
      setLoading(false);
    }
  }

  async function savePreferences(): Promise<boolean> {
    if (!canWrite) return false;
    setSaving(true);
    setMessage("");
    try {
      const next = await updateNotificationPreferences(settings, {
        show_unread_badge: draft.show_unread_badge,
        email_enabled: draft.email_enabled,
        email_digest_enabled: draft.email_digest_enabled,
        muted_source_modules: draft.muted_source_modules
      });
      setLoaded(next);
      setDraft({
        show_unread_badge: next.show_unread_badge,
        email_enabled: next.email_enabled,
        email_digest_enabled: next.email_digest_enabled,
        muted_source_modules: next.muted_source_modules
      });
      window.dispatchEvent(new CustomEvent("govoplan:notifications-changed"));
      setMessageTone("success");
      setMessage("i18n:govoplan-notifications.preferences_saved");
      return true;
    } catch (error) {
      setMessageTone("warning");
      setMessage(error instanceof Error ? error.message : translateText("i18n:govoplan-notifications.preferences_save_failed"));
      return false;
    } finally {
      setSaving(false);
    }
  }

  const saveDisabledReason = loading
    ? NOTIFICATIONS_I18N.loading
    : saving
      ? NOTIFICATIONS_I18N.saving
      : !canWrite
        ? NOTIFICATIONS_I18N.writePermissionRequired
        : !dirty
          ? NOTIFICATIONS_I18N.noChanges
          : undefined;
  const preferenceControlsDisabled = loading || saving || !canWrite;
  const emailToggleDisabled = preferenceControlsDisabled || (!mailAvailable && !draft.email_enabled);
  const digestToggleDisabled = preferenceControlsDisabled || !mailAvailable || !draft.email_enabled;

  return (
    <ContentGrid columns={2} collapseAt="workspace" className="notifications-settings-panel">
      {!canWrite ? (
        <ActionBlockerHint
          tone="info"
          reason={{
            summary: "i18n:govoplan-notifications.preferences_read_only_summary",
            details: NOTIFICATIONS_I18N.writePermissionRequired,
            requiredAction: "i18n:govoplan-notifications.permission_action",
            actor: "i18n:govoplan-notifications.permission_actor",
            target: "i18n:govoplan-notifications.permission_target"
          }}
          labels={NOTIFICATIONS_BLOCKER_LABELS}
          documentation={NOTIFICATIONS_DOCUMENTATION}
        />
      ) : null}
      <Card title="i18n:govoplan-notifications.notifications" titleHelp={<DocumentationHelpLink reference={NOTIFICATIONS_DOCUMENTATION} />}>
        <FormGrid columns={1} collapseAt="standard" className="">
          <ToggleSwitch
            label="i18n:govoplan-notifications.unread_badge"
            help="i18n:govoplan-notifications.unread_badge_help"
            checked={draft.show_unread_badge}
            disabled={preferenceControlsDisabled}
            onChange={(value) => setDraft((current) => ({ ...current, show_unread_badge: value }))}
          />
          <FormField label="i18n:govoplan-notifications.muted_sources" help="i18n:govoplan-notifications.muted_sources_help">
            <ReferenceMultiSelect
              values={draft.muted_source_modules}
              onChange={(muted_source_modules) =>
                setDraft((current) => ({ ...current, muted_source_modules }))
              }
              provider={moduleProvider}
              aria-label="i18n:govoplan-notifications.muted_sources"
              placeholder="i18n:govoplan-notifications.add_source_module"
              emptyText="i18n:govoplan-notifications.no_visible_modules"
              disabled={preferenceControlsDisabled}
            />
          </FormField>
          <div className="button-row compact-actions">
            <Button variant="primary" onClick={() => void savePreferences()} disabled={Boolean(saveDisabledReason)} disabledReason={saveDisabledReason}>
              <Save size={16} /> {saving ? "i18n:govoplan-notifications.saving" : "i18n:govoplan-notifications.save_preferences"}
            </Button>
          </div>
          {message ? <DismissibleAlert tone={messageTone} resetKey={message} floating>{message}</DismissibleAlert> : null}
        </FormGrid>
      </Card>
      <Card title="i18n:govoplan-notifications.delivery" titleHelp={<DocumentationHelpLink reference={NOTIFICATIONS_DELIVERY_DOCUMENTATION} />}>
        <FormGrid columns={1} collapseAt="standard" className="">

          <div className="notifications-settings-inline-title">
            <Mail size={16} />
            <strong>i18n:govoplan-notifications.email_notifications</strong>
          </div>
          {!mailAvailable ? (
            <ActionBlockerHint
              tone="info"
              reason={{
                summary: "i18n:govoplan-notifications.mail_unavailable_summary",
                details: NOTIFICATIONS_I18N.mailUnavailable,
                requiredAction: "i18n:govoplan-notifications.mail_unavailable_action",
                actor: "i18n:govoplan-notifications.mail_unavailable_actor",
                target: "i18n:govoplan-notifications.mail_unavailable_target"
              }}
              labels={NOTIFICATIONS_BLOCKER_LABELS}
              documentation={NOTIFICATIONS_DELIVERY_DOCUMENTATION}
            />
          ) : null}
          <ToggleSwitch
            label="i18n:govoplan-notifications.email_notifications"
            help="i18n:govoplan-notifications.email_notifications_help"
            checked={draft.email_enabled}
            disabled={emailToggleDisabled}
            onChange={(value) => setDraft((current) => ({ ...current, email_enabled: value, email_digest_enabled: value ? current.email_digest_enabled : false }))}
          />
          <ToggleSwitch
            label="i18n:govoplan-notifications.email_digest"
            help="i18n:govoplan-notifications.email_digest_help"
            checked={draft.email_digest_enabled}
            disabled={digestToggleDisabled}
            onChange={(value) => setDraft((current) => ({ ...current, email_digest_enabled: value }))}
          />
        </FormGrid>
      </Card>
    </ContentGrid>
  );
}