import { DescriptionItem, DescriptionList } from "@govoplan/core-webui";
import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import { Search } from "lucide-react";
import {
  AdminPageLayout,
  adminErrorMessage,
  Button,
  DataGrid,
  Dialog,
  DocumentationHelpLink,
  formatAdminDateTime as formatDateTime,
  hasScope,
  i18nMessage,
  mergeDeltaRows,
  TableActionGroup,
  useDeltaWatermarks,
  type ApiSettings,
  type AuthInfo,
  type DataGridColumn,
  type DataGridQueryState
} from "@govoplan/core-webui";
import {
  downloadAuditEvidenceBundle,
  exportAuditEvidenceBundle,
  fetchAdminAudit,
  fetchAdminAuditDelta,
  type AuditAdminItem,
  type AuditSortBy
} from "../../api/audit";

type Props = {
  settings: ApiSettings;
  auth: AuthInfo;
  systemMode?: boolean;
};
type AuditDetailRow = {
  id: string;
  field: string;
  value: string;
};

const I18N = {
  actionLabel: "i18n:govoplan-audit.action.f1a20801",
  actions: "i18n:govoplan-audit.actions.f1a20802",
  actor: "i18n:govoplan-audit.actor.f1a20803",
  close: "i18n:govoplan-audit.close.f1a20804",
  details: "i18n:govoplan-audit.details.f1a20805",
  eventDetails: "i18n:govoplan-audit.audit_event_details.f1a20806",
  exportEvidence: "i18n:govoplan-audit.export_page_evidence.f1a20822",
  exportingEvidence: "i18n:govoplan-audit.audit_evidence_export_is_in_progress.f1a20823",
  inspect: "i18n:govoplan-audit.inspect_audit_event.f1a20807",
  loading: "i18n:govoplan-audit.audit_evidence_is_loading.f1a20808",
  noDetails: "i18n:govoplan-audit.no_additional_details_were_recorded.f1a20809",
  noRecords: "i18n:govoplan-audit.no_audit_records_match_the_current_scope_and_filters.f1a20810",
  object: "i18n:govoplan-audit.object.f1a20811",
  reload: "i18n:govoplan-audit.reload_audit_evidence.f1a20812",
  scopeLabel: "i18n:govoplan-audit.scope.f1a20813",
  system: "i18n:govoplan-audit.system.f1a20814",
  systemAudit: "i18n:govoplan-audit.system_audit.f1a20815",
  systemDescription: "i18n:govoplan-audit.system_level_administrative_history_showing_value0_value1_of_value2.f1a20816",
  tenantAudit: "i18n:govoplan-audit.tenant_audit.f1a20817",
  tenantContext: "i18n:govoplan-audit.tenant_context.f1a20818",
  tenantDescription: "i18n:govoplan-audit.tenant_level_administrative_history_showing_value0_value1_of_value2.f1a20819",
  time: "i18n:govoplan-audit.time.f1a20820",
  value: "i18n:govoplan-audit.value.f1a20821"
} as const;

const DEFAULT_QUERY: DataGridQueryState = {
  sort: { columnId: "time", direction: "desc" },
  filters: {}
};

export default function AdminAuditPanel({ settings, auth, systemMode = false }: Props) {
  const [items, setItems] = useState<AuditAdminItem[]>([]);
  const itemsRef = useRef<AuditAdminItem[]>([]);
  const pageItemsRef = useRef<Record<string, AuditAdminItem[]>>({});
  const pageCursorsRef = useRef<Record<number, string | null>>({ 1: null });
  const { getDeltaWatermark, setDeltaWatermark, resetDeltaWatermark } = useDeltaWatermarks();
  const [total, setTotal] = useState(0);
  const [page, setPage] = useState(1);
  const [pageSize, setPageSize] = useState(10);
  const [query, setQuery] = useState<DataGridQueryState>(DEFAULT_QUERY);
  const [selected, setSelected] = useState<AuditAdminItem | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState("");
  const [reloadToken, setReloadToken] = useState(0);
  const [exporting, setExporting] = useState(false);
  const tenantId = (auth.active_tenant ?? auth.tenant).id;
  const canExport = hasScope(
    auth,
    systemMode ? "audit:system_evidence:export" : "audit:evidence:export"
  );

  const load = useCallback(async () => {
    setLoading(true);
    setError("");
    try {
      const sortColumn = query.sort?.columnId;
      const sortBy = sortColumn && ["time", "actor", "action", "object", "tenant"].includes(sortColumn)
        ? sortColumn as AuditSortBy
        : "time";
      const sortDirection = query.sort?.direction ?? "desc";
      const filters = query.filters;
      const pageCursor = page === 1 ? null : pageCursorsRef.current[page];
      const deltaMode = page === 1 || pageCursor !== undefined;
      const requestOptions = {
        scope: systemMode ? "system" as const : "tenant" as const,
        page,
        pageSize,
        cursor: pageCursor,
        sortBy,
        sortDirection,
        filters
      };
      const deltaKey = `audit:${systemMode ? "system" : "tenant"}:${tenantId}:${pageSize}:${page}:${pageCursor ?? "root"}:${JSON.stringify({ sortBy, sortDirection, filters })}`;
      const response = deltaMode
        ? await fetchAdminAuditDelta(settings, { ...requestOptions, since: getDeltaWatermark(deltaKey) })
        : await fetchAdminAudit(settings, requestOptions);
      const baseItems = pageItemsRef.current[deltaKey] ?? [];
      const nextItems = "full" in response && !response.full
        ? mergeDeltaRows(baseItems, response.items, response.deleted, (item) => item.id, { sort: compareAuditEvents(sortBy, sortDirection) }).slice(0, pageSize)
        : response.items;
      pageItemsRef.current[deltaKey] = nextItems;
      itemsRef.current = nextItems;
      setItems(nextItems);
      setTotal(response.total);
      if (!deltaMode && response.page !== page) setPage(response.page);
      if (response.cursor !== undefined) pageCursorsRef.current[page] = response.cursor ?? null;
      if (response.next_cursor !== undefined) {
        if (response.next_cursor) pageCursorsRef.current[page + 1] = response.next_cursor;
        else delete pageCursorsRef.current[page + 1];
      }
      if ("full" in response && !response.full && page === 1 && (response.items.length > 0 || response.deleted.length > 0)) {
        pageCursorsRef.current = { 1: null };
      }
      if ("watermark" in response) setDeltaWatermark(deltaKey, response.watermark);
      if (!deltaMode) resetDeltaWatermark(deltaKey);
    } catch (err) {
      setError(adminErrorMessage(err));
    } finally {
      setLoading(false);
    }
  }, [settings.accessToken, settings.apiBaseUrl, settings.apiKey, systemMode, tenantId, page, pageSize, query, reloadToken, getDeltaWatermark, setDeltaWatermark, resetDeltaWatermark]);

  useEffect(() => {
    itemsRef.current = [];
    pageItemsRef.current = {};
    pageCursorsRef.current = { 1: null };
    resetDeltaWatermark();
  }, [settings.accessToken, settings.apiBaseUrl, settings.apiKey, systemMode, tenantId, pageSize, query, resetDeltaWatermark]);

  useEffect(() => { void load(); }, [load]);

  const handleQueryChange = useCallback((next: DataGridQueryState) => {
    setQuery((current) => {
      if (JSON.stringify(current) === JSON.stringify(next)) return current;
      setPage(1);
      return next;
    });
  }, []);

  const exportPageEvidence = useCallback(async () => {
    setExporting(true);
    setError("");
    try {
      const created = await exportAuditEvidenceBundle(settings, {
        scope: systemMode ? "system" : "tenant",
        tenant_id: systemMode ? null : tenantId,
        record_ids: items.map((item) => item.id),
        max_records: Math.max(1, items.length),
        sign: false
      });
      const downloaded = await downloadAuditEvidenceBundle(settings, created.id);
      downloadJson(
        downloaded.bundle,
        `govoplan-audit-evidence-${created.id}.json`
      );
    } catch (err) {
      setError(adminErrorMessage(err));
    } finally {
      setExporting(false);
    }
  }, [items, settings, systemMode, tenantId]);

  const columns = useMemo<DataGridColumn<AuditAdminItem>[]>(() => [
    { id: "time", header: I18N.time, width: 190, minWidth: 150, maxWidth: 260, resizable: true, sticky: "start", sortable: true, filterable: true, filterType: "date", value: (row) => row.created_at, render: (row) => formatDateTime(row.created_at) },
    { id: "actor", header: I18N.actor, width: 220, minWidth: 170, maxWidth: 360, resizable: true, sortable: true, filterable: true, value: (row) => row.actor_email || "System", render: (row) => row.actor_email || I18N.system },
    { id: "action", header: I18N.actionLabel, width: 250, minWidth: 170, maxWidth: 420, resizable: true, sortable: true, filterable: true, value: (row) => row.action },
    { id: "object", header: I18N.object, width: 300, minWidth: 180, maxWidth: 640, resizable: true, fill: true, sortable: true, filterable: true, value: (row) => `${row.object_type || "-"} ${row.object_id || ""}`.trim() },
    ...(systemMode ? [{ id: "tenant", header: I18N.tenantContext, width: 190, minWidth: 150, maxWidth: 300, resizable: true, sortable: true, filterable: true, value: (row: AuditAdminItem) => row.tenant_id || "-" }] : []),
    { id: "actions", header: I18N.actions, width: 70, sticky: "end", resizable: false, align: "right", render: (row) => <TableActionGroup actions={[{ id: "inspect", label: I18N.inspect, icon: <Search aria-hidden="true" size={16} />, onClick: () => setSelected(row) }]} /> }
  ], [systemMode]);

  const detailColumns = useMemo<DataGridColumn<AuditDetailRow>[]>(() => [
    { id: "field", header: I18N.details, minWidth: 180, resizable: true, value: (row) => row.field },
    { id: "value", header: I18N.value, minWidth: 260, resizable: true, fill: true, value: (row) => row.value }
  ], []);
  const detailRows = useMemo(() => auditDetailRows(selected?.details ?? {}), [selected]);

  const firstShown = total === 0 ? 0 : (page - 1) * pageSize + 1;
  const lastShown = Math.min(total, page * pageSize);
  const pageDescription = i18nMessage(
    systemMode ? I18N.systemDescription : I18N.tenantDescription,
    { value0: firstShown, value1: lastShown, value2: total }
  );

  return (
    <>
      <AdminPageLayout
        title={systemMode ? I18N.systemAudit : I18N.tenantAudit}
        description={pageDescription}
        loading={loading}
        error={error}
        actions={(
          <>
            {canExport && (
              <Button
                onClick={() => { void exportPageEvidence(); }}
                disabled={loading || exporting || items.length === 0}
                disabledReason={exporting ? I18N.exportingEvidence : undefined}>
                {I18N.exportEvidence}
              </Button>
            )}
            <DocumentationHelpLink
              reference={{
                topicId: "audit.read-authorized-evidence",
                documentationType: "user"
              }} />
            <Button
              onClick={() => setReloadToken((value) => value + 1)}
              disabled={loading}
              disabledReason={loading ? I18N.loading : undefined}>
              {I18N.reload}
            </Button>
          </>
        )}>
        <div className="admin-table-surface">
          <DataGrid
            id={systemMode ? "admin-system-audit-v6" : "admin-tenant-audit-v6"}
            rows={items}
            columns={columns}
            initialFit="container"
            getRowKey={(row) => row.id}
            emptyText={I18N.noRecords}
            className="admin-audit-grid"
            initialSort={{ columnId: "time", direction: "desc" }}
            pagination={{
              mode: "server",
              page,
              pageSize,
              totalRows: total,
              pageSizeOptions: [10, 25, 50, 100, 250],
              disabled: loading,
              onPageChange: setPage,
              onPageSizeChange: (next) => { setPageSize(next); setPage(1); }
            }}
            onQueryChange={handleQueryChange}
          />
        </div>
      </AdminPageLayout>
      <Dialog variant="administration" size="wide"
        open={Boolean(selected)}
        title={I18N.eventDetails}
        onClose={() => setSelected(null)}
        className=""
        footer={<Button onClick={() => setSelected(null)}>{I18N.close}</Button>}>
        {selected && (
          <>
            <DescriptionList>
              <DescriptionItem term={<>{I18N.scopeLabel}</>}>{selected.scope}</DescriptionItem>
              <DescriptionItem term={<>{I18N.actionLabel}</>}>{selected.action}</DescriptionItem>
              <DescriptionItem term={<>{I18N.actor}</>}>{selected.actor_email || I18N.system}</DescriptionItem>
              <DescriptionItem term={<>{I18N.object}</>}>{selected.object_type || "-"} {selected.object_id || ""}</DescriptionItem>
              <DescriptionItem term={<>{I18N.tenantContext}</>}>{selected.tenant_id || "-"}</DescriptionItem>
              <DescriptionItem term={<>{I18N.time}</>}>{formatDateTime(selected.created_at)}</DescriptionItem>
            </DescriptionList>
            {detailRows.length ? (
              <DataGrid
                id="admin-audit-event-details-grid"
                rows={detailRows}
                columns={detailColumns}
                getRowKey={(row) => row.id}
                initialFit="container" />
            ) : <p className="muted">{I18N.noDetails}</p>}
          </>
        )}
      </Dialog>
    </>
  );
}

function downloadJson(value: unknown, filename: string): void {
  const blob = new Blob([`${JSON.stringify(value, null, 2)}\n`], { type: "application/json" });
  const url = URL.createObjectURL(blob);
  const anchor = document.createElement("a");
  anchor.href = url;
  anchor.download = filename;
  anchor.click();
  URL.revokeObjectURL(url);
}

function auditDetailRows(details: Record<string, unknown>): AuditDetailRow[] {
  return Object.entries(details)
    .sort(([left], [right]) => left.localeCompare(right))
    .map(([field, value]) => ({
      id: field,
      field,
      value: auditDetailValue(value)
    }));
}

function auditDetailValue(value: unknown): string {
  if (value === null || value === undefined) return "-";
  if (typeof value === "string") return value;
  if (typeof value === "number" || typeof value === "boolean") return String(value);
  return JSON.stringify(value);
}

function compareAuditEvents(sortBy: AuditSortBy, sortDirection: "asc" | "desc"): (left: AuditAdminItem, right: AuditAdminItem) => number {
  return (left, right) => {
    const primary = compareAuditValues(auditSortValue(left, sortBy), auditSortValue(right, sortBy));
    const directed = sortDirection === "asc" ? primary : -primary;
    return directed || right.id.localeCompare(left.id);
  };
}

function auditSortValue(item: AuditAdminItem, sortBy: AuditSortBy): string | number {
  if (sortBy === "time") return new Date(item.created_at).getTime();
  if (sortBy === "actor") return item.actor_email || "System";
  if (sortBy === "action") return item.action;
  if (sortBy === "object") return `${item.object_type || ""} ${item.object_id || ""}`;
  return item.tenant_id || "";
}

function compareAuditValues(left: string | number, right: string | number): number {
  if (typeof left === "number" && typeof right === "number") return left - right;
  return String(left).localeCompare(String(right));
}