"use client";

import { useState, useEffect, useMemo, useCallback, useRef } from "react";
import { formatDate } from "~/lib/format.js";
import { trpc } from "~/lib/trpc/client.js";
import { AllocationModal } from "./AllocationModal.js";
import type { AllocationLike, AllocationReadModel, AllocationWithDetails, ColumnDef } from "@capakraken/shared";
import { AllocationStatus, ALLOCATION_COLUMNS } from "@capakraken/shared";
import { useSelection } from "~/hooks/useSelection.js";
import { BatchActionBar } from "~/components/ui/BatchActionBar.js";
import { ConfirmDialog } from "~/components/ui/ConfirmDialog.js";
import { FilterBar } from "~/components/ui/FilterBar.js";
import { FilterChips } from "~/components/ui/FilterChips.js";
import { ResourceCombobox } from "~/components/ui/ResourceCombobox.js";
import { ProjectCombobox } from "~/components/ui/ProjectCombobox.js";
import { ColumnTogglePanel } from "~/components/ui/ColumnTogglePanel.js";
import { SortableColumnHeader } from "~/components/ui/SortableColumnHeader.js";
import { useTableSort } from "~/hooks/useTableSort.js";
import { usePermissions } from "~/hooks/usePermissions.js";
import { useColumnConfig } from "~/hooks/useColumnConfig.js";
import { useViewPrefs } from "~/hooks/useViewPrefs.js";
import { getPlanningEntryMutationId } from "~/lib/planningEntryIds.js";
import { ALLOCATION_STATUS_BADGE as STATUS_BADGE } from "~/lib/status-styles.js";
import { SuccessToast } from "~/components/ui/SuccessToast.js";
import {
  collapseAllAllocationGroups,
  createInitialCollapsedAllocationGroups,
  expandAllAllocationGroups,
  toggleCollapsedAllocationGroup,
  type CollapsedAllocationGroups,
} from "./allocationGroupState.js";
import { getAllocationEmptyState, shouldAutoRelaxAllocationFilters } from "./allocationVisibilityState.js";

/** Left-border color by allocation status for instant visual scanning */
const STATUS_LEFT_BORDER: Record<string, string> = {
  ACTIVE: "border-l-green-500",
  PROPOSED: "border-l-amber-500",
  CONFIRMED: "border-l-blue-500",
  COMPLETED: "border-l-gray-400",
  CANCELLED: "border-l-red-500",
};

/** Fragment wrapper for grouped rows — avoids unnecessary DOM nodes */
function GroupRows({ children }: { children: React.ReactNode }) {
  return <>{children}</>;
}

const ALL_ALLOC_STATUSES = [
  { value: "PROPOSED", label: "Proposed" },
  { value: "CONFIRMED", label: "Confirmed" },
  { value: "ACTIVE", label: "Active" },
  { value: "COMPLETED", label: "Completed" },
  { value: "CANCELLED", label: "Cancelled" },
] as const;

type AllocationAssignmentsView = AllocationReadModel<AllocationLike>;
type DemandRow = AllocationWithDetails & {
  sourceAllocationId?: string;
  requestedHeadcount?: number;
  unfilledHeadcount?: number;
};

type AllocationQueryError = {
  data?: {
    code?: string;
  };
  message?: string;
} | null;

function getAllocationQueryFailure(error: AllocationQueryError) {
  const code = error?.data?.code;

  if (code === "FORBIDDEN") {
    return {
      testId: "allocations-access-error",
      title: "You do not have permission to view allocations.",
      detail: "Your account is missing planning read access for this page.",
      actionLabel: null,
      actionHref: null,
    };
  }

  if (code === "UNAUTHORIZED") {
    return {
      testId: "allocations-session-error",
      title: "Your session expired.",
      detail: "Sign in again to load allocations.",
      actionLabel: "Sign in again",
      actionHref: "/auth/signin",
    };
  }

  return {
    testId: "allocations-query-error",
    title: "Allocations could not be loaded.",
    detail: error?.message ?? "Refresh the page or try again in a moment.",
    actionLabel: null,
    actionHref: null,
  };
}

export function AllocationsClient() {
  const [modalOpen, setModalOpen] = useState(false);
  const [editingAllocation, setEditingAllocation] = useState<AllocationWithDetails | null>(null);
  const [filterProjectId, setFilterProjectId] = useState<string>("");
  const [filterResourceId, setFilterResourceId] = useState<string>("");
  const [filterStatus, setFilterStatus] = useState<string>("");
  const [hidePastProjects, setHidePastProjects] = useState(true);
  const [hideCompletedProjects, setHideCompletedProjects] = useState(true);
  const [hideDraftProjects, setHideDraftProjects] = useState(false);
  const [confirmDelete, setConfirmDelete] = useState<{ single?: AllocationWithDetails; ids?: string[] } | null>(null);
  const [batchStatusPicker, setBatchStatusPicker] = useState(false);
  const [confirmBatchStatus, setConfirmBatchStatus] = useState<{ ids: string[]; status: string } | null>(null);
  const [showStatusToast, setShowStatusToast] = useState(false);

  const selection = useSelection();
  const utils = trpc.useUtils();
  const { canViewCosts } = usePermissions();

  // ─── Column visibility ────────────────────────────────────────────────────
  const baseColumns = useMemo<ColumnDef[]>(
    () => (canViewCosts ? ALLOCATION_COLUMNS : ALLOCATION_COLUMNS.filter((c) => c.key !== "cost")),
    [canViewCosts],
  );
  const { allColumns, visibleColumns, visibleKeys, setVisible } = useColumnConfig("allocations", baseColumns);
  const defaultKeys = useMemo(() => baseColumns.filter((c) => c.defaultVisible).map((c) => c.key), [baseColumns]);

  const allocationQuery = trpc.allocation.listView.useQuery(
    {
      projectId: filterProjectId || undefined,
      resourceId: filterResourceId || undefined,
      status: (filterStatus as AllocationStatus) || undefined,
    },
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    { placeholderData: (prev: any) => prev, staleTime: 15_000 },
  ) as {
    data: AllocationAssignmentsView | undefined;
    isLoading: boolean;
    isError: boolean;
    error: AllocationQueryError;
  };
  const { data: allocationView, isLoading, isError, error } = allocationQuery;
  const allocationQueryFailure = isError ? getAllocationQueryFailure(error) : null;

  const deleteDemandMutation = trpc.allocation.deleteDemandRequirement.useMutation({
    onSuccess: async () => {
      await utils.allocation.list.invalidate();
      await utils.allocation.listView.invalidate();
    },
  });

  const deleteAssignmentMutation = trpc.allocation.deleteAssignment.useMutation({
    onSuccess: async () => {
      await utils.allocation.list.invalidate();
      await utils.allocation.listView.invalidate();
    },
  });

  const batchDeleteMutation = trpc.allocation.batchDelete.useMutation({
    onSuccess: async () => {
      await utils.allocation.list.invalidate();
      await utils.allocation.listView.invalidate();
      selection.clear();
    },
  });

  const batchStatusMutation = trpc.allocation.batchUpdateStatus.useMutation({
    onSuccess: async () => {
      await utils.allocation.list.invalidate();
      await utils.allocation.listView.invalidate();
      selection.clear();
      setShowStatusToast(true);
    },
  });

  useEffect(() => {
    selection.clear();
  // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [filterProjectId, filterResourceId, filterStatus, hidePastProjects, hideCompletedProjects, hideDraftProjects]);

  function openCreate() {
    setEditingAllocation(null);
    setModalOpen(true);
  }

  function openEdit(alloc: AllocationWithDetails) {
    setEditingAllocation(alloc);
    setModalOpen(true);
  }

  function closeModal() {
    setModalOpen(false);
    setEditingAllocation(null);
  }

  const assignmentList = (allocationView?.assignments ?? []) as unknown as AllocationWithDetails[];
  const demandList = (allocationView?.demands ?? []) as unknown as DemandRow[];

  const today = new Date();
  today.setHours(0, 0, 0, 0);

  const filteredAllocations = assignmentList.filter((alloc) => {
    if (hidePastProjects && alloc.project?.endDate && new Date(alloc.project.endDate) < today) return false;
    if (hideCompletedProjects && alloc.project?.status && ["COMPLETED", "CANCELLED"].includes(alloc.project.status)) return false;
    if (hideDraftProjects && alloc.project?.status === "DRAFT") return false;
    return true;
  });

  const filteredDemands = demandList.filter((alloc) => {
    if (filterResourceId) return false;
    if (hidePastProjects && alloc.project?.endDate && new Date(alloc.project.endDate) < today) return false;
    if (hideCompletedProjects && alloc.project?.status && ["COMPLETED", "CANCELLED"].includes(alloc.project.status)) return false;
    if (hideDraftProjects && alloc.project?.status === "DRAFT") return false;
    return true;
  });

  const allocViewPrefs = useViewPrefs("allocations");
  const { sorted, sortField, sortDir, toggle } = useTableSort(filteredAllocations, {
    initialField: allocViewPrefs.savedSort?.field ?? null,
    initialDir: allocViewPrefs.savedSort?.dir ?? null,
    onSortChange: (field, dir) => {
      allocViewPrefs.setSavedSort(field && dir ? { field, dir } : null);
    },
  });
  const allocationIds = sorted.map((a) => a.id);
  const allocationMutationIdsByDisplayId = useMemo(
    () =>
      new Map(
        sorted.map((allocation) => [allocation.id, getPlanningEntryMutationId(allocation)]),
      ),
    [sorted],
  );
  const selectedMutationIds = useMemo(
    () =>
      selection.selectedArray.flatMap((displayId) => {
        const mutationId = allocationMutationIdsByDisplayId.get(displayId);
        return mutationId ? [mutationId] : [];
      }),
    [allocationMutationIdsByDisplayId, selection.selectedArray],
  );

  // ─── View mode: grouped (default) vs flat ──────────────────────────────────
  const [viewMode, setViewMode] = useState<"grouped" | "flat">(() => {
    if (typeof window === "undefined") return "grouped";
    return (localStorage.getItem("capakraken:allocations:viewMode") as "grouped" | "flat") ?? "grouped";
  });
  const [collapsedGroups, setCollapsedGroups] = useState<CollapsedAllocationGroups>(
    () => createInitialCollapsedAllocationGroups(),
  );
  // Track expanded project sub-groups: key = "resourceId::projectId"
  const [expandedSubGroups, setExpandedSubGroups] = useState<Set<string>>(new Set());
  const hasEvaluatedInitialVisibility = useRef(false);

  const toggleViewMode = useCallback(() => {
    setViewMode((prev) => {
      const next = prev === "grouped" ? "flat" : "grouped";
      localStorage.setItem("capakraken:allocations:viewMode", next);
      return next;
    });
  }, []);

  type ProjectSubGroup = {
    projectId: string;
    projectName: string;
    projectCode: string;
    allocations: AllocationWithDetails[];
    typicalHoursPerDay: number;
    earliestStart: Date;
    latestEnd: Date;
  };

  type AllocGroup = {
    resourceId: string;
    resourceName: string;
    eid: string;
    chapter: string | null;
    allocations: AllocationWithDetails[];
    projectSubGroups: ProjectSubGroup[];
  };

  const groups = useMemo<AllocGroup[]>(() => {
    const map = new Map<string, AllocGroup>();
    for (const alloc of sorted) {
      const rid = alloc.resource?.id ?? "__unassigned__";
      let group = map.get(rid);
      if (!group) {
        group = {
          resourceId: rid,
          resourceName: alloc.resource?.displayName ?? "Unassigned",
          eid: alloc.resource?.eid ?? "",
          chapter: (alloc.resource as { chapter?: string | null } | undefined)?.chapter ?? null,
          allocations: [],
          projectSubGroups: [],
        };
        map.set(rid, group);
      }
      group.allocations.push(alloc);
    }

    // Build project sub-groups within each person group
    for (const group of map.values()) {
      const projMap = new Map<string, AllocationWithDetails[]>();
      for (const alloc of group.allocations) {
        const pid = alloc.project?.id ?? "__no_project__";
        let list = projMap.get(pid);
        if (!list) { list = []; projMap.set(pid, list); }
        list.push(alloc);
      }
      group.projectSubGroups = [...projMap.entries()].map(([pid, allocs]) => {
        const first = allocs[0]!;
        let earliest = new Date(first.startDate);
        let latest = new Date(first.endDate);
        // Find the most common hoursPerDay value across allocations
        const hpdCounts = new Map<number, number>();
        for (const a of allocs) {
          const s = new Date(a.startDate);
          const e = new Date(a.endDate);
          if (s < earliest) earliest = s;
          if (e > latest) latest = e;
          hpdCounts.set(a.hoursPerDay, (hpdCounts.get(a.hoursPerDay) ?? 0) + 1);
        }
        // Pick the most frequent hoursPerDay; fall back to first
        let typicalH = first.hoursPerDay;
        let maxCount = 0;
        for (const [h, count] of hpdCounts) {
          if (count > maxCount) { typicalH = h; maxCount = count; }
        }
        return {
          projectId: pid,
          projectName: first.project?.name ?? "Unknown",
          projectCode: first.project?.shortCode ?? "",
          allocations: allocs,
          typicalHoursPerDay: typicalH,
          earliestStart: earliest,
          latestEnd: latest,
        };
      });
      group.projectSubGroups.sort((a, b) => a.projectName.localeCompare(b.projectName));
    }

    const arr = [...map.values()];
    arr.sort((a, b) => {
      if (a.resourceId === "__unassigned__") return 1;
      if (b.resourceId === "__unassigned__") return -1;
      return a.resourceName.localeCompare(b.resourceName);
    });
    return arr;
  }, [sorted]);

  const groupIds = useMemo(() => groups.map((g) => g.resourceId), [groups]);

  const toggleGroup = useCallback((resourceId: string) => {
    setCollapsedGroups((prev) => toggleCollapsedAllocationGroup(prev, groupIds, resourceId));
  }, [groupIds]);

  const collapseAll = useCallback(() => {
    setCollapsedGroups(collapseAllAllocationGroups());
  }, []);

  const expandAll = useCallback(() => {
    setCollapsedGroups(expandAllAllocationGroups());
  }, []);

  const toggleSubGroup = useCallback((resourceId: string, projectId: string) => {
    const key = `${resourceId}::${projectId}`;
    setExpandedSubGroups((prev) => {
      const next = new Set(prev);
      if (next.has(key)) next.delete(key);
      else next.add(key);
      return next;
    });
  }, []);

  function handleSort(field: string) {
    if (field === "resource") {
      toggle("resource", (a) => a.resource?.displayName ?? null);
    } else if (field === "project") {
      toggle("project", (a) => a.project?.name ?? null);
    } else {
      toggle(field);
    }
  }

  function clearAll() {
    setFilterProjectId("");
    setFilterResourceId("");
    setFilterStatus("");
    setHidePastProjects(false);
    setHideCompletedProjects(false);
    setHideDraftProjects(false);
  }

  const chips = [
    ...(filterProjectId ? [{ label: `Project filter active`, onRemove: () => setFilterProjectId("") }] : []),
    ...(filterResourceId ? [{ label: `Resource filter active`, onRemove: () => setFilterResourceId("") }] : []),
    ...(filterStatus ? [{ label: `Status: ${filterStatus}`, onRemove: () => setFilterStatus("") }] : []),
    ...(hidePastProjects ? [{ label: "Hiding past projects", onRemove: () => setHidePastProjects(false) }] : []),
    ...(hideCompletedProjects ? [{ label: "Hiding completed/cancelled", onRemove: () => setHideCompletedProjects(false) }] : []),
    ...(hideDraftProjects ? [{ label: "Hiding draft projects", onRemove: () => setHideDraftProjects(false) }] : []),
  ];

  const emptyState = getAllocationEmptyState({
    totalAssignments: assignmentList.length,
    totalDemands: demandList.length,
    visibleAssignments: filteredAllocations.length,
    visibleDemands: filteredDemands.length,
    hidePastProjects,
    hideCompletedProjects,
    hideDraftProjects,
  });

  useEffect(() => {
    if (isLoading || hasEvaluatedInitialVisibility.current) {
      return;
    }

    hasEvaluatedInitialVisibility.current = true;

    if (
      shouldAutoRelaxAllocationFilters({
        totalAssignments: assignmentList.length,
        totalDemands: demandList.length,
        visibleAssignments: filteredAllocations.length,
        visibleDemands: filteredDemands.length,
        hidePastProjects,
        hideCompletedProjects,
        hideDraftProjects,
      })
    ) {
      setHidePastProjects(false);
      setHideCompletedProjects(false);
      setHideDraftProjects(false);
    }
  }, [
    assignmentList.length,
    demandList.length,
    filteredAllocations.length,
    filteredDemands.length,
    hideCompletedProjects,
    hideDraftProjects,
    hidePastProjects,
    isLoading,
  ]);

  function formatPeriod(alloc: AllocationWithDetails) {
    return formatDate(alloc.startDate) + " \u2192 " + formatDate(alloc.endDate);
  }

  function handleSingleDelete(allocation: AllocationWithDetails) {
    const id = getPlanningEntryMutationId(allocation);

    if (!allocation.resourceId) {
      deleteDemandMutation.mutate({ id });
      return;
    }

    deleteAssignmentMutation.mutate({ id });
  }

  const singleDeletePending = deleteDemandMutation.isPending || deleteAssignmentMutation.isPending;

  // colSpan for empty/loading states: checkbox + visible columns + actions
  const totalColSpan = 1 + visibleColumns.length + 1;

  function renderAllocRow(alloc: AllocationWithDetails, isGrouped = false, rowIndex = 0) {
    const isSelected = selection.selectedIds.has(alloc.id);
    const leftBorder = STATUS_LEFT_BORDER[alloc.status] ?? "border-l-gray-300";
    return (
      <tr
        key={alloc.id}
        data-testid="allocation-row"
        className={`border-l-[3px] transition-colors hover:bg-gray-50/80 dark:hover:bg-gray-900/60 animate-row-enter ${leftBorder} ${isSelected ? "bg-brand-50 dark:bg-brand-900/20" : ""}`}
        style={{ animationDelay: `${Math.min(rowIndex * 15, 300)}ms` }}
      >
        <td className="px-4 py-3">
          <input
            type="checkbox"
            checked={isSelected}
            onChange={() => selection.toggle(alloc.id)}
            className="rounded border-gray-300 dark:border-gray-600"
          />
        </td>
        {visibleColumns.map((col) => {
          switch (col.key) {
            case "resource":
              return (
                <td key={col.key} className="px-4 py-3 text-sm font-medium text-gray-900 dark:text-gray-100">
                  {isGrouped ? <span className="text-gray-400 dark:text-gray-500">↳</span> : (alloc.resource?.displayName ?? "—")}
                </td>
              );
            case "project":
              return (
                <td key={col.key} className="px-4 py-3 text-sm text-gray-600 dark:text-gray-300">
                  {alloc.project ? (
                    <><span className="font-mono text-xs">{alloc.project.shortCode}</span> {alloc.project.name}</>
                  ) : "—"}
                </td>
              );
            case "role":
              return <td key={col.key} className="px-4 py-3 text-sm text-gray-600 dark:text-gray-300">{alloc.role}</td>;
            case "dates":
              return <td key={col.key} className="whitespace-nowrap px-4 py-3 text-xs text-gray-500 dark:text-gray-400">{formatPeriod(alloc)}</td>;
            case "hoursPerDay":
              return <td key={col.key} className="px-4 py-3 text-sm text-gray-900 dark:text-gray-100">{alloc.hoursPerDay}h</td>;
            case "cost":
              return <td key={col.key} className="px-4 py-3 text-sm text-gray-900 dark:text-gray-100">{(alloc.dailyCostCents / 100).toFixed(0)} €</td>;
            case "status":
              return (
                <td key={col.key} className="px-4 py-3">
                  <span className={`inline-block px-2 py-0.5 text-xs rounded-full font-medium ${STATUS_BADGE[alloc.status] ?? "bg-gray-100 text-gray-600 dark:bg-gray-700 dark:text-gray-400"}`}>
                    {alloc.status}
                  </span>
                </td>
              );
            default:
              return <td key={col.key} className="px-4 py-3 text-sm text-gray-500 dark:text-gray-400">—</td>;
          }
        })}
        <td className="px-4 py-3">
          <div className="flex items-center justify-end gap-2">
            <button type="button" onClick={() => openEdit(alloc)} className="text-xs font-medium text-blue-600 hover:text-blue-800 hover:underline dark:text-blue-300 dark:hover:text-blue-200">Edit</button>
            <button
              type="button"
              onClick={() => setConfirmDelete({ single: alloc })}
              disabled={singleDeletePending}
              className="text-xs font-medium text-red-500 hover:text-red-700 hover:underline disabled:opacity-50 dark:text-red-300 dark:hover:text-red-200"
            >
              Delete
            </button>
          </div>
        </td>
      </tr>
    );
  }

  return (
    <div className="app-page space-y-5 pb-24">
      <SuccessToast show={showStatusToast} message="Allocation status updated" onDone={() => setShowStatusToast(false)} />
      <div className="app-page-header gap-4">
        <div>
          <h1 className="app-page-title">Allocations</h1>
          <p className="app-page-subtitle mt-1">
            {isLoading
              ? "Loading…"
              : allocationQueryFailure
                ? allocationQueryFailure.title
              : `${filteredAllocations.length} assignment${filteredAllocations.length !== 1 ? "s" : ""}${filteredDemands.length > 0 ? ` · ${filteredDemands.length} open demand${filteredDemands.length !== 1 ? "s" : ""}` : ""}`}
          </p>
        </div>
        <div className="flex items-center gap-2">
          <a
            href="/api/reports/allocations"
            target="_blank"
            rel="noopener noreferrer"
            className="inline-flex items-center gap-2 rounded-xl border border-gray-300 bg-white px-3 py-2 text-sm font-medium text-gray-700 transition hover:border-gray-400 hover:bg-gray-50 dark:border-gray-600 dark:bg-gray-900 dark:text-gray-200 dark:hover:bg-gray-800"
          >
            ↓ PDF
          </a>
          <a
            href="/api/reports/allocations?format=xlsx"
            download
            className="inline-flex items-center gap-2 rounded-xl border border-gray-300 bg-white px-3 py-2 text-sm font-medium text-gray-700 transition hover:border-gray-400 hover:bg-gray-50 dark:border-gray-600 dark:bg-gray-900 dark:text-gray-200 dark:hover:bg-gray-800"
          >
            ↓ XLS
          </a>
          <button
            type="button"
            onClick={openCreate}
            className="rounded-xl bg-brand-600 px-4 py-2.5 text-sm font-semibold text-white transition hover:bg-brand-700 disabled:opacity-50"
          >
            New Planning Entry
          </button>
        </div>
      </div>

      <FilterBar>
        <ProjectCombobox
          value={filterProjectId || null}
          onChange={(id) => setFilterProjectId(id ?? "")}
          placeholder="Filter by project…"
          className="min-w-[280px]"
        />

        <ResourceCombobox
          value={filterResourceId || null}
          onChange={(id) => setFilterResourceId(id ?? "")}
          placeholder="Filter by resource…"
          className="min-w-[180px]"
        />

        <select
          value={filterStatus}
          onChange={(e) => setFilterStatus(e.target.value)}
          className="app-select"
        >
          <option value="">All Statuses</option>
          {ALL_ALLOC_STATUSES.map((s) => (
            <option key={s.value} value={s.value}>{s.label}</option>
          ))}
        </select>

        <label className="flex cursor-pointer items-center gap-1.5 whitespace-nowrap text-sm text-gray-600 dark:text-gray-300">
          <input
            type="checkbox"
            checked={hidePastProjects}
            onChange={(e) => setHidePastProjects(e.target.checked)}
            className="rounded border-gray-300 dark:border-gray-600"
          />
          Hide past
        </label>

        <label className="flex cursor-pointer items-center gap-1.5 whitespace-nowrap text-sm text-gray-600 dark:text-gray-300">
          <input
            type="checkbox"
            checked={hideCompletedProjects}
            onChange={(e) => setHideCompletedProjects(e.target.checked)}
            className="rounded border-gray-300 dark:border-gray-600"
          />
          Hide completed
        </label>

        <label className="flex cursor-pointer items-center gap-1.5 whitespace-nowrap text-sm text-gray-600 dark:text-gray-300">
          <input
            type="checkbox"
            checked={hideDraftProjects}
            onChange={(e) => setHideDraftProjects(e.target.checked)}
            className="rounded border-gray-300 dark:border-gray-600"
          />
          Hide drafts
        </label>
        <ColumnTogglePanel
          allColumns={allColumns}
          visibleKeys={visibleKeys}
          onSetVisible={setVisible}
          defaultKeys={defaultKeys}
        />

        {/* View mode toggle */}
        <div className="flex items-center rounded-lg border border-gray-300 dark:border-gray-600 overflow-hidden">
          <button
            type="button"
            onClick={toggleViewMode}
            title="Grouped by person"
            className={`px-2.5 py-2 text-sm transition-colors ${viewMode === "grouped" ? "bg-brand-600 text-white" : "bg-white text-gray-600 hover:bg-gray-50 dark:bg-gray-900 dark:text-gray-300 dark:hover:bg-gray-800"}`}
          >
            <svg className="h-4 w-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17 20h5v-2a3 3 0 00-5.356-1.857M17 20H7m10 0v-2c0-.656-.126-1.283-.356-1.857M7 20H2v-2a3 3 0 015.356-1.857M7 20v-2c0-.656.126-1.283.356-1.857m0 0a5.002 5.002 0 019.288 0M15 7a3 3 0 11-6 0 3 3 0 016 0z" />
            </svg>
          </button>
          <button
            type="button"
            onClick={toggleViewMode}
            title="Flat list"
            className={`px-2.5 py-2 text-sm transition-colors ${viewMode === "flat" ? "bg-brand-600 text-white" : "bg-white text-gray-600 hover:bg-gray-50 dark:bg-gray-900 dark:text-gray-300 dark:hover:bg-gray-800"}`}
          >
            <svg className="h-4 w-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M4 6h16M4 10h16M4 14h16M4 18h16" />
            </svg>
          </button>
        </div>

        {viewMode === "grouped" && groups.length > 1 && (
          <div className="flex items-center gap-1">
            <button type="button" onClick={expandAll} className="text-xs text-brand-600 hover:text-brand-800 dark:text-brand-400 dark:hover:text-brand-200 whitespace-nowrap">
              Expand all
            </button>
            <span className="text-gray-300 dark:text-gray-600">|</span>
            <button type="button" onClick={collapseAll} className="text-xs text-brand-600 hover:text-brand-800 dark:text-brand-400 dark:hover:text-brand-200 whitespace-nowrap">
              Collapse all
            </button>
          </div>
        )}
      </FilterBar>

      {/* Filter chips */}
      {chips.length > 0 && (
        <div className="mb-3">
          <FilterChips chips={chips} onClearAll={clearAll} />
        </div>
      )}

      <div className="app-data-table">
        <table data-testid="allocations-table" className="w-full">
          <thead className="border-b border-gray-200 dark:border-gray-700">
            <tr>
              <th className="px-4 py-3 w-10">
                <input
                  type="checkbox"
                  checked={selection.isAllSelected(allocationIds)}
                  ref={(el) => {
                    if (el) el.indeterminate = selection.isIndeterminate(allocationIds);
                  }}
                  onChange={() => selection.toggleAll(allocationIds)}
                  className="rounded border-gray-300 dark:border-gray-600"
                />
              </th>
              {visibleColumns.map((col) => {
                const tooltips: Record<string, { tip: string; width?: string }> = {
                  resource: { tip: "The person assigned to this time block. Grouped view clusters entries by resource." },
                  project: { tip: "The project this allocation belongs to, identified by short code and name." },
                  role: { tip: "The role this allocation was created for. May differ from the resource's primary role." },
                  dates: { tip: "Start and end date of this allocation period (inclusive)." },
                  hoursPerDay: { tip: "Planned working hours per calendar day for this allocation." },
                  cost: { tip: "Daily cost = resource LCR x hours per day. Total cost = daily cost x working days.", width: "w-72" },
                  status: { tip: "PROPOSED = requested · CONFIRMED = approved · ACTIVE = ongoing · COMPLETED = finished · CANCELLED = removed.", width: "w-72" },
                };
                const t = tooltips[col.key];
                const fieldMap: Record<string, string> = { dates: "startDate", hoursPerDay: "hoursPerDay", cost: "dailyCostCents" };
                return (
                  <SortableColumnHeader
                    key={col.key}
                    label={col.label}
                    field={fieldMap[col.key] ?? col.key}
                    sortField={sortField}
                    sortDir={sortDir}
                    onSort={handleSort}
                    {...(t?.tip ? { tooltip: t.tip } : {})}
                    {...(t?.width ? { tooltipWidth: t.width } : {})}
                  />
                );
              })}
              <th className="px-4 py-3" />
            </tr>
          </thead>
          <tbody className="divide-y divide-gray-100 dark:divide-gray-800">
            {isLoading && (
              <tr>
                <td colSpan={totalColSpan} className="py-12 text-center text-sm text-gray-500 dark:text-gray-400">Loading allocations…</td>
              </tr>
            )}

            {!isLoading && allocationQueryFailure && (
              <tr>
                <td colSpan={totalColSpan} className="py-12 text-center text-sm text-gray-500 dark:text-gray-400">
                  <div data-testid={allocationQueryFailure.testId} className="flex flex-col items-center gap-2">
                    <p className="font-medium text-gray-700 dark:text-gray-200">{allocationQueryFailure.title}</p>
                    <p>{allocationQueryFailure.detail}</p>
                    {allocationQueryFailure.actionLabel && allocationQueryFailure.actionHref && (
                      <a
                        href={allocationQueryFailure.actionHref}
                        className="rounded-lg border border-gray-300 px-3 py-1.5 text-xs font-medium text-gray-700 transition hover:border-gray-400 hover:bg-gray-50 dark:border-gray-600 dark:text-gray-200 dark:hover:bg-gray-800"
                      >
                        {allocationQueryFailure.actionLabel}
                      </a>
                    )}
                  </div>
                </td>
              </tr>
            )}

            {!isLoading && !allocationQueryFailure && sorted.length === 0 && (
              <tr>
                <td colSpan={totalColSpan} className="py-12 text-center text-sm text-gray-500 dark:text-gray-400">
                  <div data-testid="allocations-empty-state" className="flex flex-col items-center gap-2">
                    <p className="font-medium text-gray-700 dark:text-gray-200">{emptyState.title}</p>
                    <p>{emptyState.detail}</p>
                    {emptyState.showResetAction && (
                      <button
                        type="button"
                        onClick={clearAll}
                        className="rounded-lg border border-gray-300 px-3 py-1.5 text-xs font-medium text-gray-700 transition hover:border-gray-400 hover:bg-gray-50 dark:border-gray-600 dark:text-gray-200 dark:hover:bg-gray-800"
                      >
                        Show all assignments
                      </button>
                    )}
                  </div>
                </td>
              </tr>
            )}

            {!isLoading && !allocationQueryFailure && viewMode === "flat" &&
              sorted.map((alloc, index) => renderAllocRow(alloc, false, index))}

            {!isLoading && !allocationQueryFailure && viewMode === "grouped" &&
              groups.map((group) => {
                const isCollapsed = collapsedGroups === "all" || collapsedGroups.has(group.resourceId);
                const groupAllocIds = group.allocations.map((a) => a.id);
                const allGroupSelected = selection.isAllSelected(groupAllocIds);
                const groupIndeterminate = !allGroupSelected && groupAllocIds.some((id) => selection.selectedIds.has(id));
                return (
                  <GroupRows key={group.resourceId}>
                    {/* Group header */}
                    <tr
                      data-testid="allocation-group-header"
                      className="bg-gray-50 dark:bg-gray-800/50 cursor-pointer select-none hover:bg-gray-100 dark:hover:bg-gray-800/80 transition-colors"
                      onClick={() => toggleGroup(group.resourceId)}
                      onKeyDown={(e) => { if (e.key === "Enter" || e.key === " ") { e.preventDefault(); toggleGroup(group.resourceId); } }}
                      tabIndex={0}
                      role="button"
                      aria-expanded={!isCollapsed}
                    >
                      <td className="px-4 py-2.5" onClick={(e) => e.stopPropagation()}>
                        <input
                          type="checkbox"
                          checked={allGroupSelected}
                          ref={(el) => { if (el) el.indeterminate = groupIndeterminate; }}
                          onChange={() => selection.toggleAll(groupAllocIds)}
                          className="rounded border-gray-300 dark:border-gray-600"
                        />
                      </td>
                      <td colSpan={visibleColumns.length + 1} className="px-4 py-2.5">
                        <div className="flex items-center gap-2">
                          <span className="text-gray-400 dark:text-gray-500 text-xs">
                            {isCollapsed ? "▸" : "▾"}
                          </span>
                          <span className="text-sm font-semibold text-gray-900 dark:text-gray-100">
                            {group.resourceName}
                          </span>
                          {group.eid && (
                            <span className="text-xs font-mono text-gray-400 dark:text-gray-500">
                              {group.eid}
                            </span>
                          )}
                          {group.chapter && (
                            <span className="text-xs text-gray-400 dark:text-gray-500">
                              · {group.chapter}
                            </span>
                          )}
                          <span className="inline-flex items-center rounded-full bg-gray-200 px-2 py-0.5 text-xs font-medium text-gray-600 dark:bg-gray-700 dark:text-gray-300">
                            {group.allocations.length}
                          </span>
                        </div>
                      </td>
                    </tr>
                    {/* Project sub-groups within person */}
                    {!isCollapsed && group.projectSubGroups.map((subGroup) => {
                      const subKey = `${group.resourceId}::${subGroup.projectId}`;
                      const isSubExpanded = expandedSubGroups.has(subKey);

                      // Single allocation for this project — render directly, no sub-group header
                      if (subGroup.allocations.length === 1) {
                        return <GroupRows key={subKey}>{renderAllocRow(subGroup.allocations[0]!, true, 0)}</GroupRows>;
                      }

                      // Multiple allocations — show collapsible project sub-group
                      return (
                        <GroupRows key={subKey}>
                          <tr
                            data-testid="allocation-subgroup-header"
                            className="bg-gray-25 dark:bg-gray-850/30 cursor-pointer select-none hover:bg-gray-100/60 dark:hover:bg-gray-800/40 transition-colors"
                            onClick={() => toggleSubGroup(group.resourceId, subGroup.projectId)}
                            tabIndex={0}
                            role="button"
                            aria-expanded={isSubExpanded}
                            onKeyDown={(e) => { if (e.key === "Enter" || e.key === " ") { e.preventDefault(); toggleSubGroup(group.resourceId, subGroup.projectId); } }}
                          >
                            <td className="px-4 py-2" onClick={(e) => e.stopPropagation()}>
                              <input
                                type="checkbox"
                                checked={selection.isAllSelected(subGroup.allocations.map((a) => a.id))}
                                ref={(el) => {
                                  if (el) {
                                    const ids = subGroup.allocations.map((a) => a.id);
                                    el.indeterminate = !selection.isAllSelected(ids) && ids.some((id) => selection.selectedIds.has(id));
                                  }
                                }}
                                onChange={() => selection.toggleAll(subGroup.allocations.map((a) => a.id))}
                                className="rounded border-gray-300 dark:border-gray-600"
                              />
                            </td>
                            <td colSpan={visibleColumns.length + 1} className="px-4 py-2">
                              <div className="flex items-center gap-2 pl-4">
                                <span className="text-gray-400 dark:text-gray-500 text-xs">
                                  {isSubExpanded ? "▾" : "▸"}
                                </span>
                                <span className="font-mono text-xs text-gray-400 dark:text-gray-500">{subGroup.projectCode}</span>
                                <span className="text-sm text-gray-700 dark:text-gray-300">{subGroup.projectName}</span>
                                <span className="text-xs text-gray-400 dark:text-gray-500">
                                  {formatDate(subGroup.earliestStart)} → {formatDate(subGroup.latestEnd)}
                                </span>
                                <span className="text-xs text-gray-500 dark:text-gray-400">
                                  {subGroup.typicalHoursPerDay}h/day
                                </span>
                                <span className="inline-flex items-center rounded-full bg-gray-200 px-1.5 py-0.5 text-[10px] font-medium text-gray-500 dark:bg-gray-700 dark:text-gray-400">
                                  {subGroup.allocations.length}
                                </span>
                              </div>
                            </td>
                          </tr>
                          {isSubExpanded && subGroup.allocations.map((alloc, idx) => renderAllocRow(alloc, true, idx))}
                        </GroupRows>
                      );
                    })}
                  </GroupRows>
                );
              })}
          </tbody>
        </table>
      </div>

      {!isLoading && filteredDemands.length > 0 && (
        <div className="app-surface mt-6 overflow-hidden border-amber-200 dark:border-amber-900/70">
          <div className="flex items-center justify-between border-b border-amber-200 bg-amber-50/70 px-4 py-3 dark:border-amber-900/70 dark:bg-amber-950/20">
            <div>
              <h2 className="text-sm font-semibold text-amber-900 dark:text-amber-200">Open Demands</h2>
              <p className="text-xs text-amber-700 dark:text-amber-300/80">
                Placeholder demand rows not yet assigned to a resource.
              </p>
            </div>
            <span className="text-xs font-medium text-amber-700 dark:text-amber-300">
              {filteredDemands.length} item{filteredDemands.length !== 1 ? "s" : ""}
            </span>
          </div>
          <div className="divide-y divide-amber-100 dark:divide-amber-900/40">
            {filteredDemands.map((demand) => (
              <div
                key={demand.id}
                className="flex items-center justify-between gap-4 px-4 py-3 hover:bg-amber-50/40 dark:hover:bg-amber-950/10"
              >
                <div className="min-w-0">
                  <div className="text-sm font-medium text-gray-900 dark:text-gray-100 truncate">
                    {demand.project ? (
                      <><span className="font-mono text-xs">{demand.project.shortCode}</span> {demand.project.name}</>
                    ) : "Unknown project"}
                  </div>
                  <div className="mt-1 text-xs text-gray-500 dark:text-gray-400">
                    {(demand.role ?? "Placeholder role")} · {formatPeriod(demand)} · {demand.hoursPerDay}h/day
                  </div>
                </div>
                <div className="flex flex-shrink-0 items-center gap-4">
                  <div className="text-right">
                    <div className="text-xs uppercase tracking-wide text-amber-700 dark:text-amber-300">Unfilled</div>
                    <div className="text-sm font-semibold text-amber-900 dark:text-amber-200">
                      {demand.unfilledHeadcount ?? demand.headcount} / {demand.requestedHeadcount ?? demand.headcount}
                    </div>
                  </div>
                  <div className="flex items-center gap-2">
                    <button
                      type="button"
                      onClick={() => openEdit(demand as AllocationWithDetails)}
                      className="text-xs font-medium text-blue-600 hover:text-blue-800 hover:underline dark:text-blue-300 dark:hover:text-blue-200"
                    >
                      Edit
                    </button>
                    <button
                      type="button"
                      onClick={() => setConfirmDelete({ single: demand as AllocationWithDetails })}
                      disabled={singleDeletePending}
                      className="text-xs font-medium text-red-500 hover:text-red-700 hover:underline disabled:opacity-50 dark:text-red-300 dark:hover:text-red-200"
                    >
                      Delete
                    </button>
                  </div>
                </div>
              </div>
            ))}
          </div>
        </div>
      )}

      {/* Batch Status Picker */}
      {batchStatusPicker && (
        <div className="fixed inset-0 bg-black/30 z-50 flex items-center justify-center p-4" onClick={() => setBatchStatusPicker(false)}>
          <div className="min-w-[220px] rounded-2xl bg-white p-5 shadow-2xl dark:bg-gray-900" onClick={(e) => e.stopPropagation()}>
            <h3 className="mb-3 text-sm font-semibold text-gray-900 dark:text-gray-100">Set status for {selection.count} allocations</h3>
            <div className="flex flex-col gap-1">
              {ALL_ALLOC_STATUSES.map((s) => (
                <button
                  key={s.value}
                  type="button"
                  onClick={() => {
                    setConfirmBatchStatus({ ids: selectedMutationIds, status: s.value });
                    setBatchStatusPicker(false);
                  }}
                  className="w-full rounded-xl px-3 py-2 text-left text-sm transition-colors hover:bg-gray-50 dark:hover:bg-gray-800"
                >
                  <span className={`inline-block px-2 py-0.5 text-xs rounded-full font-medium ${STATUS_BADGE[s.value]}`}>
                    {s.label}
                  </span>
                </button>
              ))}
            </div>
          </div>
        </div>
      )}

      {/* Confirm single delete */}
      {confirmDelete?.single && (
        <ConfirmDialog
          title="Delete Allocation"
          message={`Delete allocation for ${confirmDelete.single.resource?.displayName ?? "resource"} on ${confirmDelete.single.project?.name ?? "project"}?`}
          confirmLabel="Delete"
          variant="danger"
          onConfirm={() => {
            handleSingleDelete(confirmDelete.single!);
            setConfirmDelete(null);
          }}
          onCancel={() => setConfirmDelete(null)}
        />
      )}

      {/* Confirm batch delete */}
      {confirmDelete?.ids && (
        <ConfirmDialog
          title="Delete Allocations"
          message={`Delete ${confirmDelete.ids.length} selected allocation${confirmDelete.ids.length !== 1 ? "s" : ""}? This cannot be undone.`}
          confirmLabel="Delete All"
          variant="danger"
          onConfirm={() => {
            batchDeleteMutation.mutate({ ids: confirmDelete.ids! });
            setConfirmDelete(null);
          }}
          onCancel={() => setConfirmDelete(null)}
        />
      )}

      {/* Confirm batch status */}
      {confirmBatchStatus && (
        <ConfirmDialog
          title="Update Allocation Status"
          message={`Set ${confirmBatchStatus.ids.length} allocation${confirmBatchStatus.ids.length !== 1 ? "s" : ""} to "${confirmBatchStatus.status}"?`}
          confirmLabel="Update"
          onConfirm={() => {
            batchStatusMutation.mutate({ ids: confirmBatchStatus.ids, status: confirmBatchStatus.status as never });
            setConfirmBatchStatus(null);
          }}
          onCancel={() => setConfirmBatchStatus(null)}
        />
      )}

      {/* Batch Action Bar */}
      <BatchActionBar
        count={selection.count}
        onClear={selection.clear}
        actions={[
          {
            label: "Set Status…",
            onClick: () => setBatchStatusPicker(true),
            disabled: batchStatusMutation.isPending,
          },
          {
            label: `Delete (${selection.count})`,
            variant: "danger",
            onClick: () => setConfirmDelete({ ids: selectedMutationIds }),
            disabled: batchDeleteMutation.isPending,
          },
        ]}
      />

      {/* Modal */}
      {modalOpen && (
        <AllocationModal allocation={editingAllocation} onClose={closeModal} onSuccess={closeModal} />
      )}
    </div>
  );
}
