import { useEffect, useMemo, useState } from 'react';
import { useNavigate, useSearchParams } from 'react-router-dom';
import { useShortcut } from '../../hooks/useShortcuts';
import { ChevronLeft, ChevronRight } from 'lucide-react';
import { toast } from 'sonner';
import Layout from '../../components/Layout';
import { TicketStatus } from '../../types';
import { useAuth } from '../../contexts/AuthContext';
import {
  useTicketsPaged,
  useBulkTickets,
  useSavedViews,
  useCreateSavedView,
  useDeleteSavedView,
  useUsers,
} from '../../api/queries';
import {
  Dialog,
  DialogContent,
  DialogFooter,
  DialogHeader,
  DialogTitle,
} from '@/components/ui/dialog';
import {
  AlertDialog,
  AlertDialogAction,
  AlertDialogCancel,
  AlertDialogContent,
  AlertDialogDescription,
  AlertDialogFooter,
  AlertDialogHeader,
  AlertDialogTitle,
} from '@/components/ui/alert-dialog';
import TicketFilters from './TicketFilters';
import BulkActions from './BulkActions';
import TicketListItem from './TicketListItem';

const PAGE_SIZE = 25;
const BULK_LIMIT = 500;

export default function Tickets() {
  const [params, setParams] = useSearchParams();
  const navigate = useNavigate();
  const { user: authUser } = useAuth();
  const { data: users = [] } = useUsers();

  const status = (params.get('status') ?? '') as TicketStatus | '';
  const severity = params.get('severity') ?? '';
  const assigneeId = params.get('assigneeId') ?? '';
  const categoryId = params.get('categoryId') ?? '';
  const typeId = params.get('typeId') ?? '';
  const itemId = params.get('itemId') ?? '';
  const search = params.get('search') ?? '';
  const page = Math.max(1, Number(params.get('page') ?? '1'));

  const [searchInput, setSearchInput] = useState(search);
  const [selected, setSelected] = useState<Set<string>>(new Set());
  const [cursor, setCursor] = useState<number>(-1);
  const [saveOpen, setSaveOpen] = useState(false);
  const [newViewName, setNewViewName] = useState('');
  const [confirmBulk, setConfirmBulk] = useState<
    | { kind: 'close' | 'setSeverity' | 'reassign'; value?: unknown; label: string }
    | null
  >(null);

  useEffect(() => {
    const t = setTimeout(() => {
      if (search !== searchInput) {
        updateParam('search', searchInput);
        updateParam('page', '1');
      }
    }, 250);
    return () => clearTimeout(t);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [searchInput]);

  const updateParam = (key: string, value: string | null) => {
    setParams(
      (prev) => {
        const next = new URLSearchParams(prev);
        if (value === null || value === '') next.delete(key);
        else next.set(key, value);
        if (key !== 'page') next.delete('page');
        return next;
      },
      { replace: true },
    );
  };

  const queryParams = {
    status: status || undefined,
    severity: severity ? Number(severity) : undefined,
    assigneeId: assigneeId || undefined,
    categoryId: categoryId || undefined,
    typeId: typeId || undefined,
    itemId: itemId || undefined,
    search: search || undefined,
    page,
    pageSize: PAGE_SIZE,
  };

  const { data, isLoading, isFetching } = useTicketsPaged(queryParams);
  const tickets = data?.data ?? [];
  const total = data?.total ?? 0;
  const totalPages = Math.max(1, Math.ceil(total / PAGE_SIZE));

  const savedViewsQ = useSavedViews();
  const createView = useCreateSavedView();
  const deleteView = useDeleteSavedView();
  const bulk = useBulkTickets();

  const allVisible = tickets.length > 0 && tickets.every((t) => selected.has(t.id));
  const someVisible = tickets.some((t) => selected.has(t.id));

  const toggleAll = () => {
    setSelected((prev) => {
      const next = new Set(prev);
      if (allVisible) tickets.forEach((t) => next.delete(t.id));
      else tickets.forEach((t) => next.add(t.id));
      return next;
    });
  };

  const toggleOne = (id: string) => {
    setSelected((prev) => {
      const next = new Set(prev);
      if (next.has(id)) next.delete(id);
      else next.add(id);
      return next;
    });
  };

  const clearSelected = () => setSelected(new Set());

  const currentFilters = useMemo(
    () => ({
      status: status || undefined,
      severity: severity ? Number(severity) : undefined,
      assigneeId: assigneeId || undefined,
      categoryId: categoryId || undefined,
      typeId: typeId || undefined,
      itemId: itemId || undefined,
      search: search || undefined,
    }),
    [status, severity, assigneeId, categoryId, typeId, itemId, search],
  );

  const runBulk = async (payload: { action: string; value?: unknown }) => {
    const ids = Array.from(selected).slice(0, BULK_LIMIT);
    try {
      const res = (await bulk.mutateAsync({ ids, ...payload })) as { updated?: number };
      toast.success(`Updated ${res.updated ?? ids.length} ticket${ids.length === 1 ? '' : 's'}`);
      clearSelected();
    } catch (e) {
      toast.error((e as Error).message || 'Bulk action failed');
    } finally {
      setConfirmBulk(null);
    }
  };

  const activeCount = Object.values(currentFilters).filter(Boolean).length;

  const handleSaveView = async () => {
    if (!newViewName.trim()) return;
    try {
      await createView.mutateAsync({
        name: newViewName.trim(),
        filters: currentFilters,
      });
      toast.success('Saved view');
      setNewViewName('');
      setSaveOpen(false);
    } catch (e) {
      toast.error((e as Error).message || 'Failed to save view');
    }
  };

  const applyView = (filters: Record<string, unknown>) => {
    const next = new URLSearchParams();
    Object.entries(filters).forEach(([k, v]) => {
      if (v !== undefined && v !== null && v !== '') next.set(k, String(v));
    });
    setParams(next, { replace: true });
    setSearchInput(String(filters.search ?? ''));
  };

  // Keyboard navigation
  useEffect(() => {
    setCursor((c) => (c >= tickets.length ? tickets.length - 1 : c));
  }, [tickets.length]);

  useShortcut('j', (e) => {
    if (tickets.length === 0) return;
    e.preventDefault();
    setCursor((c) => Math.min(tickets.length - 1, c < 0 ? 0 : c + 1));
  }, [tickets.length]);

  useShortcut('k', (e) => {
    if (tickets.length === 0) return;
    e.preventDefault();
    setCursor((c) => Math.max(0, c < 0 ? 0 : c - 1));
  }, [tickets.length]);

  useShortcut('enter', (e) => {
    if (cursor < 0 || cursor >= tickets.length) return;
    e.preventDefault();
    navigate(`/${tickets[cursor].displayId}`);
  }, [cursor, tickets]);

  useShortcut('x', (e) => {
    if (cursor < 0 || cursor >= tickets.length) return;
    e.preventDefault();
    toggleOne(tickets[cursor].id);
  }, [cursor, tickets]);

  return (
    <Layout wide>
      <TicketFilters
        status={status}
        severity={severity}
        assigneeId={assigneeId}
        categoryId={categoryId}
        typeId={typeId}
        itemId={itemId}
        searchInput={searchInput}
        onSearchChange={setSearchInput}
        onUpdateParam={updateParam}
        onSetParams={(fn) => setParams(fn, { replace: true })}
        authUser={authUser}
        users={users}
        savedViews={savedViewsQ.data ?? []}
        onDeleteView={(id) => deleteView.mutate(id)}
        onApplyView={applyView}
        onSaveView={() => setSaveOpen(true)}
        activeFilterCount={activeCount}
        total={total}
        isFetching={isFetching}
      />

      {selected.size > 0 && (
        <BulkActions
          selectedCount={selected.size}
          users={users}
          onClear={clearSelected}
          onConfirm={setConfirmBulk}
        />
      )}

      {/* Ticket list */}
      {isLoading ? (
        <div className="text-center py-16 text-muted-foreground text-sm">Loading…</div>
      ) : tickets.length === 0 ? (
        <div className="text-center py-16 text-muted-foreground text-sm">No tickets found</div>
      ) : (
        <div className="rounded-md border border-border overflow-hidden">
          <div className="flex items-center gap-3 px-4 py-2 bg-card text-xs text-muted-foreground border-b border-border">
            <input
              type="checkbox"
              checked={allVisible}
              aria-label="Select all on page"
              ref={(el) => {
                if (el) el.indeterminate = !allVisible && someVisible;
              }}
              onChange={toggleAll}
              className="cursor-pointer"
            />
            <span>
              {tickets.length} of {total}
            </span>
          </div>

          <ul className="divide-y divide-border">
            {tickets.map((ticket, idx) => (
              <TicketListItem
                key={ticket.id}
                ticket={ticket}
                selected={selected.has(ticket.id)}
                focused={idx === cursor}
                onToggle={() => toggleOne(ticket.id)}
              />
            ))}
          </ul>
        </div>
      )}

      {/* Pagination */}
      {totalPages > 1 && (
        <div className="flex items-center justify-between mt-4 text-sm">
          <div className="text-muted-foreground">
            Page {page} of {totalPages}
          </div>
          <div className="flex items-center gap-1">
            <button
              disabled={page <= 1}
              onClick={() => updateParam('page', String(page - 1))}
              className="p-1.5 rounded-md hover:bg-accent disabled:opacity-40 disabled:cursor-not-allowed"
            >
              <ChevronLeft size={16} />
            </button>
            <button
              disabled={page >= totalPages}
              onClick={() => updateParam('page', String(page + 1))}
              className="p-1.5 rounded-md hover:bg-accent disabled:opacity-40 disabled:cursor-not-allowed"
            >
              <ChevronRight size={16} />
            </button>
          </div>
        </div>
      )}

      {/* Save view dialog */}
      <Dialog open={saveOpen} onOpenChange={setSaveOpen}>
        <DialogContent>
          <DialogHeader>
            <DialogTitle>Save current filters</DialogTitle>
          </DialogHeader>
          <div className="py-2">
            <input
              autoFocus
              type="text"
              value={newViewName}
              onChange={(e) => setNewViewName(e.target.value)}
              placeholder="View name"
              className="w-full px-3 py-2 rounded-md border border-input bg-background text-sm focus:outline-none focus:ring-2 focus:ring-ring"
              onKeyDown={(e) => {
                if (e.key === 'Enter') handleSaveView();
              }}
            />
          </div>
          <DialogFooter>
            <button
              onClick={() => setSaveOpen(false)}
              className="px-3 py-1.5 rounded-md border border-input text-sm hover:bg-accent"
            >
              Cancel
            </button>
            <button
              onClick={handleSaveView}
              disabled={!newViewName.trim() || createView.isPending}
              className="px-3 py-1.5 rounded-md bg-primary text-primary-foreground text-sm disabled:opacity-50"
            >
              Save
            </button>
          </DialogFooter>
        </DialogContent>
      </Dialog>

      {/* Confirm bulk action */}
      <AlertDialog open={!!confirmBulk} onOpenChange={(o) => !o && setConfirmBulk(null)}>
        <AlertDialogContent>
          <AlertDialogHeader>
            <AlertDialogTitle>{confirmBulk?.label}</AlertDialogTitle>
            <AlertDialogDescription>
              This will affect {selected.size} ticket{selected.size === 1 ? '' : 's'}.
            </AlertDialogDescription>
          </AlertDialogHeader>
          <AlertDialogFooter>
            <AlertDialogCancel>Cancel</AlertDialogCancel>
            <AlertDialogAction
              onClick={() => {
                if (!confirmBulk) return;
                if (confirmBulk.kind === 'close') runBulk({ action: 'close' });
                else
                  runBulk({
                    action: confirmBulk.kind,
                    value: confirmBulk.value,
                  });
              }}
            >
              Confirm
            </AlertDialogAction>
          </AlertDialogFooter>
        </AlertDialogContent>
      </AlertDialog>
    </Layout>
  );
}