'use client';

import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
import { useTranslations } from 'next-intl';
import { Button } from '@/components/ui/shared/Button';
import { FORM_SELECT_CLASS } from '@/components/shared/formSelectStyles';
import { SearchBar } from '@/components/ui/shared/SearchBar';
import { TaskCaseGroupHeader } from '@/components/ui/lab/TaskCaseGroupHeader';
import { TaskProsthesisGroupHeader } from '@/components/ui/lab/TaskProsthesisGroupHeader';
import { TaskRow } from '@/components/ui/lab/TaskRow';
import { groupTasksForDisplay } from '@/components/lab/taskListGrouping';
import { getUserFacingError } from '@/components/shared/formatApiError';
import { canEditTasks, canViewTasks } from '@/components/shared/permissions';
import { useAuth } from '@/lib/hooks/useAuth';
import { useToast } from '@/lib/hooks/useToast';
import { prosthesisCatalogApi } from '@/lib/api/prosthesis-catalog';
import { tasksApi } from '@/lib/api/tasks';
import type {
  LabTaskListItem,
  LabTaskStatus,
  ListLabTasksParams,
  PaginatedLabTasks,
  TaskFilterOptions,
  TaskSortField,
} from '@/types/cases';
import type { ProsthesisCatalogEntry } from '@/types/treatment-catalog';

const PAGE_SIZE = 50;

export function TasksPage() {
  const t = useTranslations('tasks');
  const tErrors = useTranslations('errors');
  const { currentOrganization, user, isAuthReady } = useAuth();
  const { showError, setError, messages: toastMessages } = useToast();

  const [tasks, setTasks] = useState<LabTaskListItem[]>([]);
  const [pagination, setPagination] = useState<PaginatedLabTasks['pagination']>({
    page: 1,
    limit: PAGE_SIZE,
    total: 0,
    totalPages: 1,
  });
  const [filterOptions, setFilterOptions] = useState<TaskFilterOptions>({
    clinics: [],
    workflowSteps: [],
  });
  const [prosthesisCatalog, setProsthesisCatalog] = useState<ProsthesisCatalogEntry[]>([]);
  const [page, setPage] = useState(1);
  const [loading, setLoading] = useState(false);
  const [updatingTaskId, setUpdatingTaskId] = useState<string | null>(null);
  const [expandedCommentsTaskId, setExpandedCommentsTaskId] = useState<string | null>(null);

  const [search, setSearch] = useState('');
  const [clinicId, setClinicId] = useState('');
  const [statusFilter, setStatusFilter] = useState<'' | LabTaskStatus>('IN_PROGRESS');
  const [stepCompleted, setStepCompleted] = useState('');
  const [sortBy, setSortBy] = useState<TaskSortField>('date');
  const [sortDir, setSortDir] = useState<'asc' | 'desc'>('desc');

  const canView = canViewTasks(currentOrganization);
  const canEdit = canEditTasks(currentOrganization);
  const locale = user?.language ?? 'en';

  const tRef = useRef(t);
  tRef.current = t;

  const statusOptions: { value: LabTaskStatus; label: string }[] = useMemo(
    () => [
      { value: 'IN_PROGRESS', label: t('statusInProgress') },
      { value: 'COMPLETED', label: t('statusCompleted') },
    ],
    [t],
  );

  const listParams = useMemo((): ListLabTasksParams => {
    const params: ListLabTasksParams = {
      page,
      limit: PAGE_SIZE,
      sortBy,
      sortDir,
    };
    if (search.trim()) params.q = search.trim();
    if (clinicId) params.clinicOrganizationId = clinicId;
    if (statusFilter) params.status = statusFilter;
    if (stepCompleted) params.stepCompleted = stepCompleted;
    return params;
  }, [page, search, clinicId, statusFilter, stepCompleted, sortBy, sortDir]);

  const displayModel = useMemo(
    () => groupTasksForDisplay(tasks, sortBy),
    [tasks, sortBy],
  );

  const groupingDisabled = sortBy !== 'date';

  const loadTasks = useCallback(async () => {
    setLoading(true);
    setError('');
    try {
      const response = await tasksApi.list(listParams);
      setTasks(response.data.items);
      setPagination(response.data.pagination);
    } catch (error: unknown) {
      showError(getUserFacingError(error, tErrors, tRef.current('errorLoadList')));
    } finally {
      setLoading(false);
    }
  }, [listParams, showError, setError, tErrors]);

  useEffect(() => {
    if (!canView) return;
    const timeout = setTimeout(() => void loadTasks(), search ? 300 : 0);
    return () => clearTimeout(timeout);
  }, [canView, loadTasks, search]);

  useEffect(() => {
    if (!canView) return;
    void (async () => {
      try {
        const [optionsRes, catalogRes] = await Promise.all([
          tasksApi.filterOptions(),
          prosthesisCatalogApi.list(),
        ]);
        setFilterOptions(optionsRes.data);
        setProsthesisCatalog(catalogRes.data);
      } catch {
        // Non-blocking — filters fall back to empty options.
      }
    })();
  }, [canView]);

  const handleStatusUpdate = useCallback(
    async (taskId: string, status: LabTaskStatus) => {
      if (!canEdit) return;
      setUpdatingTaskId(taskId);
      setError('');
      try {
        await tasksApi.updateStatus(taskId, status);
        await loadTasks();
      } catch (error: unknown) {
        showError(getUserFacingError(error, tErrors, t('errorUpdateTask')));
      } finally {
        setUpdatingTaskId(null);
      }
    },
    [canEdit, loadTasks, setError, showError, t, tErrors],
  );

  const filterSelectClass = `${FORM_SELECT_CLASS} w-full rounded-md px-2 py-1.5 text-sm`;

  const sortHintKey = useMemo(() => {
    switch (sortBy) {
      case 'clinic':
        return 'groupingOffClinic';
      case 'patient':
        return 'groupingOffPatient';
      case 'prosthesis':
        return 'groupingOffProsthesis';
      case 'taskType':
        return 'groupingOffTaskType';
      case 'status':
        return 'groupingOffStatus';
      default:
        return null;
    }
  }, [sortBy]);

  if (!isAuthReady) {
    return <div className="text-sm text-text-muted">{t('loading')}</div>;
  }

  if (!canView) {
    return (
      <div className="surface-card p-6 max-w-xl">
        <h2 className="text-lg font-semibold text-text-primary">{t('noPermissionTitle')}</h2>
        <p className="text-sm text-text-secondary mt-2">{t('noPermissionBody')}</p>
      </div>
    );
  }

  return (
    <div className="space-y-4">
      <header className="space-y-1">
        <h1 className="text-xl sm:text-2xl font-semibold text-text-primary">{t('title')}</h1>
        <p className="text-sm text-text-secondary">{t('subtitle')}</p>
      </header>

      <section className="surface-card p-3 space-y-3">
        <SearchBar
          embedded
          value={search}
          onChange={(v) => {
            setSearch(v);
            setPage(1);
          }}
          placeholder={t('searchPlaceholder')}
        />
        <div className="grid gap-2 sm:grid-cols-2 lg:grid-cols-4">
          <label className="space-y-1">
            <span className="text-xs text-text-muted">{t('filterClinic')}</span>
            <select
              value={clinicId}
              onChange={(e) => {
                setClinicId(e.target.value);
                setPage(1);
              }}
              className={filterSelectClass}
            >
              <option value="">{t('filterClinicAll')}</option>
              {filterOptions.clinics.map((c) => (
                <option key={c.id} value={c.id}>
                  {c.name}
                </option>
              ))}
            </select>
          </label>
          <label className="space-y-1">
            <span className="text-xs text-text-muted">{t('filterStatus')}</span>
            <select
              value={statusFilter}
              onChange={(e) => {
                setStatusFilter(e.target.value as '' | LabTaskStatus);
                setPage(1);
              }}
              className={filterSelectClass}
            >
              <option value="">{t('filterStatusAll')}</option>
              {statusOptions.map((opt) => (
                <option key={opt.value} value={opt.value}>
                  {opt.label}
                </option>
              ))}
            </select>
          </label>
          <label className="space-y-1">
            <span className="text-xs text-text-muted">{t('filterStepCompleted')}</span>
            <select
              value={stepCompleted}
              onChange={(e) => {
                setStepCompleted(e.target.value);
                setPage(1);
              }}
              className={filterSelectClass}
            >
              <option value="">{t('filterStepCompletedAll')}</option>
              {filterOptions.workflowSteps.map((step) => (
                <option key={step.code} value={step.code}>
                  {step.label}
                </option>
              ))}
            </select>
          </label>
          <label className="space-y-1">
            <span className="text-xs text-text-muted">{t('sortBy')}</span>
            <div className="flex gap-1.5">
              <select
                value={sortBy}
                onChange={(e) => setSortBy(e.target.value as TaskSortField)}
                className={`${filterSelectClass} min-w-0 flex-1`}
              >
                <option value="date">{t('sortDate')}</option>
                <option value="clinic">{t('sortClinic')}</option>
                <option value="patient">{t('sortPatient')}</option>
                <option value="prosthesis">{t('sortProsthesis')}</option>
                <option value="taskType">{t('sortTaskType')}</option>
              </select>
              <select
                value={sortDir}
                onChange={(e) => setSortDir(e.target.value as 'asc' | 'desc')}
                className={`${FORM_SELECT_CLASS} w-14 shrink-0 rounded-md px-2 py-1.5 text-sm`}
                aria-label={t('sortDirection')}
              >
                <option value="desc">↓</option>
                <option value="asc">↑</option>
              </select>
            </div>
          </label>
        </div>
        {groupingDisabled && sortHintKey ? (
          <p className="text-[11px] text-text-muted">{t(sortHintKey)}</p>
        ) : null}
      </section>

      <section className="surface-card min-h-[280px]">
        {loading && tasks.length === 0 ? (
          <p className="p-3 text-sm text-text-muted">{t('loading')}</p>
        ) : tasks.length === 0 ? (
          <p className="p-3 text-sm text-text-muted">{t('emptyList')}</p>
        ) : displayModel.mode === 'grouped' ? (
          <div className="divide-y divide-border">
            {displayModel.cases.map((caseGroup) => (
              <section key={caseGroup.labCaseId} className="border-b border-border last:border-b-0">
                <TaskCaseGroupHeader caseGroup={caseGroup} locale={locale} />
                {caseGroup.prosthesisGroups.map((prosthesisGroup) => (
                  <div
                    key={prosthesisGroup.key}
                    className="border-t border-border/50 first:border-t-0"
                  >
                    <TaskProsthesisGroupHeader
                      group={prosthesisGroup}
                      prosthesisCatalog={prosthesisCatalog}
                    />
                    <ul>
                      {prosthesisGroup.tasks.map((task) => (
                        <TaskRow
                          key={task.id}
                          task={task}
                          locale={locale}
                          flatMode={false}
                          canEdit={canEdit}
                          statusOptions={statusOptions}
                          updatingTaskId={updatingTaskId}
                          commentsOpen={expandedCommentsTaskId === task.id}
                          prosthesisCatalog={prosthesisCatalog}
                          onStatusUpdate={(id, status) => void handleStatusUpdate(id, status)}
                          onToggleComments={(id) =>
                            setExpandedCommentsTaskId((prev) => (prev === id ? null : id))
                          }
                          onCommentError={showError}
                        />
                      ))}
                    </ul>
                  </div>
                ))}
              </section>
            ))}
          </div>
        ) : (
          <ul className="divide-y divide-border">
            {displayModel.tasks.map((task) => (
              <TaskRow
                key={task.id}
                task={task}
                locale={locale}
                flatMode
                canEdit={canEdit}
                statusOptions={statusOptions}
                updatingTaskId={updatingTaskId}
                commentsOpen={expandedCommentsTaskId === task.id}
                prosthesisCatalog={prosthesisCatalog}
                onStatusUpdate={(id, status) => void handleStatusUpdate(id, status)}
                onToggleComments={(id) =>
                  setExpandedCommentsTaskId((prev) => (prev === id ? null : id))
                }
                onCommentError={showError}
              />
            ))}
          </ul>
        )}
      </section>

      {pagination.totalPages > 1 && (
        <div className="flex items-center justify-between gap-3 flex-wrap">
          <p className="text-sm text-text-muted">
            {t('pageSummary', {
              page: pagination.page,
              totalPages: pagination.totalPages,
              total: pagination.total,
            })}
          </p>
          <div className="flex gap-2">
            <Button
              type="button"
              variant="secondary"
              disabled={page <= 1 || loading}
              onClick={() => setPage((p) => Math.max(1, p - 1))}
            >
              ←
            </Button>
            <Button
              type="button"
              variant="secondary"
              disabled={page >= pagination.totalPages || loading}
              onClick={() => setPage((p) => p + 1)}
            >
              →
            </Button>
          </div>
        </div>
      )}
    </div>
  );
}