import { useMemo, useState } from "react";
import { useTranslation } from "react-i18next";
import { ListTree } from "lucide-react";
import type { CategoryTreeNode } from "../../shared/types";
import type { OrphanCategory } from "../../utils/categoryHierarchy";
import CategoryCombobox from "../shared/CategoryCombobox";
import { buildParentOptions } from "./parentOptions";

interface Props {
  /** The orphan categories, one per group to reattach; `null` while the check runs. */
  orphans: OrphanCategory[] | null;
  /** The translated text of a refused reattachment, or of a check that failed. */
  error: string | null;
  /** The active categories, as the tree has them: names and parent choices. */
  categories: CategoryTreeNode[];
  isSaving: boolean;
  onReattach: (orphan: OrphanCategory, parentId: number | null) => void;
  onClose: () => void;
}

/** The value of the « Racine » option of each row's combobox. */
const ROOT = "";

/**
 * « Vérifier la hiérarchie » (#393): the orphan categories of the profile, one
 * row per group to reattach, each with its reason and a new parent. The root
 * is preselected; the other choices are those of the category form
 * (`buildParentOptions`, the row's category treated as the one being edited).
 * The service applies the rules again and may refuse (a parent that holds
 * transactions, for one): the translated refusal shows above the list.
 *
 * The comboboxes open their list in a portal (#429), so the scrolling list of
 * rows never cuts it.
 */
export default function HierarchyCheckModal({
  orphans,
  error,
  categories,
  isSaving,
  onReattach,
  onClose,
}: Props) {
  const { t } = useTranslation();
  /** The parent picked on each row, by orphan id; no entry means the root. */
  const [choices, setChoices] = useState<Record<number, number>>({});

  const optionsByOrphan = useMemo(() => {
    const byOrphan = new Map<number, CategoryTreeNode[]>();
    for (const orphan of orphans ?? []) {
      byOrphan.set(orphan.id, buildParentOptions(categories, { editingId: orphan.id }));
    }
    return byOrphan;
  }, [orphans, categories]);

  const rootOption = useMemo(() => [{ value: ROOT, label: t("categories.hierarchy.root") }], [t]);

  /** The row's parent: the one picked if it is still offered, else the root. */
  const choiceOf = (orphanId: number): number | null => {
    const picked = choices[orphanId];
    if (picked === undefined) return null;
    return optionsByOrphan.get(orphanId)?.some((c) => c.id === picked) ? picked : null;
  };

  const choose = (orphanId: number, parentId: number | null) => {
    setChoices((previous) => {
      const next = { ...previous };
      if (parentId === null) delete next[orphanId];
      else next[orphanId] = parentId;
      return next;
    });
  };

  const nameOf = (id: number): string => {
    const category = categories.find((c) => c.id === id);
    if (!category) return "—";
    return category.i18n_key ? t(category.i18n_key, { defaultValue: category.name }) : category.name;
  };

  return (
    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50">
      <div
        role="dialog"
        aria-modal="true"
        aria-label={t("categories.hierarchy.check")}
        className="bg-[var(--card)] rounded-xl border border-[var(--border)] shadow-lg p-6 max-w-2xl w-full mx-4 max-h-[85vh] flex flex-col"
      >
        <div className="flex items-center gap-3 mb-3">
          <div className="p-2 rounded-full bg-[var(--primary)]/10">
            <ListTree size={20} className="text-[var(--primary)]" />
          </div>
          <h2 className="text-lg font-semibold">{t("categories.hierarchy.check")}</h2>
        </div>
        <p className="text-sm text-[var(--muted-foreground)] mb-4">{t("categories.hierarchy.intro")}</p>

        {error && (
          <div role="alert" className="mb-4 p-3 rounded-lg bg-[var(--negative)]/10 text-[var(--negative)] text-sm">
            {error}
          </div>
        )}

        {orphans === null ? (
          error ? null : (
            <p className="text-sm text-[var(--muted-foreground)]">{t("categories.hierarchy.checking")}</p>
          )
        ) : orphans.length === 0 ? (
          <p className="text-sm font-medium">{t("categories.hierarchy.none")}</p>
        ) : (
          <>
            <p className="text-sm font-medium mb-2">{t("categories.hierarchy.count", { count: orphans.length })}</p>
            <ul className="flex-1 min-h-0 overflow-y-auto divide-y divide-[var(--border)]">
              {orphans.map((orphan) => {
                const name = nameOf(orphan.id);
                const choice = choiceOf(orphan.id);
                return (
                  <li key={orphan.id} className="py-3 flex flex-wrap items-center gap-3">
                    <div className="flex-1 min-w-[10rem]">
                      <p className="text-sm font-medium">{name}</p>
                      <p className="text-xs text-[var(--muted-foreground)]">
                        {t(`categories.hierarchy.reasons.${orphan.reason}`)}
                      </p>
                    </div>
                    <div className="w-56">
                      <CategoryCombobox
                        categories={optionsByOrphan.get(orphan.id) ?? []}
                        value={choice}
                        onChange={(id) => choose(orphan.id, id)}
                        extraOptions={rootOption}
                        activeExtra={choice === null ? ROOT : null}
                        onExtraSelect={() => choose(orphan.id, null)}
                        ariaLabel={t("categories.hierarchy.newParentFor", { name })}
                        compact
                      />
                    </div>
                    <button
                      type="button"
                      onClick={() => onReattach(orphan, choice)}
                      disabled={isSaving}
                      className="px-3 py-1.5 rounded-lg bg-[var(--primary)] text-white text-sm font-medium hover:opacity-90 disabled:opacity-50"
                    >
                      {t("categories.hierarchy.reattach")}
                    </button>
                  </li>
                );
              })}
            </ul>
          </>
        )}

        <div className="flex justify-end mt-4">
          <button
            type="button"
            onClick={onClose}
            className="px-4 py-2 text-sm rounded-lg border border-[var(--border)] hover:bg-[var(--muted)] transition-colors"
          >
            {t("common.close")}
          </button>
        </div>
      </div>
    </div>
  );
}