import { useEffect, useState } from "react";
import { useTranslation } from "react-i18next";
import { ChevronLeft, ChevronRight } from "lucide-react";
import { hasPagerContent, pageCount } from "./pagerContent";
import { FocusSafeButton } from "./FocusSafeButton";
import SegmentedToggle from "./SegmentedToggle";

// The Prev / page-input / Next + "N per page" cluster, lifted out of DataTable so a non-table view
// (the channel manager's card layout) can paginate the same way. Controlled: the caller owns page +
// size and slices its own rows; this only renders the controls and reports changes. `sizeLabel` lets
// the caller say "Rows per page" or "Cards per page". Returns null when there's nothing to page.

export default function Pager({
  page,
  size,
  total,
  pageSizeOptions,
  onPageChange,
  onSizeChange,
  sizeLabel,
}: {
  /** Current page (0-based). */
  page: number;
  /** Page size; `<= 0` means "All" (one page). */
  size: number;
  /** Total item count across all pages. */
  total: number;
  pageSizeOptions: number[];
  onPageChange: (page: number) => void;
  onSizeChange: (size: number) => void;
  sizeLabel: string;
}) {
  const { t } = useTranslation();
  const totalPages = pageCount(total, size);
  const safePage = Math.min(page, totalPages - 1);

  // Local text for the editable "jump to page" box (committed on Enter/blur).
  const [pageInput, setPageInput] = useState(String(safePage + 1));
  useEffect(() => setPageInput(String(safePage + 1)), [safePage]);

  // Turning the page — or resizing it, which re-slices from a different first item — swaps the whole
  // list, so put the reader at its top; landing mid-list in a page you haven't seen is disorienting.
  // The page scroller is the app's <main> (PageScroller documents itself as the ONE scroller; the
  // same implicit contract BackToTop and lib/listPaging's scrollParent (VirtualGrid, listNav) already rely on).
  function scrollListToTop() {
    document.querySelector("main")?.scrollTo({ top: 0 });
  }
  function goToPage(p: number) {
    onPageChange(p);
    scrollListToTop();
  }
  function commitPageInput() {
    const n = parseInt(pageInput, 10);
    if (!isNaN(n)) goToPage(Math.min(totalPages - 1, Math.max(0, n - 1)));
    else setPageInput(String(safePage + 1));
  }

  if (!hasPagerContent(total, size)) return null;
  return (
    <div className="flex items-center gap-3 flex-wrap">
      {totalPages > 1 && (
        <div className="flex items-center gap-2">
          <FocusSafeButton
            onClick={() => goToPage(Math.max(0, safePage - 1))}
            disabled={safePage === 0}
            className="glass-card glass-hover flex items-center gap-1 px-3 py-1.5 rounded-lg disabled:opacity-40 transition"
          >
            <ChevronLeft className="w-4 h-4" />
            {t("datatable.pager.prev")}
          </FocusSafeButton>
          <span className="text-muted flex items-center gap-1.5">
            {t("datatable.pager.pageLabel")}
            <input
              type="number"
              min={1}
              max={totalPages}
              value={pageInput}
              onChange={(e) => setPageInput(e.target.value)}
              onBlur={commitPageInput}
              onKeyDown={(e) => e.key === "Enter" && commitPageInput()}
              aria-label={t("datatable.pager.pageLabel")}
              className="w-14 bg-surface border border-border rounded-md px-1.5 py-1 text-xs text-center tabular-nums focus:outline-hidden focus:ring-2 focus:ring-accent/40"
            />
            {t("datatable.pager.ofTotal", { total: totalPages })}
          </span>
          <FocusSafeButton
            onClick={() => goToPage(Math.min(totalPages - 1, safePage + 1))}
            disabled={safePage >= totalPages - 1}
            className="glass-card glass-hover flex items-center gap-1 px-3 py-1.5 rounded-lg disabled:opacity-40 transition"
          >
            {t("datatable.pager.next")}
            <ChevronRight className="w-4 h-4" />
          </FocusSafeButton>
        </div>
      )}
      {total > 0 && (
        <div className="flex items-center gap-2 text-muted">
          <span aria-hidden="true">{sizeLabel}</span>
          {/* A handful of fixed sizes plus "All": segmented, the house control for a short fixed set. */}
          <SegmentedToggle
            ariaLabel={sizeLabel}
            value={String(size)}
            onChange={(v) => {
              onSizeChange(Number(v));
              scrollListToTop();
            }}
            options={[
              ...pageSizeOptions.map((n) => ({ value: String(n), label: String(n) })),
              { value: "0", label: t("datatable.all") },
            ]}
          />
        </div>
      )}
    </div>
  );
}