"use client";

/**
 * "Termine" — the visits half of the checkups page.
 *
 * Two lists rather than one, and the split is the server's: upcoming reads
 * soonest-first, past reads newest-first, and the API resolves both so the
 * ordering lives in one place. A client that split and re-sorted one array
 * would be the second place it lives.
 *
 * No new nav entry and no new route. `/checkups` already owns exactly the right
 * sentence — when do I have to do what, where — and is deliberately not module
 * gated, which is also why a visit carries no module key of its own.
 */
import { CalendarClock, ContactRound, History, Plus } from "lucide-react";
import Link from "next/link";
import { Fragment, useState } from "react";

import { SinceLastVisit } from "@/components/day/since-last-visit";
import { Button } from "@/components/ui/button";
import { EmptyState } from "@/components/ui/empty-state";
import { PageHeader } from "@/components/ui/page-header";
import { QueryErrorCard } from "@/components/ui/query-error-card";
import { SectionHeading } from "@/components/ui/section-heading";
import { Skeleton } from "@/components/ui/skeleton";
import { useDeepLinkedRecord } from "@/hooks/use-deep-linked-record";
import { useRecordCapabilities } from "@/hooks/use-record-capabilities";
import { useEncounters, type Encounter } from "@/hooks/use-encounters";
import { apiGet } from "@/lib/api/api-fetch";
import { useTranslations } from "@/lib/i18n/context";
import { EncounterSheet } from "./encounter-sheet";
import { VisitCard } from "./visit-card";

/** One visit by id, for a link to a visit older than the list reads. */
function fetchVisit(id: string): Promise<Encounter | null> {
  return apiGet<Encounter>(`/api/encounters/${encodeURIComponent(id)}`).catch(
    () => null,
  );
}

export function VisitsSection({ enabled = true }: { enabled?: boolean }) {
  const { t } = useTranslations();
  const { canWriteDomain, canManageDomain } = useRecordCapabilities();
  // `POST /api/encounters` answers at WRITE under the profile section; the
  // edit and the delete behind the row are both MANAGE. Only the add was
  // asked, so every row stayed tappable into a sheet whose Save and Delete
  // the server refuses.
  const canAddVisit = canWriteDomain("profile");
  const canManageVisits = canManageDomain("profile");
  const list = useEncounters(enabled);

  // `null` closed, `"new"` create, a row edits it.
  const [editing, setEditing] = useState<Encounter | "new" | null>(null);
  const [session, setSession] = useState(0);
  const openSheet = (target: Encounter | "new") => {
    setEditing(target);
    setSession((n) => n + 1);
  };

  const upcoming = list.data?.upcoming ?? [];
  const past = list.data?.past ?? [];

  // `?visit=<id>` — a document's link chip names the visit it is filed
  // against. Scroll to it, and open it for someone who may edit it.
  useDeepLinkedRecord({
    param: "visit",
    records: list.data ? [...upcoming, ...past] : undefined,
    anchorAttribute: "data-encounter-id",
    open: canManageVisits ? openSheet : undefined,
    // The list reads the newest hundred of each arm; a search hit can name an
    // older visit, which is read on its own.
    resolve: fetchVisit,
  });
  const empty = upcoming.length === 0 && past.length === 0;
  // The last visit that took place: the start of the visit preparation.
  const lastDone = past.find((encounter) => encounter.status === "DONE");

  const addButton = canAddVisit ? (
    <Button
      type="button"
      className="min-h-11"
      data-slot="visits-add"
      onClick={() => openSheet("new")}
    >
      <Plus className="size-4" aria-hidden />
      {t("encounters.add")}
    </Button>
  ) : null;

  return (
    <section aria-labelledby="visits-section-title" className="space-y-4">
      <PageHeader
        titleId="visits-section-title"
        title={t("encounters.sectionTitle")}
        description={t("encounters.sectionDescription")}
        actions={
          <>
            <Button asChild variant="outline" className="min-h-11">
              <Link href="/checkups/practitioners">
                <ContactRound className="size-4" aria-hidden />
                {t("practitioners.linkLabel")}
              </Link>
            </Button>
            {/* The empty state carries the add action while there is no
                visit. */}
            {!list.isPending && !list.isError && empty ? null : addButton}
          </>
        }
      />

      {list.isError ? (
        <QueryErrorCard
          error={list.error}
          title={t("encounters.loadError")}
          onRetry={() => void list.refetch()}
        />
      ) : list.isPending ? (
        <div className="space-y-2">
          {Array.from({ length: 3 }, (_, index) => (
            <Skeleton key={index} className="h-20 w-full rounded-xl" />
          ))}
        </div>
      ) : empty ? (
        <EmptyState
          icon={<CalendarClock className="size-6" aria-hidden />}
          title={t("encounters.emptyTitle")}
          description={t("encounters.emptyDescription")}
          action={addButton ?? undefined}
        />
      ) : (
        <div className="space-y-6">
          {upcoming.length > 0 ? (
            <div className="space-y-2" data-slot="visits-upcoming">
              <SectionHeading
                icon={CalendarClock}
                title={t("encounters.upcomingHeading")}
              />
              {upcoming.map((encounter, i) => (
                <Fragment key={encounter.id}>
                  <VisitCard
                    encounter={encounter}
                    onOpen={canManageVisits ? openSheet : undefined}
                  />
                  {/* v1.42 — the next appointment carries what happened
                      since the last one, each date opening its day. The
                      component draws its own card, and none when it has
                      nothing to list. */}
                  {i === 0 && lastDone ? (
                    <SinceLastVisit next={encounter} last={lastDone} />
                  ) : null}
                </Fragment>
              ))}
            </div>
          ) : null}

          {past.length > 0 ? (
            <div className="space-y-2" data-slot="visits-past">
              <SectionHeading
                icon={History}
                title={t("encounters.pastHeading")}
              />
              {past.map((encounter) => (
                <VisitCard
                  key={encounter.id}
                  encounter={encounter}
                  onOpen={canManageVisits ? openSheet : undefined}
                />
              ))}
            </div>
          ) : null}
        </div>
      )}

      {/* `key` changes on every open, so the sheet remounts with a fresh draft
          instead of copying props into state from an effect. It stays mounted
          while closing, which is what keeps the exit animation. */}
      <EncounterSheet
        key={session}
        open={editing !== null}
        onOpenChange={(open) => {
          if (!open) setEditing(null);
        }}
        encounter={editing === "new" ? null : editing}
      />
    </section>
  );
}