"use client";

import React from "react";
import Link from "next/link";
import { CalendarDays, RefreshCw } from "lucide-react";

import { getYears } from "@/lib/frontend/apiClient";
import { branchPath, yearPath } from "@/lib/frontend/routes";
import { sortNumericStringsDesc } from "@/lib/frontend/explorer/sorters";
import { mapExplorerError } from "@/lib/frontend/explorer/errorMapping";
import { buildLoginUrl, LOGIN_REASONS } from "@/lib/frontend/authRedirect";
import { useExplorerQuery } from "@/lib/frontend/hooks/useExplorerQuery";
import { useDebouncedVisibility } from "@/lib/frontend/hooks/useDebouncedVisibility";

import ExplorerBreadcrumbs from "@/components/explorer/breadcrumbs/ExplorerBreadcrumbs";
import ExplorerPageShell from "@/components/explorer/ExplorerPageShell";
import ExplorerSectionCard from "@/components/explorer/ExplorerSectionCard";
import ExplorerLoading from "@/components/explorer/states/ExplorerLoading";
import ExplorerEmpty from "@/components/explorer/states/ExplorerEmpty";
import ExplorerError from "@/components/explorer/states/ExplorerError";
import ExplorerNotFound from "@/components/explorer/states/ExplorerNotFound";

import ForbiddenView from "@/components/system/ForbiddenView";
import { Button } from "@/components/ui/button";

const LOADING_DELAY_MS = 300;

export default function YearsExplorer({ branch }) {
	const loadFn = React.useCallback(() => getYears(branch), [branch]);
	const { status, data, error, retry } = useExplorerQuery(loadFn, [loadFn]);

	const mapped = React.useMemo(() => mapExplorerError(error), [error]);

	const showLoadingUi = useDebouncedVisibility(status === "loading", {
		delayMs: LOADING_DELAY_MS,
		minVisibleMs: 0,
	});

	React.useEffect(() => {
		if (mapped?.kind !== "unauthenticated") return;

		const next =
			typeof window !== "undefined"
				? `${window.location.pathname}${window.location.search}`
				: branchPath(branch);

		window.location.replace(
			buildLoginUrl({ reason: LOGIN_REASONS.EXPIRED, next }),
		);
	}, [mapped?.kind, branch]);

	const breadcrumbsNode = <ExplorerBreadcrumbs branch={branch} />;

	const actions = (
		<Button variant="outline" size="sm" onClick={retry} title="Aktualisieren">
			<RefreshCw className="h-4 w-4" />
			Aktualisieren
		</Button>
	);

	if (showLoadingUi) {
		return (
			<ExplorerPageShell
				title="Jahre"
				description="Wählen Sie ein Jahr, um die Lieferscheine anzuzeigen."
				breadcrumbs={breadcrumbsNode}
				actions={actions}
			>
				<ExplorerSectionCard title="Verfügbare Jahre" description="Lade Daten…">
					<ExplorerLoading variant="grid" count={8} />
				</ExplorerSectionCard>
			</ExplorerPageShell>
		);
	}

	if (status === "loading") {
		return (
			<ExplorerPageShell
				title="Jahre"
				description="Wählen Sie ein Jahr, um die Lieferscheine anzuzeigen."
				breadcrumbs={breadcrumbsNode}
				actions={actions}
			>
				<div className="h-16" aria-hidden="true" />
			</ExplorerPageShell>
		);
	}

	if (status === "error" && mapped) {
		if (mapped.kind === "forbidden") {
			return <ForbiddenView attemptedBranch={branch} />;
		}

		if (mapped.kind === "notfound") {
			return (
				<ExplorerPageShell
					title="Jahre"
					description="Wählen Sie ein Jahr, um die Lieferscheine anzuzeigen."
					breadcrumbs={breadcrumbsNode}
					actions={actions}
				>
					<ExplorerNotFound branchRootHref={branchPath(branch)} />
				</ExplorerPageShell>
			);
		}

		if (mapped.kind === "unauthenticated") {
			return (
				<ExplorerPageShell
					title="Jahre"
					description="Sitzung abgelaufen — Weiterleitung zum Login…"
					breadcrumbs={breadcrumbsNode}
				>
					<div className="h-16" aria-hidden="true" />
				</ExplorerPageShell>
			);
		}

		return (
			<ExplorerPageShell
				title="Jahre"
				description="Wählen Sie ein Jahr, um die Lieferscheine anzuzeigen."
				breadcrumbs={breadcrumbsNode}
				actions={actions}
			>
				<ExplorerSectionCard title="Verfügbare Jahre" description="Fehler">
					<ExplorerError
						title={mapped.title}
						description={mapped.description}
						onRetry={retry}
					/>
				</ExplorerSectionCard>
			</ExplorerPageShell>
		);
	}

	const years = Array.isArray(data?.years) ? data.years : [];
	const sorted = sortNumericStringsDesc(years);

	return (
		<ExplorerPageShell
			title="Jahre"
			description="Wählen Sie ein Jahr, um die Lieferscheine anzuzeigen."
			breadcrumbs={breadcrumbsNode}
			actions={actions}
		>
			<ExplorerSectionCard
				title="Verfügbare Jahre"
				description={`Niederlassung ${branch}`}
				headerRight={
					<span className="rounded-md bg-muted px-2 py-1 text-xs text-muted-foreground">
						{sorted.length} Jahr{sorted.length === 1 ? "" : "e"}
					</span>
				}
			>
				{sorted.length === 0 ? (
					<ExplorerEmpty
						title="Keine Jahre gefunden"
						description="Für diese Niederlassung wurden keine Jahre gefunden."
						upHref={null}
					/>
				) : (
					<div className="grid grid-cols-2 gap-2 sm:grid-cols-3 md:grid-cols-4">
						{sorted.map((y) => (
							<Button
								key={y}
								variant="outline"
								className="w-full justify-start"
								asChild
							>
								<Link href={yearPath(branch, y)}>
									<CalendarDays className="h-4 w-4" />
									{y}
								</Link>
							</Button>
						))}
					</div>
				)}
			</ExplorerSectionCard>
		</ExplorerPageShell>
	);
}