"use client";

import { useCallback, useEffect, useState } from "react";
import { api, type AdminShortUrl, type ShortUrlStats } from "@/lib/api";
import { usePagedList } from "@/lib/use-paged-list";
import { ListShell, EmptyRow } from "@/components/list-shell";
import { Table, THead, TR, TH, TD } from "@/components/ui/table";
import { fmtDate } from "@/lib/utils";
import { Clamp } from "@/components/ui/clamp";

export default function ShortUrlsPage() {
  // ── Stats ────────────────────────────────────────────────────────────────
  const [stats, setStats] = useState<ShortUrlStats | null>(null);
  const [from, setFrom] = useState("");
  const [to, setTo] = useState("");

  useEffect(() => {
    // Fetch once both custom dates are set, or once both are cleared (fixed
    // windows only). A half-filled range waits for the second date.
    const ready = (!!from && !!to) || (!from && !to);
    if (!ready) return;
    let cancelled = false;
    api
      .shortUrlStats(from || undefined, to || undefined)
      .then((s) => {
        if (!cancelled) setStats(s);
      })
      .catch(() => {
        /* leave the previous stats in place on error */
      });
    return () => {
      cancelled = true;
    };
  }, [from, to]);

  // ── Paginated list ─────────────────────────────────────────────────────────
  const [q, setQ] = useState("");
  const fetcher = useCallback(
    (limit: number, offset: number) => api.shortUrls(q, limit, offset),
    [q],
  );
  const list = usePagedList<AdminShortUrl>(fetcher, [q]);

  return (
    <div className="space-y-8">
      <section className="space-y-4">
        <div className="flex flex-wrap items-end justify-between gap-3">
          <h1 className="text-lg font-semibold text-foreground">
            Short URL stats
          </h1>
          {/* Custom date range (inclusive). Clearing both returns to the fixed
              windows below. */}
          <div className="flex items-end gap-2">
            <label className="flex flex-col text-xs text-muted-foreground">
              From
              <input
                type="date"
                value={from}
                max={to || undefined}
                onChange={(e) => setFrom(e.target.value)}
                className="mt-1 rounded-md border border-border bg-card px-2.5 py-1.5 text-sm text-foreground"
              />
            </label>
            <label className="flex flex-col text-xs text-muted-foreground">
              To
              <input
                type="date"
                value={to}
                min={from || undefined}
                onChange={(e) => setTo(e.target.value)}
                className="mt-1 rounded-md border border-border bg-card px-2.5 py-1.5 text-sm text-foreground"
              />
            </label>
            {(from || to) && (
              <button
                type="button"
                onClick={() => {
                  setFrom("");
                  setTo("");
                }}
                className="rounded-md px-2.5 py-1.5 text-sm text-muted-foreground hover:text-foreground"
              >
                Clear
              </button>
            )}
          </div>
        </div>

        <div className="grid grid-cols-1 gap-4 sm:grid-cols-2 lg:grid-cols-4">
          <StatCard label="Today" created={stats?.today.created} clicks={stats?.today.clicks} />
          <StatCard label="This week" created={stats?.week.created} clicks={stats?.week.clicks} />
          <StatCard label="This month" created={stats?.month.created} clicks={stats?.month.clicks} />
          <StatCard
            label="All time"
            created={stats?.total_urls}
            clicks={stats?.total_clicks}
          />
          {stats?.range && (
            <StatCard
              label={`Custom · ${from} → ${to}`}
              created={stats.range.created}
              clicks={stats.range.clicks}
              highlight
            />
          )}
        </div>
      </section>

      <ListShell
        title="Shortened URLs"
        total={list.total}
        searchPlaceholder="Search by code or target URL…"
        onQueryChange={setQ}
        list={list}
      >
        <Table>
          <THead>
            <TR>
              <TH>Code</TH>
              <TH>Target</TH>
              <TH>Type</TH>
              <TH>Clicks</TH>
              <TH>Status</TH>
              <TH>Created</TH>
            </TR>
          </THead>
          <tbody>
            {list.items.length === 0 && !list.loading ? (
              <EmptyRow cols={6} label="No shortened URLs found." />
            ) : (
              list.items.map((s) => (
                <TR key={s.code}>
                  <TD className="whitespace-nowrap font-mono text-xs">
                    {s.code}
                  </TD>
                  <TD className="max-w-md">
                    <a
                      href={s.long_url}
                      target="_blank"
                      rel="noopener noreferrer"
                      className="block text-primary hover:underline"
                    >
                      <Clamp>{s.long_url}</Clamp>
                    </a>
                  </TD>
                  <TD className="whitespace-nowrap text-muted-foreground">
                    {s.content_type || "—"}
                  </TD>
                  <TD className="whitespace-nowrap">
                    <span className="font-medium">
                      {s.click_count.toLocaleString()}
                    </span>
                    <span className="ml-1 text-xs text-muted-foreground">
                      ({s.human_click_count.toLocaleString()} human)
                    </span>
                  </TD>
                  <TD className="whitespace-nowrap">
                    <span
                      className={
                        s.disabled ? "text-destructive" : "text-foreground"
                      }
                    >
                      {s.disabled ? "Disabled" : "Active"}
                    </span>
                  </TD>
                  <TD className="whitespace-nowrap">{fmtDate(s.created_at)}</TD>
                </TR>
              ))
            )}
          </tbody>
        </Table>
      </ListShell>
    </div>
  );
}

function StatCard({
  label,
  created,
  clicks,
  highlight,
}: {
  label: string;
  created?: number;
  clicks?: number;
  highlight?: boolean;
}) {
  return (
    <div
      className={
        "rounded-xl border bg-card p-4 " +
        (highlight ? "border-primary/40" : "border-border")
      }
    >
      <div className="truncate text-xs font-medium uppercase tracking-wide text-muted-foreground">
        {label}
      </div>
      <div className="mt-2 grid grid-cols-2 gap-2">
        <div>
          <div className="text-2xl font-semibold text-foreground">
            {(created ?? 0).toLocaleString()}
          </div>
          <div className="text-xs text-muted-foreground">created</div>
        </div>
        <div>
          <div className="text-2xl font-semibold text-foreground">
            {(clicks ?? 0).toLocaleString()}
          </div>
          <div className="text-xs text-muted-foreground">clicks</div>
        </div>
      </div>
    </div>
  );
}