import { AnimatePresence, motion } from "framer-motion";
import { useCallback, useEffect, useRef, useState } from "react";
import { useNavigate, useSearchParams } from "react-router-dom";
import { useAuth } from "../context/AuthContext";
import { api } from "../lib/api";
import { compactNumber } from "../lib/format";
import type { OwnerStats, ShortLink } from "../lib/types";
import { UrlCard } from "../components/UrlCard";
import { UrlRow } from "../components/UrlRow";
import { Pagination } from "../components/Pagination";
import { PinManager } from "../components/PinManager";
import { EditLinkModal } from "../components/EditLinkModal";
import { QrModal } from "../components/QrModal";
import { Button } from "../components/ui/Button";
import { useToast } from "../components/ui/Toast";
import { Search, X, Plus } from "../components/icons";

type View = "comfortable" | "compact";
const PAGE_SIZE: Record<View, number> = { comfortable: 5, compact: 8 };

function useDebouncedValue<T>(value: T, delay: number): T {
  const [debounced, setDebounced] = useState(value);
  useEffect(() => {
    const t = setTimeout(() => setDebounced(value), delay);
    return () => clearTimeout(t);
  }, [value, delay]);
  return debounced;
}

function ViewToggle({ view, onChange }: { view: View; onChange: (v: View) => void }) {
  const opts: { value: View; label: string; rows: number }[] = [
    { value: "comfortable", label: "Comfortable view", rows: 2 },
    { value: "compact", label: "Compact view", rows: 3 },
  ];
  return (
    <div className="flex shrink-0 gap-0.5 rounded-xl bg-surface-2 p-1">
      {opts.map((o) => (
        <button
          key={o.value}
          onClick={() => onChange(o.value)}
          aria-label={o.label}
          aria-pressed={view === o.value}
          className={`press focusable grid h-8 w-9 place-items-center rounded-lg ${
            view === o.value
              ? "bg-surface text-ink shadow-[0_1px_2px_rgba(0,0,0,0.08),0_0_0_1px_var(--line)]"
              : "text-muted hover:text-ink"
          }`}
        >
          <svg width="15" height="15" viewBox="0 0 15 15" fill="none" stroke="currentColor" strokeWidth="1.5">
            {Array.from({ length: o.rows }).map((_, i) => (
              <rect
                key={i}
                x="2"
                y={2 + i * (11 / o.rows)}
                width="11"
                height={11 / o.rows - 1.5}
                rx="1"
              />
            ))}
          </svg>
        </button>
      ))}
    </div>
  );
}

export function Dashboard() {
  const { user, loading: authLoading } = useAuth();
  const navigate = useNavigate();
  const toast = useToast();

  const [view, setView] = useState<View>(
    () => (localStorage.getItem("snip-view") as View) || "comfortable",
  );
  const [searchParams, setSearchParams] = useSearchParams();
  const [pinTarget, setPinTarget] = useState<ShortLink | null>(null);
  const [editTarget, setEditTarget] = useState<ShortLink | null>(null);
  const [qrTarget, setQrTarget] = useState<ShortLink | null>(null);

  // Server-driven page + aggregate stats (the client never loads all links).
  const [pageData, setPageData] = useState<{ items: ShortLink[]; total: number } | null>(null);
  const [stats, setStats] = useState<OwnerStats | null>(null);

  // Search + page live in the URL (?q=&page=) so they survive a refresh / share.
  const query = searchParams.get("q") ?? "";
  const debouncedQuery = useDebouncedValue(query, 300);
  const rawPage = parseInt(searchParams.get("page") ?? "1", 10);
  const requestedPage = Number.isFinite(rawPage) && rawPage > 0 ? rawPage : 1;
  const pageSize = PAGE_SIZE[view];

  useEffect(() => {
    if (!authLoading && !user) navigate("/login");
  }, [authLoading, user, navigate]);

  useEffect(() => {
    localStorage.setItem("snip-view", view);
  }, [view]);

  // Fetch the current page from the API (debounced search, server pagination).
  const reqId = useRef(0);
  const loadPage = useCallback(async () => {
    if (!user) return;
    const id = ++reqId.current;
    const res = await api.listLinks({
      page: requestedPage,
      pageSize,
      q: debouncedQuery.trim() || undefined,
    });
    if (id === reqId.current) {
      setPageData({ items: res.items, total: res.total });
    }
  }, [user, requestedPage, pageSize, debouncedQuery]);

  const loadStats = useCallback(async () => {
    if (!user) return;
    setStats(await api.stats());
  }, [user]);

  useEffect(() => {
    loadPage();
  }, [loadPage]);
  useEffect(() => {
    loadStats();
  }, [loadStats]);

  const pageCount = pageData ? Math.max(1, Math.ceil(pageData.total / pageSize)) : 1;
  const safePage = Math.min(requestedPage, pageCount);

  // Keep the URL honest if it points past the last page (deletes, ?page=99…).
  useEffect(() => {
    if (pageData && requestedPage > pageCount) {
      const next = new URLSearchParams(searchParams);
      if (pageCount <= 1) next.delete("page");
      else next.set("page", String(pageCount));
      setSearchParams(next, { replace: true });
    }
  }, [pageData, requestedPage, pageCount, searchParams, setSearchParams]);

  function updateSearch(q: string) {
    const next = new URLSearchParams(searchParams);
    if (q) next.set("q", q);
    else next.delete("q");
    next.delete("page"); // a new search jumps back to page 1
    setSearchParams(next, { replace: true });
  }

  function changeView(v: View) {
    setView(v);
    const next = new URLSearchParams(searchParams);
    next.delete("page"); // page sizes differ between views
    setSearchParams(next, { replace: true });
  }

  function goToPage(p: number) {
    const next = new URLSearchParams(searchParams);
    if (p <= 1) next.delete("page");
    else next.set("page", String(p));
    setSearchParams(next);
    window.scrollTo({ top: 0, behavior: "smooth" });
  }

  // Hold-to-delete already asked for intent, so remove the row immediately
  // and reconcile with the server after.
  async function deleteLink(link: ShortLink) {
    setPageData((pd) =>
      pd ? { items: pd.items.filter((l) => l.id !== link.id), total: pd.total - 1 } : pd,
    );
    try {
      await api.deleteLink(link.id);
      toast(`Deleted ${link.code}`, "info");
    } catch {
      toast("Couldn't delete that link", "error");
    }
    await Promise.all([loadPage(), loadStats()]);
  }

  // "/" jumps to search from anywhere on the page.
  const searchRef = useRef<HTMLInputElement>(null);
  useEffect(() => {
    function onKey(e: KeyboardEvent) {
      const t = e.target as HTMLElement;
      if (e.key !== "/" || t.closest("input, textarea, [contenteditable]")) return;
      e.preventDefault();
      searchRef.current?.focus();
    }
    window.addEventListener("keydown", onKey);
    return () => window.removeEventListener("keydown", onKey);
  }, []);

  // Edit / PIN: patch the row in place (totals are unaffected).
  function applyUpdate(updated: ShortLink, message: string) {
    setPageData((pd) =>
      pd
        ? { ...pd, items: pd.items.map((l) => (l.id === updated.id ? { ...l, ...updated } : l)) }
        : pd,
    );
    toast(message, "success");
  }

  const items = pageData?.items ?? [];
  const total = pageData?.total ?? 0;
  const totalLinks = stats?.totalLinks ?? 0;

  const statTiles = [
    { label: "Active links", value: compactNumber(totalLinks) },
    { label: "Total clicks", value: compactNumber(stats?.totalClicks ?? 0) },
    {
      label: "Clicks this week",
      value: `+${compactNumber(stats?.weekClicks ?? 0)}`,
      accent: true,
    },
  ];

  const hasAnyLinks = totalLinks > 0;

  return (
    <div className="mx-auto max-w-4xl px-4 pb-24 pt-8">
      {/* header */}
      <div className="flex flex-wrap items-end justify-between gap-3">
        <div>
          <h1 className="text-2xl font-semibold tracking-[-0.02em] text-ink sm:text-[28px]">
            Links
          </h1>
        </div>
        <Button size="md" onClick={() => navigate("/")}>
          <Plus size={16} /> New link
        </Button>
      </div>

      {/* stat tiles */}
      <div className="card mt-6 grid grid-cols-3 divide-x divide-[var(--line)]">
        {statTiles.map((s) => (
          <div key={s.label} className="px-4 py-3.5 sm:px-5 sm:py-4">
            <p className="text-[12px] text-muted">{s.label}</p>
            <p
              className={`mt-0.5 text-xl font-semibold tabular-nums tracking-[-0.02em] sm:text-2xl ${
                s.accent ? "text-accent" : "text-ink"
              }`}
            >
              {stats ? s.value : <span className="text-[var(--ring)]">—</span>}
            </p>
          </div>
        ))}
      </div>

      {/* toolbar: search + view toggle */}
      {hasAnyLinks && (
        <div className="mt-6 flex items-center gap-2.5">
          <div className="field flex h-10 flex-1 items-center gap-2 px-3">
            <Search size={16} className="shrink-0 text-muted" />
            <input
              ref={searchRef}
              value={query}
              onChange={(e) => updateSearch(e.target.value)}
              placeholder="Search links…"
              aria-label="Search links"
              className="h-full w-full bg-transparent text-[16px] text-ink outline-none placeholder:text-muted sm:text-sm"
            />
            {!query && (
              <kbd className="hidden h-5 shrink-0 place-items-center rounded border border-line px-1.5 text-[11px] text-muted sm:grid">
                /
              </kbd>
            )}
            {query && (
              <button
                onClick={() => updateSearch("")}
                aria-label="Clear search"
                className="press focusable grid h-6 w-6 shrink-0 place-items-center rounded-md text-muted hover:bg-surface-2 hover:text-ink"
              >
                <X size={14} />
              </button>
            )}
          </div>
          <ViewToggle view={view} onChange={changeView} />
        </div>
      )}

      {/* result meta */}
      {hasAnyLinks && (
        <p className="mt-3 px-0.5 text-xs tabular-nums text-muted">
          {query ? (
            <>
              <span className="font-medium text-ink">{total}</span> of {totalLinks}{" "}
              {totalLinks === 1 ? "link" : "links"} match “{query}”
            </>
          ) : (
            <>
              Showing <span className="font-medium text-ink">{items.length}</span> of{" "}
              {totalLinks} {totalLinks === 1 ? "link" : "links"}
            </>
          )}
        </p>
      )}

      {/* list */}
      <div className="mt-4">
        {pageData === null ? (
          <div className="space-y-3">
            {[0, 1, 2].map((i) => (
              <div
                key={i}
                className="card animate-pulse opacity-60"
                style={{ animationDelay: `${i * 120}ms`, height: view === "compact" ? 64 : 172 }}
              />
            ))}
          </div>
        ) : total === 0 && !debouncedQuery ? (
          <div className="card grid place-items-center gap-2 p-12 text-center">
            <p className="text-base font-semibold text-ink">No links yet</p>
            <p className="max-w-xs text-sm text-muted">
              Links you shorten while signed in show up here, with clicks per day.
            </p>
            <Button className="mt-2" onClick={() => navigate("/")}>
              Shorten a link
            </Button>
          </div>
        ) : total === 0 ? (
          <div className="card grid place-items-center gap-1.5 p-10 text-center">
            <p className="text-base font-semibold text-ink">No matches</p>
            <p className="text-sm text-muted">Nothing matches “{query}”.</p>
            <button
              onClick={() => updateSearch("")}
              className="focusable mt-1 rounded-lg text-sm font-medium text-ink underline underline-offset-2"
            >
              Clear search
            </button>
          </div>
        ) : (
          <>
            {/* Rows rise in (staggered) when a page loads, but not while typing a
                search — animation on every keystroke reads as lag. Deleting
                collapses the row so the ones below slide up instead of jumping. */}
            <div>
              <AnimatePresence initial={false}>
                {items.map((link, i) => {
                  const props = {
                    link,
                    onEdit: setEditTarget,
                    onDelete: deleteLink,
                    onDeleteTap: () => toast("Hold to delete", "info"),
                    onManagePin: setPinTarget,
                    onShowQr: setQrTarget,
                  };
                  return (
                    <motion.div
                      key={link.id}
                      exit={{ opacity: 0, height: 0, transition: { duration: 0.2, ease: [0.23, 1, 0.32, 1] } }}
                      className="overflow-hidden"
                    >
                      <div
                        className={`${view === "compact" ? "pb-2" : "pb-3"} ${query ? "" : "rise"}`}
                        style={{ animationDelay: `${i * 40}ms` }}
                      >
                        {view === "compact" ? <UrlRow {...props} /> : <UrlCard {...props} />}
                      </div>
                    </motion.div>
                  );
                })}
              </AnimatePresence>
            </div>

            <Pagination page={safePage} pageCount={pageCount} onPage={goToPage} />
          </>
        )}
      </div>

      <EditLinkModal
        link={editTarget}
        onClose={() => setEditTarget(null)}
        onSaved={(updated, message) => {
          applyUpdate(updated, message);
          setEditTarget(null);
        }}
      />

      <PinManager
        link={pinTarget}
        onClose={() => setPinTarget(null)}
        onSaved={(updated, message) => {
          applyUpdate(updated, message);
          setPinTarget(null);
        }}
      />

      <QrModal link={qrTarget} onClose={() => setQrTarget(null)} />
    </div>
  );
}