"use client";

/**
 * CaseLibraryBrowser — filterable, sortable, searchable view of every
 * narrated case file. Powers /bureau.
 *
 * The previous /bureau dumped 80+ cards in a flat grid; the audit flagged
 * that as the hardest page to navigate. Now the reader gets:
 *
 *   - A search input that matches title and opening (substring, both
 *     languages).
 *   - Agency chips with live counts (DoW, FBI, NASA, …, Other).
 *   - Decade chips (1940s … 2020s).
 *   - Sort dropdown: most recent / oldest first / newest first / A–Z.
 *
 * State is URL-synced so a filtered view can be linked or bookmarked.
 * Pure client filter — all 84-ish cases are passed in once and filtered in
 * memory. Cheap.
 */
import Link from "next/link";
import { useMemo, useState, useEffect } from "react";
import { useRouter, useSearchParams } from "next/navigation";
import { Search, X } from "lucide-react";
import type { Agency, CaseFile } from "@/lib/cases";

type SortKey = "recent" | "year-desc" | "year-asc" | "az";

const COPY = {
  "pt-br": {
    search_placeholder: "Buscar por título ou texto…",
    clear: "Limpar busca",
    sort_label: "Ordenar",
    sorts: {
      recent: "Mais recentes",
      "year-desc": "Ano: ↓ recente",
      "year-asc":  "Ano: ↑ antigo",
      az: "A–Z",
    } as Record<SortKey, string>,
    all: "Todos",
    no_decade: "sem data",
    showing: (shown: number, total: number) =>
      `Mostrando ${shown} de ${total} casos`,
    no_results: "Nenhum caso bate com esses filtros.",
    reset: "Limpar filtros",
    open_case: "ler o caso completo →",
  },
  en: {
    search_placeholder: "Search by title or text…",
    clear: "Clear search",
    sort_label: "Sort",
    sorts: {
      recent: "Most recent",
      "year-desc": "Year: newest first",
      "year-asc":  "Year: oldest first",
      az: "A–Z",
    } as Record<SortKey, string>,
    all: "All",
    no_decade: "undated",
    showing: (shown: number, total: number) =>
      `Showing ${shown} of ${total} cases`,
    no_results: "No case matches these filters.",
    reset: "Clear filters",
    open_case: "read the full case file →",
  },
} as const;

const AGENCY_ORDER: Agency[] = ["DoW", "FBI", "NASA", "CIA", "DoE", "ODNI", "DoD", "Other"];

export function CaseLibraryBrowser({
  locale,
  cases,
}: { locale: "pt-br" | "en"; cases: CaseFile[] }) {
  const t = COPY[locale];
  const router = useRouter();
  const params = useSearchParams();

  // Initial state from URL params.
  const [q, setQ] = useState(params.get("q") ?? "");
  const [agency, setAgency] = useState<Agency | null>((params.get("agency") as Agency) ?? null);
  const [decade, setDecade] = useState<string | null>(params.get("decade"));
  const [sort, setSort] = useState<SortKey>((params.get("sort") as SortKey) ?? "recent");

  // Push state to URL (replaceState) so the browser bar stays canonical.
  useEffect(() => {
    const sp = new URLSearchParams();
    if (q.trim()) sp.set("q", q.trim());
    if (agency) sp.set("agency", agency);
    if (decade) sp.set("decade", decade);
    if (sort && sort !== "recent") sp.set("sort", sort);
    const qs = sp.toString();
    router.replace(qs ? `/bureau?${qs}` : "/bureau", { scroll: false });
  }, [q, agency, decade, sort, router]);

  const agencyCounts = useMemo(() => {
    const m = new Map<Agency, number>();
    for (const c of cases) m.set(c.agency, (m.get(c.agency) ?? 0) + 1);
    return m;
  }, [cases]);

  const decadeCounts = useMemo(() => {
    const m = new Map<string, number>();
    for (const c of cases) {
      const d = c.decade ?? "—";
      m.set(d, (m.get(d) ?? 0) + 1);
    }
    return m;
  }, [cases]);

  const decadeKeys = useMemo(() => {
    const ks = [...decadeCounts.keys()];
    // Sort 1940s, 1950s, … 2020s, "—" last.
    return ks.sort((a, b) => {
      if (a === "—") return 1;
      if (b === "—") return -1;
      return parseInt(a, 10) - parseInt(b, 10);
    });
  }, [decadeCounts]);

  const filtered = useMemo(() => {
    const qq = q.trim().toLowerCase();
    let r = cases.filter((c) => {
      if (agency && c.agency !== agency) return false;
      if (decade) {
        const d = c.decade ?? "—";
        if (d !== decade) return false;
      }
      if (qq) {
        const inEn = c.topic.toLowerCase().includes(qq);
        const inPt = (c.topic_pt_br ?? "").toLowerCase().includes(qq);
        const inOp = c.opening.toLowerCase().includes(qq);
        if (!(inEn || inPt || inOp)) return false;
      }
      return true;
    });
    if (sort === "year-desc") {
      r = [...r].sort((a, b) => (b.year ?? -Infinity) - (a.year ?? -Infinity));
    } else if (sort === "year-asc") {
      r = [...r].sort((a, b) => (a.year ?? Infinity) - (b.year ?? Infinity));
    } else if (sort === "az") {
      const key = (c: CaseFile) => (locale === "pt-br" ? (c.topic_pt_br ?? c.topic) : c.topic).toLowerCase();
      r = [...r].sort((a, b) => key(a).localeCompare(key(b)));
    } // recent: cases are pre-sorted by mtime
    return r;
  }, [cases, q, agency, decade, sort, locale]);

  const hasActiveFilter = q.trim() !== "" || agency !== null || decade !== null;

  return (
    <div>
      {/* Search + sort row */}
      <div className="flex flex-col md:flex-row md:items-center gap-3 mb-4">
        <div className="relative flex-1">
          <span className="pointer-events-none absolute left-3 top-1/2 -translate-y-1/2 text-[#9aa6b8]">
            <Search size={16} aria-hidden="true" />
          </span>
          <input
            value={q}
            onChange={(e) => setQ(e.target.value)}
            placeholder={t.search_placeholder}
            aria-label={t.search_placeholder}
            className="w-full bg-[#0a0e1a] border border-[rgba(224,192,128,0.25)] focus:border-[#e0c080] rounded-full pl-10 pr-10 py-2.5 font-display text-[15px] text-[#e7ecf3] placeholder:text-[#5a6678] outline-none transition-colors"
          />
          {q && (
            <button
              type="button"
              onClick={() => setQ("")}
              aria-label={t.clear}
              className="absolute right-3 top-1/2 -translate-y-1/2 text-[#9aa6b8] hover:text-[#e0c080]"
            >
              <X size={16} aria-hidden="true" />
            </button>
          )}
        </div>
        <label className="inline-flex items-center gap-2 text-[12px] font-mono text-[#9aa6b8]">
          <span className="uppercase tracking-widest text-[10px]">{t.sort_label}</span>
          <select
            value={sort}
            onChange={(e) => setSort(e.target.value as SortKey)}
            className="bg-[#0a0e1a] border border-[rgba(224,192,128,0.25)] focus:border-[#e0c080] rounded px-2.5 py-1.5 font-mono text-[12px] text-[#e7ecf3] outline-none"
          >
            {(Object.keys(t.sorts) as SortKey[]).map((k) => (
              <option key={k} value={k}>{t.sorts[k]}</option>
            ))}
          </select>
        </label>
      </div>

      {/* Agency chips */}
      <ChipRow
        label="agency"
        items={[
          { key: null,  label: t.all, count: cases.length },
          ...AGENCY_ORDER
            .filter((a) => (agencyCounts.get(a) ?? 0) > 0)
            .map((a) => ({ key: a as string | null, label: a, count: agencyCounts.get(a) ?? 0 })),
        ]}
        active={agency}
        onPick={(k) => setAgency(k as Agency | null)}
      />

      {/* Decade chips */}
      <ChipRow
        label="decade"
        items={[
          { key: null, label: t.all, count: cases.length },
          ...decadeKeys.map((d) => ({
            key: d,
            label: d === "—" ? t.no_decade : d,
            count: decadeCounts.get(d) ?? 0,
          })),
        ]}
        active={decade}
        onPick={setDecade}
      />

      {/* Result count + reset */}
      <div className="mt-4 mb-3 flex items-center justify-between text-[11px] font-mono text-[#9aa6b8]">
        <span>{t.showing(filtered.length, cases.length)}</span>
        {hasActiveFilter && (
          <button
            type="button"
            onClick={() => { setQ(""); setAgency(null); setDecade(null); }}
            className="text-[#e0c080] hover:underline"
          >
            ✕ {t.reset}
          </button>
        )}
      </div>

      {/* Grid */}
      {filtered.length === 0 ? (
        <div className="text-center text-[#5a6678] font-mono text-[13px] py-12 border border-dashed border-[rgba(224,192,128,0.18)] rounded-lg">
          {t.no_results}
        </div>
      ) : (
        <div className="grid md:grid-cols-2 gap-4">
          {filtered.map((c) => <CaseCard key={c.slug} c={c} locale={locale} />)}
        </div>
      )}
    </div>
  );
}

function ChipRow({
  label,
  items,
  active,
  onPick,
}: {
  label: string;
  items: { key: string | null; label: string; count: number }[];
  active: string | null;
  onPick: (k: string | null) => void;
}) {
  return (
    <div className="flex flex-wrap items-center gap-1.5 mb-2" role="group" aria-label={label}>
      {items.map((it) => {
        const isActive = active === it.key;
        return (
          <button
            key={String(it.key)}
            type="button"
            onClick={() => onPick(it.key)}
            aria-pressed={isActive}
            className={
              isActive
                ? "inline-flex items-center gap-1.5 px-3 py-1 rounded-full border border-[#e0c080] bg-[rgba(224,192,128,0.16)] text-[#e0c080] text-[12px] font-mono"
                : "inline-flex items-center gap-1.5 px-3 py-1 rounded-full border border-[rgba(224,192,128,0.20)] text-[#cbd2dd] hover:text-[#e0c080] hover:border-[rgba(224,192,128,0.45)] text-[12px] font-mono transition-colors"
            }
          >
            <span>{it.label}</span>
            <span className="text-[10px] text-[#9aa6b8]">{it.count}</span>
          </button>
        );
      })}
    </div>
  );
}

function CaseCard({ c, locale }: { c: CaseFile; locale: "pt-br" | "en" }) {
  const title = locale === "pt-br" ? (c.topic_pt_br ?? c.topic) : c.topic;
  const meta: string[] = [];
  if (c.year !== null) meta.push(String(c.year));
  meta.push(c.agency);
  return (
    <Link
      href={`/c/${c.slug}`}
      className="block rounded-lg border border-[rgba(224,192,128,0.18)] bg-[#0d1220] p-4 hover:border-[#e0c080] transition-colors group"
    >
      <div className="text-[10px] font-mono uppercase tracking-[0.18em] text-[#9aa6b8] mb-1.5">
        {meta.join(" · ")}
      </div>
      <h3 className="font-display text-[19px] text-[#e7ecf3] leading-snug mb-2 group-hover:text-[#e0c080] transition-colors">
        {title}
      </h3>
      {c.opening && (
        <p className="text-[13px] text-[#cbd2dd] leading-relaxed line-clamp-3">
          {c.opening}
        </p>
      )}
    </Link>
  );
}