"use client";

import { useState, Suspense, useEffect } from "react";
import Link from "next/link";
import { useSearchParams, useRouter } from "next/navigation";
import { useSections } from "@/hooks/useSections";
import { useSearch, type SearchMode } from "@/hooks/useSearch";
import SearchBar from "@/components/SearchBar";
import { EmptyState, ErrorState } from "@/components/EmptyState";
import { Search, SearchX } from "lucide-react";

function SearchContent() {
  const searchParams = useSearchParams();
  const router = useRouter();
  const initialQ = searchParams.get("q") ?? "";
  const initialMode = (searchParams.get("mode") as SearchMode) ?? "hybrid";

  const [query, setQuery] = useState(initialQ);
  const [mode, setMode] = useState<SearchMode>(
    ["hybrid", "keyword", "semantic"].includes(initialMode) ? initialMode : "hybrid",
  );
  const [selectedSection, setSelectedSection] = useState<string>("all");

  const { data: liveSections } = useSections();
  const sections = liveSections ?? [];

  // SWR search — debounced inside hook (180ms)
  const { hits, error, isValidating, isLoading } = useSearch(query, mode, 30);
  const loading = isLoading || isValidating;

  // Keep URL in sync (debounced via hook timing is fine — push without blocking render)
  useEffect(() => {
    const q = query.trim();
    const target = q ? `/search?q=${encodeURIComponent(q)}&mode=${mode}` : `/search?mode=${mode}`;
    const current = `${searchParams.toString() ? `/search?${searchParams.toString()}` : "/search"}`;
    if (target !== current && q) {
      router.replace(target);
    }
  }, [query, mode]); // eslint-disable-line react-hooks/exhaustive-deps

  const filteredHits = selectedSection === "all" ? hits : hits.filter((r) => r.section === selectedSection);

  function handleModeChange(newMode: SearchMode) {
    setMode(newMode);
    const q = query.trim();
    const qs = q ? `?q=${encodeURIComponent(q)}&mode=${newMode}` : `?mode=${newMode}`;
    router.replace(`/search${qs}`);
  }

  const suggestions = [
    "stack alignment",
    "ret2win exploit",
    "bullmq worker",
    "streamable http",
    "full-text search",
    "caddy reverse proxy",
    "pgvector cosine",
  ];

  return (
    <div className="max-w-4xl space-y-8">
      <div>
        <h1 className="text-3xl font-extrabold text-[var(--text-primary)] tracking-tight mb-2">Multi-Modal Search Console</h1>
        <p className="text-xs sm:text-sm text-[var(--text-muted)] leading-relaxed">
          Query across knowledge documents and CTF writeups using PostgreSQL Full-Text Search (tsvector), Cosine Vector Embeddings, or Reciprocal Rank Fusion (RRF).
        </p>
      </div>

      <div className="bg-[var(--bg-surface)] border border-[var(--border-color)] rounded-xl p-4 sm:p-5 shadow-xs space-y-4">
        <SearchBar value={query} onChange={setQuery} placeholder="Search by keywords, challenge names, tools, concepts..." autoFocus onClear={() => setQuery("")} />

        <div className="flex flex-col sm:flex-row sm:items-center justify-between gap-3 pt-2.5 border-t border-[var(--border-color)] text-xs">
          <div className="flex items-center gap-1.5 flex-wrap">
            <span className="text-[var(--text-dim)] font-mono uppercase text-[10px] mr-1">Algorithm:</span>
            {[
              { id: "hybrid", label: "Hybrid (RRF)", desc: "Reciprocal Rank Fusion (FTS + Vector)" },
              { id: "keyword", label: "Keyword (FTS)", desc: "PostgreSQL GIN tsvector" },
              { id: "semantic", label: "Semantic Vector", desc: "Cosine Similarity Embeddings" },
            ].map((m) => (
              <button
                key={m.id}
                type="button"
                onClick={() => handleModeChange(m.id as SearchMode)}
                title={m.desc}
                className={`px-3 py-1 rounded-md border text-xs font-medium transition-all cursor-pointer ${mode === m.id ? "bg-[var(--brand)] border-[var(--brand)] text-[var(--brand-fg)] font-semibold shadow-xs" : "bg-[var(--bg-elevated)] border-[var(--border-color)] text-[var(--text-muted)] hover:text-[var(--text-primary)]"}`}
              >
                {m.label}
              </button>
            ))}
          </div>

          <div className="flex items-center gap-1 flex-wrap">
            <button
              type="button"
              onClick={() => setSelectedSection("all")}
              className={`px-2.5 py-1 rounded-md text-xs font-medium transition-colors ${selectedSection === "all" ? "bg-[var(--bg-elevated-hover)] text-[var(--text-primary)] font-semibold" : "text-[var(--text-dim)] hover:text-[var(--text-muted)]"}`}
            >
              All
            </button>
            {sections.map((s) => (
              <button
                key={s.id}
                type="button"
                onClick={() => setSelectedSection(s.id)}
                className={`px-2.5 py-1 rounded-md text-xs font-medium transition-colors ${selectedSection === s.id ? "bg-[var(--bg-elevated-hover)] text-[var(--text-primary)] font-semibold" : "text-[var(--text-dim)] hover:text-[var(--text-muted)]"}`}
              >
                {s.label}
              </button>
            ))}
          </div>
        </div>
      </div>

      {error && <ErrorState message={(error as Error).message} onRetry={() => setQuery((q) => q + " ")} />}

      {loading && (
        <div className="flex items-center justify-center gap-3 py-10 text-[var(--text-muted)] text-xs font-mono" role="status" aria-live="polite">
          <div className="w-4 h-4 border-2 border-[var(--text-muted)] border-t-transparent rounded-full animate-spin" />
          <span>SEARCHING_VECTOR_SPACE...</span>
        </div>
      )}

      {!loading && query.trim() && filteredHits.length === 0 && !error && (
        <EmptyState
          title="No matching documents found"
          description="Try switching algorithm mode to Hybrid or Semantic, or search with different keywords."
          icon={SearchX}
        />
      )}

      {!loading && !query.trim() && (
        <div className="p-6 text-center bg-[var(--bg-surface)] border border-[var(--border-color)] rounded-xl space-y-3 shadow-xs">
          <p className="text-[10px] font-mono uppercase tracking-wider text-[var(--text-muted)]">Popular Queries:</p>
          <div className="flex justify-center flex-wrap gap-2 text-xs">
            {suggestions.map((term) => (
              <button
                key={term}
                onClick={() => setQuery(term)}
                className="px-3 py-1 bg-[var(--bg-elevated)] hover:bg-[var(--bg-elevated-hover)] border border-[var(--border-color)] hover:border-[var(--text-muted)] rounded-md text-[var(--text-secondary)] hover:text-[var(--text-primary)] transition-all font-mono text-xs cursor-pointer"
              >
                {term}
              </button>
            ))}
          </div>
        </div>
      )}

      {!loading && filteredHits.length > 0 && (
        <div className="space-y-3 animate-fade-in">
          <div className="flex items-center justify-between text-xs text-[var(--text-dim)] font-mono" aria-live="polite">
            <span>Found {filteredHits.length} result{filteredHits.length !== 1 ? "s" : ""}</span>
            <span>Ranked by {mode} score</span>
          </div>
          <div className="space-y-2.5">
            {filteredHits.map((r) => (
              <Link
                key={r.slug}
                href={`/${r.slug}`}
                className="group block bg-[var(--bg-surface)] hover:bg-[var(--bg-surface-hover)] border border-[var(--border-color)] hover:border-[var(--text-muted)] rounded-xl p-4.5 transition-all shadow-xs"
              >
                <div className="flex items-center justify-between gap-3 mb-2">
                  <div className="flex items-center gap-2">
                    <span className="text-[10px] font-mono px-1.5 py-0.2 rounded bg-[var(--bg-elevated)] border border-[var(--border-color)] text-[var(--text-muted)] uppercase font-semibold">{r.section}</span>
                    <span className="text-xs text-[var(--text-dim)] font-mono truncate">/{r.slug}</span>
                  </div>
                  <span className="text-xs font-mono text-[var(--text-dim)] bg-[var(--bg-elevated)] px-2 py-0.5 rounded">{r.score.toFixed(3)}</span>
                </div>
                <h2 className="text-sm font-semibold text-[var(--text-primary)] group-hover:underline mb-1.5">{r.title}</h2>
                {r.snippet && (
                  <p
                    className="text-xs text-[var(--text-muted)] leading-relaxed line-clamp-2 [&>mark]:bg-[var(--bg-elevated-hover)] [&>mark]:text-[var(--text-primary)] [&>mark]:font-semibold"
                    // snippet from Postgres ts_headline — sanitized by DB
                    dangerouslySetInnerHTML={{ __html: r.snippet }}
                  />
                )}
              </Link>
            ))}
          </div>
        </div>
      )}
    </div>
  );
}

export default function SearchPage() {
  return (
    <Suspense fallback={<div className="max-w-4xl py-12"><h1 className="text-2xl font-bold text-[var(--text-primary)] mb-4">Search</h1><p className="text-sm text-[var(--text-muted)]">Loading search module...</p></div>}>
      <SearchContent />
    </Suspense>
  );
}