"use client";

import { useState, useEffect, useRef } from "react";
import Link from "next/link";
import { useRouter } from "next/navigation";
import {
  Search,
  Plus,
  ArrowRight,
  BookOpen,
  Flag,
  Sparkles,
  X,
} from "lucide-react";

interface Hit {
  slug: string;
  title: string;
  section: string;
  snippet?: string;
  score: number;
}

interface QuickAction {
  id: string;
  title: string;
  subtitle: string;
  icon: any;
  href?: string;
  action?: () => void;
}

export default function CommandMenu() {
  const [open, setOpen] = useState(false);
  const [query, setQuery] = useState("");
  const [results, setResults] = useState<Hit[]>([]);
  const [loading, setLoading] = useState(false);
  const [selectedIndex, setSelectedIndex] = useState(0);
  const router = useRouter();
  const inputRef = useRef<HTMLInputElement>(null);

  const quickActions: QuickAction[] = [
    {
      id: "create-doc",
      title: "Create New Document",
      subtitle: "Write technical doc, writeup, or note",
      icon: Plus,
      href: "/create",
    },
    {
      id: "hybrid-search",
      title: "Multi-Modal Hybrid Search",
      subtitle: "Full-text + Semantic vector search console",
      icon: Search,
      href: "/search",
    },
    {
      id: "browse-docs",
      title: "Documentation Hub",
      subtitle: "System setup, API references, protocol specs",
      icon: BookOpen,
      href: "/docs",
    },
    {
      id: "browse-writeups",
      title: "CTF & Writeups Directory",
      subtitle: "Pwn, Reverse, Web, Crypto writeups and solutions",
      icon: Flag,
      href: "/writeups",
    },
    {
      id: "browse-research",
      title: "Research & Benchmarks",
      subtitle: "Architecture notes, benchmarks, experiments",
      icon: Sparkles,
      href: "/research",
    },
  ];

  // Global shortcut ⌘K or /
  useEffect(() => {
    function handleKeyDown(e: KeyboardEvent) {
      if ((e.metaKey || e.ctrlKey) && e.key.toLowerCase() === "k") {
        e.preventDefault();
        setOpen((prev) => !prev);
      } else if (e.key === "/" && !["INPUT", "TEXTAREA"].includes((e.target as HTMLElement)?.tagName)) {
        e.preventDefault();
        setOpen(true);
      } else if (e.key === "Escape" && open) {
        setOpen(false);
      }
    }
    window.addEventListener("keydown", handleKeyDown);
    return () => window.removeEventListener("keydown", handleKeyDown);
  }, [open]);

  useEffect(() => {
    if (open) {
      setTimeout(() => inputRef.current?.focus(), 50);
      setQuery("");
      setResults([]);
      setSelectedIndex(0);
    }
  }, [open]);

  // Debounced search
  useEffect(() => {
    if (!query.trim()) {
      setResults([]);
      return;
    }
    const timer = setTimeout(async () => {
      setLoading(true);
      try {
        const res = await fetch(`/api/search?q=${encodeURIComponent(query)}&limit=10`);
        const data = await res.json();
        setResults(data.results || []);
        setSelectedIndex(0);
      } catch {
        setResults([]);
      } finally {
        setLoading(false);
      }
    }, 120);
    return () => clearTimeout(timer);
  }, [query]);

  function handleNavigate(href: string) {
    setOpen(false);
    router.push(href);
  }

  const totalItems = query.trim() ? results.length : quickActions.length;

  function handleKeyNavigation(e: React.KeyboardEvent) {
    if (e.key === "ArrowDown") {
      e.preventDefault();
      setSelectedIndex((prev) => (totalItems > 0 ? (prev + 1) % totalItems : 0));
    } else if (e.key === "ArrowUp") {
      e.preventDefault();
      setSelectedIndex((prev) => (totalItems > 0 ? (prev - 1 + totalItems) % totalItems : 0));
    } else if (e.key === "Enter") {
      e.preventDefault();
      if (query.trim() && results[selectedIndex]) {
        handleNavigate(`/${results[selectedIndex].slug}`);
      } else if (!query.trim() && quickActions[selectedIndex]?.href) {
        handleNavigate(quickActions[selectedIndex].href!);
      }
    }
  }

  if (!open) {
    return (
      <button
        onClick={() => setOpen(true)}
        type="button"
        className="hidden md:flex items-center gap-2.5 px-3 py-1.5 bg-[var(--bg-elevated)] hover:bg-[var(--bg-elevated-hover)] border border-[var(--border-color)] hover:border-[var(--text-muted)] text-xs text-[var(--text-muted)] hover:text-[var(--text-primary)] rounded-md transition-all shadow-xs cursor-pointer group"
      >
        <Search className="w-3.5 h-3.5 text-[var(--text-dim)] group-hover:text-[var(--text-primary)] transition-colors" />
        <span className="font-sans">Search...</span>
        <kbd className="ml-2 font-mono bg-[var(--bg-surface)] px-1.5 py-0.2 rounded border border-[var(--border-color)] text-[10px] text-[var(--text-muted)]">
          ⌘K
        </kbd>
      </button>
    );
  }

  return (
    <div className="fixed inset-0 z-50 flex items-start justify-center pt-16 sm:pt-24 px-4">
      {/* Backdrop */}
      <div
        className="fixed inset-0 bg-black/60 backdrop-blur-xs transition-opacity"
        onClick={() => setOpen(false)}
      />

      {/* Modal */}
      <div className="relative w-full max-w-2xl bg-[var(--bg-surface)] border border-[var(--border-color)] rounded-xl shadow-2xl overflow-hidden animate-fade-in">
        {/* Search input bar */}
        <div className="flex items-center gap-3 px-4 sm:px-5 py-3.5 border-b border-[var(--border-color)] bg-[var(--bg-elevated)]">
          <Search className="w-4 h-4 text-[var(--text-muted)] shrink-0" />
          <input
            ref={inputRef}
            type="text"
            value={query}
            onChange={(e) => setQuery(e.target.value)}
            onKeyDown={handleKeyNavigation}
            placeholder="Search documents, writeups, concepts, or tools..."
            className="w-full bg-transparent text-[var(--text-primary)] placeholder-[var(--text-dim)] text-sm focus:outline-none"
          />
          {loading && (
            <div className="w-4 h-4 border-2 border-[var(--text-muted)] border-t-transparent rounded-full animate-spin shrink-0" />
          )}
          <button
            onClick={() => setOpen(false)}
            type="button"
            className="text-[10px] font-mono text-[var(--text-dim)] hover:text-[var(--text-primary)] bg-[var(--bg-surface)] px-1.5 py-0.5 rounded border border-[var(--border-color)]"
          >
            ESC
          </button>
        </div>

        {/* Results / Quick Actions List */}
        <div className="max-h-[22rem] overflow-y-auto p-2">
          {query.trim() === "" ? (
            <div className="p-1 space-y-0.5">
              <div className="px-2.5 py-1 text-[10px] font-mono uppercase tracking-wider text-[var(--text-muted)]">
                Quick Shortcuts
              </div>
              {quickActions.map((action, idx) => {
                const Icon = action.icon;
                const isSelected = idx === selectedIndex;
                return (
                  <div
                    key={action.id}
                    onClick={() => action.href && handleNavigate(action.href)}
                    onMouseEnter={() => setSelectedIndex(idx)}
                    className={`flex items-center justify-between gap-3 px-3 py-2 rounded-lg cursor-pointer transition-colors ${
                      isSelected
                        ? "bg-[var(--bg-elevated)] text-[var(--text-primary)]"
                        : "hover:bg-[var(--bg-elevated)] text-[var(--text-secondary)]"
                    }`}
                  >
                    <div className="flex items-center gap-2.5">
                      <div className={`p-1.5 rounded ${isSelected ? "bg-[var(--brand)] text-[var(--brand-fg)]" : "bg-[var(--bg-elevated)] text-[var(--text-muted)]"}`}>
                        <Icon className="w-3.5 h-3.5" />
                      </div>
                      <div>
                        <div className="text-xs font-semibold text-[var(--text-primary)]">
                          {action.title}
                        </div>
                        <div className="text-[11px] text-[var(--text-muted)]">
                          {action.subtitle}
                        </div>
                      </div>
                    </div>
                    <ArrowRight className={`w-3.5 h-3.5 text-[var(--text-dim)] ${isSelected ? "text-[var(--text-primary)]" : ""}`} />
                  </div>
                );
              })}
            </div>
          ) : results.length === 0 && !loading ? (
            <div className="px-4 py-10 text-center text-xs text-[var(--text-muted)] space-y-1">
              <p>No knowledge base items matched &quot;{query}&quot;</p>
            </div>
          ) : (
            <ul className="space-y-1 p-1">
              {results.map((hit, index) => {
                const isSelected = index === selectedIndex;
                return (
                  <li
                    key={hit.slug}
                    onClick={() => handleNavigate(`/${hit.slug}`)}
                    onMouseEnter={() => setSelectedIndex(index)}
                    className={`flex items-start justify-between gap-3 px-3 py-2.5 rounded-lg cursor-pointer transition-colors ${
                      isSelected
                        ? "bg-[var(--bg-elevated)] text-[var(--text-primary)] border border-[var(--border-color)]"
                        : "hover:bg-[var(--bg-elevated)] text-[var(--text-secondary)] border border-transparent"
                    }`}
                  >
                    <div className="min-w-0 flex-1">
                      <div className="flex items-center gap-2 mb-0.5">
                        <span className="text-[10px] font-mono px-1.5 py-0.2 bg-[var(--bg-elevated)] border border-[var(--border-color)] rounded text-[var(--text-muted)] uppercase font-semibold">
                          {hit.section}
                        </span>
                        <span className={`text-xs sm:text-sm font-semibold ${isSelected ? "text-[var(--text-primary)]" : "text-[var(--text-primary)]"} truncate`}>
                          {hit.title}
                        </span>
                      </div>
                      {hit.snippet && (
                        <p
                          className="text-xs text-[var(--text-muted)] line-clamp-1 mt-1 [&>mark]:bg-[var(--bg-elevated-hover)] [&>mark]:text-[var(--text-primary)] [&>mark]:font-semibold"
                          dangerouslySetInnerHTML={{ __html: hit.snippet }}
                        />
                      )}
                    </div>
                    <span className="text-[10px] font-mono text-[var(--text-dim)] shrink-0 self-center">
                      /{hit.slug}
                    </span>
                  </li>
                );
              })}
            </ul>
          )}
        </div>

        {/* Footer */}
        <div className="flex items-center justify-between px-4 py-2 border-t border-[var(--border-color)] bg-[var(--bg-elevated)] text-[10px] text-[var(--text-muted)] font-mono">
          <div className="flex items-center gap-2">
            <span>[ ↑↓ NAVIGATE ]</span>
            <span>[ ↵ SELECT ]</span>
          </div>
          <Link
            href={`/search?q=${encodeURIComponent(query)}`}
            onClick={() => setOpen(false)}
            className="hover:text-[var(--text-primary)] font-medium flex items-center gap-1"
          >
            <span>Full Search Console</span>
            <ArrowRight className="w-3 h-3" />
          </Link>
        </div>
      </div>
    </div>
  );
}