"use client";

import { useEffect, useId, useMemo, useRef, useState, type CSSProperties, type KeyboardEvent } from "react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";

export type SearchCommandItem = {
  id: string;
  label: string;
  /** Heading the result sits under. */
  group?: string;
  /** Small text on the right of the result. */
  hint?: string;
  /** Extra words that also find this result. */
  keywords?: string;
};

type SearchCommandProps = {
  items: SearchCommandItem[];
  /** Called when a result is picked. */
  onSelect?: (item: SearchCommandItem) => void;
  /** Name for screen readers. */
  label?: string;
  placeholder?: string;
  /** Key that jumps to the box from anywhere on the page. Empty string turns it off. */
  hotkey?: string;
  /** Highlight and match colour. */
  accent?: string;
  /** Wrapper look (width etc.). */
  className?: string;
};

function Match({ text, query }: { text: string; query: string }) {
  const at = query ? text.toLowerCase().indexOf(query.toLowerCase()) : -1;
  if (at < 0) return text;
  return (
    <>
      {text.slice(0, at)}
      <mark className="bg-transparent font-semibold text-[var(--sc)]">{text.slice(at, at + query.length)}</mark>
      {text.slice(at + query.length)}
    </>
  );
}

/* SearchCommand: an inline search box with grouped results under it. The match lights up in each result, a highlight glides with the arrow keys, and one key jumps to the box from anywhere. */
export function SearchCommand({
  items,
  onSelect,
  label = "Search",
  placeholder = "Search…",
  hotkey = "/",
  accent = "#a78bfa",
  className = "w-full max-w-md",
}: SearchCommandProps) {
  const reduce = useReducedMotion();
  const uid = useId();
  const listId = `${uid}-list`;
  const optId = (i: number) => `${uid}-opt-${i}`;
  const input = useRef<HTMLInputElement>(null);
  const [text, setText] = useState("");
  const [open, setOpen] = useState(false);
  const [focused, setFocused] = useState(false);
  const [active, setActive] = useState(0);
  const query = text.trim();

  const groups = useMemo(() => {
    const q = query.toLowerCase();
    const found = new Map<string, SearchCommandItem[]>();
    for (const item of items) {
      if (!`${item.label} ${item.keywords ?? ""}`.toLowerCase().includes(q)) continue;
      const key = item.group ?? "";
      found.set(key, [...(found.get(key) ?? []), item]);
    }
    return [...found];
  }, [items, query]);
  const results = groups.flatMap(([, list]) => list);
  const current = Math.min(active, results.length - 1);

  useEffect(() => {
    if (open) document.getElementById(`${uid}-opt-${current}`)?.scrollIntoView({ block: "nearest" });
  }, [open, current, uid]);

  useEffect(() => {
    if (!hotkey) return;
    const onKey = (e: globalThis.KeyboardEvent) => {
      const el = e.target as HTMLElement;
      if (e.key !== hotkey || e.ctrlKey || e.metaKey || e.altKey) return;
      if (el.isContentEditable || ["INPUT", "TEXTAREA", "SELECT"].includes(el.tagName)) return;
      e.preventDefault();
      input.current?.focus();
    };
    window.addEventListener("keydown", onKey);
    return () => window.removeEventListener("keydown", onKey);
  }, [hotkey]);

  const pick = (item?: SearchCommandItem) => {
    if (!item) return;
    onSelect?.(item);
    setText("");
    setActive(0);
    setOpen(false);
  };

  const onKey = (e: KeyboardEvent<HTMLInputElement>) => {
    if (e.key === "ArrowDown" || e.key === "ArrowUp") {
      e.preventDefault();
      if (!open) return setOpen(true);
      const dir = e.key === "ArrowDown" ? 1 : -1;
      const size = results.length || 1;
      setActive((n) => (Math.min(n, size - 1) + dir + size) % size);
    } else if (e.key === "Enter" && open) {
      e.preventDefault();
      pick(results[current]);
    } else if (e.key === "Escape") {
      e.preventDefault();
      if (text) setText("");
      else if (open) setOpen(false);
      else input.current?.blur();
      setActive(0);
    }
  };

  const optionIndex = (item: SearchCommandItem) => results.indexOf(item);

  return (
    <div role="search" className={className} style={{ "--sc": accent } as CSSProperties}>
      <div className="relative">
        <svg aria-hidden viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" className="pointer-events-none absolute top-1/2 left-4 size-[18px] -translate-y-1/2 text-white/45">
          <circle cx="11" cy="11" r="7" />
          <path d="m20 20-3.8-3.8" />
        </svg>
        <input
          ref={input}
          type="text"
          role="combobox"
          aria-label={label}
          aria-autocomplete="list"
          aria-expanded={open}
          aria-controls={listId}
          aria-activedescendant={open && current >= 0 ? optId(current) : undefined}
          autoComplete="off"
          spellCheck={false}
          placeholder={placeholder}
          value={text}
          onChange={(e) => {
            setText(e.target.value);
            setActive(0);
            setOpen(true);
          }}
          onFocus={() => {
            setFocused(true);
            setOpen(true);
          }}
          onBlur={() => {
            setFocused(false);
            setOpen(false);
          }}
          onClick={() => setOpen(true)}
          onKeyDown={onKey}
          className="h-12 w-full rounded-xl border border-white/12 bg-[#0f0d1c] pr-12 pl-11 text-base text-white outline-none transition-colors duration-200 placeholder:text-white/40 hover:border-white/25 focus:border-[var(--sc)] focus:ring-2 focus:ring-[color-mix(in_srgb,var(--sc)_30%,transparent)] motion-reduce:transition-none"
        />
        {hotkey && !focused && (
          <kbd className="pointer-events-none absolute top-1/2 right-3 -translate-y-1/2 rounded-md border border-white/15 px-1.5 py-0.5 font-mono text-xs text-white/50">{hotkey}</kbd>
        )}

        <AnimatePresence>
          {open && (
            <motion.div
              onMouseDown={(e) => e.preventDefault()}
              initial={reduce ? { opacity: 0 } : { opacity: 0, y: -6, scale: 0.98 }}
              animate={reduce ? { opacity: 1 } : { opacity: 1, y: 0, scale: 1 }}
              exit={reduce ? { opacity: 0, transition: { duration: 0 } } : { opacity: 0, y: -4, scale: 0.98, transition: { duration: 0.12 } }}
              transition={reduce ? { duration: 0 } : { type: "spring", stiffness: 520, damping: 34 }}
              className="absolute inset-x-0 top-full z-20 mt-2 max-h-64 origin-top overflow-auto rounded-[14px] border border-white/10 bg-[#141026] p-1.5 shadow-2xl shadow-black/50"
            >
              <div id={listId} role="listbox" aria-label={label}>
                {groups.map(([group, list]) => (
                  <div key={group} role="group" aria-label={group || undefined}>
                    {group && (
                      <div aria-hidden className="px-3 pt-2 pb-1 text-xs font-medium text-white/40">
                        {group}
                      </div>
                    )}
                    {list.map((item) => {
                      const i = optionIndex(item);
                      const isActive = i === current;
                      return (
                        <div
                          key={item.id}
                          id={optId(i)}
                          role="option"
                          aria-selected={isActive}
                          onMouseMove={() => !isActive && setActive(i)}
                          onClick={() => pick(item)}
                          className={`relative flex min-h-10 cursor-pointer items-center gap-3 rounded-lg px-3 py-2 text-[15px] ${isActive ? "text-white" : "text-white/70"}`}
                        >
                          {isActive && (
                            <motion.span
                              layoutId={`${uid}-hl`}
                              aria-hidden
                              className="absolute inset-0 rounded-lg"
                              style={{ background: "color-mix(in srgb, var(--sc) 16%, transparent)" }}
                              transition={reduce ? { duration: 0 } : { type: "spring", stiffness: 520, damping: 38 }}
                            />
                          )}
                          <span className="relative min-w-0 flex-1 truncate">
                            <Match text={item.label} query={query} />
                          </span>
                          {item.hint && <span className="relative shrink-0 text-xs text-white/40">{item.hint}</span>}
                        </div>
                      );
                    })}
                  </div>
                ))}
              </div>
              {results.length === 0 && <p className="px-3 py-5 text-center text-sm text-white/50">Nothing found for “{query}”</p>}
            </motion.div>
          )}
        </AnimatePresence>
        <p aria-live="polite" className="sr-only">
          {open && query ? `${results.length} results` : ""}
        </p>
      </div>
    </div>
  );
}