"use client";

import { useEffect, useMemo, useRef, useState } from "react";
import { Check, Search, X } from "lucide-react";

const MONO = "var(--font-mono, ui-monospace, SFMono-Regular, Menlo, monospace)";

/**
 * 语言选择自定义下拉（统一站点样式）：
 * - variant="toolbar"：广场工具台（含"全部语言"与清除）
 * - variant="editor"：新建/编辑片段表单（药丸形，语言必选）
 */
export default function SnippetLangSelect({
  value,
  onChange,
  languages,
  allowAll = true,
  variant = "toolbar",
  ariaLabel = "选择语言",
  allLabel = "全部语言",
  disabled = false,
}: {
  value: string;
  onChange: (v: string) => void;
  languages: string[];
  allowAll?: boolean;
  variant?: "toolbar" | "editor";
  ariaLabel?: string;
  allLabel?: string;
  disabled?: boolean;
}) {
  const [open, setOpen] = useState(false);
  const [q, setQ] = useState("");
  const ref = useRef<HTMLDivElement>(null);
  const inputRef = useRef<HTMLInputElement>(null);

  useEffect(() => {
    if (!open) return;
    setQ("");
    const t = window.setTimeout(() => inputRef.current?.focus(), 30);
    const onDown = (e: MouseEvent) => {
      if (ref.current && !ref.current.contains(e.target as Node)) setOpen(false);
    };
    const onKey = (e: KeyboardEvent) => {
      if (e.key === "Escape") setOpen(false);
    };
    document.addEventListener("mousedown", onDown);
    document.addEventListener("keydown", onKey);
    return () => {
      window.clearTimeout(t);
      document.removeEventListener("mousedown", onDown);
      document.removeEventListener("keydown", onKey);
    };
  }, [open]);

  const filtered = useMemo(() => {
    const kw = q.trim().toLowerCase();
    return kw ? languages.filter((l) => l.includes(kw)) : languages;
  }, [q, languages]);

  const triggerCls =
    variant === "editor"
      ? "j13-sn-search h-8 rounded-full pl-3 pr-2.5 text-[12.5px] gap-1.5"
      : "j13-sn-search w-full h-9 rounded-lg px-3 text-[12.5px] gap-2";
  const wrapCls = variant === "editor" ? "relative shrink-0" : "relative shrink-0 sm:w-44 w-full";
  const menuCls =
    variant === "editor"
      ? "j13-sn-lang-menu absolute z-30 mt-1.5 left-0 w-56 rounded-xl overflow-hidden"
      : "j13-sn-lang-menu absolute z-30 mt-1.5 left-0 right-0 sm:right-auto sm:w-60 rounded-xl overflow-hidden";

  return (
    <div ref={ref} className={wrapCls}>
      <button
        type="button"
        onClick={() => !disabled && setOpen((v) => !v)}
        aria-haspopup="listbox"
        aria-expanded={open}
        aria-label={ariaLabel}
        disabled={disabled}
        className={`${triggerCls} flex items-center disabled:opacity-60 disabled:cursor-not-allowed`}
        style={{ background: "var(--panel)", border: "1px solid transparent", color: "var(--ink)" }}
      >
        <span
          className="w-[6px] h-[6px] rounded-full shrink-0"
          style={{ background: value ? "var(--accent)" : "var(--ink-3)", opacity: value ? 1 : 0.5 }}
        />
        <span
          className="truncate text-left flex-1"
          style={{ fontFamily: MONO, color: value ? "var(--ink)" : "var(--ink-3)" }}
        >
          {value || allLabel}
        </span>
        {allowAll && value ? (
          <span
            role="button"
            tabIndex={-1}
            aria-label="清除语言筛选"
            onClick={(e) => {
              e.stopPropagation();
              onChange("");
            }}
            className="w-5 h-5 -mr-1 flex items-center justify-center rounded-md hover:bg-[var(--panel-2)] transition-colors"
            style={{ color: "var(--ink-3)" }}
          >
            <X size={11} />
          </span>
        ) : (
          <ArrowDownIcon className="shrink-0" rotated={open} />
        )}
      </button>

      {open && (
        <div
          className={menuCls}
          style={{
            background: "var(--panel)",
            border: "1px solid var(--line-2)",
            boxShadow: "var(--shadow-lg)",
          }}
          role="listbox"
        >
          <div className="p-2" style={{ borderBottom: "1px solid var(--line)" }}>
            <div className="relative">
              <Search
                size={12}
                className="absolute left-2.5 top-1/2 -translate-y-1/2 pointer-events-none"
                style={{ color: "var(--ink-3)" }}
              />
              <input
                ref={inputRef}
                value={q}
                onChange={(e) => setQ(e.target.value)}
                placeholder="筛选语言…"
                aria-label="筛选语言"
                className="w-full h-8 rounded-md pl-7 pr-2 text-[12px] outline-none"
                style={{ background: "var(--panel-2)", border: "1px solid transparent", color: "var(--ink)" }}
              />
            </div>
          </div>
          <ul className="max-h-56 overflow-y-auto py-1">
            {allowAll ? (
              <LangOption
                active={value === ""}
                onClick={() => {
                  onChange("");
                  setOpen(false);
                }}
                label={allLabel}
                dotDim
              />
            ) : null}
            {filtered.length === 0 ? (
              <li className="px-3 py-3 text-center text-[12px]" style={{ color: "var(--ink-3)" }}>
                没有匹配的语言
              </li>
            ) : (
              filtered.map((l) => (
                <LangOption
                  key={l}
                  active={value === l}
                  onClick={() => {
                    onChange(l);
                    setOpen(false);
                  }}
                  label={l}
                  mono
                />
              ))
            )}
          </ul>
        </div>
      )}
    </div>
  );
}

function ArrowDownIcon({ className = "", rotated }: { className?: string; rotated: boolean }) {
  return (
    <svg
      width="12"
      height="12"
      viewBox="0 0 24 24"
      fill="none"
      stroke="currentColor"
      strokeWidth="2.2"
      strokeLinecap="round"
      strokeLinejoin="round"
      className={`${className} ${rotated ? "rotate-180" : ""}`}
      style={{ color: "var(--ink-3)", transition: "transform 160ms ease" }}
      aria-hidden
    >
      <path d="m6 9 6 6 6-6" />
    </svg>
  );
}

function LangOption({
  active,
  onClick,
  label,
  mono,
  dotDim,
}: {
  active: boolean;
  onClick: () => void;
  label: string;
  mono?: boolean;
  dotDim?: boolean;
}) {
  return (
    <li>
      <button
        type="button"
        role="option"
        aria-selected={active}
        onClick={onClick}
        className="w-full flex items-center gap-2 px-2.5 py-1.5 text-left text-[12.5px] transition-colors hover:bg-[var(--panel-2)]"
        style={{
          color: active ? "var(--accent)" : "var(--ink-2)",
          background: active ? "var(--accent-soft)" : undefined,
          fontFamily: mono ? MONO : undefined,
        }}
      >
        <span
          className="w-[5px] h-[5px] rounded-full shrink-0"
          style={{
            background: active ? "var(--accent)" : "var(--ink-3)",
            opacity: active ? 1 : dotDim ? 0.5 : 0.3,
          }}
        />
        <span className="flex-1 truncate">{label}</span>
        {active ? <Check size={12} className="shrink-0" /> : null}
      </button>
    </li>
  );
}