import { useEffect, useRef, useState, type KeyboardEvent } from "react";
import type { Environment } from "../core/model";
import { EnvBadge } from "./EnvBadge";
import { Icon } from "./icons";

export function EnvironmentSwitcher({ environments, activeId, onSelect }: {
  environments: Environment[];
  activeId: string | null;
  onSelect: (id: string | null) => void;
}) {
  const [open, setOpen] = useState(false);
  const root = useRef<HTMLDivElement>(null);
  const trigger = useRef<HTMLButtonElement>(null);
  const menu = useRef<HTMLDivElement>(null);
  const active = environments.find((env) => env.id === activeId);

  useEffect(() => {
    if (!open) return;
    const selected = menu.current?.querySelector<HTMLElement>('[aria-checked="true"]');
    (selected ?? menu.current?.querySelector<HTMLElement>('[role="menuitemradio"]'))?.focus();
    const closeOutside = (event: PointerEvent) => {
      if (event.target instanceof Node && !root.current?.contains(event.target)) setOpen(false);
    };
    const closeOnResize = () => setOpen(false);
    window.addEventListener("pointerdown", closeOutside, true);
    window.addEventListener("resize", closeOnResize);
    return () => {
      window.removeEventListener("pointerdown", closeOutside, true);
      window.removeEventListener("resize", closeOnResize);
    };
  }, [open]);

  const choose = (id: string | null) => {
    onSelect(id);
    setOpen(false);
    trigger.current?.focus();
  };

  const onMenuKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
    if (event.key === "Escape") {
      event.preventDefault();
      setOpen(false);
      trigger.current?.focus();
      return;
    }
    if (event.key === "Tab") {
      setOpen(false);
      return;
    }
    if (!["ArrowDown", "ArrowUp", "Home", "End"].includes(event.key)) return;
    event.preventDefault();
    const options = Array.from(menu.current?.querySelectorAll<HTMLButtonElement>('[role="menuitemradio"]') ?? []);
    if (!options.length) return;
    const current = options.indexOf(document.activeElement as HTMLButtonElement);
    const next = event.key === "Home" ? 0 : event.key === "End" ? options.length - 1
      : (current + (event.key === "ArrowDown" ? 1 : -1) + options.length) % options.length;
    options[next].focus();
  };

  return <div className="env-switcher" ref={root}>
    <button ref={trigger} type="button" className="env-switch-trigger" aria-label={`当前环境：${active?.name ?? "不使用环境"}`}
      aria-haspopup="menu" aria-expanded={open} aria-controls={open ? "env-switch-menu" : undefined}
      title={active?.baseUrl || "选择请求环境"} onClick={() => setOpen((value) => !value)}>
      {active ? <EnvBadge envId={active.id} name={active.name} size={18} /> : <Icon name="circle-slash" size={16} className="ops-faint" />}
      <span className="truncate">{active?.name ?? "不使用环境"}</span>
      <Icon name="chevron-down" size={14} className="ops-faint ml-auto shrink-0" />
    </button>
    {open && <div id="env-switch-menu" ref={menu} role="menu" aria-label="切换请求环境" className="env-switch-menu" onKeyDown={onMenuKeyDown}>
      <div className="env-switch-heading">请求环境</div>
      <button type="button" role="menuitemradio" aria-checked={!active} className="env-switch-option" onClick={() => choose(null)}>
        <Icon name="circle-slash" size={17} className="ops-faint shrink-0" />
        <span className="min-w-0 flex-1 text-left"><span className="block font-semibold">不使用环境</span><span className="ops-faint block text-[11px]">直接使用请求中填写的完整地址</span></span>
        {!active && <Icon name="circle-check" size={15} className="ops-accent shrink-0" />}
      </button>
      <div className="env-switch-divider" />
      <div className="env-switch-options">
        {environments.map((env) => <button type="button" role="menuitemradio" aria-checked={env.id === activeId}
          key={env.id} className="env-switch-option" onClick={() => choose(env.id)}>
          <EnvBadge envId={env.id} name={env.name} size={22} />
          <span className="min-w-0 flex-1 text-left"><span className="block truncate font-semibold">{env.name}</span><span className="ops-faint block truncate text-[11px]" title={env.baseUrl || "未设置前置 URL"}>{env.baseUrl || "未设置前置 URL"}</span></span>
          {env.id === activeId && <Icon name="circle-check" size={15} className="ops-accent shrink-0" />}
        </button>)}
      </div>
      {environments.length === 0 && <p className="ops-faint px-3 py-2 text-xs">暂无环境，可点击左侧“管理环境”创建。</p>}
    </div>}
  </div>;
}