import { type ReactNode, type RefObject, useLayoutEffect, useRef, useState } from "react";

import { cn } from "~/lib/utils.ts";

type Thumb = { x: number; y: number; w: number; h: number };

/**
 * 分段控件的滑块:量出容器里当前选中项(`selector`)的位置写进 style,选中项变化、尺寸变化时跟着滑过去。
 * 第一次量到之前不画,量到后才挂过渡,避免首屏从左上角滑进来。与 uhd_web SegmentedTabs、控制台侧栏同一做法。
 */
export function useSlidingThumb(container: RefObject<HTMLElement | null>, selector: string, deps: unknown[] = []) {
  const [thumb, setThumb] = useState<Thumb | null>(null);
  const [animate, setAnimate] = useState(false);
  useLayoutEffect(() => {
    const el = container.current;
    if (!el) return;
    const measure = () => {
      const active = el.querySelector<HTMLElement>(selector);
      setThumb((prev) => {
        if (!active) return null;
        const next = { x: active.offsetLeft, y: active.offsetTop, w: active.offsetWidth, h: active.offsetHeight };
        return prev && prev.x === next.x && prev.y === next.y && prev.w === next.w && prev.h === next.h ? prev : next;
      });
    };
    measure();
    const raf = requestAnimationFrame(() => setAnimate(true));
    const ro = new ResizeObserver(measure);
    ro.observe(el);
    for (const child of Array.from(el.children)) ro.observe(child);
    // radix Tabs 的选中态写在 data-state 上,不一定引起本组件重渲染
    const mo = new MutationObserver(measure);
    mo.observe(el, { subtree: true, attributes: true, attributeFilter: ["data-state", "aria-checked"] });
    return () => {
      cancelAnimationFrame(raf);
      ro.disconnect();
      mo.disconnect();
    };
  }, [container, selector, ...deps]);
  return { thumb, animate };
}

/** 滑块本体(`seg-thumb` 玻璃),放在相对定位的容器里、选项之前 */
export function SegThumb({ thumb, animate, className }: { thumb: Thumb | null; animate: boolean; className?: string }) {
  if (!thumb) return null;
  return (
    <span
      aria-hidden
      className={cn(
        "seg-thumb pointer-events-none absolute top-0 left-0 rounded-full",
        animate && "tab-slider",
        className,
      )}
      style={{ transform: `translate(${thumb.x}px, ${thumb.y}px)`, width: thumb.w, height: thumb.h }}
    />
  );
}

export type SegmentedOption<V extends string> = {
  value: V;
  label: ReactNode;
  icon?: ReactNode;
  /** 跟在标签后面的数量,弱一档显示 */
  count?: ReactNode;
  /** 只有图标时给读屏与悬停提示 */
  title?: string;
  disabled?: boolean;
};

/**
 * 单选分段控件:筛选(全部 / 已启用)、视图(卡片 / 列表)、分组(进行中 / 已完成)这类互斥选项。
 * 选中项由一枚滑动的 `seg-thumb` 承担,文字提一档;没有实心选中块。多选的筛选条件用 `pill-selected` 胶囊,不用它。
 */
export function SegmentedControl<V extends string>({
  value,
  onChange,
  options,
  label,
  size = "sm",
  className,
  fill = false,
}: {
  value: V;
  onChange: (v: V) => void;
  options: SegmentedOption<V>[];
  /** 读屏用的组名 */
  label: string;
  size?: "xs" | "sm";
  className?: string;
  /** 铺满容器宽度,选项等分 */
  fill?: boolean;
}) {
  const ref = useRef<HTMLDivElement>(null);
  const { thumb, animate } = useSlidingThumb(ref, '[aria-checked="true"]', [value, options.length]);
  return (
    <div
      ref={ref}
      role="radiogroup"
      aria-label={label}
      className={cn(
        "relative isolate items-center gap-0.5",
        fill ? "flex w-full" : "inline-flex max-w-full",
        className,
      )}
    >
      <SegThumb thumb={thumb} animate={animate} className="-z-[1]" />
      {options.map((o) => {
        const on = o.value === value;
        return (
          <button
            key={o.value}
            type="button"
            role="radio"
            aria-checked={on}
            aria-label={o.title}
            title={o.title}
            disabled={o.disabled}
            onClick={() => onChange(o.value)}
            className={cn(
              "inline-flex shrink-0 cursor-pointer items-center justify-center gap-1.5 rounded-full font-medium whitespace-nowrap outline-none transition-colors duration-base focus-visible:ring-2 focus-visible:ring-ring/50 disabled:cursor-not-allowed disabled:opacity-50 [&_svg]:size-3.5 [&_svg]:shrink-0",
              size === "xs" ? "h-7 px-2.5 text-meta" : "h-8 px-3 text-caption",
              o.label === "" && (size === "xs" ? "w-7 px-0" : "w-8 px-0"),
              fill && "flex-1",
              on ? "text-foreground" : "text-muted-foreground hover:text-foreground",
            )}
          >
            {o.icon}
            {o.label === "" ? null : o.label}
            {o.count != null ? (
              <span className={cn("tabular-nums", on ? "text-muted-foreground" : "text-muted-foreground/70")}>
                {o.count}
              </span>
            ) : null}
          </button>
        );
      })}
    </div>
  );
}