import { ArrowLeft } from "lucide-react";
import { createContext, type ReactNode, useCallback, useContext, useEffect, useMemo, useRef, useState } from "react";
import { createPortal } from "react-dom";
import { Button } from "~/components/ui/button.tsx";
import { Sheet, SheetContent, SheetDescription, SheetHeader, SheetTitle } from "~/components/ui/sheet.tsx";
import { cn } from "~/lib/utils.ts";

/** 桌面宽度:md ≈ 32rem,lg ≈ 44rem,xl ≈ 64rem(内容重的记录:订阅对比、站点);手机一律全宽 */
export type DetailSheetWidth = "md" | "lg" | "xl";
const WIDTH: Record<DetailSheetWidth, string> = {
  md: "sm:max-w-lg",
  lg: "sm:max-w-2xl",
  xl: "sm:max-w-5xl",
};

/**
 * 抽屉里再开的 DetailSheet 不叠第二层抽屉(console-ia.md §9):在同一个抽屉里换成子视图,
 * 顶部是「返回」,关掉子视图回到原来的内容(滚动位置不丢)。
 */
type Nest = {
  host: HTMLElement | null;
  push: (close: () => void) => () => void;
};
const NestContext = createContext<Nest | null>(null);

type Props = {
  open: boolean;
  onOpenChange: (open: boolean) => void;
  title: ReactNode;
  description?: ReactNode;
  /** 标题下面一行的操作按钮(记录抽屉的主操作、更多) */
  actions?: ReactNode;
  children: ReactNode;
  footer?: ReactNode;
  width?: DetailSheetWidth;
  className?: string;
};

/**
 * 右侧详情抽屉(手机全宽)。内容区自带纵向滚动;footer 固定在底部放操作按钮。
 *   <DetailSheet open={!!id} onOpenChange={(o) => !o && setId(null)} title="详情" description="…">
 *     <KvList items={…} />
 *   </DetailSheet>
 * 从列表打开记录时配合 useRecordSheet(record-sheet.tsx)把打开的记录写进地址栏。
 */
export function DetailSheet(props: Props) {
  const nest = useContext(NestContext);
  if (nest) return <NestedView {...props} nest={nest} />;
  return <RootSheet {...props} />;
}

function RootSheet({
  open,
  onOpenChange,
  title,
  description,
  actions,
  children,
  footer,
  width = "md",
  className,
}: Props) {
  const [host, setHost] = useState<HTMLDivElement | null>(null);
  const stack = useRef<(() => void)[]>([]);
  const [depth, setDepth] = useState(0);
  const push = useCallback((close: () => void) => {
    stack.current.push(close);
    setDepth(stack.current.length);
    return () => {
      stack.current = stack.current.filter((c) => c !== close);
      setDepth(stack.current.length);
    };
  }, []);
  const nest = useMemo<Nest>(() => ({ host, push }), [host, push]);
  return (
    <Sheet open={open} onOpenChange={onOpenChange}>
      <SheetContent
        side="right"
        className={cn("w-full gap-0 p-0", WIDTH[width], className)}
        // 打开时焦点落在抽屉本身而不是第一个按钮 / 标签,避免一打开就亮焦点框;Tab 仍从抽屉内开始
        onOpenAutoFocus={(e) => {
          e.preventDefault();
          (e.currentTarget as HTMLElement | null)?.focus({ preventScroll: true });
        }}
        onEscapeKeyDown={(e) => {
          // 有子视图时 Esc 先回到上一层
          const top = stack.current.at(-1);
          if (top) {
            e.preventDefault();
            top();
          }
        }}
      >
        <NestContext.Provider value={nest}>
          <div className={cn("flex min-h-0 flex-1 flex-col", depth > 0 && "invisible")} aria-hidden={depth > 0}>
            <SheetFrame title={title} description={description} actions={actions} footer={footer}>
              {children}
            </SheetFrame>
          </div>
          <div ref={setHost} className={cn("absolute inset-0 flex flex-col", depth === 0 && "hidden")} />
        </NestContext.Provider>
      </SheetContent>
    </Sheet>
  );
}

function SheetFrame({
  title,
  description,
  actions,
  footer,
  children,
  back,
}: Pick<Props, "title" | "description" | "actions" | "footer" | "children"> & { back?: () => void }) {
  return (
    <>
      <SheetHeader className="border-b border-[var(--shell-border)] px-5 py-4 pr-14">
        {back ? (
          <Button variant="ghost" size="sm" className="-ml-2 mb-1 self-start" onClick={back}>
            <ArrowLeft />
            返回
          </Button>
        ) : null}
        {back ? (
          // 子视图在同一个对话框里,标题不再占用对话框的 Title / Description
          <>
            <h2 className="line-clamp-2 text-lead font-semibold break-words text-foreground">{title}</h2>
            {description ? <div className="text-sm break-words text-muted-foreground">{description}</div> : null}
          </>
        ) : (
          <>
            <SheetTitle className="line-clamp-2 text-lead break-words">{title}</SheetTitle>
            {description ? (
              <SheetDescription asChild>
                <div className="break-words">{description}</div>
              </SheetDescription>
            ) : null}
          </>
        )}
        {actions ? <div className="mt-2 flex flex-wrap items-center gap-2">{actions}</div> : null}
      </SheetHeader>
      <div className="min-h-0 flex-1 space-y-5 overflow-y-auto px-5 py-4">{children}</div>
      {footer ? (
        <div className="flex flex-wrap items-center justify-end gap-2 border-t border-[var(--shell-border)] px-5 py-3">
          {footer}
        </div>
      ) : null}
    </>
  );
}

/** 抽屉里的子视图:渲染进外层抽屉的同一块区域,盖住原内容 */
function NestedView({ open, onOpenChange, nest, ...frame }: Props & { nest: Nest }) {
  const close = useRef(() => onOpenChange(false));
  close.current = () => onOpenChange(false);
  const { push, host } = nest;
  useEffect(() => {
    if (!open) return;
    return push(() => close.current());
  }, [open, push]);
  if (!open || !host) return null;
  return createPortal(
    <div className="flex min-h-0 flex-1 flex-col">
      <SheetFrame {...frame} back={() => close.current()} />
    </div>,
    host,
  );
}

/** 抽屉/卡片内的小节:大写小标签 + 内容 */
export function DetailSection({
  title,
  children,
  actions,
}: {
  title: string;
  children: ReactNode;
  actions?: ReactNode;
}) {
  return (
    <section>
      <div className="mb-2 flex items-center justify-between gap-2">
        <h3 className="text-label font-semibold tracking-[0.18em] text-muted-foreground uppercase">{title}</h3>
        {actions}
      </div>
      {children}
    </section>
  );
}