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

/**
 * OpsModal — 统一模态基件(设计规范 v2 §2.2)
 *
 * - variant: info(仅"确定")/ confirm(取消+确定)/ input(带输入框,返回字符串)
 * - danger: 主按钮渲染为红色(危险操作确认)
 * - 可访问性:焦点陷阱(Tab 在模态内循环)、关闭后焦点归还触发元素、
 *   Esc 关闭、遮罩点击关闭
 * - 样式全部走 styles.css 的 --ops-* 令牌,亮暗主题随行
 */
export type OpsModalVariant = "info" | "confirm" | "input";

export type OpsModalProps = {
  title: ReactNode;
  variant?: OpsModalVariant;
  /** 主按钮红色(删除/截断等危险确认) */
  danger?: boolean;
  okLabel?: string;
  cancelLabel?: string;
  /** input 变体:输入框标签 */
  label?: string;
  /** input 变体:默认值 */
  defaultValue?: string;
  /** input 变体:占位符 */
  placeholder?: string;
  /** 层级,默认 var(--ops-z-modal);确认框传 var(--ops-z-confirm) */
  zIndex?: string | number;
  /** 宽版(max-w-2xl),DDL 等长文本展示用 */
  wide?: boolean;
  /** 确认回调;input 变体携带输入值 */
  onOk: (value?: string) => void;
  /** 取消回调(Esc / 遮罩点击 / 取消按钮),info 变体缺省时回落到 onOk */
  onCancel?: () => void;
  children?: ReactNode;
};

const FOCUSABLE =
  'button:not([disabled]), [href], input:not([disabled]), select:not([disabled]), textarea:not([disabled]), [tabindex]:not([tabindex="-1"])';

export function OpsModal(props: OpsModalProps) {
  const {
    title,
    variant = "info",
    danger = false,
    okLabel = "确定",
    cancelLabel = "取消",
    label,
    defaultValue = "",
    placeholder,
    zIndex = "var(--ops-z-modal)",
    wide = false,
    onOk,
    onCancel,
    children,
  } = props;

  const overlayRef = useRef<HTMLDivElement>(null);
  const dialogRef = useRef<HTMLDivElement>(null);
  const inputRef = useRef<HTMLInputElement>(null);
  const [value, setValue] = useState(defaultValue);
  // 回调放 ref,避免键盘监听因回调变化反复挂载
  const cbRef = useRef({ onOk, onCancel });
  cbRef.current = { onOk, onCancel };

  const cancel = () => (cbRef.current.onCancel ?? cbRef.current.onOk)();
  const submit = () => cbRef.current.onOk(variant === "input" ? value : undefined);

  // 焦点管理:打开时聚焦输入框/主按钮,Tab 在模态内循环,Esc 关闭,卸载时焦点归还触发元素
  useEffect(() => {
    const dialog = dialogRef.current;
    if (!dialog) return;
    const prev = document.activeElement as HTMLElement | null;
    const focusables = () =>
      Array.from(dialog.querySelectorAll<HTMLElement>(FOCUSABLE)).filter(
        (el) => el.offsetParent !== null || el === document.activeElement,
      );
    const initial =
      variant === "input" && inputRef.current ? inputRef.current : focusables().pop();
    initial?.focus();
    if (variant === "input") inputRef.current?.select();

    const onKey = (e: KeyboardEvent) => {
      // 模态可叠加(如确认框盖在通知模态上):仅最上层响应键盘
      const overlays = document.querySelectorAll(".ops-modal-overlay");
      if (overlays.length && overlays[overlays.length - 1] !== overlayRef.current) return;
      if (e.key === "Escape") {
        e.preventDefault();
        e.stopPropagation();
        cancel();
        return;
      }
      if (e.key !== "Tab") return;
      const items = focusables();
      if (!items.length) return;
      const first = items[0];
      const last = items[items.length - 1];
      const active = document.activeElement as HTMLElement | null;
      if (e.shiftKey) {
        if (!active || !dialog.contains(active) || active === first) {
          e.preventDefault();
          last.focus();
        }
      } else if (!active || !dialog.contains(active) || active === last) {
        e.preventDefault();
        first.focus();
      }
    };
    window.addEventListener("keydown", onKey, true);
    return () => {
      window.removeEventListener("keydown", onKey, true);
      // 焦点归还触发元素
      prev?.focus?.();
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  return (
    <div
      ref={overlayRef}
      className="ops-modal-overlay"
      style={{ zIndex }}
      onMouseDown={(e) => {
        // 仅点击遮罩本体(非对话框内容)才关闭
        if (e.target === overlayRef.current) cancel();
      }}
    >
      <div
        ref={dialogRef}
        className={`ops-modal w-full ${wide ? "max-w-2xl" : "max-w-md"}`}
        role="alertdialog"
        aria-modal="true"
        aria-label={typeof title === "string" ? title : undefined}
      >
        <div className="ops-modal-header">{title}</div>
        <div className="ops-modal-body">
          {children}
          {variant === "input" && (
            <form
              onSubmit={(e) => {
                e.preventDefault();
                submit();
              }}
            >
              {label && (
                <label
                  htmlFor="ops-modal-input"
                  className="mb-1 block"
                  style={{ fontSize: "var(--ops-text-sm)", color: "var(--ops-muted)" }}
                >
                  {label}
                </label>
              )}
              <input
                id="ops-modal-input"
                ref={inputRef}
                type="text"
                className="ops-input w-full"
                value={value}
                placeholder={placeholder}
                onChange={(e) => setValue(e.target.value)}
              />
            </form>
          )}
        </div>
        <div className="ops-modal-footer">
          {variant !== "info" && (
            <button type="button" className="ops-btn-secondary min-w-[72px]" onClick={cancel}>
              {cancelLabel}
            </button>
          )}
          <button
            type="button"
            className={`${danger ? "ops-btn-danger" : "ops-btn-primary"} min-w-[72px]`}
            onClick={submit}
          >
            {okLabel}
          </button>
        </div>
      </div>
    </div>
  );
}