import type { Terminal as XTerm } from 'xterm';
import type { FitAddon } from 'xterm-addon-fit';

/** FitAddon 适配终端并同步远端 PTY 尺寸（WebSSH resize） // Logan.Li */
export function fitTerminal(fit: FitAddon, term: XTerm, ws?: WebSocket | null) {
  fit.fit();
  if (ws?.readyState === WebSocket.OPEN) {
    const { cols, rows } = term;
    if (cols > 0 && rows > 0) {
      ws.send(JSON.stringify({ status: 1, cols, rows }));
    }
  }
}

/** 等待容器就绪后挂载 xterm，并延迟二次 fit 消除右侧黑边 // Logan.Li */
export function mountXterm(
  term: XTerm,
  fit: FitAddon,
  getContainer: () => HTMLDivElement | null,
  ws?: WebSocket | null,
) {
  const applyFit = () => {
    try {
      fitTerminal(fit, term, ws);
      term.focus();
    } catch {
      /* noop */
    }
  };

  const tryMount = () => {
    const el = getContainer();
    if (!el) {
      requestAnimationFrame(tryMount);
      return;
    }
    if (!term.element) {
      term.open(el);
    }
    requestAnimationFrame(applyFit);
    setTimeout(applyFit, 100);
    setTimeout(applyFit, 300);
  };

  tryMount();
}

/** ResizeObserver 监听容器尺寸，持续 fit // Logan.Li */
export function attachTerminalResize(
  container: HTMLDivElement,
  fit: FitAddon,
  term: XTerm,
  ws?: WebSocket | null,
) {
  let timer: ReturnType<typeof setTimeout>;
  const ro = new ResizeObserver(() => {
    clearTimeout(timer);
    timer = setTimeout(() => {
      try {
        fitTerminal(fit, term, ws);
      } catch {
        /* noop */
      }
    }, 60);
  });
  ro.observe(container);
  return () => {
    clearTimeout(timer);
    ro.disconnect();
  };
}