// React port of ../../drawer.ts (#35): the mobile off-canvas sidebar. On
// desktop the `drawer-open` class is inert — CSS gates the drawer styling to
// narrow viewports (styles.css, `.app-shell`).
//
// Anything that puts a new view in the content area must close the drawer, or
// it renders behind the sidebar and the tap reads as a dead button — this
// listens for the same TOGGLE_DRAWER_EVENT/OPEN_SPAWN_EVENT/SPAWN_SIMILAR_EVENT
// the rest of the shell already raises, so it needs no wiring from callers.

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

import { OPEN_SPAWN_EVENT, SPAWN_SIMILAR_EVENT, TOGGLE_DRAWER_EVENT } from "../../uiEvents.js";

export interface DrawerProps {
  sidebar: ReactNode;
  children: ReactNode;
  className?: string;
}

export function Drawer({ sidebar, children, className }: DrawerProps) {
  const [open, setOpen] = useState(false);
  const sidebarRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    const onToggle = () => setOpen((o) => !o);
    const onClose = () => setOpen(false);
    document.addEventListener(TOGGLE_DRAWER_EVENT, onToggle);
    document.addEventListener(OPEN_SPAWN_EVENT, onClose);
    document.addEventListener(SPAWN_SIMILAR_EVENT, onClose);
    return () => {
      document.removeEventListener(TOGGLE_DRAWER_EVENT, onToggle);
      document.removeEventListener(OPEN_SPAWN_EVENT, onClose);
      document.removeEventListener(SPAWN_SIMILAR_EVENT, onClose);
    };
  }, []);

  // Horizontal swipes drive the drawer (right opens, left closes) rather than
  // the browser's back/forward navigation. Only a clearly horizontal gesture
  // past a threshold counts, so vertical terminal scrolling (which owns its
  // own touch handler) is untouched.
  useEffect(() => {
    const mobileMq = window.matchMedia("(max-width: 859px)");
    let sx = 0;
    let sy = 0;
    let tracking = false;

    const onTouchStart = (e: TouchEvent) => {
      tracking = mobileMq.matches && e.touches.length === 1;
      if (tracking) {
        sx = e.touches[0].clientX;
        sy = e.touches[0].clientY;
      }
    };
    const onTouchEnd = (e: TouchEvent) => {
      if (!tracking) return;
      tracking = false;
      const t = e.changedTouches[0];
      const dx = t.clientX - sx;
      const dy = t.clientY - sy;
      if (Math.abs(dx) < 60 || Math.abs(dx) < Math.abs(dy) * 1.5) return;
      setOpen((o) => {
        if (dx > 0 && !o) return true;
        if (dx < 0 && o) return false;
        return o;
      });
    };

    document.addEventListener("touchstart", onTouchStart, { passive: true });
    document.addEventListener("touchend", onTouchEnd, { passive: true });
    return () => {
      document.removeEventListener("touchstart", onTouchStart);
      document.removeEventListener("touchend", onTouchEnd);
    };
  }, []);

  return (
    <div className={`app-shell flex h-full min-h-0 ${open ? "drawer-open" : ""} ${className ?? ""}`}>
      <div
        ref={sidebarRef}
        className="sidebar flex h-full min-h-0 flex-col bg-surface"
        onClick={(e) => {
          if ((e.target as HTMLElement).closest(".tree-leaf")) setOpen(false);
        }}
      >
        {sidebar}
      </div>
      <section className="content min-h-0 flex-1">{children}</section>
      <div className="mv-backdrop" onClick={() => setOpen(false)} />
    </div>
  );
}