package xmu

import (
	"xgob"
	"xgob/util"
	"xgob/xproto"
)

/* The main difference between this and C/libXmu is that this version
   searches for the client window in the shallowest windows first, and
   C/libXmu searches the topmost windows first.

   This change allows us to avoid as many round-trips as possible.
*/

func tryChildren(c *xgob.Connection, children []xproto.Window) xproto.Window {
	queryCookies := make([]chan xproto.QueryTreeReply, 0)
	propCookies := make([]chan xproto.GetPropertyReply, 0)

	state := util.Atom(c, "WM_STATE")

	for {
		if len(children) == 0 {
			break
		}

		// Reset cookie jars
		queryCookies = queryCookies[:0]
		propCookies = propCookies[:0]

		for _, child := range children {
			propCookies = append(propCookies, xproto.GetProperty(c, false, child, state, xproto.Atom(0), 0, 0))
			queryCookies = append(queryCookies, xproto.QueryTree(c, child))
		}
		c.Flush()
		for i, cookie := range propCookies {
			s := <-cookie
			if s.Error == nil && s.Type != xproto.Atom(0) {
				return children[i]
			}
		}

		children = children[:0]
		for _, cookie := range queryCookies {
			children = append(children, (<-cookie).Children...)
		}

	}
	return 0
}

func ClientWindow(c *xgob.Connection, win xproto.Window) xproto.Window {
	stateCookie := xproto.GetProperty(c, false, win, util.Atom(c, "WM_STATE"), xproto.Atom(0), 0, 0)
	treeCookie := xproto.QueryTree(c, win)
	c.Flush()
	state := <-stateCookie
	if state.Error != nil && state.Type != xproto.Atom(0) {
		return win
	}

	tree := <-treeCookie
	if rv := tryChildren(c, tree.Children); rv != 0 {
		win = rv
	}
	return win
}