// 25 july 2014

package ui

import (
	"unsafe"
)

// #include "winapi_windows.h"
import "C"

/*
On Windows, container controls are just regular controls; their children have to be children of the parent window, and changing the contents of a switching container (such as a tab control) must be done manually. Mind the odd code here.

TODO
- make sure all tabs cannot be deselected (that is, make sure the current tab can never have index -1)
*/

type tab struct {
	*widgetbase
	tabs			[]Control
	curparent		*window
}

func newTab() Tab {
	w := newWidget(C.xWC_TABCONTROL,
		C.TCS_TOOLTIPS | C.WS_TABSTOP,
		0)
	t := &tab{
		widgetbase:	w,
	}
	C.controlSetControlFont(w.hwnd)
	C.setTabSubclass(w.hwnd, unsafe.Pointer(t))
	return t
}

func (t *tab) unparent() {
	t.widgetbase.unparent()
	for _, c := range t.tabs {
		c.unparent()
	}
	t.curparent = nil
}

func (t *tab) parent(win *window) {
	t.widgetbase.parent(win)
	for _, c := range t.tabs {
		c.parent(win)
	}
	t.curparent = win
}

func (t *tab) Append(name string, control Control) {
	t.tabs = append(t.tabs, control)
	if t.curparent == nil {
		control.unparent()
	} else {
		control.parent(t.curparent)
	}
	C.tabAppend(t.hwnd, toUTF16(name))
}

//export tabChanging
func tabChanging(data unsafe.Pointer, current C.LRESULT) {
	t := (*tab)(data)
	t.tabs[int(current)].containerHide()
}

//export tabChanged
func tabChanged(data unsafe.Pointer, new C.LRESULT) {
	t := (*tab)(data)
	t.tabs[int(new)].containerShow()
}

// a tab control contains other controls; size appropriately
func (t *tab) allocate(x int, y int, width int, height int, d *sizing) []*allocation {
	var r C.RECT

	// first, append the tab control itself
	a := t.widgetbase.allocate(x, y, width, height, d)
	// now figure out what the rect for each child is
	r.left = C.LONG(x)				// load rect with existing values
	r.top = C.LONG(y)
	r.right = C.LONG(x + width)
	r.bottom = C.LONG(y + height)
	C.tabGetContentRect(t.hwnd, &r)
	// and allocate
	// don't allocate to just hte current tab; allocate to all tabs!
	for _, c := range t.tabs {
		a = append(a, c.allocate(int(r.left), int(r.top), int(r.right - r.left), int(r.bottom - r.top), d)...)
	}
	return a
}