package sectr

UI_BoxFlag :: enum u64 {
	Disabled,

	Focusable,
	Click_To_Focus,

	Mouse_Clickable,
	Keyboard_Clickable,

	// Pan_X,
	// Pan_Y,

	// Scroll_X,
	// Scroll_Y,

	// Screenspace,
	Count,
}
UI_BoxFlags :: bit_set[UI_BoxFlag; u64]
// UI_BoxFlag_Scroll :: UI_BoxFlags { .Scroll_X, .Scroll_Y }

UI_RenderBoxInfo :: struct {
	using computed : UI_Computed,
	using style    : UI_Style,
	text         : StrRunesPair,
	font_size    : UI_Scalar,
	border_width : UI_Scalar,
}

UI_Box :: struct {
	// Cache ID
	key   : UI_Key,
	// label : string,
	label : StrRunesPair,
	text  : StrRunesPair,

	// Regenerated per frame.

	// first, last : The first and last child of this box
	// prev, next  : The adjacent neighboring boxes who are children of to the same parent
	using links   : DLL_NodeFull( UI_Box ),
	parent        : ^UI_Box,
	num_children  : i32,
	ancestors     : i32, // This value for rooted widgets gets set to -1 after rendering see ui_box_make() for the reason.
	parent_index  : i32,

	flags    : UI_BoxFlags,
	computed : UI_Computed,

	layout : UI_Layout,
	style  : UI_Style,

	// Persistent Data
	hot_delta      : f32,
	active_delta   : f32,
	disabled_delta : f32,
	style_delta    : f32,
	first_frame    : b8,
	// root_order_id  : i16,

	// prev_computed : UI_Computed,
	// prev_style    : UI_Style,v
	// mouse         : UI_InteractState,
	// keyboard      : UI_InteractState,
}

ui_box_equal :: #force_inline proc "contextless" ( a, b : ^ UI_Box ) -> b32 {
	BoxSize :: size_of(UI_Box)

	result : b32 = true
	result &= a.key   == b.key   // We assume for now the label is the same as the key, if not something is terribly wrong.
	result &= a.flags == b.flags
	return result
}

ui_box_from_key :: #force_inline proc ( cache : ^HMapZPL(UI_Box), key : UI_Key ) -> (^UI_Box) {
	return zpl_hmap_get( cache, cast(u64) key )
}

ui_box_make :: proc( flags : UI_BoxFlags, label : string ) -> (^ UI_Box)
{
	// profile(#procedure)

	using ui := get_state().ui_context

	key := ui_key_from_string( label )

	curr_box : (^ UI_Box)
	prev_box := zpl_hmap_get( prev_cache, cast(u64) key )
	{
		// profile("Assigning current box")

		set_result : ^ UI_Box
		set_error  : AllocatorError
		if prev_box != nil
		{
			// Previous history was found, copy over previous state.
			set_result, set_error = zpl_hmap_set( curr_cache, cast(u64) key, (prev_box ^) )
		}
		else {
			box : UI_Box
			box.key   = key
			box.label = str_intern( label )
			// set_result, set_error = zpl_hmap_set( prev_cache, cast(u64) key, box )
			set_result, set_error = zpl_hmap_set( curr_cache, cast(u64) key, box )
		}

		verify( set_error == AllocatorError.None, "Failed to set zpl_hmap due to allocator error" )
		curr_box = set_result

		curr_box.first_frame = prev_box == nil
	}

	curr_box.flags = flags

	// Clear non-persistent data
	curr_box.computed.fresh = false
	curr_box.links          = {}
	curr_box.num_children   = 0

	// If there is a parent, setup the relevant references
	parent := stack_peek( & parent_stack )
	if parent != nil
	{
		when false {
			dll_full_push_back( parent, curr_box, nil )
		}
		else
		{
			//    |
			//    v
			// parent.first <nil>
			if parent.first == nil {
				parent.first  = curr_box
				parent.last   = curr_box
				curr_box.next = nil
				curr_box.prev = nil
			}
			else {
				// Positin is set to last, insert at end
				// <parent.last.prev> <parent.last> curr_box
				parent.last.next = curr_box
				curr_box.prev    = parent.last
				parent.last      = curr_box
				curr_box.next    = nil
			}
		}

		curr_box.parent_index = parent.num_children
		parent.num_children  += 1
		curr_box.parent       = parent
		curr_box.ancestors    = parent.ancestors + 1
	}

	ui.built_box_count += 1
	return curr_box
}

ui_box_tranverse_next :: proc "contextless" ( box : ^ UI_Box ) -> (^ UI_Box)
{
	// Check to make sure parent is present on the screen, if its not don't bother.
	// If current has children, do them first
	using state := get_state()
	if box.first != nil
	{
		is_app_ui := ui_context == & screen_ui
		if is_app_ui || intersects_range2( view_get_bounds(), box.computed.bounds)
		{
			return box.first
		}
	}

	if box.next == nil
	{
		// There is no more adjacent nodes
		if box.parent != nil
		{
			parent := box.parent
			// Attempt to find a parent with a next, otherwise we just return a parent with nil
			for ; parent.parent != nil;
			{
				if parent.next != nil {
					break
				}
				parent = parent.parent
			}

			// Lift back up to parent, and set it to its next.
			return parent.next
		}
	}

	return box.next
}