use imgui_sys;
use ImStr;
use ImVec2;
use ImGuiWindowFlags;

use super::{ImGuiWindowFlags_NoMove, ImGuiWindowFlags_NoScrollbar, ImGuiWindowFlags_NoScrollWithMouse,
            ImGuiWindowFlags_NoCollapse, ImGuiWindowFlags_AlwaysAutoResize,
            ImGuiWindowFlags_ShowBorders, ImGuiWindowFlags_NoInputs, ImGuiWindowFlags_MenuBar,
            ImGuiWindowFlags_HorizontalScrollbar, ImGuiWindowFlags_NoFocusOnAppearing,
            ImGuiWindowFlags_NoBringToFrontOnFocus, ImGuiWindowFlags_AlwaysVerticalScrollbar,
            ImGuiWindowFlags_AlwaysHorizontalScrollbar, ImGuiWindowFlags_AlwaysUseWindowPadding};

#[must_use]
pub struct ChildFrame<'p> {
    name: &'p ImStr,
    size: ImVec2,
    flags: ImGuiWindowFlags,
}

impl<'p> ChildFrame<'p> {
    pub(crate) fn new<S: Into<ImVec2>>(name: &'p ImStr, size: S) -> ChildFrame<'p> {
        ChildFrame {
            name,
            size: size.into(),
            flags: ImGuiWindowFlags::empty(),
        }
    }
    #[inline]
    pub fn movable(mut self, value: bool) -> Self {
        self.flags.set(ImGuiWindowFlags_NoMove, !value);
        self
    }
    #[inline]
    pub fn show_scrollbar(mut self, value: bool) -> Self {
        self.flags.set(ImGuiWindowFlags_NoScrollbar, !value);
        self
    }
    #[inline]
    pub fn show_scrollbar_with_mouse(mut self, value: bool) -> Self {
        self.flags.set(ImGuiWindowFlags_NoScrollWithMouse, !value);
        self
    }
    #[inline]
    pub fn collapsible(mut self, value: bool) -> Self {
        self.flags.set(ImGuiWindowFlags_NoCollapse, !value);
        self
    }
    #[inline]
    pub fn always_resizable(mut self, value: bool) -> Self {
        self.flags.set(ImGuiWindowFlags_AlwaysAutoResize, value);
        self
    }
    #[inline]
    pub fn show_borders(mut self, value: bool) -> Self {
        self.flags.set(ImGuiWindowFlags_ShowBorders, value);
        self
    }
    #[inline]
    pub fn input_allow(mut self, value: bool) -> Self {
        self.flags.set(ImGuiWindowFlags_NoInputs, !value);
        self
    }
    #[inline]
    pub fn show_menu(mut self, value: bool) -> Self {
        self.flags.set(ImGuiWindowFlags_MenuBar, value);
        self
    }
    #[inline]
    pub fn scrollbar_horizontal(mut self, value: bool) -> Self {
        self.flags.set(ImGuiWindowFlags_HorizontalScrollbar, value);
        self
    }
    #[inline]
    pub fn focus_on_appearing(mut self, value: bool) -> Self {
        self.flags.set(ImGuiWindowFlags_NoFocusOnAppearing, !value);
        self
    }
    #[inline]
    pub fn bring_to_front_on_focus(mut self, value: bool) -> Self {
        self.flags.set(
            ImGuiWindowFlags_NoBringToFrontOnFocus,
            !value,
        );
        self
    }
    #[inline]
    pub fn always_show_vertical_scroll_bar(mut self, value: bool) -> Self {
        self.flags.set(
            ImGuiWindowFlags_AlwaysVerticalScrollbar,
            value,
        );
        self
    }
    #[inline]
    pub fn always_show_horizontal_scroll_bar(mut self, value: bool) -> Self {
        self.flags.set(
            ImGuiWindowFlags_AlwaysHorizontalScrollbar,
            value,
        );
        self
    }
    #[inline]
    pub fn always_use_window_padding(mut self, value: bool) -> Self {
        self.flags.set(
            ImGuiWindowFlags_AlwaysUseWindowPadding,
            value,
        );
        self
    }
    pub fn build<F: FnOnce()>(self, f: F) {
        // See issue for history.
        // https://github.com/Gekkio/imgui-rs/pull/58
        let show_border = false;

        let render_child_frame = unsafe { imgui_sys::igBeginChild(self.name.as_ptr(), self.size, show_border, self.flags) };
        if render_child_frame {
            f();
        }
        unsafe { imgui_sys::igEndChild() };
    }
}