use std::any::Any;
use std::marker::PhantomPinned;
use std::pin::Pin;
use std::sync::Arc;

use crate::co;
use crate::gui::base::Base;
use crate::gui::events::{ComboBoxEvents, WindowEvents};
use crate::gui::layout_arranger::{Horz, Vert};
use crate::gui::native_controls::base_native_control::{
	BaseNativeControl, OptsId,
};
use crate::gui::native_controls::combo_box_items::ComboBoxItems;
use crate::gui::privs::{auto_ctrl_id, multiply_dpi_or_dtu, ui_font};
use crate::msg::wm;
use crate::prelude::{
	GuiChild, GuiChildFocus, GuiEvents, GuiNativeControl,
	GuiNativeControlEvents, GuiParent, GuiWindow, GuiWindowText, Handle,
	user_Hwnd,
};
use crate::user::decl::{HWND, POINT, SIZE};

struct Obj { // actual fields of ComboBox
	base: BaseNativeControl,
	opts_id: OptsId<ComboBoxOpts>,
	events: ComboBoxEvents,
	_pin: PhantomPinned,
}

/// Native
/// [combo box](https://docs.microsoft.com/en-us/windows/win32/controls/about-combo-boxes)
/// control.
#[cfg_attr(docsrs, doc(cfg(feature = "gui")))]
#[derive(Clone)]
pub struct ComboBox(Pin<Arc<Obj>>);

unsafe impl Send for ComboBox {}

impl GuiWindow for ComboBox {
	fn hwnd(&self) -> HWND {
		self.0.base.hwnd()
	}

	fn as_any(&self) -> &dyn Any {
		self
	}
}

impl GuiWindowText for ComboBox {}

impl GuiChild for ComboBox {
	fn ctrl_id(&self) -> u16 {
		match &self.0.opts_id {
			OptsId::Wnd(opts) => opts.ctrl_id,
			OptsId::Dlg(ctrl_id) => *ctrl_id,
		}
	}
}

impl GuiChildFocus for ComboBox {}

impl GuiNativeControl for ComboBox {
	fn on_subclass(&self) -> &WindowEvents {
		self.0.base.on_subclass()
	}
}

impl GuiNativeControlEvents<ComboBoxEvents> for ComboBox {
	fn on(&self) -> &ComboBoxEvents {
		if !self.hwnd().is_null() {
			panic!("Cannot add events after the control creation.");
		} else if !self.0.base.parent().hwnd().is_null() {
			panic!("Cannot add events after the parent window creation.");
		}
		&self.0.events
	}
}

impl ComboBox {
	/// Instantiates a new `ComboBox` object, to be created on the parent window
	/// with
	/// [`HWND::CreateWindowEx`](crate::prelude::user_Hwnd::CreateWindowEx).
	#[must_use]
	pub fn new(parent: &impl GuiParent, opts: ComboBoxOpts) -> ComboBox {
		let parent_ref = unsafe { Base::from_guiparent(parent) };
		let opts = ComboBoxOpts::define_ctrl_id(opts);
		let (ctrl_id, horz, vert) = (opts.ctrl_id, opts.horz_resize, opts.vert_resize);

		let new_self = Self(
			Arc::pin(
				Obj {
					base: BaseNativeControl::new(parent_ref),
					opts_id: OptsId::Wnd(opts),
					events: ComboBoxEvents::new(parent_ref, ctrl_id),
					_pin: PhantomPinned,
				},
			),
		);

		let self2 = new_self.clone();
		parent_ref.privileged_on().wm(parent_ref.creation_msg(), move |_| {
			self2.create(horz, vert);
			Ok(None) // not meaningful
		});
		new_self
	}

	/// Instantiates a new `ComboBox` object, to be loaded from a dialog
	/// resource with
	/// [`HWND::GetDlgItem`](crate::prelude::user_Hwnd::GetDlgItem).
	#[must_use]
	pub fn new_dlg(
		parent: &impl GuiParent,
		ctrl_id: u16,
		resize_behavior: (Horz, Vert)) -> ComboBox
	{
		let parent_ref = unsafe { Base::from_guiparent(parent) };

		let new_self = Self(
			Arc::pin(
				Obj {
					base: BaseNativeControl::new(parent_ref),
					opts_id: OptsId::Dlg(ctrl_id),
					events: ComboBoxEvents::new(parent_ref, ctrl_id),
					_pin: PhantomPinned,
				},
			),
		);

		let self2 = new_self.clone();
		parent_ref.privileged_on().wm_init_dialog(move |_| {
			self2.create(resize_behavior.0, resize_behavior.1);
			Ok(true) // not meaningful
		});

		new_self
	}

	fn create(&self, horz: Horz, vert: Vert) {
		if vert == Vert::Resize {
			panic!("ComboBox cannot be resized with Vert::Resize.");
		}

		match &self.0.opts_id {
			OptsId::Wnd(opts) => {
				let mut pos = opts.position;
				let mut sz = SIZE::new(opts.width as _, 0);
				multiply_dpi_or_dtu(
					self.0.base.parent(), Some(&mut pos), Some(&mut sz));

				self.0.base.create_window(
					"COMBOBOX", None, pos, sz,
					opts.ctrl_id,
					opts.window_ex_style,
					opts.window_style | opts.combo_box_style.into(),
				);

				self.hwnd().SendMessage(
					wm::SetFont { hfont: ui_font(), redraw: true });
				self.items().add(&opts.items);
				self.items().select(opts.selected_item);
			},
			OptsId::Dlg(ctrl_id) => self.0.base.create_dlg(*ctrl_id),
		}

		self.0.base.parent().add_to_layout_arranger(self.hwnd(), horz, vert);
	}

	/// Item methods.
	#[must_use]
	pub const fn items(&self) -> ComboBoxItems {
		ComboBoxItems::new(self)
	}
}

//------------------------------------------------------------------------------

/// Options to create a [`ComboBox`](crate::gui::ComboBox) programmatically with
/// [`ComboBox::new`](crate::gui::ComboBox::new).
#[cfg_attr(docsrs, doc(cfg(feature = "gui")))]
pub struct ComboBoxOpts {
	/// Control position within parent client area, to be
	/// [created](https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-createwindowexw).
	///
	/// If the parent window is a dialog, the values are in Dialog Template
	/// Units; otherwise in pixels, which will be multiplied to match current
	/// system DPI.
	///
	/// Defaults to 0 x 0.
	pub position: POINT,
	/// Control width, to be
	/// [created](https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-createwindowexw).
	///
	/// If the parent window is a dialog, the value is in Dialog Template Units;
	/// otherwise in pixels, which will be multiplied to match current system
	/// DPI.
	///
	/// Defaults to 120.
	pub width: u32,
	/// Combo box styles to be
	/// [created](https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-createwindowexw).
	///
	/// Defaults to `CBS::DROPDOWNLIST`.
	///
	/// Suggestions:
	/// * replace with `CBS::DROPDOWN` to allow the user to type a text;
	/// * add `CBS::SORT` to automatically sort the items.
	pub combo_box_style: co::CBS,
	/// Window styles to be
	/// [created](https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-createwindowexw).
	///
	/// Defaults to `WS::CHILD | WS::VISIBLE | WS::TABSTOP | WS::GROUP`.
	pub window_style: co::WS,
	/// Extended window styles to be
	/// [created](https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-createwindowexw).
	///
	/// Defaults to `WS_EX::LEFT`.
	pub window_ex_style: co::WS_EX,

	/// The control ID.
	///
	/// Defaults to an auto-generated ID.
	pub ctrl_id: u16,
	/// Horizontal behavior when the parent is resized.
	///
	/// Defaults to `Horz::None`.
	pub horz_resize: Horz,
	/// Vertical behavior when the parent is resized.
	///
	/// Defaults to `Vert::None`.
	///
	/// **Note:** A `ComboBox` cannot be resized vertically, so it will panic if
	/// you use `Vert::Resize`.
	pub vert_resize: Vert,

	/// Items to be added right away to the control.
	///
	/// Defaults to none.
	pub items: Vec<String>,
	/// Index of the item initially selected. The item must exist.
	///
	/// Defaults to `None`.
	pub selected_item: Option<u32>,
}

impl Default for ComboBoxOpts {
	fn default() -> Self {
		Self {
			position: POINT::new(0, 0),
			width: 120,
			combo_box_style: co::CBS::DROPDOWNLIST,
			window_style: co::WS::CHILD | co::WS::VISIBLE | co::WS::TABSTOP | co::WS::GROUP,
			window_ex_style: co::WS_EX::LEFT,
			ctrl_id: 0,
			horz_resize: Horz::None,
			vert_resize: Vert::None,
			items: Vec::<String>::default(),
			selected_item: None,
		}
	}
}

impl ComboBoxOpts {
	fn define_ctrl_id(mut self) -> Self {
		if self.ctrl_id == 0 {
			self.ctrl_id = auto_ctrl_id();
		}
		self
	}
}