// Copyright © SixtyFPS GmbH <info@slint-ui.com>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-commercial

//! This module contains the GraphicsWindow that used to be within corelib.

// cspell:ignore borderless corelib nesw webgl winit winsys xlib

use core::cell::{Cell, RefCell};
use core::pin::Pin;
use std::rc::{Rc, Weak};

use crate::event_loop::WinitWindow;
use crate::renderer::{WinitCompatibleCanvas, WinitCompatibleRenderer};
use const_field_offset::FieldOffsets;
use corelib::component::ComponentRc;
use corelib::input::KeyboardModifiers;
use corelib::items::{ItemRef, MouseCursor};
use corelib::layout::Orientation;
use corelib::window::{WindowAdapter, WindowAdapterSealed, WindowHandleAccess};
use corelib::Property;
use corelib::{graphics::*, Coord};
use i_slint_core as corelib;
use winit::dpi::LogicalSize;

/// GraphicsWindow is an implementation of the [WindowAdapter][`crate::eventloop::WindowAdapter`] trait. This is
/// typically instantiated by entry factory functions of the different graphics back ends.
pub(crate) struct GLWindow<Renderer: WinitCompatibleRenderer + 'static> {
    window: corelib::api::Window,
    self_weak: Weak<Self>,
    map_state: RefCell<GraphicsWindowBackendState<Renderer>>,
    keyboard_modifiers: std::cell::Cell<KeyboardModifiers>,
    currently_pressed_key_code: std::cell::Cell<Option<winit::event::VirtualKeyCode>>,

    renderer: Renderer,

    #[cfg(target_arch = "wasm32")]
    virtual_keyboard_helper: RefCell<Option<super::wasm_input_helper::WasmInputHelper>>,
}

impl<Renderer: WinitCompatibleRenderer + 'static> GLWindow<Renderer> {
    /// Creates a new reference-counted instance.
    ///
    /// Arguments:
    /// * `graphics_backend_factory`: The factor function stored in the GraphicsWindow that's called when the state
    ///   of the window changes to mapped. The event loop and window builder parameters can be used to create a
    ///   backing window.
    pub(crate) fn new(#[cfg(target_arch = "wasm32")] canvas_id: String) -> Rc<dyn WindowAdapter> {
        let self_rc = Rc::new_cyclic(|self_weak| Self {
            window: corelib::api::Window::new(self_weak.clone() as _),
            self_weak: self_weak.clone(),
            map_state: RefCell::new(GraphicsWindowBackendState::Unmapped {
                requested_position: None,
                requested_size: None,
            }),
            keyboard_modifiers: Default::default(),
            currently_pressed_key_code: Default::default(),
            renderer: Renderer::new(
                &(self_weak.clone() as _),
                #[cfg(target_arch = "wasm32")]
                canvas_id,
            ),
            #[cfg(target_arch = "wasm32")]
            virtual_keyboard_helper: Default::default(),
        });
        self_rc as _
    }

    fn is_mapped(&self) -> bool {
        matches!(&*self.map_state.borrow(), GraphicsWindowBackendState::Mapped { .. })
    }

    fn borrow_mapped_window(&self) -> Option<std::cell::Ref<MappedWindow<Renderer>>> {
        if self.is_mapped() {
            std::cell::Ref::map(self.map_state.borrow(), |state| match state {
                GraphicsWindowBackendState::Unmapped{..} => {
                    panic!("borrow_mapped_window must be called after checking if the window is mapped")
                }
                GraphicsWindowBackendState::Mapped(window) => window,
            }).into()
        } else {
            None
        }
    }

    fn unmap(&self) {
        let old_mapped = match self.map_state.replace(GraphicsWindowBackendState::Unmapped {
            requested_position: None,
            requested_size: None,
        }) {
            GraphicsWindowBackendState::Unmapped { .. } => return,
            GraphicsWindowBackendState::Mapped(old_mapped) => old_mapped,
        };

        old_mapped.canvas.with_window_handle(|winit_window| {
            crate::event_loop::unregister_window(winit_window.id());
        });

        self.renderer.release_canvas(old_mapped.canvas);
    }

    fn show_impl(&self) {
        let (requested_position, requested_size) = match &*self.map_state.borrow() {
            GraphicsWindowBackendState::Unmapped { requested_position, requested_size } => {
                (requested_position.clone(), requested_size.clone())
            }
            GraphicsWindowBackendState::Mapped(_) => return,
        };

        let runtime_window = self.window().window_handle();
        let component_rc = runtime_window.component();
        let component = ComponentRc::borrow_pin(&component_rc);

        let (window_title, no_frame, is_resizable) = if let Some(window_item) =
            runtime_window.window_item().as_ref().map(|i| i.as_pin_ref())
        {
            (
                window_item.title().to_string(),
                window_item.no_frame(),
                window_item.height() <= 0 as _ && window_item.width() <= 0 as _,
            )
        } else {
            ("Slint Window".to_string(), false, true)
        };

        let mut window_builder = winit::window::WindowBuilder::new()
            .with_title(window_title)
            .with_resizable(is_resizable);

        let scale_factor_override = runtime_window.scale_factor();
        // If the scale factor was already set programmatically, use that
        // else, use the SLINT_SCALE_FACTOR if set, otherwise use the one from winit
        let scale_factor_override = if scale_factor_override > 1. {
            Some(scale_factor_override as f64)
        } else {
            std::env::var("SLINT_SCALE_FACTOR")
                .ok()
                .and_then(|x| x.parse::<f64>().ok())
                .filter(|f| *f > 0.)
        };

        let into_size = |s: winit::dpi::LogicalSize<f32>| -> winit::dpi::Size {
            if let Some(f) = scale_factor_override {
                s.to_physical::<f32>(f).into()
            } else {
                s.into()
            }
        };

        let layout_info_h = component.as_ref().layout_info(Orientation::Horizontal);
        let layout_info_v = component.as_ref().layout_info(Orientation::Vertical);
        let s =
            LogicalSize::new(layout_info_h.preferred_bounded(), layout_info_v.preferred_bounded());

        let window_builder =
            if std::env::var("SLINT_FULLSCREEN").is_ok() {
                window_builder.with_fullscreen(Some(winit::window::Fullscreen::Borderless(None)))
            } else {
                if layout_info_h.min >= 1. || layout_info_v.min >= 1. {
                    window_builder = window_builder.with_min_inner_size(into_size(
                        LogicalSize::new(layout_info_h.min, layout_info_v.min),
                    ))
                }
                if layout_info_h.max < f32::MAX || layout_info_v.max < f32::MAX {
                    window_builder = window_builder.with_max_inner_size(into_size(
                        LogicalSize::new(layout_info_h.max, layout_info_v.max),
                    ))
                }

                if let Some(requested_size) = requested_size {
                    // It would be nice to bound this with our constraints, but those are in logical coordinates
                    // and we don't know the scale factor yet...
                    window_builder.with_inner_size(winit::dpi::Size::new(
                        winit::dpi::PhysicalSize::new(requested_size.width, requested_size.height),
                    ))
                } else if s.width > 0 as Coord && s.height > 0 as Coord {
                    // Make sure that the window's inner size is in sync with the root window item's
                    // width/height.
                    runtime_window.set_window_item_geometry(s.width, s.height);
                    window_builder.with_inner_size(into_size(s))
                } else {
                    window_builder
                }
            };

        let window_builder =
            if no_frame { window_builder.with_decorations(false) } else { window_builder };

        let window_builder = if let Some(requested_position) = requested_position {
            window_builder.with_position(winit::dpi::Position::new(
                winit::dpi::PhysicalPosition::new(requested_position.x, requested_position.y),
            ))
        } else {
            window_builder
        };

        let canvas = self.renderer.create_canvas(window_builder);

        let id = canvas.with_window_handle(|winit_window| {
            self.window.window_handle().set_scale_factor(
                scale_factor_override.unwrap_or_else(|| winit_window.scale_factor()) as _,
            );
            // On wasm, with_inner_size on the WindowBuilder don't have effect, so apply manually
            #[cfg(target_arch = "wasm32")]
            if (s.width > 0 as Coord && s.height > 0 as Coord) {
                winit_window.set_inner_size(s);
            }
            winit_window.id()
        });

        self.map_state.replace(GraphicsWindowBackendState::Mapped(MappedWindow {
            canvas,
            constraints: Default::default(),
        }));

        crate::event_loop::register_window(id, self.self_weak.upgrade().unwrap());
    }
}

impl<Renderer: WinitCompatibleRenderer + 'static> WinitWindow for GLWindow<Renderer> {
    fn currently_pressed_key_code(&self) -> &Cell<Option<winit::event::VirtualKeyCode>> {
        &self.currently_pressed_key_code
    }

    fn current_keyboard_modifiers(&self) -> &Cell<KeyboardModifiers> {
        &self.keyboard_modifiers
    }

    /// Draw the items of the specified `component` in the given window.
    fn draw(&self) {
        let window = match self.borrow_mapped_window() {
            Some(window) => window,
            None => return, // caller bug, doesn't make sense to call draw() when not mapped
        };

        self.renderer.render(&window.canvas, self);
    }

    fn with_window_handle(&self, callback: &mut dyn FnMut(&winit::window::Window)) {
        if let Some(mapped_window) = self.borrow_mapped_window() {
            mapped_window.canvas.with_window_handle(callback);
        }
    }

    fn constraints(&self) -> (corelib::layout::LayoutInfo, corelib::layout::LayoutInfo) {
        self.borrow_mapped_window().map(|window| window.constraints.get()).unwrap_or_default()
    }

    fn set_constraints(
        &self,
        constraints: (corelib::layout::LayoutInfo, corelib::layout::LayoutInfo),
    ) {
        if let Some(window) = self.borrow_mapped_window() {
            window.constraints.set(constraints);
        }
    }

    fn set_icon(&self, icon: corelib::graphics::Image) {
        let image_inner: &ImageInner = (&icon).into();
        let pixel_buffer = match image_inner {
            ImageInner::EmbeddedImage { buffer, .. } => buffer.clone(),
            _ => return,
        };

        // This could become a method in SharedPixelBuffer...
        let rgba_pixels: Vec<u8> = match &pixel_buffer {
            SharedImageBuffer::RGB8(pixels) => pixels
                .as_bytes()
                .chunks(3)
                .flat_map(|rgb| IntoIterator::into_iter([rgb[0], rgb[1], rgb[2], 255]))
                .collect(),
            SharedImageBuffer::RGBA8(pixels) => pixels.as_bytes().to_vec(),
            SharedImageBuffer::RGBA8Premultiplied(pixels) => pixels
                .as_bytes()
                .chunks(4)
                .flat_map(|rgba| {
                    let alpha = rgba[3] as u32;
                    IntoIterator::into_iter(rgba)
                        .take(3)
                        .map(move |component| (*component as u32 * alpha / 255) as u8)
                        .chain(std::iter::once(alpha as u8))
                })
                .collect(),
        };

        self.with_window_handle(&mut |window| {
            window.set_window_icon(
                winit::window::Icon::from_rgba(
                    rgba_pixels.clone(), // FIXME: if the closure were FnOnce we could move rgba_pixels
                    pixel_buffer.width(),
                    pixel_buffer.height(),
                )
                .ok(),
            );
        })
    }

    #[cfg(target_arch = "wasm32")]
    fn input_method_focused(&self) -> bool {
        match self.virtual_keyboard_helper.try_borrow() {
            Ok(vkh) => vkh.as_ref().map_or(false, |h| h.has_focus()),
            // the only location in which the virtual_keyboard_helper is mutably borrowed is from
            // show_virtual_keyboard, which means we have the focus
            Err(_) => true,
        }
    }

    fn resize_event(&self, size: winit::dpi::PhysicalSize<u32>) {
        if let Some(mapped_window) = self.borrow_mapped_window() {
            self.window().set_size(corelib::api::PhysicalSize::new(size.width, size.height));
            mapped_window.canvas.resize_event()
        }
    }

    fn inner_size(&self) -> corelib::api::PhysicalSize {
        match &*self.map_state.borrow() {
            GraphicsWindowBackendState::Unmapped { requested_size, .. } => {
                requested_size.unwrap_or_default()
            }
            GraphicsWindowBackendState::Mapped(mapped_window) => {
                mapped_window.canvas.with_window_handle(|winit_window| {
                    let size = winit_window.inner_size();
                    corelib::api::PhysicalSize::new(size.width, size.height)
                })
            }
        }
    }
}

impl<Renderer: WinitCompatibleRenderer + 'static> WindowAdapter for GLWindow<Renderer> {
    fn window(&self) -> &corelib::api::Window {
        &self.window
    }
}

impl<Renderer: WinitCompatibleRenderer + 'static> WindowAdapterSealed for GLWindow<Renderer> {
    fn request_redraw(&self) {
        self.with_window_handle(&mut |window| window.request_redraw())
    }

    fn unregister_component<'a>(
        &self,
        component: corelib::component::ComponentRef,
        _items: &mut dyn Iterator<Item = Pin<ItemRef<'a>>>,
    ) {
        match &*self.map_state.borrow() {
            GraphicsWindowBackendState::Unmapped { .. } => {}
            GraphicsWindowBackendState::Mapped(mapped_window) => {
                mapped_window.canvas.component_destroyed(component)
            }
        }
    }

    fn request_window_properties_update(&self) {
        self.with_window_handle(&mut |window| {
            let window_id = window.id();
            crate::event_loop::with_window_target(|event_loop| {
                event_loop
                    .event_loop_proxy()
                    .send_event(crate::event_loop::CustomEvent::UpdateWindowProperties(window_id))
            })
            .ok();
        })
    }

    fn apply_window_properties(&self, window_item: Pin<&i_slint_core::items::WindowItem>) {
        // Make the unwrap() calls on self.borrow_mapped_window*() safe
        if !self.is_mapped() {
            return;
        }

        WinitWindow::apply_window_properties(self as &dyn WinitWindow, window_item);
    }

    fn apply_geometry_constraint(
        &self,
        constraints_horizontal: corelib::layout::LayoutInfo,
        constraints_vertical: corelib::layout::LayoutInfo,
    ) {
        self.apply_constraints(constraints_horizontal, constraints_vertical)
    }

    fn show(&self) {
        // Creating a new winit::Window requires access to the running event loop (`&EventLoopWindowTarget`), which
        // is only possible from within the event loop handler with wasm, as `run()` consumes the event loop. Work
        // around by invoking `show()` from within the event loop handler.
        #[cfg(target_arch = "wasm32")]
        corelib::api::invoke_from_event_loop({
            let self_weak = send_wrapper::SendWrapper::new(self.self_weak.clone());

            move || {
                if let Some(this) = self_weak.take().upgrade() {
                    this.show_impl();
                }
            }
        });
        #[cfg(not(target_arch = "wasm32"))]
        self.show_impl();
    }

    fn hide(&self) {
        self.unmap();

        /* FIXME:
        if let Some(existing_blinker) = self.cursor_blinker.borrow().upgrade() {
            existing_blinker.stop();
        }*/
        crate::event_loop::with_window_target(|event_loop| {
            event_loop.event_loop_proxy().send_event(crate::event_loop::CustomEvent::WindowHidden)
        })
        .unwrap();
    }

    fn set_mouse_cursor(&self, cursor: MouseCursor) {
        let winit_cursor = match cursor {
            MouseCursor::Default => winit::window::CursorIcon::Default,
            MouseCursor::None => winit::window::CursorIcon::Default,
            MouseCursor::Help => winit::window::CursorIcon::Help,
            MouseCursor::Pointer => winit::window::CursorIcon::Hand,
            MouseCursor::Progress => winit::window::CursorIcon::Progress,
            MouseCursor::Wait => winit::window::CursorIcon::Wait,
            MouseCursor::Crosshair => winit::window::CursorIcon::Crosshair,
            MouseCursor::Text => winit::window::CursorIcon::Text,
            MouseCursor::Alias => winit::window::CursorIcon::Alias,
            MouseCursor::Copy => winit::window::CursorIcon::Copy,
            MouseCursor::Move => winit::window::CursorIcon::Move,
            MouseCursor::NoDrop => winit::window::CursorIcon::NoDrop,
            MouseCursor::NotAllowed => winit::window::CursorIcon::NotAllowed,
            MouseCursor::Grab => winit::window::CursorIcon::Grab,
            MouseCursor::Grabbing => winit::window::CursorIcon::Grabbing,
            MouseCursor::ColResize => winit::window::CursorIcon::ColResize,
            MouseCursor::RowResize => winit::window::CursorIcon::RowResize,
            MouseCursor::NResize => winit::window::CursorIcon::NResize,
            MouseCursor::EResize => winit::window::CursorIcon::EResize,
            MouseCursor::SResize => winit::window::CursorIcon::SResize,
            MouseCursor::WResize => winit::window::CursorIcon::WResize,
            MouseCursor::NeResize => winit::window::CursorIcon::NeResize,
            MouseCursor::NwResize => winit::window::CursorIcon::NwResize,
            MouseCursor::SeResize => winit::window::CursorIcon::SeResize,
            MouseCursor::SwResize => winit::window::CursorIcon::SwResize,
            MouseCursor::EwResize => winit::window::CursorIcon::EwResize,
            MouseCursor::NsResize => winit::window::CursorIcon::NsResize,
            MouseCursor::NeswResize => winit::window::CursorIcon::NeswResize,
            MouseCursor::NwseResize => winit::window::CursorIcon::NwseResize,
        };
        self.with_window_handle(&mut |winit_window| {
            winit_window.set_cursor_visible(cursor != MouseCursor::None);
            winit_window.set_cursor_icon(winit_cursor);
        });
    }

    fn renderer(&self) -> &dyn i_slint_core::renderer::Renderer {
        &self.renderer
    }

    #[cfg(target_arch = "wasm32")]
    fn show_virtual_keyboard(&self, _it: corelib::items::InputType) {
        let mut vkh = self.virtual_keyboard_helper.borrow_mut();
        let h = vkh.get_or_insert_with(|| {
            let canvas = self.borrow_mapped_window().unwrap().canvas.html_canvas_element().clone();
            super::wasm_input_helper::WasmInputHelper::new(self.self_weak.clone(), canvas)
        });
        h.show();
    }

    #[cfg(target_arch = "wasm32")]
    fn hide_virtual_keyboard(&self) {
        if let Some(h) = &*self.virtual_keyboard_helper.borrow() {
            h.hide()
        }
    }

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

    fn position(&self) -> corelib::api::PhysicalPosition {
        match &*self.map_state.borrow() {
            GraphicsWindowBackendState::Unmapped { requested_position, .. } => {
                requested_position.unwrap_or_default()
            }
            GraphicsWindowBackendState::Mapped(mapped_window) => mapped_window
                .canvas
                .with_window_handle(|winit_window| match winit_window.outer_position() {
                    Ok(outer_position) => {
                        corelib::api::PhysicalPosition::new(outer_position.x, outer_position.y)
                    }
                    Err(_) => Default::default(),
                }),
        }
    }

    fn set_position(&self, position: corelib::api::PhysicalPosition) {
        match &mut *self.map_state.borrow_mut() {
            GraphicsWindowBackendState::Unmapped { requested_position, .. } => {
                *requested_position = Some(position)
            }
            GraphicsWindowBackendState::Mapped(mapped_window) => {
                mapped_window.canvas.with_window_handle(|winit_window| {
                    winit_window.set_outer_position(winit::dpi::Position::new(
                        winit::dpi::PhysicalPosition::new(position.x, position.y),
                    ))
                })
            }
        }
    }

    fn set_inner_size(&self, size: corelib::api::PhysicalSize) {
        if let Ok(mut map_state) = self.map_state.try_borrow_mut() {
            // otherwise we are called from the resize event
            match &mut *map_state {
                GraphicsWindowBackendState::Unmapped { requested_size, .. } => {
                    *requested_size = Some(size)
                }
                GraphicsWindowBackendState::Mapped(mapped_window) => {
                    mapped_window.canvas.with_window_handle(|winit_window| {
                        winit_window
                            .set_inner_size(winit::dpi::PhysicalSize::new(size.width, size.height));
                    });
                }
            }
        }
    }
}

impl<Renderer: WinitCompatibleRenderer + 'static> Drop for GLWindow<Renderer> {
    fn drop(&mut self) {
        self.unmap();
    }
}

struct MappedWindow<Renderer: WinitCompatibleRenderer> {
    canvas: Renderer::Canvas,
    constraints: Cell<(corelib::layout::LayoutInfo, corelib::layout::LayoutInfo)>,
}

enum GraphicsWindowBackendState<Renderer: WinitCompatibleRenderer> {
    Unmapped {
        requested_position: Option<corelib::api::PhysicalPosition>,
        requested_size: Option<corelib::api::PhysicalSize>,
    },
    Mapped(MappedWindow<Renderer>),
}

#[derive(FieldOffsets)]
#[repr(C)]
#[pin]
struct WindowProperties {
    scale_factor: Property<f32>,
}

impl Default for WindowProperties {
    fn default() -> Self {
        Self { scale_factor: Property::new(1.0) }
    }
}