// Take a look at the license at the top of the repository in the LICENSE file.

// rustdoc-stripper-ignore-next
//! Traits intended for subclassing [`PixbufAnimation`](crate::PixbufAnimation).

use std::{
    mem::MaybeUninit,
    time::{Duration, SystemTime},
};

use glib::{prelude::*, subclass::prelude::*, translate::*};
use once_cell::sync::Lazy;

use crate::{Pixbuf, PixbufAnimation, PixbufAnimationIter};

pub trait PixbufAnimationImpl: ObjectImpl {
    /// Checks whether the animation is a static image.
    ///
    /// If you load a file with gdk_pixbuf_animation_new_from_file() and it
    /// turns out to be a plain, unanimated image, then this function will
    /// return `TRUE`. Use gdk_pixbuf_animation_get_static_image() to retrieve
    /// the image.
    ///
    /// # Returns
    ///
    /// `TRUE` if the "animation" was really just an image
    fn is_static_image(&self) -> bool {
        self.parent_is_static_image()
    }

    /// Retrieves a static image for the animation.
    ///
    /// If an animation is really just a plain image (has only one frame),
    /// this function returns that image.
    ///
    /// If the animation is an animation, this function returns a reasonable
    /// image to use as a static unanimated image, which might be the first
    /// frame, or something more sophisticated depending on the file format.
    ///
    /// If an animation hasn't loaded any frames yet, this function will
    /// return `NULL`.
    ///
    /// # Returns
    ///
    /// unanimated image representing the animation
    fn static_image(&self) -> Option<Pixbuf> {
        self.parent_static_image()
    }

    fn size(&self) -> (i32, i32) {
        self.parent_size()
    }

    /// Get an iterator for displaying an animation.
    ///
    /// The iterator provides the frames that should be displayed at a
    /// given time.
    ///
    /// @start_time would normally come from g_get_current_time(), and marks
    /// the beginning of animation playback. After creating an iterator, you
    /// should immediately display the pixbuf returned by
    /// gdk_pixbuf_animation_iter_get_pixbuf(). Then, you should install
    /// a timeout (with g_timeout_add()) or by some other mechanism ensure
    /// that you'll update the image after
    /// gdk_pixbuf_animation_iter_get_delay_time() milliseconds. Each time
    /// the image is updated, you should reinstall the timeout with the new,
    /// possibly-changed delay time.
    ///
    /// As a shortcut, if @start_time is `NULL`, the result of
    /// g_get_current_time() will be used automatically.
    ///
    /// To update the image (i.e. possibly change the result of
    /// gdk_pixbuf_animation_iter_get_pixbuf() to a new frame of the animation),
    /// call gdk_pixbuf_animation_iter_advance().
    ///
    /// If you're using #GdkPixbufLoader, in addition to updating the image
    /// after the delay time, you should also update it whenever you
    /// receive the area_updated signal and
    /// gdk_pixbuf_animation_iter_on_currently_loading_frame() returns
    /// `TRUE`. In this case, the frame currently being fed into the loader
    /// has received new data, so needs to be refreshed. The delay time for
    /// a frame may also be modified after an area_updated signal, for
    /// example if the delay time for a frame is encoded in the data after
    /// the frame itself. So your timeout should be reinstalled after any
    /// area_updated signal.
    ///
    /// A delay time of -1 is possible, indicating "infinite".
    /// ## `start_time`
    /// time when the animation starts playing
    ///
    /// # Returns
    ///
    /// an iterator to move over the animation
    fn iter(&self, start_time: SystemTime) -> PixbufAnimationIter {
        self.parent_iter(start_time)
    }
}

mod sealed {
    pub trait Sealed {}
    impl<T: super::PixbufAnimationImplExt> Sealed for T {}
}

pub trait PixbufAnimationImplExt: sealed::Sealed + ObjectSubclass {
    fn parent_is_static_image(&self) -> bool {
        unsafe {
            let data = Self::type_data();
            let parent_class = data.as_ref().parent_class() as *mut ffi::GdkPixbufAnimationClass;
            let f = (*parent_class)
                .is_static_image
                .expect("No parent class implementation for \"is_static_image\"");

            from_glib(f(self
                .obj()
                .unsafe_cast_ref::<PixbufAnimation>()
                .to_glib_none()
                .0))
        }
    }

    fn parent_static_image(&self) -> Option<Pixbuf> {
        unsafe {
            let data = Self::type_data();
            let parent_class = data.as_ref().parent_class() as *mut ffi::GdkPixbufAnimationClass;
            let f = (*parent_class)
                .get_static_image
                .expect("No parent class implementation for \"get_static_image\"");

            from_glib_none(f(self
                .obj()
                .unsafe_cast_ref::<PixbufAnimation>()
                .to_glib_none()
                .0))
        }
    }

    fn parent_size(&self) -> (i32, i32) {
        unsafe {
            let data = Self::type_data();
            let parent_class = data.as_ref().parent_class() as *mut ffi::GdkPixbufAnimationClass;
            let f = (*parent_class)
                .get_size
                .expect("No parent class implementation for \"get_size\"");
            let mut width = MaybeUninit::uninit();
            let mut height = MaybeUninit::uninit();
            f(
                self.obj()
                    .unsafe_cast_ref::<PixbufAnimation>()
                    .to_glib_none()
                    .0,
                width.as_mut_ptr(),
                height.as_mut_ptr(),
            );
            (width.assume_init(), height.assume_init())
        }
    }

    fn parent_iter(&self, start_time: SystemTime) -> PixbufAnimationIter {
        unsafe {
            let data = Self::type_data();
            let parent_class = data.as_ref().parent_class() as *mut ffi::GdkPixbufAnimationClass;
            let f = (*parent_class)
                .get_iter
                .expect("No parent class implementation for \"get_iter\"");

            let diff = start_time
                .duration_since(SystemTime::UNIX_EPOCH)
                .expect("failed to convert time");
            let time = glib::ffi::GTimeVal {
                tv_sec: diff.as_secs() as _,
                tv_usec: diff.subsec_micros() as _,
            };
            from_glib_full(f(
                self.obj()
                    .unsafe_cast_ref::<PixbufAnimation>()
                    .to_glib_none()
                    .0,
                &time,
            ))
        }
    }
}

impl<T: PixbufAnimationImpl> PixbufAnimationImplExt for T {}

unsafe impl<T: PixbufAnimationImpl> IsSubclassable<T> for PixbufAnimation {
    fn class_init(class: &mut ::glib::Class<Self>) {
        Self::parent_class_init::<T>(class);

        let klass = class.as_mut();
        klass.get_static_image = Some(animation_get_static_image::<T>);
        klass.get_size = Some(animation_get_size::<T>);
        klass.get_iter = Some(animation_get_iter::<T>);
        klass.is_static_image = Some(animation_is_static_image::<T>);
    }
}

unsafe extern "C" fn animation_is_static_image<T: PixbufAnimationImpl>(
    ptr: *mut ffi::GdkPixbufAnimation,
) -> glib::ffi::gboolean {
    let instance = &*(ptr as *mut T::Instance);
    let imp = instance.imp();

    imp.is_static_image().into_glib()
}

unsafe extern "C" fn animation_get_size<T: PixbufAnimationImpl>(
    ptr: *mut ffi::GdkPixbufAnimation,
    width_ptr: *mut libc::c_int,
    height_ptr: *mut libc::c_int,
) {
    if width_ptr.is_null() && height_ptr.is_null() {
        return;
    }

    let instance = &*(ptr as *mut T::Instance);
    let imp = instance.imp();

    let (width, height) = imp.size();
    if !width_ptr.is_null() {
        *width_ptr = width;
    }
    if !height_ptr.is_null() {
        *height_ptr = height;
    }
}

static STATIC_IMAGE_QUARK: Lazy<glib::Quark> =
    Lazy::new(|| glib::Quark::from_str("gtk-rs-subclass-static-image"));

unsafe extern "C" fn animation_get_static_image<T: PixbufAnimationImpl>(
    ptr: *mut ffi::GdkPixbufAnimation,
) -> *mut ffi::GdkPixbuf {
    let instance = &*(ptr as *mut T::Instance);
    let imp = instance.imp();

    let instance = imp.obj();
    let static_image = imp.static_image();
    // Ensure that a) the static image stays alive as long as the animation instance and b) that
    // the same static image is returned every time. This is a requirement by the gdk-pixbuf API.
    if let Some(old_image) = instance.qdata::<Option<Pixbuf>>(*STATIC_IMAGE_QUARK) {
        let old_image = old_image.as_ref();

        if let Some(old_image) = old_image {
            assert_eq!(
                Some(old_image),
                static_image.as_ref(),
                "Did not return same static image again"
            );
        }
    }
    instance.set_qdata(*STATIC_IMAGE_QUARK, static_image.clone());
    static_image.to_glib_none().0
}

unsafe extern "C" fn animation_get_iter<T: PixbufAnimationImpl>(
    ptr: *mut ffi::GdkPixbufAnimation,
    start_time_ptr: *const glib::ffi::GTimeVal,
) -> *mut ffi::GdkPixbufAnimationIter {
    let instance = &*(ptr as *mut T::Instance);
    let imp = instance.imp();

    let start_time = SystemTime::UNIX_EPOCH
        + Duration::from_secs((*start_time_ptr).tv_sec.try_into().unwrap())
        + Duration::from_micros((*start_time_ptr).tv_usec.try_into().unwrap());

    imp.iter(start_time).into_glib_ptr()
}