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

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

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

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

use crate::{Pixbuf, PixbufAnimationIter};

pub trait PixbufAnimationIterImpl: ObjectImpl {
    // rustdoc-stripper-ignore-next
    /// Time in milliseconds, returning `None` implies showing the same pixbuf forever.
    // rustdoc-stripper-ignore-next-stop
    /// Gets the number of milliseconds the current pixbuf should be displayed,
    /// or -1 if the current pixbuf should be displayed forever.
    ///
    /// The `g_timeout_add()` function conveniently takes a timeout in milliseconds,
    /// so you can use a timeout to schedule the next update.
    ///
    /// Note that some formats, like GIF, might clamp the timeout values in the
    /// image file to avoid updates that are just too quick. The minimum timeout
    /// for GIF images is currently 20 milliseconds.
    ///
    /// # Returns
    ///
    /// delay time in milliseconds (thousandths of a second)
    fn delay_time(&self) -> Option<Duration> {
        self.parent_delay_time()
    }

    /// Gets the current pixbuf which should be displayed.
    ///
    /// The pixbuf might not be the same size as the animation itself
    /// (gdk_pixbuf_animation_get_width(), gdk_pixbuf_animation_get_height()).
    ///
    /// This pixbuf should be displayed for gdk_pixbuf_animation_iter_get_delay_time()
    /// milliseconds.
    ///
    /// The caller of this function does not own a reference to the returned
    /// pixbuf; the returned pixbuf will become invalid when the iterator
    /// advances to the next frame, which may happen anytime you call
    /// gdk_pixbuf_animation_iter_advance().
    ///
    /// Copy the pixbuf to keep it (don't just add a reference), as it may get
    /// recycled as you advance the iterator.
    ///
    /// # Returns
    ///
    /// the pixbuf to be displayed
    fn pixbuf(&self) -> Pixbuf {
        self.parent_pixbuf()
    }

    /// Used to determine how to respond to the area_updated signal on
    /// #GdkPixbufLoader when loading an animation.
    ///
    /// The `::area_updated` signal is emitted for an area of the frame currently
    /// streaming in to the loader. So if you're on the currently loading frame,
    /// you will need to redraw the screen for the updated area.
    ///
    /// # Returns
    ///
    /// `TRUE` if the frame we're on is partially loaded, or the last frame
    fn on_currently_loading_frame(&self) -> bool {
        self.parent_on_currently_loading_frame()
    }

    /// Possibly advances an animation to a new frame.
    ///
    /// Chooses the frame based on the start time passed to
    /// gdk_pixbuf_animation_get_iter().
    ///
    /// @current_time would normally come from g_get_current_time(), and
    /// must be greater than or equal to the time passed to
    /// gdk_pixbuf_animation_get_iter(), and must increase or remain
    /// unchanged each time gdk_pixbuf_animation_iter_get_pixbuf() is
    /// called. That is, you can't go backward in time; animations only
    /// play forward.
    ///
    /// As a shortcut, pass `NULL` for the current time and g_get_current_time()
    /// will be invoked on your behalf. So you only need to explicitly pass
    /// @current_time if you're doing something odd like playing the animation
    /// at double speed.
    ///
    /// If this function returns `FALSE`, there's no need to update the animation
    /// display, assuming the display had been rendered prior to advancing;
    /// if `TRUE`, you need to call gdk_pixbuf_animation_iter_get_pixbuf()
    /// and update the display with the new pixbuf.
    /// ## `current_time`
    /// current time
    ///
    /// # Returns
    ///
    /// `TRUE` if the image may need updating
    fn advance(&self, current_time: SystemTime) -> bool {
        self.parent_advance(current_time)
    }
}

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

pub trait PixbufAnimationIterImplExt: sealed::Sealed + ObjectSubclass {
    fn parent_delay_time(&self) -> Option<Duration> {
        unsafe {
            let data = Self::type_data();
            let parent_class =
                data.as_ref().parent_class() as *mut ffi::GdkPixbufAnimationIterClass;
            let f = (*parent_class)
                .get_delay_time
                .expect("No parent class implementation for \"get_delay_time\"");

            let time = f(self
                .obj()
                .unsafe_cast_ref::<PixbufAnimationIter>()
                .to_glib_none()
                .0);
            if time < 0 {
                None
            } else {
                Some(Duration::from_millis(time as u64))
            }
        }
    }

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

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

    fn parent_on_currently_loading_frame(&self) -> bool {
        unsafe {
            let data = Self::type_data();
            let parent_class =
                data.as_ref().parent_class() as *mut ffi::GdkPixbufAnimationIterClass;
            let f = (*parent_class)
                .on_currently_loading_frame
                .expect("No parent class implementation for \"on_currently_loading_frame\"");

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

    fn parent_advance(&self, current_time: SystemTime) -> bool {
        unsafe {
            let data = Self::type_data();
            let parent_class =
                data.as_ref().parent_class() as *mut ffi::GdkPixbufAnimationIterClass;
            let f = (*parent_class)
                .advance
                .expect("No parent class implementation for \"advance\"");

            let diff = current_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(f(
                self.obj()
                    .unsafe_cast_ref::<PixbufAnimationIter>()
                    .to_glib_none()
                    .0,
                &time,
            ))
        }
    }
}

impl<T: PixbufAnimationIterImpl> PixbufAnimationIterImplExt for T {}

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

        let klass = class.as_mut();
        klass.get_delay_time = Some(animation_iter_get_delay_time::<T>);
        klass.get_pixbuf = Some(animation_iter_get_pixbuf::<T>);
        klass.on_currently_loading_frame = Some(animation_iter_on_currently_loading_frame::<T>);
        klass.advance = Some(animation_iter_advance::<T>);
    }
}

unsafe extern "C" fn animation_iter_get_delay_time<T: PixbufAnimationIterImpl>(
    ptr: *mut ffi::GdkPixbufAnimationIter,
) -> i32 {
    let instance = &*(ptr as *mut T::Instance);
    let imp = instance.imp();

    imp.delay_time().map(|t| t.as_millis() as i32).unwrap_or(-1)
}

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

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

    let pixbuf = imp.pixbuf();
    // Ensure that the pixbuf stays alive until the next call
    imp.obj().set_qdata(*PIXBUF_QUARK, pixbuf.clone());
    pixbuf.to_glib_none().0
}

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

    imp.on_currently_loading_frame().into_glib()
}

unsafe extern "C" fn animation_iter_advance<T: PixbufAnimationIterImpl>(
    ptr: *mut ffi::GdkPixbufAnimationIter,
    current_time_ptr: *const glib::ffi::GTimeVal,
) -> glib::ffi::gboolean {
    let instance = &*(ptr as *mut T::Instance);
    let imp = instance.imp();

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

    imp.advance(current_time).into_glib()
}