use std::{
    collections::{BTreeSet, VecDeque},
    fmt,
    ops::{Deref, DerefMut},
};

use crate::{
    dpi::{PhysicalPosition, PhysicalSize},
    monitor::{MonitorHandle as RootMonitorHandle, VideoMode as RootVideoMode},
    platform_impl::platform::{
        app_state,
        ffi::{id, nil, CGFloat, CGRect, CGSize, NSInteger, NSUInteger},
    },
};

#[derive(Debug, PartialEq, Eq, Hash)]
pub struct VideoMode {
    pub(crate) size: (u32, u32),
    pub(crate) bit_depth: u16,
    pub(crate) refresh_rate: u16,
    pub(crate) screen_mode: id,
    pub(crate) monitor: MonitorHandle,
}

impl Clone for VideoMode {
    fn clone(&self) -> VideoMode {
        VideoMode {
            size: self.size,
            bit_depth: self.bit_depth,
            refresh_rate: self.refresh_rate,
            screen_mode: unsafe { msg_send![self.screen_mode, retain] },
            monitor: self.monitor.clone(),
        }
    }
}

impl Drop for VideoMode {
    fn drop(&mut self) {
        unsafe {
            assert_main_thread!("`VideoMode` can only be dropped on the main thread on iOS");
            let () = msg_send![self.screen_mode, release];
        }
    }
}

impl VideoMode {
    unsafe fn retained_new(uiscreen: id, screen_mode: id) -> VideoMode {
        assert_main_thread!("`VideoMode` can only be created on the main thread on iOS");
        let os_capabilities = app_state::os_capabilities();
        let refresh_rate: NSInteger = if os_capabilities.maximum_frames_per_second {
            msg_send![uiscreen, maximumFramesPerSecond]
        } else {
            // https://developer.apple.com/library/archive/technotes/tn2460/_index.html
            // https://en.wikipedia.org/wiki/IPad_Pro#Model_comparison
            //
            // All iOS devices support 60 fps, and on devices where `maximumFramesPerSecond` is not
            // supported, they are all guaranteed to have 60hz refresh rates. This does not
            // correctly handle external displays. ProMotion displays support 120fps, but they were
            // introduced at the same time as the `maximumFramesPerSecond` API.
            //
            // FIXME: earlier OSs could calculate the refresh rate using
            // `-[CADisplayLink duration]`.
            os_capabilities.maximum_frames_per_second_err_msg("defaulting to 60 fps");
            60
        };
        let size: CGSize = msg_send![screen_mode, size];
        VideoMode {
            size: (size.width as u32, size.height as u32),
            bit_depth: 32,
            refresh_rate: refresh_rate as u16,
            screen_mode: msg_send![screen_mode, retain],
            monitor: MonitorHandle::retained_new(uiscreen),
        }
    }

    pub fn size(&self) -> PhysicalSize {
        self.size.into()
    }

    pub fn bit_depth(&self) -> u16 {
        self.bit_depth
    }

    pub fn refresh_rate(&self) -> u16 {
        self.refresh_rate
    }

    pub fn monitor(&self) -> RootMonitorHandle {
        RootMonitorHandle {
            inner: self.monitor.clone(),
        }
    }
}

#[derive(PartialEq, Eq, Hash, PartialOrd, Ord)]
pub struct Inner {
    uiscreen: id,
}

impl Drop for Inner {
    fn drop(&mut self) {
        unsafe {
            let () = msg_send![self.uiscreen, release];
        }
    }
}

#[derive(PartialEq, Eq, Hash, PartialOrd, Ord)]
pub struct MonitorHandle {
    inner: Inner,
}

impl Deref for MonitorHandle {
    type Target = Inner;

    fn deref(&self) -> &Inner {
        unsafe {
            assert_main_thread!(
                "`MonitorHandle` methods can only be run on the main thread on iOS"
            );
        }
        &self.inner
    }
}

impl DerefMut for MonitorHandle {
    fn deref_mut(&mut self) -> &mut Inner {
        unsafe {
            assert_main_thread!(
                "`MonitorHandle` methods can only be run on the main thread on iOS"
            );
        }
        &mut self.inner
    }
}

unsafe impl Send for MonitorHandle {}
unsafe impl Sync for MonitorHandle {}

impl Clone for MonitorHandle {
    fn clone(&self) -> MonitorHandle {
        MonitorHandle::retained_new(self.uiscreen)
    }
}

impl Drop for MonitorHandle {
    fn drop(&mut self) {
        unsafe {
            assert_main_thread!("`MonitorHandle` can only be dropped on the main thread on iOS");
        }
    }
}

impl fmt::Debug for MonitorHandle {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        #[derive(Debug)]
        struct MonitorHandle {
            name: Option<String>,
            size: PhysicalSize,
            position: PhysicalPosition,
            hidpi_factor: f64,
        }

        let monitor_id_proxy = MonitorHandle {
            name: self.name(),
            size: self.size(),
            position: self.position(),
            hidpi_factor: self.hidpi_factor(),
        };

        monitor_id_proxy.fmt(f)
    }
}

impl MonitorHandle {
    pub fn retained_new(uiscreen: id) -> MonitorHandle {
        unsafe {
            assert_main_thread!("`MonitorHandle` can only be cloned on the main thread on iOS");
            let () = msg_send![uiscreen, retain];
        }
        MonitorHandle {
            inner: Inner { uiscreen },
        }
    }
}

impl Inner {
    pub fn name(&self) -> Option<String> {
        unsafe {
            let main = main_uiscreen();
            if self.uiscreen == main.uiscreen {
                Some("Primary".to_string())
            } else if self.uiscreen == mirrored_uiscreen(&main).uiscreen {
                Some("Mirrored".to_string())
            } else {
                uiscreens()
                    .iter()
                    .position(|rhs| rhs.uiscreen == self.uiscreen)
                    .map(|idx| idx.to_string())
            }
        }
    }

    pub fn size(&self) -> PhysicalSize {
        unsafe {
            let bounds: CGRect = msg_send![self.ui_screen(), nativeBounds];
            (bounds.size.width as f64, bounds.size.height as f64).into()
        }
    }

    pub fn position(&self) -> PhysicalPosition {
        unsafe {
            let bounds: CGRect = msg_send![self.ui_screen(), nativeBounds];
            (bounds.origin.x as f64, bounds.origin.y as f64).into()
        }
    }

    pub fn hidpi_factor(&self) -> f64 {
        unsafe {
            let scale: CGFloat = msg_send![self.ui_screen(), nativeScale];
            scale as f64
        }
    }

    pub fn video_modes(&self) -> impl Iterator<Item = RootVideoMode> {
        let mut modes = BTreeSet::new();
        unsafe {
            let available_modes: id = msg_send![self.uiscreen, availableModes];
            let available_mode_count: NSUInteger = msg_send![available_modes, count];

            for i in 0..available_mode_count {
                let mode: id = msg_send![available_modes, objectAtIndex: i];
                modes.insert(RootVideoMode {
                    video_mode: VideoMode::retained_new(self.uiscreen, mode),
                });
            }
        }

        modes.into_iter()
    }
}

// MonitorHandleExtIOS
impl Inner {
    pub fn ui_screen(&self) -> id {
        self.uiscreen
    }

    pub fn preferred_video_mode(&self) -> RootVideoMode {
        unsafe {
            let mode: id = msg_send![self.uiscreen, preferredMode];
            RootVideoMode {
                video_mode: VideoMode::retained_new(self.uiscreen, mode),
            }
        }
    }
}

// requires being run on main thread
pub unsafe fn main_uiscreen() -> MonitorHandle {
    let uiscreen: id = msg_send![class!(UIScreen), mainScreen];
    MonitorHandle::retained_new(uiscreen)
}

// requires being run on main thread
unsafe fn mirrored_uiscreen(monitor: &MonitorHandle) -> MonitorHandle {
    let uiscreen: id = msg_send![monitor.uiscreen, mirroredScreen];
    MonitorHandle::retained_new(uiscreen)
}

// requires being run on main thread
pub unsafe fn uiscreens() -> VecDeque<MonitorHandle> {
    let screens: id = msg_send![class!(UIScreen), screens];
    let count: NSUInteger = msg_send![screens, count];
    let mut result = VecDeque::with_capacity(count as _);
    let screens_enum: id = msg_send![screens, objectEnumerator];
    loop {
        let screen: id = msg_send![screens_enum, nextObject];
        if screen == nil {
            break result;
        }
        result.push_back(MonitorHandle::retained_new(screen));
    }
}