use std::{
    ops::Deref,
    sync::{Mutex, Weak},
};

use cocoa::{
    appkit::{CGFloat, NSScreen, NSWindow, NSWindowStyleMask},
    base::{id, nil},
    foundation::{NSPoint, NSSize, NSString},
};
use dispatch::Queue;
use objc::rc::autoreleasepool;
use objc::runtime::NO;

use crate::{
    dpi::LogicalSize,
    platform_impl::platform::{ffi, util::IdRef, window::SharedState},
};

// Unsafe wrapper type that allows us to dispatch things that aren't Send.
// This should *only* be used to dispatch to the main queue.
// While it is indeed not guaranteed that these types can safely be sent to
// other threads, we know that they're safe to use on the main thread.
struct MainThreadSafe<T>(T);

unsafe impl<T> Send for MainThreadSafe<T> {}

impl<T> Deref for MainThreadSafe<T> {
    type Target = T;
    fn deref(&self) -> &T {
        &self.0
    }
}

unsafe fn set_style_mask(ns_window: id, ns_view: id, mask: NSWindowStyleMask) {
    ns_window.setStyleMask_(mask);
    // If we don't do this, key handling will break
    // (at least until the window is clicked again/etc.)
    ns_window.makeFirstResponder_(ns_view);
}

// Always use this function instead of trying to modify `styleMask` directly!
// `setStyleMask:` isn't thread-safe, so we have to use Grand Central Dispatch.
// Otherwise, this would vomit out errors about not being on the main thread
// and fail to do anything.
pub unsafe fn set_style_mask_async(ns_window: id, ns_view: id, mask: NSWindowStyleMask) {
    let ns_window = MainThreadSafe(ns_window);
    let ns_view = MainThreadSafe(ns_view);
    Queue::main().exec_async(move || {
        set_style_mask(*ns_window, *ns_view, mask);
    });
}
pub unsafe fn set_style_mask_sync(ns_window: id, ns_view: id, mask: NSWindowStyleMask) {
    if msg_send![class!(NSThread), isMainThread] {
        set_style_mask(ns_window, ns_view, mask);
    } else {
        let ns_window = MainThreadSafe(ns_window);
        let ns_view = MainThreadSafe(ns_view);
        Queue::main().exec_sync(move || {
            set_style_mask(*ns_window, *ns_view, mask);
        })
    }
}

// `setContentSize:` isn't thread-safe either, though it doesn't log any errors
// and just fails silently. Anyway, GCD to the rescue!
pub unsafe fn set_content_size_async(ns_window: id, size: LogicalSize<f64>) {
    let ns_window = MainThreadSafe(ns_window);
    Queue::main().exec_async(move || {
        ns_window.setContentSize_(NSSize::new(size.width as CGFloat, size.height as CGFloat));
    });
}

// `setFrameTopLeftPoint:` isn't thread-safe, but fortunately has the courtesy
// to log errors.
pub unsafe fn set_frame_top_left_point_async(ns_window: id, point: NSPoint) {
    let ns_window = MainThreadSafe(ns_window);
    Queue::main().exec_async(move || {
        ns_window.setFrameTopLeftPoint_(point);
    });
}

// `setFrameTopLeftPoint:` isn't thread-safe, and fails silently.
pub unsafe fn set_level_async(ns_window: id, level: ffi::NSWindowLevel) {
    let ns_window = MainThreadSafe(ns_window);
    Queue::main().exec_async(move || {
        ns_window.setLevel_(level as _);
    });
}

// `toggleFullScreen` is thread-safe, but our additional logic to account for
// window styles isn't.
pub unsafe fn toggle_full_screen_async(
    ns_window: id,
    ns_view: id,
    not_fullscreen: bool,
    shared_state: Weak<Mutex<SharedState>>,
) {
    let ns_window = MainThreadSafe(ns_window);
    let ns_view = MainThreadSafe(ns_view);
    let shared_state = MainThreadSafe(shared_state);
    Queue::main().exec_async(move || {
        // `toggleFullScreen` doesn't work if the `StyleMask` is none, so we
        // set a normal style temporarily. The previous state will be
        // restored in `WindowDelegate::window_did_exit_fullscreen`.
        if not_fullscreen {
            let curr_mask = ns_window.styleMask();
            let required =
                NSWindowStyleMask::NSTitledWindowMask | NSWindowStyleMask::NSResizableWindowMask;
            if !curr_mask.contains(required) {
                set_style_mask(*ns_window, *ns_view, required);
                if let Some(shared_state) = shared_state.upgrade() {
                    trace!("Locked shared state in `toggle_full_screen_callback`");
                    let mut shared_state_lock = shared_state.lock().unwrap();
                    (*shared_state_lock).saved_style = Some(curr_mask);
                    trace!("Unlocked shared state in `toggle_full_screen_callback`");
                }
            }
        }
        // Window level must be restored from `CGShieldingWindowLevel()
        // + 1` back to normal in order for `toggleFullScreen` to do
        // anything
        ns_window.setLevel_(0);
        ns_window.toggleFullScreen_(nil);
    });
}

pub unsafe fn restore_display_mode_async(ns_screen: u32) {
    Queue::main().exec_async(move || {
        ffi::CGRestorePermanentDisplayConfiguration();
        assert_eq!(ffi::CGDisplayRelease(ns_screen), ffi::kCGErrorSuccess);
    });
}

// `setMaximized` is not thread-safe
pub unsafe fn set_maximized_async(
    ns_window: id,
    is_zoomed: bool,
    maximized: bool,
    shared_state: Weak<Mutex<SharedState>>,
) {
    let ns_window = MainThreadSafe(ns_window);
    let shared_state = MainThreadSafe(shared_state);
    Queue::main().exec_async(move || {
        if let Some(shared_state) = shared_state.upgrade() {
            trace!("Locked shared state in `set_maximized`");
            let mut shared_state_lock = shared_state.lock().unwrap();

            // Save the standard frame sized if it is not zoomed
            if !is_zoomed {
                shared_state_lock.standard_frame = Some(NSWindow::frame(*ns_window));
            }

            shared_state_lock.maximized = maximized;

            let curr_mask = ns_window.styleMask();
            if shared_state_lock.fullscreen.is_some() {
                // Handle it in window_did_exit_fullscreen
                return;
            } else if curr_mask.contains(NSWindowStyleMask::NSResizableWindowMask) {
                // Just use the native zoom if resizable
                ns_window.zoom_(nil);
            } else {
                // if it's not resizable, we set the frame directly
                let new_rect = if maximized {
                    let screen = NSScreen::mainScreen(nil);
                    NSScreen::visibleFrame(screen)
                } else {
                    shared_state_lock.saved_standard_frame()
                };
                ns_window.setFrame_display_(new_rect, NO);
            }

            trace!("Unlocked shared state in `set_maximized`");
        }
    });
}

// `orderOut:` isn't thread-safe. Calling it from another thread actually works,
// but with an odd delay.
pub unsafe fn order_out_async(ns_window: id) {
    let ns_window = MainThreadSafe(ns_window);
    Queue::main().exec_async(move || {
        ns_window.orderOut_(nil);
    });
}

// `makeKeyAndOrderFront:` isn't thread-safe. Calling it from another thread
// actually works, but with an odd delay.
pub unsafe fn make_key_and_order_front_async(ns_window: id) {
    let ns_window = MainThreadSafe(ns_window);
    Queue::main().exec_async(move || {
        ns_window.makeKeyAndOrderFront_(nil);
    });
}

// `setTitle:` isn't thread-safe. Calling it from another thread invalidates the
// window drag regions, which throws an exception when not done in the main
// thread
pub unsafe fn set_title_async(ns_window: id, title: String) {
    let ns_window = MainThreadSafe(ns_window);
    Queue::main().exec_async(move || {
        let title = IdRef::new(NSString::alloc(nil).init_str(&title));
        ns_window.setTitle_(*title);
    });
}

// `close:` is thread-safe, but we want the event to be triggered from the main
// thread. Though, it's a good idea to look into that more...
pub unsafe fn close_async(ns_window: id) {
    let ns_window = MainThreadSafe(ns_window);
    Queue::main().exec_async(move || {
        autoreleasepool(move || {
            ns_window.close();
        });
    });
}
