//! The three GObject subclasses WPE requires of an embedder.
 //!
 //! WebKit does not hand us a view to render into; it *asks the display for
 //! one*. So embedding means implementing all three of:
 //!
 //! * `WPEDisplay`  — vends the view and the toplevel (`create_view`,
 //!   `create_toplevel`). `WebKitWebView`'s `display` property is
 //!   construct-only and takes this.
 //! * `WPEToplevel` — **owns buffer-format negotiation.** WebKit asks the
 //!   toplevel, not the display. Leave `create_toplevel` NULL and
 //!   `render_buffer` silently never fires, with a perfectly healthy web
 //!   process and no error anywhere.
 //! * `WPEView`     — receives finished frames via `render_buffer`.
 //!
 //! Registration goes through [`register_subclass`] rather than a Rust struct
 //! embedding the parent, because WPE's instance structs are opaque
 //! (`WPE_DECLARE_DERIVABLE_TYPE` typedefs `struct _WPEView` and never defines
 //! it). `g_type_query` reports the parent's sizes at runtime instead, which is
 //! ABI-safe and survives WPE growing a field. The *class* structs are public,
 //! so bindgen lays them out correctly and installing a vfunc is a field set.
 
 use std::ffi::{c_char, c_void, CString};
 
 use super::ffi::*;
 
 /// Register a GObject subclass of `parent`, sized from the runtime type query.
 pub(super) unsafe fn register_subclass(
     parent: GType,
     name: &str,
     class_init: unsafe extern "C" fn(*mut c_void, *mut c_void),
 ) -> GType {
     let mut q: GTypeQuery = std::mem::zeroed();
     g_type_query(parent, &mut q);
     assert!(q.type_ != 0, "parent type {name} not registered");
     let cname = CString::new(name).expect("subclass name");
     g_type_register_static_simple(
         parent,
         cname.as_ptr(),
         q.class_size,
         std::mem::transmute::<_, GClassInitFunc>(class_init),
         q.instance_size,
         None,
         0,
     )
 }
 
 pub(super) const fn fourcc(a: u8, b: u8, c: u8, d: u8) -> u32 {
     (a as u32) | ((b as u32) << 8) | ((c as u32) << 16) | ((d as u32) << 24)
 }
 
 /// Registered once, on first host construction. GType registration is
 /// process-wide and re-registering the same name aborts.
 pub(super) struct Types {
     pub display: GType,
     pub view: GType,
     pub toplevel: GType,
     pub clipboard: GType,
 }
 
 static mut TYPES: Option<Types> = None;
 
 pub(super) unsafe fn types() -> &'static Types {
     #[allow(static_mut_refs)]
     if TYPES.is_none() {
         TYPES = Some(Types {
             view: register_subclass(wpe_view_get_type(), "CceWpeView", view_class_init),
             toplevel: register_subclass(
                 wpe_toplevel_get_type(),
                 "CceWpeToplevel",
                 toplevel_class_init,
             ),
             display: register_subclass(wpe_display_get_type(), "CceWpeDisplay", display_class_init),
             clipboard: register_subclass(
                 wpe_clipboard_get_type(),
                 "CceWpeClipboard",
                 clipboard_class_init,
             ),
         });
     }
     #[allow(static_mut_refs)]
     TYPES.as_ref().unwrap()
 }
 
 // ---- view ----
 
 /// Set by the host before it creates a webview; `render_buffer` hands frames
 /// here. One host per process for now (see `WebKitHost::new`).
 ///
 /// Returns whether the sink is **keeping** the buffer. If it is, releasing it
 /// is the sink's job — it reads the pixels out at the next pump and hands the
 /// memory back then.
 pub(super) static mut FRAME_SINK: Option<Box<dyn FnMut(*mut WPEView, *mut WPEBuffer) -> bool>> =
     None;
 
 unsafe extern "C" fn view_render_buffer(
     view: *mut WPEView,
     buffer: *mut WPEBuffer,
     _damage: *const WPERectangle,
     _n_damage: u32,
     _error: *mut *mut GError,
 ) -> gboolean {
     // The two halves mean different things and are no longer said together.
     // `rendered` means *displayed*: said at once, so the engine's own frame
     // pacing never waits on our readback. `released` means *the memory is
     // yours again*, and that has to wait until the pixels have been copied
     // out of it — so the sink says it, at the pump that reads the buffer.
     // (Saying neither is what stalls the engine after exactly one frame.)
     //
     // Holding the buffer until then is also the backpressure: the engine
     // cannot run arbitrarily far ahead of a browser that is not keeping up,
     // and a frame superseded before anyone read it is handed back unread
     // rather than copied.
     wpe_view_buffer_rendered(view, buffer);
     #[allow(static_mut_refs)]
     let held = FRAME_SINK.as_mut().is_some_and(|sink| sink(view, buffer));
     if !held {
         wpe_view_buffer_released(view, buffer);
     }
     1
 }
 
 unsafe extern "C" fn view_class_init(class: *mut c_void, _data: *mut c_void) {
     (*(class as *mut WPEViewClass)).render_buffer = Some(view_render_buffer);
 }
 
 // ---- toplevel ----
 
 unsafe extern "C" fn toplevel_formats(_t: *mut WPEToplevel) -> *mut WPEBufferFormats {
     // Mappable ARGB/XRGB linear: what we can read back on the CPU and hand
     // straight to `cce_ui::vk::upload_rgba`. DMABuf comes later (phase 2).
     let b = wpe_buffer_formats_builder_new(std::ptr::null_mut());
     wpe_buffer_formats_builder_append_group(
         b,
         std::ptr::null_mut(),
         WPEBufferFormatUsage::WPE_BUFFER_FORMAT_USAGE_MAPPING,
     );
     for cc in [fourcc(b'A', b'R', b'2', b'4'), fourcc(b'X', b'R', b'2', b'4')] {
         wpe_buffer_formats_builder_append_format(b, cc, 0);
     }
     wpe_buffer_formats_builder_end(b)
 }
 
 unsafe extern "C" fn toplevel_resize(t: *mut WPEToplevel, w: i32, h: i32) -> gboolean {
     wpe_toplevel_resized(t, w, h);
     1
 }
 
 unsafe extern "C" fn toplevel_class_init(class: *mut c_void, _data: *mut c_void) {
     let c = class as *mut WPEToplevelClass;
     (*c).get_preferred_buffer_formats = Some(toplevel_formats);
     (*c).resize = Some(toplevel_resize);
 }
 
 // ---- display ----
 
 unsafe extern "C" fn display_connect(_d: *mut WPEDisplay, _e: *mut *mut GError) -> gboolean {
     1
 }
 
 unsafe extern "C" fn display_create_view(d: *mut WPEDisplay) -> *mut WPEView {
     let prop = CString::new("display").unwrap();
     g_object_new(types().view, prop.as_ptr(), d, std::ptr::null::<c_char>()) as *mut WPEView
 }
 
 unsafe extern "C" fn display_create_toplevel(
     d: *mut WPEDisplay,
     max_views: u32,
 ) -> *mut WPEToplevel {
     let (p1, p2) = (
         CString::new("display").unwrap(),
         CString::new("max-views").unwrap(),
     );
     g_object_new(
         types().toplevel,
         p1.as_ptr(),
         d,
         p2.as_ptr(),
         max_views,
         std::ptr::null::<c_char>(),
     ) as *mut WPEToplevel
 }
 
 /// One clipboard per process, cached: `get_clipboard` is called repeatedly
 /// and must return the same object, since WebKit tracks its change count.
 static mut CLIPBOARD: *mut WPEClipboard = std::ptr::null_mut();
 
 unsafe extern "C" fn display_get_clipboard(d: *mut WPEDisplay) -> *mut WPEClipboard {
     if CLIPBOARD.is_null() {
         let prop = CString::new("display").unwrap();
         CLIPBOARD = g_object_new(types().clipboard, prop.as_ptr(), d, std::ptr::null::<c_char>())
             as *mut WPEClipboard;
     }
     CLIPBOARD
 }
 
 unsafe extern "C" fn display_class_init(class: *mut c_void, _data: *mut c_void) {
     let c = class as *mut WPEDisplayClass;
     (*c).connect = Some(display_connect);
     (*c).create_view = Some(display_create_view);
     (*c).create_toplevel = Some(display_create_toplevel);
     // Without this, WebKit has no clipboard at all: Ctrl+V in a page reads
     // nothing and Ctrl+C writes nowhere, silently.
     (*c).get_clipboard = Some(display_get_clipboard);
 }
 
 // ---- clipboard ----
 //
 // Routed through `cce_ui`'s wl-copy/wl-paste helpers, which is what the Servo
 // backend does too — it keeps the browser on the same clipboard path as the
 // rest of the DE rather than opening a second connection of its own.
 
 /// Formats we answer to. WebKit asks by MIME type; anything textual maps to
 /// the one string the toolkit deals in.
 fn is_text_format(f: &str) -> bool {
     f.starts_with("text/plain") || f == "UTF8_STRING" || f == "STRING"
 }
 
 unsafe extern "C" fn clipboard_read(
     _clipboard: *mut WPEClipboard,
     format: *const c_char,
 ) -> *mut GBytes {
     let format = if format.is_null() {
         String::new()
     } else {
         std::ffi::CStr::from_ptr(format).to_string_lossy().into_owned()
     };
     if !is_text_format(&format) {
         return std::ptr::null_mut();
     }
     let Some(text) = cce_ui::widget::clipboard::read_from_clipboard() else {
         return std::ptr::null_mut();
     };
     let bytes = text.into_bytes().into_boxed_slice();
     let len = bytes.len();
     // The GBytes owns the buffer and frees it through the notify below.
     g_bytes_new_with_free_func(
         Box::into_raw(bytes) as *const c_void,
         len as u64,
         Some(free_boxed_bytes),
         std::ptr::null_mut(),
     )
 }
 
 unsafe extern "C" fn free_boxed_bytes(p: gpointer) {
     drop(Box::from_raw(p as *mut u8));
 }
 
 /// Set while we push the system clipboard into WPE, so the `changed` that
 /// results is not echoed straight back out again.
 pub(super) static mut SYNCING: bool = false;
 
 /// Make WPE aware of what the system clipboard holds.
 ///
 /// WPE only knows about content it has been *given*: `read` is never called
 /// for a clipboard it believes is empty, which is why paste silently did
 /// nothing until this existed. A native Wayland backend would push this on
 /// every selection change; we do it at the moment it matters — the paste —
 /// rather than polling `wl-paste` in the background forever.
 pub(super) unsafe fn sync_system_clipboard(display: *mut WPEDisplay) {
     let Some(text) = cce_ui::widget::clipboard::read_from_clipboard() else {
         return;
     };
     let clipboard = wpe_display_get_clipboard(display);
     if clipboard.is_null() {
         return;
     }
     let content = wpe_clipboard_content_new();
     let c = CString::new(text).unwrap_or_default();
     wpe_clipboard_content_set_text(content, c.as_ptr());
     SYNCING = true;
     wpe_clipboard_set_content(clipboard, content);
     SYNCING = false;
     wpe_clipboard_content_unref(content);
 
 }
 
 /// The page put something on the clipboard. `is_local` distinguishes that
 /// from us being told about someone else's copy — without the check we would
 /// echo a foreign clipboard straight back and clobber it.
 /// The parent `changed`, kept because overriding it without chaining up is
 /// what silently broke paste: `wpe_clipboard_set_content` routes through this
 /// vfunc, and the **base implementation is what actually stores the content
 /// and bumps the change count**. Without the chain-up, `set_content` appeared
 /// to succeed while WPE still reported no formats and an empty clipboard, so
 /// WebKit never even called `read`.
 static mut PARENT_CHANGED: Option<
     unsafe extern "C" fn(*mut WPEClipboard, *mut GPtrArray, gboolean, *mut WPEClipboardContent),
 > = None;
 
 unsafe extern "C" fn clipboard_changed(
     clipboard: *mut WPEClipboard,
     formats: *mut GPtrArray,
     is_local: gboolean,
     content: *mut WPEClipboardContent,
 ) {
     if let Some(parent) = PARENT_CHANGED {
         parent(clipboard, formats, is_local, content);
     }
     // SYNCING guards the other direction: we just pushed the system
     // clipboard in, and copying it straight back out is a pointless round
     // trip through wl-copy.
     if is_local == 0 || content.is_null() || SYNCING {
         return;
     }
     // Borrowed from the content, not ours to free.
     let text = wpe_clipboard_content_get_text(content);
     if !text.is_null() {
         let s = std::ffi::CStr::from_ptr(text).to_string_lossy().into_owned();
         cce_ui::widget::clipboard::copy_to_clipboard(&s);
     }
 }
 
 unsafe extern "C" fn clipboard_class_init(class: *mut c_void, _data: *mut c_void) {
     let c = class as *mut WPEClipboardClass;
     let parent = g_type_class_peek_parent(class as gpointer) as *mut WPEClipboardClass;
     PARENT_CHANGED = (!parent.is_null()).then(|| (*parent).changed).flatten();
     (*c).read = Some(clipboard_read);
     (*c).changed = Some(clipboard_changed);
 }