ui: add initial Profile hover previews

The idea with these is that on notedeck you can just hover your cursor
over a profile link to see the profile. I just have a stub for now, but
full design coming soon after.

Also simplify the preview system even further with a macro. In the
future I imagine we can grep every preview in the codebase, and then
include this as a string inside this macro. This is some kind of
template metaprogramming insanity but in theory it could work.

Signed-off-by: William Casarin <jb55@jb55.com>

src/ui/profile/mod.rs

@@ -0,0 +1,3 @@
+pub mod preview;
+
+pub use preview::ProfilePreview;

src/ui/profile/preview.rs

@@ -0,0 +1,65 @@
+use nostrdb::ProfileRecord;
+
+pub struct ProfilePreview<'a> {
+    profile: &'a ProfileRecord<'a>,
+}
+
+impl<'a> ProfilePreview<'a> {
+    pub fn new(profile: &'a ProfileRecord<'a>) -> Self {
+        ProfilePreview { profile }
+    }
+}
+
+impl<'a> egui::Widget for ProfilePreview<'a> {
+    fn ui(self, ui: &mut egui::Ui) -> egui::Response {
+        ui.horizontal(|ui| {
+            ui.label("Profile");
+            let name = if let Some(name) = crate::profile::get_profile_name(self.profile) {
+                name
+            } else {
+                "nostrich"
+            };
+            ui.label(name);
+        })
+        .response
+    }
+}
+
+mod previews {
+    use super::*;
+    use crate::test_data::test_profile_record;
+    use crate::ui::{Preview, View};
+    use egui::Widget;
+
+    pub struct ProfilePreviewPreview<'a> {
+        profile: ProfileRecord<'a>,
+    }
+
+    impl<'a> ProfilePreviewPreview<'a> {
+        pub fn new() -> Self {
+            let profile = test_profile_record();
+            ProfilePreviewPreview { profile }
+        }
+    }
+
+    impl<'a> Default for ProfilePreviewPreview<'a> {
+        fn default() -> Self {
+            ProfilePreviewPreview::new()
+        }
+    }
+
+    impl<'a> View for ProfilePreviewPreview<'a> {
+        fn ui(&mut self, ui: &mut egui::Ui) {
+            ProfilePreview::new(&self.profile).ui(ui);
+        }
+    }
+
+    impl<'a> Preview for ProfilePreview<'a> {
+        /// A preview of the profile preview :D
+        type Prev = ProfilePreviewPreview<'a>;
+
+        fn preview() -> Self::Prev {
+            ProfilePreviewPreview::new()
+        }
+    }
+}