task-073

Co-authored-by: Joe Carstairs <jcarstairs@scottlogic.com>
Reviewed-on: https://git.joeac.net/joeac/schist/pulls/1
Co-authored-by: Joe Carstairs <me@joeac.net>
Co-committed-by: Joe Carstairs <me@joeac.net>

1 files changed, 128 insertions, 0 deletions

diff --git a/schist_desktop_gui/src/gui/components/navigation/update_navigation.rs b/schist_desktop_gui/src/gui/components/navigation/update_navigation.rs
new file mode 100644
index 0000000..f86867f
--- /dev/null
+++ b/schist_desktop_gui/src/gui/components/navigation/update_navigation.rs
@@ -0,0 +1,128 @@
+use iced::Element;
+
+use super::{Action, Message, Navigation};
+
+pub fn update_navigation<'a, TOption>(
+    navigation: &mut Navigation<TOption>,
+    message: Message<TOption>,
+) -> Action<TOption>
+where
+    TOption: Clone + PartialEq + Into<Element<'a, Message<TOption>>>,
+{
+    match message {
+        Message::SelectOption(option) => {
+            if navigation
+                .active_option
+                .as_ref()
+                .is_some_and(|active_option| active_option.clone() == option)
+            {
+                Action::None
+            } else if let Some(index) = navigation
+                .options_before_active
+                .iter()
+                .position(|o| o.clone() == option)
+            {
+                let split = navigation.options_before_active.split_at(index);
+                navigation.options_after_active = vec![
+                    navigation
+                        .active_option
+                        .clone()
+                        .map_or(vec![], |active_option| vec![active_option]),
+                    split.1.split_at(1).1.to_vec(),
+                    navigation.options_after_active.clone(),
+                ]
+                .concat();
+                navigation.options_before_active = split.0.to_vec();
+                navigation.active_option = Some(option.clone());
+                Action::SelectOption(option)
+            } else if let Some(index) = navigation
+                .options_after_active
+                .iter()
+                .position(|o| o.clone() == option)
+            {
+                let split = navigation.options_after_active.split_at(index);
+                navigation.options_before_active = vec![
+                    navigation.options_before_active.clone(),
+                    split.0.to_vec(),
+                    navigation
+                        .active_option
+                        .clone()
+                        .map_or(vec![], |active_option| vec![active_option]),
+                ]
+                .concat();
+                navigation.active_option = Some(option.clone());
+                navigation.options_after_active = split.1.split_at(1).1.to_vec();
+                Action::SelectOption(option)
+            } else {
+                if let Some(active_option) = &navigation.active_option {
+                    navigation.options_before_active.push(active_option.clone());
+                }
+                navigation
+                    .options_before_active
+                    .append(&mut navigation.options_after_active);
+                navigation.active_option = Some(option.clone());
+                navigation.options_after_active = vec![];
+                Action::SelectOption(option)
+            }
+        }
+        Message::SetOptions(options) => {
+            let active_option_index =
+                navigation
+                    .active_option
+                    .clone()
+                    .map_or(Option::None, |active_option| {
+                        options
+                            .iter()
+                            .position(|option| active_option == option.clone())
+                    });
+            if let Some(active_option_index) = active_option_index {
+                let split = options.split_at(active_option_index);
+                navigation.options_before_active = split.0.to_vec();
+                navigation.options_after_active = split.1.split_at(1).1.to_vec();
+                Action::None
+            } else {
+                navigation.options_before_active = options
+                    .split_last()
+                    .map_or_else(Vec::new, |(_last, rest)| rest.to_vec());
+                navigation.active_option = options.last().cloned();
+                options
+                    .last()
+                    .cloned()
+                    .map_or(Action::None, Action::SelectOption)
+            }
+        }
+        Message::SelectNext => {
+            if let Some(next) = navigation.options_after_active.clone().first() {
+                navigation.options_before_active = vec![
+                    navigation.options_before_active.clone(),
+                    navigation.active_option.clone().map_or(vec![], |o| vec![o]),
+                ]
+                .concat();
+                navigation.active_option = Some(next.clone());
+                navigation.options_after_active =
+                    navigation.options_after_active.split_at(1).1.to_vec();
+                Action::SelectOption(next.clone())
+            } else {
+                Action::None
+            }
+        }
+        Message::SelectPrev => {
+            if let Some(prev) = navigation.options_before_active.clone().last() {
+                navigation.options_after_active = vec![
+                    navigation.active_option.clone().map_or(vec![], |o| vec![o]),
+                    navigation.options_after_active.clone(),
+                ]
+                .concat();
+                navigation.active_option = Some(prev.clone());
+                navigation.options_before_active = navigation
+                    .options_before_active
+                    .split_last()
+                    .map(|split| split.1.to_vec())
+                    .unwrap_or_else(Vec::new);
+                Action::SelectOption(prev.clone())
+            } else {
+                Action::None
+            }
+        }
+    }
+}