WIP: menu

src/page.rs

@@ -4,35 +4,87 @@ pub enum Page {
     Main,
     Patterns,
     Audio,
-    Doc,
+    Help,
+    Dict,
 }
 
 impl Page {
+    /// All pages for iteration
+    pub const ALL: &'static [Page] = &[
+        Page::Main,
+        Page::Patterns,
+        Page::Audio,
+        Page::Help,
+        Page::Dict,
+    ];
+
+    /// Grid dimensions (cols, rows)
+    pub const GRID_SIZE: (i8, i8) = (3, 2);
+
+    /// Grid position (col, row) for each page
+    /// Layout:
+    ///         col 0      col 1       col 2
+    /// row 0              Patterns    Help
+    /// row 1   Dict       Sequencer   Audio
+    pub const fn grid_pos(self) -> (i8, i8) {
+        match self {
+            Page::Dict => (0, 1),
+            Page::Main => (1, 1),
+            Page::Patterns => (1, 0),
+            Page::Audio => (2, 1),
+            Page::Help => (2, 0),
+        }
+    }
+
+    /// Find page at grid position, if any
+    pub fn at_pos(col: i8, row: i8) -> Option<Page> {
+        Self::ALL.iter().copied().find(|p| p.grid_pos() == (col, row))
+    }
+
+    /// Display name for the page
+    pub const fn name(self) -> &'static str {
+        match self {
+            Page::Main => "Sequencer",
+            Page::Patterns => "Patterns",
+            Page::Audio => "Audio",
+            Page::Help => "Help",
+            Page::Dict => "Dict",
+        }
+    }
+
     pub fn left(&mut self) {
-        *self = match self {
-            Page::Main | Page::Patterns => Page::Doc,
-            Page::Audio => Page::Main,
-            Page::Doc => Page::Audio,
+        let (col, row) = self.grid_pos();
+        for offset in 1..=Self::GRID_SIZE.0 {
+            let new_col = (col - offset).rem_euclid(Self::GRID_SIZE.0);
+            if let Some(page) = Self::at_pos(new_col, row) {
+                *self = page;
+                return;
+            }
         }
     }
 
     pub fn right(&mut self) {
-        *self = match self {
-            Page::Main | Page::Patterns => Page::Audio,
-            Page::Audio => Page::Doc,
-            Page::Doc => Page::Main,
+        let (col, row) = self.grid_pos();
+        for offset in 1..=Self::GRID_SIZE.0 {
+            let new_col = (col + offset).rem_euclid(Self::GRID_SIZE.0);
+            if let Some(page) = Self::at_pos(new_col, row) {
+                *self = page;
+                return;
+            }
         }
     }
 
     pub fn up(&mut self) {
-        if *self == Page::Main {
-            *self = Page::Patterns;
+        let (col, row) = self.grid_pos();
+        if let Some(page) = Self::at_pos(col, row - 1) {
+            *self = page;
         }
     }
 
     pub fn down(&mut self) {
-        if *self == Page::Patterns {
-            *self = Page::Main;
+        let (col, row) = self.grid_pos();
+        if let Some(page) = Self::at_pos(col, row + 1) {
+            *self = page;
         }
     }
 }