Work on the display functionality

src/model/display.rs

@@ -1,18 +1,19 @@
+use std::collections::VecDeque;
+
 use super::song::{Plan, Song, Verse};
 
 pub struct PlaylistEntry {
     pub song: Song,
-    pub plan_name: String,
+    pub plan_name: Option<String>,
 }
 
 pub struct PlaylistVerseRef {
     pub song_index: usize,
-    pub song_map: String,
     pub map_verse_index: usize,
 }
 
 pub struct Display {
-    pub playlist: Vec<PlaylistEntry>,
+    pub playlist: VecDeque<PlaylistEntry>,
     current: PlaylistVerseRef,
     frozen_at: Option<PlaylistVerseRef>,
     pub blanked: bool,
@@ -27,13 +28,102 @@ impl Display {
         if self.blanked {
             None
         } else {
+            let verse_ref = self.verse_ref();
+            let entry = self.entry(verse_ref)?;
+            entry.song.verses.get(self.verse_name(verse_ref)?)
         }
     }
 
-    pub fn entry(&self) -> Option<PlaylistEntry> {
-        let vref = self.verse_ref();
-        self.playlist.get(vref.song_index)
+    pub fn entry(&self, verse_ref: &PlaylistVerseRef) -> Option<&PlaylistEntry> {
+        self.playlist.get(verse_ref.song_index)
     }
 
-    pub fn plan() -> Plan {}
+    pub fn plan(&self, verse_ref: &PlaylistVerseRef) -> Option<&Plan> {
+        let PlaylistEntry { song, plan_name } = self.entry(verse_ref)?;
+        // TODO: this could "fail silently" and use the default plan
+        Some(song.plan(plan_name.as_deref()))
+    }
+
+    pub fn verse_name(&self, verse_ref: &PlaylistVerseRef) -> Option<&String> {
+        self.plan(verse_ref)?.get(verse_ref.map_verse_index)
+    }
+
+    pub fn clamp(&mut self) {
+        // ensure all plan names exist or fallback to defaults
+        for p in self.playlist.iter_mut() {
+            if let Some(plan_name) = p.plan_name.as_mut() {
+                if !p.song.other_plans.contains_key(plan_name) {
+                    p.plan_name = None;
+                }
+            }
+        }
+
+        // ensure song index is within bounds or be 0
+        self.current.song_index = self.current.song_index.clamp(0, self.playlist.len());
+        if let Some(frozen_at) = self.frozen_at.as_mut() {
+            frozen_at.song_index = frozen_at.song_index.clamp(0, self.playlist.len());
+        }
+
+        // ensure map verse index is within bounds or be 0
+        if let Some(plan) = self.plan(&self.current) {
+            self.current.map_verse_index = self.current.map_verse_index.clamp(0, plan.len());
+        }
+        let new_frozen_map_verse_index = match &self.frozen_at {
+            Some(frozen_at) => {
+                if let Some(plan) = self.plan(&frozen_at) {
+                    frozen_at.map_verse_index.clamp(0, plan.len())
+                } else {
+                    0
+                }
+            }
+            None => 0,
+        };
+        if let Some(frozen_at) = self.frozen_at.as_mut() {
+            frozen_at.map_verse_index = new_frozen_map_verse_index
+        }
+    }
+}
+
+mod test {
+    use super::*;
+
+    fn default(playlist: VecDeque<PlaylistEntry>) -> Display {
+        let current = PlaylistVerseRef {
+            song_index: 0,
+            map_verse_index: 0,
+        };
+
+        Display {
+            playlist,
+            current,
+            frozen_at: None,
+            blanked: false,
+        }
+    }
+
+    fn two_song_playlist() -> VecDeque<PlaylistEntry> {
+        VecDeque::from([
+            PlaylistEntry {
+                song: "Song1\n\ns1verse1\n\ns1verse2".parse().unwrap(),
+                plan_name: None,
+            },
+            PlaylistEntry {
+                song: "Song2\n\ns2verse1\n\ns2verse2".parse().unwrap(),
+                plan_name: None,
+            },
+        ])
+    }
+
+    #[test]
+    fn displays_no_verse_when_empty() {
+        let playlist: VecDeque<PlaylistEntry> = VecDeque::from(vec![]);
+        let display = default(playlist);
+        assert_eq!(display.verse(), None)
+    }
+
+    #[test]
+    fn displays_the_first_verse_when_a_song_is_there() {
+        let display = default(two_song_playlist());
+        assert_eq!(display.verse().unwrap().content, "s1verse1")
+    }
 }

src/model/song.rs

@@ -29,11 +29,11 @@ pub struct Song {
 }
 
 impl Song {
-    pub fn plan(&self, plan_name: Option<String>) -> &VecDeque<String> {
+    pub fn plan(&self, plan_name: Option<&str>) -> &VecDeque<String> {
         plan_name
             .map(|plan_name| {
                 self.other_plans
-                    .get(&plan_name)
+                    .get(plan_name)
                     .unwrap_or(&self.default_plan)
             })
             .unwrap_or(&self.default_plan)
@@ -144,10 +144,9 @@ impl FromStr for Song {
 }
 
 mod test {
+    use super::*;
     use std::collections::VecDeque;
 
-    use super::{Song, Verse};
-
     #[test]
     fn parses_simple_song() {
         let song: Song = r#"Song Title