1 files changed, 98 insertions, 0 deletions
diff --git a/src/trajectory.rs b/src/trajectory.rs
new file mode 100644
index 0000000..214e16c
--- /dev/null
+++ b/src/trajectory.rs
@@ -0,0 +1,98 @@
+use serde::{Deserialize, Serialize};
+use std::{collections::HashSet, time::SystemTime};
+
+use crate::learner::Learning;
+
+#[derive(Serialize, Deserialize, Debug)]
+struct LastData {
+    timestamp: SystemTime,
+    album: String,
+}
+
+#[derive(Serialize, Deserialize, Default)]
+pub struct Trajectory {
+    last_data: Option<LastData>,
+    streak_kind: Option<Action>,
+    history: Vec<String>,
+}
+
+#[derive(Serialize, Deserialize, Clone, PartialEq, Debug)]
+pub enum Action {
+    Skip,
+    More,
+}
+
+impl From<Option<&Learning>> for Action {
+    fn from(learning: Option<&Learning>) -> Action {
+        if let Some(ts) = learning {
+            match ts {
+                Learning::SkipExtend | Learning::MoreToSkip(_, _) => Action::Skip,
+                Learning::MoreExtend(_, _) | Learning::SkipToMore(_, _) => Action::More,
+            }
+        } else {
+            Action::Skip
+        }
+    }
+}
+
+impl Trajectory {
+    pub fn prune(&mut self, valid: &HashSet<String>) {
+        self.history.retain_mut(|x| valid.contains(x));
+
+        if let Some(ref last_data) = self.last_data
+            && !valid.contains(&last_data.album)
+        {
+            self.last_data = None
+        }
+    }
+
+    pub fn slice(&self) -> &[String] {
+        &self.history
+    }
+
+    pub fn log(&mut self, new_album: &str) {
+        self.last_data = Some(LastData {
+            timestamp: SystemTime::now(),
+            album: new_album.to_string(),
+        })
+    }
+
+    pub fn step(&mut self, skip_window_secs: u64) -> Option<Learning> {
+        if let Some(ref last_data) = self.last_data {
+            let action = if SystemTime::now()
+                .duration_since(last_data.timestamp)
+                .ok()
+                .is_some_and(|d| d.as_secs() < skip_window_secs)
+            {
+                Action::Skip
+            } else {
+                Action::More
+            };
+
+            let last_album = last_data.album.clone();
+            let current_streak = self.history.clone();
+
+            let learning = if let Some(ref kind) = self.streak_kind
+                && kind == &action
+            {
+                self.history.push(last_album.clone());
+                match action {
+                    Action::Skip => Learning::SkipExtend,
+                    Action::More => Learning::MoreExtend(current_streak, last_album),
+                }
+            } else {
+                self.history.clear();
+                self.history.push(last_album.clone());
+                match action {
+                    Action::Skip => Learning::MoreToSkip(current_streak, last_album),
+                    Action::More => Learning::SkipToMore(current_streak, last_album),
+                }
+            };
+
+            self.streak_kind = Some(action);
+            Some(learning)
+        } else {
+            None
+        }
+    }
+}