feat: TUI Phase 1 common widgets + scoring/path beads

crates/lore-tui/src/navigation.rs

@@ -0,0 +1,339 @@
+#![allow(dead_code)] // Phase 1: consumed by LoreApp in bd-6pmy
+
+//! Browser-like navigation stack with vim-style jump list.
+//!
+//! Supports back/forward (browser), jump back/forward (vim Ctrl+O/Ctrl+I),
+//! and breadcrumb generation. State is preserved when navigating away —
+//! screens are never cleared on pop.
+
+use crate::message::Screen;
+
+// ---------------------------------------------------------------------------
+// NavigationStack
+// ---------------------------------------------------------------------------
+
+/// Browser-like navigation with back/forward stacks and a vim jump list.
+///
+/// The jump list only records "significant" hops — detail views and
+/// cross-references — skipping list/dashboard screens that users
+/// visit briefly during drilling.
+pub struct NavigationStack {
+    back_stack: Vec<Screen>,
+    current: Screen,
+    forward_stack: Vec<Screen>,
+    jump_list: Vec<Screen>,
+    jump_index: usize,
+}
+
+impl NavigationStack {
+    /// Create a new stack starting at the Dashboard.
+    #[must_use]
+    pub fn new() -> Self {
+        Self {
+            back_stack: Vec::new(),
+            current: Screen::Dashboard,
+            forward_stack: Vec::new(),
+            jump_list: Vec::new(),
+            jump_index: 0,
+        }
+    }
+
+    /// The currently displayed screen.
+    #[must_use]
+    pub fn current(&self) -> &Screen {
+        &self.current
+    }
+
+    /// Whether the current screen matches the given screen.
+    #[must_use]
+    pub fn is_at(&self, screen: &Screen) -> bool {
+        &self.current == screen
+    }
+
+    /// Navigate to a new screen.
+    ///
+    /// Pushes current to back_stack, clears forward_stack (browser behavior),
+    /// and records detail hops in the jump list.
+    pub fn push(&mut self, screen: Screen) {
+        let old = std::mem::replace(&mut self.current, screen);
+        self.back_stack.push(old);
+        self.forward_stack.clear();
+
+        // Record significant hops in jump list (vim behavior):
+        // truncate any forward entries beyond jump_index, then append.
+        if self.current.is_detail_or_entity() {
+            self.jump_list.truncate(self.jump_index);
+            self.jump_list.push(self.current.clone());
+            self.jump_index = self.jump_list.len();
+        }
+    }
+
+    /// Go back to the previous screen.
+    ///
+    /// Returns `None` at root (can't pop past the initial screen).
+    pub fn pop(&mut self) -> Option<&Screen> {
+        let prev = self.back_stack.pop()?;
+        let old = std::mem::replace(&mut self.current, prev);
+        self.forward_stack.push(old);
+        Some(&self.current)
+    }
+
+    /// Go forward (redo a pop).
+    ///
+    /// Returns `None` if there's nothing to go forward to.
+    pub fn go_forward(&mut self) -> Option<&Screen> {
+        let next = self.forward_stack.pop()?;
+        let old = std::mem::replace(&mut self.current, next);
+        self.back_stack.push(old);
+        Some(&self.current)
+    }
+
+    /// Jump backward through the jump list (vim Ctrl+O).
+    ///
+    /// Only visits detail/entity screens.
+    pub fn jump_back(&mut self) -> Option<&Screen> {
+        if self.jump_index == 0 {
+            return None;
+        }
+        self.jump_index -= 1;
+        self.jump_list.get(self.jump_index)
+    }
+
+    /// Jump forward through the jump list (vim Ctrl+I).
+    pub fn jump_forward(&mut self) -> Option<&Screen> {
+        if self.jump_index >= self.jump_list.len() {
+            return None;
+        }
+        let screen = self.jump_list.get(self.jump_index)?;
+        self.jump_index += 1;
+        Some(screen)
+    }
+
+    /// Reset to a single screen, clearing all history.
+    pub fn reset_to(&mut self, screen: Screen) {
+        self.current = screen;
+        self.back_stack.clear();
+        self.forward_stack.clear();
+        self.jump_list.clear();
+        self.jump_index = 0;
+    }
+
+    /// Breadcrumb labels for the current navigation path.
+    ///
+    /// Returns the back stack labels plus the current screen label.
+    #[must_use]
+    pub fn breadcrumbs(&self) -> Vec<&str> {
+        self.back_stack
+            .iter()
+            .chain(std::iter::once(&self.current))
+            .map(Screen::label)
+            .collect()
+    }
+
+    /// Navigation depth (1 = at root, 2 = one push deep, etc.).
+    #[must_use]
+    pub fn depth(&self) -> usize {
+        self.back_stack.len() + 1
+    }
+
+    /// Whether there's anything to go back to.
+    #[must_use]
+    pub fn can_go_back(&self) -> bool {
+        !self.back_stack.is_empty()
+    }
+
+    /// Whether there's anything to go forward to.
+    #[must_use]
+    pub fn can_go_forward(&self) -> bool {
+        !self.forward_stack.is_empty()
+    }
+}
+
+impl Default for NavigationStack {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::message::EntityKey;
+
+    #[test]
+    fn test_new_starts_at_dashboard() {
+        let nav = NavigationStack::new();
+        assert!(nav.is_at(&Screen::Dashboard));
+        assert_eq!(nav.depth(), 1);
+    }
+
+    #[test]
+    fn test_push_pop_preserves_order() {
+        let mut nav = NavigationStack::new();
+        nav.push(Screen::IssueList);
+        nav.push(Screen::IssueDetail(EntityKey::issue(1, 42)));
+
+        assert!(nav.is_at(&Screen::IssueDetail(EntityKey::issue(1, 42))));
+        assert_eq!(nav.depth(), 3);
+
+        nav.pop();
+        assert!(nav.is_at(&Screen::IssueList));
+
+        nav.pop();
+        assert!(nav.is_at(&Screen::Dashboard));
+    }
+
+    #[test]
+    fn test_pop_at_root_returns_none() {
+        let mut nav = NavigationStack::new();
+        assert!(nav.pop().is_none());
+        assert!(nav.is_at(&Screen::Dashboard));
+    }
+
+    #[test]
+    fn test_forward_stack_cleared_on_new_push() {
+        let mut nav = NavigationStack::new();
+        nav.push(Screen::IssueList);
+        nav.push(Screen::Search);
+        nav.pop(); // back to IssueList, Search in forward
+        assert!(nav.can_go_forward());
+
+        nav.push(Screen::Timeline); // new push clears forward
+        assert!(!nav.can_go_forward());
+    }
+
+    #[test]
+    fn test_go_forward_restores() {
+        let mut nav = NavigationStack::new();
+        nav.push(Screen::IssueList);
+        nav.push(Screen::Search);
+        nav.pop(); // back to IssueList
+
+        let screen = nav.go_forward();
+        assert!(screen.is_some());
+        assert!(nav.is_at(&Screen::Search));
+    }
+
+    #[test]
+    fn test_go_forward_returns_none_when_empty() {
+        let mut nav = NavigationStack::new();
+        assert!(nav.go_forward().is_none());
+    }
+
+    #[test]
+    fn test_jump_list_skips_list_screens() {
+        let mut nav = NavigationStack::new();
+        nav.push(Screen::IssueList); // not a detail — skip
+        nav.push(Screen::IssueDetail(EntityKey::issue(1, 1))); // detail — record
+        nav.push(Screen::MrList); // not a detail — skip
+        nav.push(Screen::MrDetail(EntityKey::mr(1, 2))); // detail — record
+
+        assert_eq!(nav.jump_list.len(), 2);
+    }
+
+    #[test]
+    fn test_jump_back_and_forward() {
+        let mut nav = NavigationStack::new();
+        let issue = Screen::IssueDetail(EntityKey::issue(1, 1));
+        let mr = Screen::MrDetail(EntityKey::mr(1, 2));
+
+        nav.push(Screen::IssueList);
+        nav.push(issue.clone());
+        nav.push(Screen::MrList);
+        nav.push(mr.clone());
+
+        // jump_index is at 2 (past the end of 2 items)
+        let prev = nav.jump_back();
+        assert_eq!(prev, Some(&mr));
+
+        let prev = nav.jump_back();
+        assert_eq!(prev, Some(&issue));
+
+        // at beginning
+        assert!(nav.jump_back().is_none());
+
+        // forward
+        let next = nav.jump_forward();
+        assert_eq!(next, Some(&issue));
+
+        let next = nav.jump_forward();
+        assert_eq!(next, Some(&mr));
+
+        // at end
+        assert!(nav.jump_forward().is_none());
+    }
+
+    #[test]
+    fn test_jump_list_truncates_on_new_push() {
+        let mut nav = NavigationStack::new();
+        nav.push(Screen::IssueDetail(EntityKey::issue(1, 1)));
+        nav.push(Screen::IssueDetail(EntityKey::issue(1, 2)));
+        nav.push(Screen::IssueDetail(EntityKey::issue(1, 3)));
+
+        // jump back twice
+        nav.jump_back();
+        nav.jump_back();
+        // jump_index = 1, pointing at issue 2
+
+        // new detail push truncates forward entries
+        nav.push(Screen::MrDetail(EntityKey::mr(1, 99)));
+
+        // should have issue(1,1) and mr(1,99), not issue(1,2) or issue(1,3)
+        assert_eq!(nav.jump_list.len(), 2);
+        assert_eq!(nav.jump_list[1], Screen::MrDetail(EntityKey::mr(1, 99)));
+    }
+
+    #[test]
+    fn test_reset_clears_all_history() {
+        let mut nav = NavigationStack::new();
+        nav.push(Screen::IssueList);
+        nav.push(Screen::Search);
+        nav.push(Screen::IssueDetail(EntityKey::issue(1, 1)));
+
+        nav.reset_to(Screen::Dashboard);
+
+        assert!(nav.is_at(&Screen::Dashboard));
+        assert_eq!(nav.depth(), 1);
+        assert!(!nav.can_go_back());
+        assert!(!nav.can_go_forward());
+        assert!(nav.jump_list.is_empty());
+    }
+
+    #[test]
+    fn test_breadcrumbs_reflect_stack() {
+        let mut nav = NavigationStack::new();
+        assert_eq!(nav.breadcrumbs(), vec!["Dashboard"]);
+
+        nav.push(Screen::IssueList);
+        assert_eq!(nav.breadcrumbs(), vec!["Dashboard", "Issues"]);
+
+        nav.push(Screen::IssueDetail(EntityKey::issue(1, 42)));
+        assert_eq!(nav.breadcrumbs(), vec!["Dashboard", "Issues", "Issue"]);
+    }
+
+    #[test]
+    fn test_default_is_new() {
+        let nav = NavigationStack::default();
+        assert!(nav.is_at(&Screen::Dashboard));
+        assert_eq!(nav.depth(), 1);
+    }
+
+    #[test]
+    fn test_can_go_back_and_forward() {
+        let mut nav = NavigationStack::new();
+        assert!(!nav.can_go_back());
+        assert!(!nav.can_go_forward());
+
+        nav.push(Screen::IssueList);
+        assert!(nav.can_go_back());
+        assert!(!nav.can_go_forward());
+
+        nav.pop();
+        assert!(!nav.can_go_back());
+        assert!(nav.can_go_forward());
+    }
+}