Start working on tree layouting

cove-tui/src/chat.rs

@@ -57,9 +57,10 @@ impl<M: Msg, S: MsgStore<M>> Chat<M, S> {
 
     pub fn render(&mut self, frame: &mut Frame, pos: Pos, size: Size) {
         match self.mode {
-            Mode::Tree => self
-                .tree
-                .render(&mut self.store, &self.room, frame, pos, size),
+            Mode::Tree => {
+                self.tree
+                    .render(&mut self.store, &self.room, &self.cursor, frame, pos, size)
+            }
         }
     }
 }

cove-tui/src/chat/tree.rs

@@ -6,7 +6,7 @@ use crossterm::event::KeyEvent;
 use crossterm::style::ContentStyle;
 use toss::frame::{Frame, Pos, Size};
 
-use crate::store::{Msg, MsgStore};
+use crate::store::{Msg, MsgStore, Tree};
 
 use super::Cursor;
 
@@ -30,61 +30,97 @@ struct MsgBlock {
     content: Vec<String>,
 }
 
-struct Layout<I>(VecDeque<Block<I>>);
+/// Pre-layouted messages as a sequence of blocks.
+///
+/// These blocks are straightforward to render, but also provide a level of
+/// abstraction between the layouting and actual displaying of messages. This
+/// might be useful in the future to ensure the cursor is always on a visible
+/// message, for example.
+///
+/// The following equation describes the relationship between the
+/// [`Layout::top_line`] and [`Layout::bottom_line`] fields:
+///
+/// `bottom_line - top_line + 1 = sum of all heights`
+///
+/// This ensures that `top_line` is always the first line and `bottom_line` is
+/// always the last line in a nonempty [`Layout`]. In an empty layout, the
+/// equation simplifies to
+///
+/// `top_line = bottom_line + 1`
+struct Layout<I> {
+    blocks: VecDeque<Block<I>>,
+    /// The top line of the first block. Useful for prepending blocks,
+    /// especially to empty [`Layout`]s.
+    top_line: i32,
+    /// The bottom line of the last block. Useful for appending blocks,
+    /// especially to empty [`Layout`]s.
+    bottom_line: i32,
+}
 
 impl<I: PartialEq> Layout<I> {
-    pub fn new() -> Self {
-        Self(VecDeque::new())
+    fn new() -> Self {
+        Self::new_below(0)
     }
 
-    fn mark_cursor(&mut self, id: &I) {
-        for block in &mut self.0 {
-            if block.id.as_ref() == Some(id) {
-                block.cursor = true;
-            }
+    /// Create a new [`Layout`] such that prepending a single line will result
+    /// in `top_line = bottom_line = line`.
+    fn new_below(line: i32) -> Self {
+        Self {
+            blocks: VecDeque::new(),
+            top_line: line + 1,
+            bottom_line: line,
         }
     }
 
-    fn calculate_offsets_with_cursor(&mut self, line: i32) {
-        let cursor_index = self
-            .0
-            .iter()
-            .enumerate()
-            .find(|(_, b)| b.cursor)
-            .expect("layout must contain cursor block")
-            .0;
+    fn mark_cursor(&mut self, id: &I) -> usize {
+        let mut cursor = None;
+        for (i, block) in self.blocks.iter_mut().enumerate() {
+            if block.id.as_ref() == Some(id) {
+                block.cursor = true;
+                if cursor.is_some() {
+                    panic!("more than one cursor in layout");
+                }
+                cursor = Some(i);
+            }
+        }
+        cursor.expect("no cursor in layout")
+    }
+
+    fn calculate_offsets_with_cursor(&mut self, cursor: &Cursor<I>, height: i32) {
+        let cursor_index = self.mark_cursor(&cursor.id);
+        let cursor_line = ((height - 1) as f32 * cursor.proportion).round() as i32;
 
         // Propagate lines from cursor to both ends
-        self.0[cursor_index].line = line;
+        self.blocks[cursor_index].line = cursor_line;
         for i in (0..cursor_index).rev() {
             // let succ_line = self.0[i + 1].line;
             // let curr = &mut self.0[i];
             // curr.line = succ_line - curr.height;
-            self.0[i].line = self.0[i + 1].line - self.0[i].height;
+            self.blocks[i].line = self.blocks[i + 1].line - self.blocks[i].height;
         }
-        for i in (cursor_index + 1)..self.0.len() {
+        for i in (cursor_index + 1)..self.blocks.len() {
             // let pred = &self.0[i - 1];
             // self.0[i].line = pred.line + pred.height;
-            self.0[i].line = self.0[i - 1].line + self.0[i - 1].height;
+            self.blocks[i].line = self.blocks[i - 1].line + self.blocks[i - 1].height;
+        }
+        self.top_line = self.blocks.front().expect("blocks nonempty").line;
+        let bottom = self.blocks.back().expect("blocks nonempty");
+        self.bottom_line = bottom.line + bottom.height - 1;
+    }
+
+    fn prepend(&mut self, mut layout: Self) {
+        while let Some(mut block) = layout.blocks.pop_back() {
+            self.top_line -= block.height;
+            block.line = self.top_line;
+            self.blocks.push_front(block);
         }
     }
 
-    fn calculate_offsets_without_cursor(&mut self, height: i32) {
-        if let Some(back) = self.0.back_mut() {
-            back.line = height - back.height;
-        }
-        for i in (0..self.0.len() - 1).rev() {
-            self.0[i].line = self.0[i + 1].line - self.0[i].height;
-        }
-    }
-
-    pub fn calculate_offsets(&mut self, height: i32, cursor: Option<Cursor<I>>) {
-        if let Some(cursor) = cursor {
-            let line = ((height - 1) as f32 * cursor.proportion) as i32;
-            self.mark_cursor(&cursor.id);
-            self.calculate_offsets_with_cursor(line);
-        } else {
-            self.calculate_offsets_without_cursor(height);
+    fn append(&mut self, mut layout: Self) {
+        while let Some(mut block) = layout.blocks.pop_front() {
+            block.line = self.bottom_line + 1;
+            self.bottom_line += block.height;
+            self.blocks.push_back(block);
         }
     }
 }
@@ -103,24 +139,49 @@ impl<M: Msg> TreeView<M> {
         }
     }
 
+    fn layout_tree(tree: Tree<M>) -> Layout<M::Id> {
+        todo!()
+    }
+
     async fn layout<S: MsgStore<M>>(
         &mut self,
         room: &str,
         store: S,
-        cursor: &mut Option<Cursor<M::Id>>,
+        cursor: &Option<Cursor<M::Id>>,
+        size: Size,
     ) -> Layout<M::Id> {
+        let height: i32 = size.height.into();
         if let Some(cursor) = cursor {
             // TODO Ensure focus lies on cursor path, otherwise unfocus
             // TODO Unfold all messages on path to cursor
+
+            // Produce layout of cursor subtree (with correct offsets)
             let cursor_path = store.path(room, &cursor.id).await;
-            // TODO Produce layout of cursor subtree (with correct offsets)
+            let cursor_tree = store.tree(room, cursor_path.first()).await;
+            let mut layout = Self::layout_tree(cursor_tree);
+            layout.calculate_offsets_with_cursor(cursor, height);
+
             // TODO Expand layout upwards and downwards if there is no focus
             todo!()
         } else {
             // TODO Ensure there is no focus
-            // TODO Produce layout of last tree (with correct offsets)
-            // TODO Expand layout upwards
-            todo!()
+
+            // Start layout at the bottom of the screen
+            let mut layout = Layout::new_below(height);
+
+            // Expand layout upwards until the edge of the screen
+            let mut tree_id = store.last_tree(room).await;
+            while layout.top_line > 0 {
+                if let Some(actual_tree_id) = &tree_id {
+                    let tree = store.tree(room, actual_tree_id).await;
+                    layout.prepend(Self::layout_tree(tree));
+                    tree_id = store.prev_tree(room, actual_tree_id).await;
+                } else {
+                    break;
+                }
+            }
+
+            layout
         }
     }
 
@@ -139,6 +200,7 @@ impl<M: Msg> TreeView<M> {
         &mut self,
         store: &mut S,
         room: &str,
+        cursor: &Option<Cursor<M::Id>>,
         frame: &mut Frame,
         pos: Pos,
         size: Size,

cove-tui/src/store.rs

@@ -85,5 +85,9 @@ impl<M: Msg> Tree<M> {
 #[async_trait]
 pub trait MsgStore<M: Msg> {
     async fn path(&self, room: &str, id: &M::Id) -> Path<M::Id>;
-    async fn thread(&self, room: &str, root: &M::Id) -> Tree<M>;
+    async fn tree(&self, room: &str, root: &M::Id) -> Tree<M>;
+    async fn prev_tree(&self, room: &str, tree: &M::Id) -> Option<M::Id>;
+    async fn next_tree(&self, room: &str, tree: &M::Id) -> Option<M::Id>;
+    async fn first_tree(&self, room: &str) -> Option<M::Id>;
+    async fn last_tree(&self, room: &str) -> Option<M::Id>;
 }

cove-tui/src/store/dummy.rs

@@ -1,5 +1,4 @@
-use std::collections::HashMap;
-use std::thread::Thread;
+use std::collections::{HashMap, HashSet};
 
 use async_trait::async_trait;
 use chrono::{DateTime, TimeZone, Utc};
@@ -90,6 +89,24 @@ impl DummyStore {
             }
         }
     }
+
+    fn trees(&self) -> Vec<usize> {
+        let mut trees = HashSet::new();
+        for m in self.msgs.values() {
+            match m.parent() {
+                Some(parent) if !self.msgs.contains_key(&parent) => {
+                    trees.insert(parent);
+                }
+                Some(_) => {}
+                None => {
+                    trees.insert(m.id());
+                }
+            }
+        }
+        let mut trees: Vec<usize> = trees.into_iter().collect();
+        trees.sort_unstable();
+        trees
+    }
 }
 
 #[async_trait]
@@ -105,9 +122,35 @@ impl MsgStore<DummyMsg> for DummyStore {
         Path::new(segments)
     }
 
-    async fn thread(&self, _room: &str, root: &usize) -> Tree<DummyMsg> {
+    async fn tree(&self, _room: &str, root: &usize) -> Tree<DummyMsg> {
         let mut msgs = vec![];
         self.collect_tree(*root, &mut msgs);
         Tree::new(*root, msgs)
     }
+
+    async fn prev_tree(&self, _room: &str, tree: &usize) -> Option<usize> {
+        let trees = self.trees();
+        trees
+            .iter()
+            .zip(trees.iter().skip(1))
+            .find(|(_, t)| *t == tree)
+            .map(|(t, _)| *t)
+    }
+
+    async fn next_tree(&self, _room: &str, tree: &usize) -> Option<usize> {
+        let trees = self.trees();
+        trees
+            .iter()
+            .zip(trees.iter().skip(1))
+            .find(|(t, _)| *t == tree)
+            .map(|(_, t)| *t)
+    }
+
+    async fn first_tree(&self, _room: &str) -> Option<usize> {
+        self.trees().first().cloned()
+    }
+
+    async fn last_tree(&self, _room: &str) -> Option<usize> {
+        self.trees().last().cloned()
+    }
 }