From df95b239e78121ddf4314d47e1c20dad626752fb Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Thu, 18 Mar 2021 10:52:05 +0530
Subject: add history to command mode

---
 src/app.rs     |   7 ++-
 src/command.rs | 141 +++++++++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 138 insertions(+), 10 deletions(-)

diff --git a/src/app.rs b/src/app.rs
index 0eac084..9ba93f4 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -248,6 +248,7 @@ impl<'ctx> AppState<'ctx> {
     }
 
     fn eval_command(&mut self) {
+        self.command_box.hist_append();
         match self.command_box.text.as_str() {
             "(save)" => {
                 let image = self.export();
@@ -648,7 +649,11 @@ impl<'ctx> AppState<'ctx> {
                                 Keycode::Delete => self.command_box.delete(),
                                 Keycode::Left => self.command_box.backward(),
                                 Keycode::Right => self.command_box.forward(),
-                                Keycode::Return => self.eval_command(),
+                                Keycode::Up => self.command_box.hist_prev(),
+                                Keycode::Down => self.command_box.hist_next(),
+                                Keycode::Return => {
+                                    self.eval_command();
+                                }
                                 Keycode::Escape => {
                                     self.command_box.clear();
                                     self.mode = Mode::Draw;
diff --git a/src/command.rs b/src/command.rs
index 3beb700..064d767 100644
--- a/src/command.rs
+++ b/src/command.rs
@@ -1,20 +1,16 @@
 #[derive(Debug)]
 pub struct CommandBox {
-    pub enabled: bool,
-    pub history: Vec<String>,
+    pub history: History<String>,
+    pub hist_idx: Option<usize>,
     pub text: String,
     pub cursor: usize,
 }
 
-// cursor value of 0 is behind all text
-// cursor value of n is after n characters (insert after index n - 1)
-// cursor value of text.len() is after all text
-
 impl CommandBox {
     pub fn new() -> Self {
         CommandBox {
-            enabled: false,
-            history: vec![],
+            history: History::new(64),
+            hist_idx: None,
             text: String::new(),
             cursor: 0,
         }
@@ -26,6 +22,14 @@ impl CommandBox {
         }
     }
 
+    fn cursor_end(&mut self) {
+        self.cursor = self.text.len();
+    }
+
+    fn cursor_start(&mut self) {
+        self.cursor = 0;
+    }
+
     pub fn backward(&mut self) {
         self.cursor = self.cursor.saturating_sub(1);
     }
@@ -56,10 +60,73 @@ impl CommandBox {
         self.text.clear();
         self.cursor = 0;
     }
+
+    pub fn hist_append(&mut self) {
+        self.history.append(self.text.drain(..).collect());
+        self.cursor_start();
+    }
+
+    fn get_from_hist(&self) -> String {
+        let size = self.history.items.len();
+        self.history.items[size - 1 - self.hist_idx.unwrap()].clone()
+    }
+
+    pub fn hist_prev(&mut self) {
+        if let Some(idx) = self.hist_idx {
+            if !(idx + 1 >= self.history.items.len()) {
+                self.hist_idx = Some(idx + 1);
+                self.text = self.get_from_hist();
+                self.cursor_end();
+            }
+        } else {
+            self.hist_idx = Some(0);
+            self.text = self.get_from_hist();
+            self.cursor_end();
+        }
+    }
+
+    pub fn hist_next(&mut self) {
+        if let Some(idx) = self.hist_idx {
+            // most recent hist item, reset command box
+            if idx == 0 {
+                self.hist_idx = None;
+                self.text = "(".into();
+            } else {
+                self.hist_idx = Some(idx - 1);
+                self.text = self.get_from_hist();
+            }
+            self.cursor_end();
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct History<T> {
+    pub items: Vec<T>,
+    pub max_size: usize,
+}
+
+impl<T> History<T> {
+    pub fn new(max_size: usize) -> Self {
+        if max_size == 0 {
+            panic!();
+        }
+        Self {
+            items: vec![],
+            max_size,
+        }
+    }
+
+    pub fn append(&mut self, item: T) {
+        if self.items.len() >= self.max_size {
+            self.items.remove(0);
+        }
+        self.items.push(item);
+    }
 }
 
 #[cfg(test)]
-mod tests {
+mod command_tests {
     use super::*;
 
     fn setup_with(text: &str) -> CommandBox {
@@ -131,4 +198,60 @@ mod tests {
         cmd.forward();
         assert_eq!(cmd.cursor, 1);
     }
+
+    #[test]
+    fn hist_append() {
+        let mut cmd = setup_with("hello");
+        cmd.hist_append();
+        cmd.push_str("another");
+        cmd.hist_append();
+        cmd.push_str("one");
+        cmd.hist_append();
+        assert_eq!(cmd.history.items.len(), 3);
+    }
+
+    #[test]
+    fn hist_prev() {
+        let mut cmd = setup_with("hello");
+        cmd.hist_append();
+        cmd.push_str("another");
+        cmd.hist_append();
+        cmd.push_str("one");
+        cmd.hist_append();
+
+        cmd.hist_prev();
+        assert_eq!(&cmd.text, "one");
+        cmd.hist_prev();
+        assert_eq!(&cmd.text, "another");
+    }
+
+    #[test]
+    fn hist_next() {
+        let mut cmd = setup_with("hello");
+        cmd.hist_append();
+        cmd.push_str("another");
+        cmd.hist_append();
+        cmd.push_str("one");
+        cmd.hist_append();
+
+        cmd.hist_prev();
+        cmd.hist_prev();
+        cmd.hist_next();
+        assert_eq!(&cmd.text, "one");
+    }
+}
+
+#[cfg(test)]
+mod history_tests {
+    use super::*;
+    #[test]
+    fn append() {
+        let mut h = History::<u32>::new(4);
+        h.append(5);
+        h.append(6);
+        h.append(7);
+        h.append(8);
+        h.append(9);
+        assert_eq!(h.items, vec![6, 7, 8, 9]);
+    }
 }
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