From 93d35012231902b1fad36cd5b87b3a08eea97c44 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Fri, 5 Mar 2021 16:36:39 -0500
Subject: [PATCH] Draw a welcome message

---
 src/editor.rs   | 55 +++++++++++++++++++++++++++++++----------
 src/main.rs     |  2 ++
 src/terminal.rs | 66 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 110 insertions(+), 13 deletions(-)
 create mode 100644 src/terminal.rs

diff --git a/src/editor.rs b/src/editor.rs
index c0b9d8b..134741f 100644
--- a/src/editor.rs
+++ b/src/editor.rs
@@ -1,48 +1,77 @@
-use std::io::{self, stdout};
+use crate::Terminal;
 use termion::event::Key;
-use termion::input::TermRead;
-use termion::raw::IntoRawMode;
+
+const VERSION: &str = env!("CARGO_PKG_VERSION");
 
 pub struct Editor {
     should_quit: bool,
+    terminal: Terminal,
 }
 
 impl Editor {
     pub fn run(&mut self) {
-        let _stdout = stdout().into_raw_mode().unwrap();
-
         loop {
-            if let Err(error) = self.process_keypress() {
+            if let Err(error) = self.refresh_screen() {
                 die(error);
             }
             if self.should_quit {
                 break;
             }
+            if let Err(error) = self.process_keypress() {
+                die(error);
+            }
         }
     }
 
     pub fn default() -> Self {
-        Self { should_quit: false }
+        Self {
+            should_quit: false,
+            terminal: Terminal::default().expect("Failed to initialize terminal"),
+        }
+    }
+
+    fn refresh_screen(&self) -> Result<(), std::io::Error> {
+        Terminal::cursor_hide();
+        Terminal::cursor_position(0, 0);
+        if self.should_quit {
+            Terminal::clear_screen();
+            println!("Goodbye.\r");
+        } else {
+            self.draw_rows();
+            Terminal::cursor_position(0, 0);
+        }
+        Terminal::cursor_show();
+        Terminal::flush()
     }
 
     fn process_keypress(&mut self) -> Result<(), std::io::Error> {
-        let pressed_key = read_key()?;
+        let pressed_key = Terminal::read_key()?;
         match pressed_key {
             Key::Ctrl('q') => self.should_quit = true,
             _ => (),
         }
         Ok(())
     }
-}
 
-fn read_key() -> Result<Key, std::io::Error> {
-    loop {
-        if let Some(key) = io::stdin().lock().keys().next() {
-            return key;
+    fn draw_rows(&self) {
+        let height = self.terminal.size().height;
+
+        for row in 0..height - 1 {
+            Terminal::clear_current_line();
+
+            if row == height / 3 {
+                let welcome_message = format!("Hecto editor -- version {}", VERSION);
+
+                let width = std::cmp::min(self.terminal.size() as usize, welcome_message.len());
+                println!("{}\r", &welcome_message[..width]);
+            } else {
+                println!("~\r");
+            }
         }
     }
 }
 
 fn die(e: std::io::Error) {
+    Terminal::clear_screen();
     panic!(e);
 }
diff --git a/src/main.rs b/src/main.rs
index 8a00098..2d0d27b 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,7 +1,9 @@
 #![warn(clippy::all, clippy::pedantic)]
 mod editor;
+mod terminal;
 
 use editor::Editor;
+pub use terminal::Terminal;
 
 fn main() {
     Editor::default().run();
diff --git a/src/terminal.rs b/src/terminal.rs
new file mode 100644
index 0000000..fb8435d
--- /dev/null
+++ b/src/terminal.rs
@@ -0,0 +1,66 @@
+use std::io::{self, stdout, Write};
+use termion::event::Key;
+use termion::input::TermRead;
+use termion::raw::{IntoRawMode, RawTerminal};
+
+pub struct Size {
+    pub width: u16,
+    pub height: u16,
+}
+
+pub struct Terminal {
+    size: Size,
+    _stdout: RawTerminal<std::io::Stdout>,
+}
+
+impl Terminal {
+    pub fn default() -> Result<Self, std::io::Error> {
+        let size = termion::terminal_size()?;
+        Ok(Self {
+            size: Size {
+                width: size.0,
+                height: size.1,
+            },
+            _stdout: stdout().into_raw_mode()?,
+        })
+    }
+
+    pub fn size(&self) -> &Size {
+        &self.size
+    }
+
+    pub fn clear_screen() {
+        print!("{}", termion::clear::All);
+    }
+
+    pub fn cursor_position(x: u16, y: u16) {
+        let x = x.saturating_add(1);
+        let y = y.saturating_add(1);
+
+        print!("{}", termion::cursor::Goto(x, y));
+    }
+
+    pub fn flush() -> Result<(), std::io::Error> {
+        io::stdout().flush()
+    }
+
+    pub fn read_key() -> Result<Key, std::io::Error> {
+        loop {
+            if let Some(key) = io::stdin().lock().keys().next() {
+                return key;
+            }
+        }
+    }
+
+    pub fn cursor_hide() {
+        print!("{}", termion::cursor::Hide);
+    }
+
+    pub fn cursor_show() {
+        print!("{}", termion::cursor::Show);
+    }
+
+    pub fn clear_current_line() {
+        print!("{}", termion::clear::CurrentLine);
+    }
+}
\ No newline at end of file