Improve editor (#77)

* Show write status in editor

* Add 'help edit' command

* Show pathname in status bar

* Update status bar colors

* Avoid clearing before printing by overwriting whole lines

src/user/editor.rs

@@ -1,4 +1,6 @@
 use crate::{kernel, print, user};
+use crate::kernel::console::Style;
+use alloc::format;
 use alloc::string::String;
 use alloc::vec::Vec;
 use core::cmp;
@@ -56,26 +58,43 @@ impl Editor {
 
         if let Some(file) = &mut self.file {
             file.write(&contents.as_bytes()).unwrap();
+            let status = format!("Wrote {}L to '{}'", n, self.pathname);
+            self.print_status(&status, "Yellow");
             user::shell::ExitCode::CommandSuccessful
         } else {
-            print!("Could not write to '{}'\n", self.pathname);
+            let status = format!("Could not write to '{}'", self.pathname);
+            self.print_status(&status, "LightRed");
             user::shell::ExitCode::CommandError
         }
     }
 
+    fn print_status(&mut self, status: &str, background: &str) {
+        let csi_color = Style::color("Black").with_background(background);
+        let csi_reset = Style::reset();
+        let (x, y) = kernel::vga::cursor_position();
+        kernel::vga::set_writer_position(0, self.height());
+        print!("{}{:width$}{}", csi_color, status, csi_reset, width = self.width());
+        kernel::vga::set_writer_position(x, y);
+        kernel::vga::set_cursor_position(x, y);
+    }
+
     fn print_screen(&mut self) {
         let mut lines: Vec<String> = Vec::new();
         let from = self.offset;
         let to = cmp::min(self.lines.len(), self.offset + self.height());
         for i in from..to {
-            let n = cmp::min(self.lines[i].len(), 80);
-            lines.push(self.lines[i][0..n].into()) // TODO: Use `offset_x .. offset_x + n`
+            let n = self.width();
+            let line = format!("{:width$}", self.lines[i], width = n);
+            lines.push(line[0..n].into()); // TODO: Use `offset_x .. offset_x + n`
         }
-        kernel::vga::clear_screen();
+        kernel::vga::set_writer_position(0, 0);
         print!("{}", lines.join("\n"));
+        let status = format!("Editing '{}'", self.pathname);
+        self.print_status(&status, "LightGray");
     }
 
     pub fn run(&mut self) -> user::shell::ExitCode {
+        kernel::vga::clear_screen();
         self.print_screen();
         kernel::vga::set_cursor_position(0, 0);
         kernel::vga::set_writer_position(0, 0);
@@ -87,10 +106,6 @@ impl Editor {
                 '\0' => {
                     continue;
                 }
-                '\x03' => { // Ctrl C
-                    kernel::vga::clear_screen();
-                    break;
-                }
                 '\x11' => { // Ctrl Q
                     // TODO: Warn if modifications have not been saved
                     kernel::vga::clear_screen();
@@ -100,8 +115,9 @@ impl Editor {
                     self.save();
                 },
                 '\x18' => { // Ctrl X
+                    let res = self.save();
                     kernel::vga::clear_screen();
-                    return self.save();
+                    return res;
                 },
                 '\n' => { // Newline
                     let new_line = self.lines[self.offset + y].split_off(x);
@@ -234,7 +250,7 @@ impl Editor {
     }
 
     fn height(&self) -> usize {
-        kernel::vga::screen_height()
+        kernel::vga::screen_height() - 1 // Leave out one line for status line
     }
 
     fn width(&self) -> usize {

src/user/help.rs

@@ -1,7 +1,27 @@
 use crate::{print, user};
 use crate::kernel::console::Style;
 
-pub fn main(_args: &[&str]) -> user::shell::ExitCode {
+pub fn main(args: &[&str]) -> user::shell::ExitCode {
+    if args.len() > 1 {
+        help_command(args[1])
+    } else {
+        help_summary()
+    }
+}
+
+fn help_command(cmd: &str) -> user::shell::ExitCode {
+    match cmd {
+        "edit" => help_edit(),
+        _      => help_unknown(cmd),
+    }
+}
+
+fn help_unknown(cmd: &str) -> user::shell::ExitCode {
+    print!("Help not found for command '{}'\n", cmd);
+    user::shell::ExitCode::CommandError
+}
+
+fn help_summary() -> user::shell::ExitCode {
     let csi_color = Style::color("Yellow");
     let csi_reset = Style::reset();
     print!("{}Commands:{}\n", csi_color, csi_reset);
@@ -12,7 +32,7 @@ pub fn main(_args: &[&str]) -> user::shell::ExitCode {
         ("d", "elete <file>",      "Delete file or empty directory\n"),
         ("e", "dit <file>",        "Edit existing or new file\n"),
         ("g", "oto <dir>",         "Go to directory\n"),
-        ("h", "elp",               "Display this text\n"),
+        ("h", "elp <command>",     "Display help about a command\n"),
         ("l", "ist <dir>",         "List entries in directory\n"),
         ("m", "ove <file> <file>", "Move file from source to destination\n"),
         ("p", "rint <string>",     "Print string to screen\n"),
@@ -33,3 +53,29 @@ pub fn main(_args: &[&str]) -> user::shell::ExitCode {
     print!("Made with <3 in 2019-2020 by Vincent Ollivier <v@vinc.cc>\n");
     user::shell::ExitCode::CommandSuccessful
 }
+
+fn help_edit() -> user::shell::ExitCode {
+    let csi_color = Style::color("Yellow");
+    let csi_reset = Style::reset();
+    print!("MOROS text editor is somewhat inspired by nano, but with an even smaller range\n");
+    print!("of features.\n");
+    print!("\n");
+    print!("{}Shortcuts:{}\n", csi_color, csi_reset);
+    print!("\n");
+
+    let shortcuts = [
+        ("^Q", "Quit editor"),
+        ("^W", "Write to file"),
+        ("^X", "Write to file and quit"),
+        ("^T", "Go to top of file"),
+        ("^B", "Go to bottom of file"),
+        ("^A", "Go to beginning of line"),
+        ("^E", "Go to end of line"),
+    ];
+    for (shortcut, usage) in &shortcuts {
+        let csi_color = Style::color("LightGreen");
+        let csi_reset = Style::reset();
+        print!("  {}{}{}    {}\n", csi_color, shortcut, csi_reset, usage);
+    }
+    user::shell::ExitCode::CommandSuccessful
+}