Add CLI Width/Height validations

2 files changed, 45 insertions, 0 deletions

diff --git a/CLI/rust/src/game_of_life.rs b/CLI/rust/src/game_of_life.rs
index fffaa42..c854e7f 100644
--- a/CLI/rust/src/game_of_life.rs
+++ b/CLI/rust/src/game_of_life.rs
@@ -1,5 +1,8 @@
 use clap::{crate_authors, crate_version, App, Arg, ArgMatches, Error};
 
+/// Options module for validations and Opts struct
+pub(crate) mod opts;
+
 /// Define the Clap CLI for running Game of Life simulation
 ///
 /// Using Clap to define the available options that can be used with game of life
@@ -29,6 +32,7 @@ pub(crate) fn options() -> Result<ArgMatches, Error> {
                 .about("Specify the width of generated universe. [default: terminal width]")
                 .takes_value(true)
                 .long("width")
+                .validator(opts::validators::is_fitting_term_width)
                 .display_order(2)
         )
         .arg(
@@ -36,6 +40,7 @@ pub(crate) fn options() -> Result<ArgMatches, Error> {
                 .about("Specify the width of generated universe. [default: terminal height]")
                 .takes_value(true)
                 .long("height")
+                .validator(opts::validators::is_fitting_term_height)
                 .display_order(3)
         )
         .arg(
diff --git a/CLI/rust/src/game_of_life/opts.rs b/CLI/rust/src/game_of_life/opts.rs
new file mode 100644
index 0000000..c0ece98
--- /dev/null
+++ b/CLI/rust/src/game_of_life/opts.rs
@@ -0,0 +1,40 @@
+/// Clap validators module
+///
+/// Used for validating different CLI args (like width, height and delay)
+/// Ref: https://docs.rs/clap/3.0.0-beta.2/clap/struct.Arg.html#method.validator
+pub(crate) mod validators {
+    use terminal_size::{terminal_size, Height, Width};
+
+    /// Validator to check if width configuration can be used
+    ///
+    /// The maximum width allowed is the current terminal window width
+    pub(crate) fn is_fitting_term_width(val: &str) -> Result<(), String> {
+        let (Width(term_width), Height(_)) = terminal_size().unwrap();
+        match val.parse::<u16>() {
+            Ok(n) if n > 0 && n <= term_width => Ok(()),
+            Ok(_) => Err(format!(
+                "must be between 1 and {} (current terminal width)",
+                term_width
+            )),
+            Err(e) => Err(e.to_string()),
+        }
+    }
+
+    /// Validator to check if height configuration can be used
+    ///
+    /// The maximum height allowed is the current terminal window height - 2
+    /// The last 2 lines are used for status reporting (seed/input) and space
+    /// for ease of use
+    pub(crate) fn is_fitting_term_height(val: &str) -> Result<(), String> {
+        let (Width(_), Height(term_height)) = terminal_size().unwrap();
+        let term_height = term_height - 2;
+        match val.parse::<u16>() {
+            Ok(n) if n > 0 && n <= term_height => Ok(()),
+            Ok(_) => Err(format!(
+                "must be between 1 and {} (current terminal height)",
+                term_height
+            )),
+            Err(e) => Err(e.to_string()),
+        }
+    }
+}