Added --monday-as-first flag (-m for short)

README.md

@@ -31,6 +31,7 @@ USAGE:
 
 FLAGS:
     -h, --help       Prints help information
+    -m, --monday-as-first    Use Monday as first day of the week
     -V, --version    Prints version information
 
 OPTIONS:
@@ -55,4 +56,4 @@ ${color #888}27 ${color}28 29 30
 Thus I put this in my `conky.config` file:
 ```
 ${execpi 600 conky-calendar --today-color dd3a21 --weekend-color 888}
-```
+```

src/main.rs

@@ -91,26 +91,48 @@ fn main() {
                 .value_name("COLOR")
                 .takes_value(true),
         )
+        .arg(
+            Arg::with_name("monday-as-first")
+                .short("m")
+                .long("monday-as-first")
+                .help("Use Monday as first day of the week")
+         )
         .get_matches();
 
     let now = Local::now(); // current date & time via chrono
 
+    let labels = match matches.is_present("monday-as-first") {
+        true => String::from("Mo Tu We Th Fr Sa Su"),
+        false => String::from("Su Mo Tu We Th Fr Sa"),
+    };
+
     // weekday labels
     if matches.is_present("label-color") {
         println!(
-            "${{color #{color}}}{:^20}\nSu Mo Tu We Th Fr Sa${{color}}",
+            "${{color #{color}}}{:^20}\n{}${{color}}",
             now.format("%B %Y"),
+            labels,
             color = matches.value_of("label-color").unwrap()
         );
     } else {
-        println!("{:^20}\nSu Mo Tu We Th Fr Sa", now.format("%B %Y"));
+        println!("{:^20}\n{}", now.format("%B %Y"), labels);
     }
 
     // calculate where the numbers go, add spaces to offset the first day
     let first_day_of_month = NaiveDate::from_ymd(now.year(), now.month(), 1);
 
+    let initial_offset = match matches.is_present("monday-as-first") {
+        true => first_day_of_month.weekday().num_days_from_monday(),
+        false => first_day_of_month.weekday().num_days_from_sunday(),
+    };
+
+    let (saturday_day, sunday_day) = match matches.is_present("monday-as-first") {
+        true => (5, 6),
+        false => (6, 0),
+    };
+
     let mut col = 0;
-    for _ in 0..first_day_of_month.weekday().num_days_from_sunday() {
+    for _ in 0..initial_offset {
         print!("{:^3}", "");
         col = col + 1;
     }
@@ -127,7 +149,7 @@ fn main() {
                 day,
                 color = matches.value_of("today-color").unwrap()
             );
-        } else if matches.is_present("weekend-color") && (col == 0 || col == 6) { // color weekends if needed
+        } else if matches.is_present("weekend-color") && (col == saturday_day || col == sunday_day) { // color weekends if needed
             print!(
                 "${{color #{color}}}{:^3}${{color}}",
                 day,