add toggle subcommand

3 files changed, 54 insertions, 1 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 6dfc369..9a7e672 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -5,7 +5,7 @@
 [package]
 name        = "vtcol"
 description = "Set Linux console color scheme"
-version     = "0.42.3"
+version     = "0.42.4"
 authors     = [ "Philipp Gesang <phg@phi-gamma.net>" ]
 repository  = "https://github.com/phi-gamma/vtcol"
 keywords    = [ "linux", "virtual_terminal", "tty", "console", "system" ]
diff --git a/README.rst b/README.rst
index 58ec09a..1809902 100644
--- a/README.rst
+++ b/README.rst
@@ -42,6 +42,11 @@ To show the current scheme of the active console use the ``get`` subcommand: ::
     $ vtcol get
     solarized_dark
 
+It is also possible to use vtcol to switch between two themes by means of the
+``toggle`` subcommand. E. g. to cycle between “dark mode” and “light mode”: ::
+
+    $ vtcol toggle solarized solarized_light
+
 To view a scheme’s definition, for instance in order to verify that **vtcol**
 parses it correctly, use the ``dump`` command. ::
 
diff --git a/src/vtcol.rs b/src/vtcol.rs
index 45cbbd4..81f586f 100644
--- a/src/vtcol.rs
+++ b/src/vtcol.rs
@@ -185,6 +185,8 @@ enum Job
     Set(Scheme),
     /** Get currently active scheme. */
     Get,
+    /** Toggle between two schemes. */
+    Toggle(Scheme, Scheme),
 }
 
 impl<'a> Job
@@ -231,6 +233,22 @@ impl<'a> Job
             .subcommand(
                 SubCommand::with_name("get").about("get current color scheme"),
             )
+            .subcommand(
+                SubCommand::with_name("toggle")
+                    .about("toggle between two schemes")
+                    .arg(
+                        Arg::with_name("one")
+                            .value_name("NAME1")
+                            .help("predefined color scheme")
+                            .takes_value(true),
+                    )
+                    .arg(
+                        Arg::with_name("two")
+                            .value_name("NAME2")
+                            .help("predefined color scheme")
+                            .takes_value(true),
+                    ),
+            )
             .arg(
                 Arg::with_name("verbose")
                     .short("v")
@@ -276,6 +294,18 @@ impl<'a> Job
                 Ok(Self::Set(scheme))
             },
             ("get", _) => Ok(Self::Get),
+            ("toggle", Some(subm)) => {
+                match (subm.value_of("one"), subm.value_of("two")) {
+                    (Some(one), Some(two)) => {
+                        vrb!("toggle schemes [{}] and [{}]", one, two);
+                        Ok(Self::Toggle(Scheme::from(one), Scheme::from(two)))
+                    },
+                    _ =>
+                        Err(anyhow!(
+                            "please supply two schemes to toggle between"
+                        )),
+                }
+            },
             (junk, _) =>
                 Err(anyhow!(
                     "invalid subcommand [{}]; try ``{} --help``",
@@ -323,6 +353,7 @@ impl<'a> Job
             Self::List => Self::schemes(),
             Self::Set(scm) => Self::set_scheme(scm)?,
             Self::Get => Self::get_scheme()?,
+            Self::Toggle(one, two) => Self::toggle_scheme(one, two)?,
         }
 
         Ok(())
@@ -357,6 +388,23 @@ impl<'a> Job
 
         Ok(())
     }
+
+    /** Toggle between two schemes. Defaults to ``one`` in case neither scheme
+    is active.
+    */
+    fn toggle_scheme(one: Scheme, two: Scheme) -> Result<()>
+    {
+        let fd = get_console_fd()?;
+        vrb!("console fd: {}", fd);
+
+        let pal = ioctl_gio_cmap(fd)?;
+
+        if pal == Palette::from(&one) {
+            Self::set_scheme(two)
+        } else {
+            Self::set_scheme(one)
+        }
+    }
 } /* [impl Job] */
 
 /* Rust appears to come with two wrappers for ``ioctl(2)``, but neither can be utilized for our