ci: completion/manpage generation script spring cleaning (#795)

* ci: spring cleaning of completions autogen

This commit changes a few things/cleans up stuff:
- Completion and manpage generation now drops the files off in
  `./target/tmp/bottom` rather than arbitrarily in the build directory.
  This was originally done because I was lazy and just needed it to work
  in CI, but it's kinda gross if you want to build the manpages in your
  own directory.
- CI was updated to handle this.
- Only run if the `BTM_GENERATE` env var is actually non-empty.

* docs: update for manpage/completion gen

* ci: auto delete autogen comp/manpage dir

* ci: fix incorrect mv for autogen

The mv was too late, should be earlier in the workflow.

* ci: specify shell in autogen delete

* docs: more updates to manpage/comp docs

* ci: unify env vars

* ci: skip autogen on build-msi

1 files changed, 29 insertions, 22 deletions

diff --git a/build.rs b/build.rs
index 5e069fb5..c46c3e82 100644
--- a/build.rs
+++ b/build.rs
@@ -23,32 +23,39 @@ fn create_dir(dir: &Path) -> Result<()> {
 }
 
 fn main() -> Result<()> {
-    if env::var_os("BTM_GENERATE").is_some() {
-        // OUT_DIR is where extra build files are written to for Cargo.
-        let completion_out_dir = PathBuf::from("completion");
-        let manpage_out_dir = PathBuf::from("manpage");
-
-        create_dir(&completion_out_dir)?;
-        create_dir(&manpage_out_dir)?;
-
-        // Generate completions
-        let mut app = build_app();
-        generate_to(Shell::Bash, &mut app, "btm", &completion_out_dir)?;
-        generate_to(Shell::Zsh, &mut app, "btm", &completion_out_dir)?;
-        generate_to(Shell::Fish, &mut app, "btm", &completion_out_dir)?;
-        generate_to(Shell::PowerShell, &mut app, "btm", &completion_out_dir)?;
-        generate_to(Shell::Elvish, &mut app, "btm", &completion_out_dir)?;
-
-        // Generate manpage
-        let app = app.name("btm");
-        let man = clap_mangen::Man::new(app);
-        let mut buffer: Vec<u8> = Default::default();
-        man.render(&mut buffer)?;
-        std::fs::write(manpage_out_dir.join("btm.1"), buffer)?;
+    const COMPLETION_DIR: &str = "target/tmp/bottom/completion";
+    const MANPAGE_DIR: &str = "target/tmp/bottom/manpage";
+
+    match env::var_os("BTM_GENERATE") {
+        Some(var) if !var.is_empty() => {
+            let completion_out_dir = PathBuf::from(COMPLETION_DIR);
+            let manpage_out_dir = PathBuf::from(MANPAGE_DIR);
+
+            create_dir(&completion_out_dir)?;
+            create_dir(&manpage_out_dir)?;
+
+            // Generate completions
+            let mut app = build_app();
+            generate_to(Shell::Bash, &mut app, "btm", &completion_out_dir)?;
+            generate_to(Shell::Zsh, &mut app, "btm", &completion_out_dir)?;
+            generate_to(Shell::Fish, &mut app, "btm", &completion_out_dir)?;
+            generate_to(Shell::PowerShell, &mut app, "btm", &completion_out_dir)?;
+            generate_to(Shell::Elvish, &mut app, "btm", &completion_out_dir)?;
+
+            // Generate manpage
+            let app = app.name("btm");
+            let man = clap_mangen::Man::new(app);
+            let mut buffer: Vec<u8> = Default::default();
+            man.render(&mut buffer)?;
+            std::fs::write(manpage_out_dir.join("btm.1"), buffer)?;
+        }
+        _ => {}
     }
 
     println!("cargo:rerun-if-changed=build.rs");
     println!("cargo:rerun-if-changed=./src/clap.rs");
+    println!("cargo:rerun-if-changed=.{}", COMPLETION_DIR);
+    println!("cargo:rerun-if-changed=.{}", MANPAGE_DIR);
     println!("cargo:rerun-if-env-changed=BTM_GENERATE");
 
     Ok(())