Generate completion & manpage (#357)

* Generate completion & manpage

* Write changelog

7 files changed, 111 insertions, 24 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c7a8623..50e080a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ## [Unreleased]
 
+## [0.22.2] - 2024-01-28
+
+## Added
+
+* Generate completion & manpage #357 - @cyqsimon
+
 ## [0.22.1] - 2024-01-28
 
 ## Fixed
diff --git a/Cargo.lock b/Cargo.lock
index 029e70a..9750474 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -168,6 +168,8 @@ dependencies = [
  "chrono",
  "clap",
  "clap-verbosity-flag",
+ "clap_complete",
+ "clap_mangen",
  "crossterm",
  "derivative",
  "http_req",
@@ -341,6 +343,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "clap_complete"
+version = "4.4.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df631ae429f6613fcd3a7c1adbdb65f637271e561b03680adaa6573015dfb106"
+dependencies = [
+ "clap",
+]
+
+[[package]]
 name = "clap_derive"
 version = "4.4.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -359,6 +370,16 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "702fc72eb24e5a1e48ce58027a675bc24edd52096d5397d4aea7c6dd9eca0bd1"
 
 [[package]]
+name = "clap_mangen"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4a7c2b01e5e779c19f46a94bbd398f33ae63b0f78c07108351fb4536845bb7fd"
+dependencies = [
+ "clap",
+ "roff",
+]
+
+[[package]]
 name = "colorchoice"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1515,6 +1536,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "roff"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b833d8d034ea094b1ea68aa6d5c740e0d04bad9d16568d08ba6f76823a114316"
+
+[[package]]
 name = "rstest"
 version = "0.18.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/Cargo.toml b/Cargo.toml
index 3d02830..e795554 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -60,7 +60,15 @@ pnet_base = "0.34.0"
 regex = "1.10.3"
 rstest = "0.18.2"
 
-[target.'cfg(target_os = "windows")'.build-dependencies]
+[build-dependencies]
 anyhow = "1.0.79"
+clap = { version = "4.4.18", features = ["derive"] }
+clap-verbosity-flag = "2.1.2"
+clap_complete = "4.4.9"
+clap_mangen = "0.2.17"
+derivative = "2.2.0"
+strum = { version = "0.25.0", features = ["derive"] }
+
+[target.'cfg(target_os = "windows")'.build-dependencies]
 http_req = "0.10.2"
 zip = "0.6.6"
diff --git a/build.rs b/build.rs
index d20e5b5..7481214 100644
--- a/build.rs
+++ b/build.rs
@@ -1,8 +1,41 @@
+use std::{env, fs::File};
+
+use anyhow::anyhow;
+use clap::CommandFactory;
+use clap_complete::Shell;
+use clap_mangen::Man;
+
 fn main() {
+    build_completion_manpage().unwrap();
+
     #[cfg(target_os = "windows")]
     download_windows_npcap_sdk().unwrap();
 }
 
+include!("src/cli.rs");
+
+fn build_completion_manpage() -> anyhow::Result<()> {
+    let mut cmd = Opt::command();
+
+    // build into `BANDWHICH_GEN_DIR` with a fallback to `OUT_DIR`
+    let gen_dir: PathBuf = env::var_os("BANDWHICH_GEN_DIR")
+        .or_else(|| env::var_os("OUT_DIR"))
+        .ok_or(anyhow!("OUT_DIR is unset"))?
+        .into();
+
+    // completion
+    for &shell in Shell::value_variants() {
+        clap_complete::generate_to(shell, &mut cmd, "bandwhich", &gen_dir)?;
+    }
+
+    // manpage
+    let mut manpage_out = File::create(gen_dir.join("bandwhich.1"))?;
+    let manpage = Man::new(cmd);
+    manpage.render(&mut manpage_out)?;
+
+    Ok(())
+}
+
 #[cfg(target_os = "windows")]
 fn download_windows_npcap_sdk() -> anyhow::Result<()> {
     use std::{
diff --git a/src/cli.rs b/src/cli.rs
index 644a500..7a2fbc3 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -1,10 +1,9 @@
 use std::{net::Ipv4Addr, path::PathBuf};
 
-use clap::{Args, Parser};
+use clap::{Args, Parser, ValueEnum, ValueHint};
 use clap_verbosity_flag::{InfoLevel, Verbosity};
 use derivative::Derivative;
-
-use crate::display::BandwidthUnitFamily;
+use strum::EnumIter;
 
 #[derive(Clone, Debug, Derivative, Parser)]
 #[derivative(Default)]
@@ -30,7 +29,7 @@ pub struct Opt {
     /// A dns server ip to use instead of the system default
     pub dns_server: Option<Ipv4Addr>,
 
-    #[arg(long)]
+    #[arg(long, value_hint = ValueHint::FilePath)]
     /// Enable debug logging to a file
     pub log_to: Option<PathBuf>,
 
@@ -58,9 +57,24 @@ pub struct RenderOpts {
 
     #[arg(short, long, value_enum, default_value_t)]
     /// Choose a specific family of units
-    pub unit_family: BandwidthUnitFamily,
+    pub unit_family: UnitFamily,
 
     #[arg(short, long)]
     /// Show total (cumulative) usages
     pub total_utilization: bool,
 }
+
+// IMPRV: it would be nice if we can `#[cfg_attr(not(build), derive(strum::EnumIter))]` this
+// unfortunately there is no configuration option for build script detection
+#[derive(Copy, Clone, Debug, Default, Eq, PartialEq, ValueEnum, EnumIter)]
+pub enum UnitFamily {
+    #[default]
+    /// bytes, in powers of 2^10
+    BinBytes,
+    /// bits, in powers of 2^10
+    BinBits,
+    /// bytes, in powers of 10^3
+    SiBytes,
+    /// bits, in powers of 10^3
+    SiBits,
+}
diff --git a/src/display/components/display_bandwidth.rs b/src/display/components/display_bandwidth.rs
index 5d7a510..bf2b526 100644
--- a/src/display/components/display_bandwidth.rs
+++ b/src/display/components/display_bandwidth.rs
@@ -1,7 +1,8 @@
 use std::fmt;
 
-use clap::ValueEnum;
-use strum::EnumIter;
+use derivative::Derivative;
+
+use crate::cli::UnitFamily;
 
 #[derive(Copy, Clone, Debug)]
 pub struct DisplayBandwidth {
@@ -16,17 +17,14 @@ impl fmt::Display for DisplayBandwidth {
     }
 }
 
-#[derive(Copy, Clone, Debug, Default, Eq, PartialEq, ValueEnum, EnumIter)]
-pub enum BandwidthUnitFamily {
-    #[default]
-    /// bytes, in powers of 2^10
-    BinBytes,
-    /// bits, in powers of 2^10
-    BinBits,
-    /// bytes, in powers of 10^3
-    SiBytes,
-    /// bits, in powers of 10^3
-    SiBits,
+/// Type wrapper around [`UnitFamily`] to provide extra functionality.
+#[derive(Copy, Clone, Derivative, Default, Eq, PartialEq)]
+#[derivative(Debug = "transparent")]
+pub struct BandwidthUnitFamily(UnitFamily);
+impl From<UnitFamily> for BandwidthUnitFamily {
+    fn from(value: UnitFamily) -> Self {
+        Self(value)
+    }
 }
 impl BandwidthUnitFamily {
     #[inline]
@@ -39,9 +37,9 @@ impl BandwidthUnitFamily {
         /// Binary base: 2^10.
         const BB: f64 = 1024.0;
 
-        use BandwidthUnitFamily as F;
+        use UnitFamily as F;
         // probably could macro this stuff, but I'm too lazy
-        match self {
+        match self.0 {
             F::BinBytes => [
                 (1.0, BB * STEP_UP_FRAC, "B"),
                 (BB, BB.powi(2) * STEP_UP_FRAC, "KiB"),
@@ -99,11 +97,12 @@ mod tests {
     use itertools::Itertools;
     use strum::IntoEnumIterator;
 
-    use crate::display::{BandwidthUnitFamily, DisplayBandwidth};
+    use crate::{cli::UnitFamily, display::DisplayBandwidth};
 
     #[test]
     fn bandwidth_formatting() {
-        let test_bandwidths_formatted = BandwidthUnitFamily::iter()
+        let test_bandwidths_formatted = UnitFamily::iter()
+            .map_into()
             .cartesian_product(
                 // I feel like this is a decent selection of values
                 (-6..60)
diff --git a/src/display/ui.rs b/src/display/ui.rs
index 4b6d716..4a2866e 100644
--- a/src/display/ui.rs
+++ b/src/display/ui.rs
@@ -33,7 +33,7 @@ where
         let state = {
             let mut state = UIState::default();
             state.interface_name = opts.interface.clone();
-            state.unit_family = opts.render_opts.unit_family;
+            state.unit_family = opts.render_opts.unit_family.into();
             state.cumulative_mode = opts.render_opts.total_utilization;
             state
         };