Support generating shell completions (#235)

* Add gen-completions subcommand for generating shell completions

* Update documentation about generating shell completions

* Include the shell completions in release tarball

4 files changed, 44 insertions, 2 deletions

diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index 8784435c..7298ce2e 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -116,7 +116,7 @@ jobs:
         PKG_STAGING="${{ env.CICD_INTERMEDIATES_DIR }}/package"
         ARCHIVE_DIR="${PKG_STAGING}/${PKG_BASENAME}/"
         mkdir -p "${ARCHIVE_DIR}"
-        mkdir -p "${ARCHIVE_DIR}/autocomplete"
+        mkdir -p "${ARCHIVE_DIR}/completions"
 
         # Binary
         cp "${{ steps.strip.outputs.BIN_PATH }}" "$ARCHIVE_DIR"
@@ -124,6 +124,11 @@ jobs:
         # README, LICENSE and CHANGELOG files
         cp "README.md" "LICENSE" "$ARCHIVE_DIR"
 
+        # Shell completions
+        for sh in 'bash' 'fish' 'zsh'; do
+          "${{ steps.strip.outputs.BIN_PATH }}" gen-completions -s $sh -o "${ARCHIVE_DIR}/completions"
+        done
+
         # base compressed package
         pushd "${PKG_STAGING}/" >/dev/null
         case ${{ matrix.job.target }} in
diff --git a/README.md b/README.md
index 7abb664f..5f3fe338 100644
--- a/README.md
+++ b/README.md
@@ -59,6 +59,7 @@ I wanted to. And I **really** don't want to.
 - [History stats](docs/stats.md)
 - [Running your own server](docs/server.md)
 - [Key binding](docs/key-binding.md)
+- [Shell completions](docs/shell-completions.md)
 
 ## Supported Shells
 
diff --git a/docs/shell-completions.md b/docs/shell-completions.md
new file mode 100644
index 00000000..4adf82b0
--- /dev/null
+++ b/docs/shell-completions.md
@@ -0,0 +1,19 @@
+# `atuin gen-completions`
+
+[Shell completions](https://en.wikipedia.org/wiki/Command-line_completion) for Atuin can be generated by specifying the output directory and desired shell via `gen-completions` subcommand.
+
+```
+$ atuin gen-completions --shell bash --out-dir $HOME
+
+Shell completion for BASH is generated in "/home/user"
+```
+
+Possible values for the `--shell` argument are the following:
+
+- `bash`
+- `fish`
+- `zsh`
+- `powershell`
+- `elvish`
+
+Also, see the [supported shells](./../README.md#supported-shells).
diff --git a/src/command/mod.rs b/src/command/mod.rs
index dc1f01fb..d82ad13b 100644
--- a/src/command/mod.rs
+++ b/src/command/mod.rs
@@ -1,6 +1,7 @@
 use std::path::PathBuf;
 
 use eyre::{Result, WrapErr};
+use structopt::clap::Shell;
 use structopt::StructOpt;
 
 use atuin_client::database::Sqlite;
@@ -92,6 +93,15 @@ pub enum AtuinCmd {
 
     #[structopt(about = "print the encryption key for transfer to another machine")]
     Key,
+
+    #[structopt(about = "generate shell completions")]
+    GenCompletions {
+        #[structopt(long, short, help = "set the shell for generating completions")]
+        shell: Shell,
+
+        #[structopt(long, short, help = "set the output directory")]
+        out_dir: String,
+    },
 }
 
 impl AtuinCmd {
@@ -157,11 +167,18 @@ impl AtuinCmd {
                 println!("{}", encode);
                 Ok(())
             }
-
             Self::Uuid => {
                 println!("{}", uuid_v4());
                 Ok(())
             }
+            Self::GenCompletions { shell, out_dir } => {
+                AtuinCmd::clap().gen_completions(env!("CARGO_PKG_NAME"), shell, &out_dir);
+                println!(
+                    "Shell completion for {} is generated in {:?}",
+                    shell, out_dir
+                );
+                Ok(())
+            }
         }
     }
 }