woodpecker-cli: install autocompletion for bash/fish/zsh

pkgs/development/tools/continuous-integration/woodpecker/cli.nix

@@ -1,4 +1,10 @@
-{ buildGoModule, callPackage }:
+{
+  buildGoModule,
+  callPackage,
+  installShellFiles,
+  lib,
+  stdenv,
+}:
 let
   common = callPackage ./common.nix { };
 in
@@ -8,13 +14,23 @@ buildGoModule {
     version
     src
     ldflags
-    postInstall
     vendorHash
     ;
 
   subPackages = "cmd/cli";
 
+  nativeBuildInputs = [ installShellFiles ];
+
   env.CGO_ENABLED = 0;
+  postInstall = ''
+    ${common.postInstall}
+  ''
+  + lib.optionalString (stdenv.buildPlatform.canExecute stdenv.hostPlatform) ''
+    installShellCompletion --cmd woodpecker-cli \
+      --bash <($out/bin/woodpecker-cli completion bash) \
+      --fish <($out/bin/woodpecker-cli completion fish ) \
+      --zsh <($out/bin/woodpecker-cli completion zsh)
+  '';
 
   meta = common.meta // {
     description = "Command line client for the Woodpecker Continuous Integration server";