magefiles: add gen:completions

.gitignore

@@ -1,4 +1,5 @@
 dist/
+completions/
 *.wasm
 .vscode/settings.json
 .env.local

magefiles/gen.go

@@ -4,6 +4,7 @@ package main
 
 import (
 	"fmt"
+	"os"
 
 	"github.com/magefile/mage/mg"
 	"github.com/magefile/mage/sh"
@@ -29,3 +30,22 @@ func (Gen) Proto() error {
 	return RunSh("go", Tool())("run", "github.com/bufbuild/buf/cmd/buf",
 		"generate", "-o", "../pkg/proto", "../proto/internal", "--template", "../buf.gen.yaml")
 }
+
+func (Gen) Completions() error {
+	if err := RunSh("mkdir", WithDir("."))("-p", "./completions"); err != nil {
+		return err
+	}
+
+	for _, shell := range []string{"bash", "zsh", "fish"} {
+		f, err := os.Create("./completions/spicedb." + shell)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+
+		if err := RunSh("go", WithDir("."), WithStdout(f))("run", "./cmd/spicedb/main.go", "completion", shell); err != nil {
+			return err
+		}
+	}
+	return nil
+}