dev,ci: Add mage target to generate auto-completion scripts

.github/workflows/release-snapshot.yml

@@ -65,6 +65,8 @@ jobs:
         key: ${{ runner.os }}-tools-${{ hashFiles('tools/**') }}
     - name: Make Mage
       run: make tools/bin/mage
+    - name: Auto-completion scripts
+      run: tools/bin/mage cli:autocomplete
     - name: Install JS SDK dependencies
       run: tools/bin/mage jsSDK:deps
     - name: Build JS SDK

.github/workflows/release-tag.yml

@@ -30,6 +30,8 @@ jobs:
         go mod download
     - name: Make Mage
       run: make tools/bin/mage
+    - name: Auto-completion scripts
+      run: tools/bin/mage cli:autocomplete
     - name: Install JS SDK dependencies
       run: tools/bin/mage jsSDK:deps
     - name: Build JS SDK

tools/mage/cli.go

@@ -0,0 +1,71 @@
+// Copyright © 2020 The Things Network Foundation, The Things Industries B.V.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ttnmage
+
+import (
+	"fmt"
+	"os"
+	"path"
+
+	"github.com/magefile/mage/mg"
+)
+
+// Cli namespace.
+type Cli mg.Namespace
+
+// Autocomplete generates scripts for auto-completion.
+func (Cli) Autocomplete() error {
+	for _, cfg := range []struct {
+		which      string
+		shell      string
+		filename   string
+		executable string
+	}{
+		{
+			"ttn-lw-cli", "bash", "ttn-lw-cli-snap", "ttn-lw-stack.ttn-lw-cli",
+		},
+		{
+			"ttn-lw-cli", "bash", "ttn-lw-cli", "ttn-lw-cli",
+		},
+		{
+			"ttn-lw-cli", "fish", "ttn-lw-cli.fish", "ttn-lw-cli",
+		},
+		{
+			"ttn-lw-cli", "zsh", "_ttn-lw-cli", "ttn-lw-cli",
+		},
+		{
+			"ttn-lw-stack", "bash", "ttn-lw-stack", "ttn-lw-stack",
+		},
+		{
+			"ttn-lw-stack", "fish", "ttn-lw-stack.fish", "ttn-lw-stack",
+		},
+		{
+			"ttn-lw-stack", "zsh", "_ttn-lw-stack", "ttn-lw-stack",
+		},
+	} {
+		f, err := os.Create(path.Join("config", "completion", cfg.shell, cfg.filename))
+		if err != nil {
+			return err
+		}
+		if err = execGo(
+			f, os.Stderr,
+			"run", fmt.Sprintf("./cmd/%s", cfg.which), "complete",
+			"--shell", cfg.shell,
+			"--executable", cfg.executable); err != nil {
+			return err
+		}
+	}
+	return nil
+}