feat: kubesafe completions (#18)

Author: Telemaco019

README.md

@@ -63,6 +63,8 @@ $ brew install kubesafe
 $ go install github.com/telemaco019/kubesafe/kubesafe@latest
 ```
 
+For shell completion setup, see [Shell completion](#shell-completion).
+
 ## Managing contexts
 
 Kubesafe makes it easy to manage your safe contexts and protected commands. To see all available options, run:
@@ -183,6 +185,53 @@ use `kubesafe` as your `kubectl` command.
 
     </details>
 
+## Shell completion
+
+Kubesafe supports shell completion for Bash, Zsh, and Fish. The completion scripts automatically delegate to the wrapped command's completion system when completing subcommands (e.g., `kubesafe kubectl get <TAB>` uses kubectl's completions).
+
+### Bash
+
+```bash
+# Load completions for commands you want to wrap (required for delegation)
+source <(kubectl completion bash)
+source <(helm completion bash)  # Add other commands as needed
+
+# Load kubesafe completion
+source <(kubesafe completion bash)
+```
+
+To load completions for each session, add the above lines to your `~/.bashrc`.
+
+### Zsh
+
+```zsh
+# Load completions for commands you want to wrap (required for delegation)
+source <(kubectl completion zsh)
+source <(helm completion zsh)  # Add other commands as needed
+
+# Load kubesafe completion
+source <(kubesafe completion zsh)
+```
+
+To load completions for each session, add the above lines to your `~/.zshrc`.
+
+### Fish
+
+```fish
+# Load completions for commands you want to wrap (required for delegation)
+kubectl completion fish | source
+helm completion fish | source  # Add other commands as needed
+
+# Load kubesafe completion
+kubesafe completion fish | source
+```
+
+To load completions for each session, run:
+
+```fish
+kubesafe completion fish > ~/.config/fish/completions/kubesafe.fish
+```
+
 ## Similar tools
 
 Kubesafe draws inspiration from existing kubectl plugins that offer similar features but are restricted to working exclusively with kubectl:

internal/cmd/completion.go

@@ -0,0 +1,214 @@
+/*
+ * Copyright 2026 Michele Zanotti <m.zanotti019@gmail.com>
+ *
+ * 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 cmd
+
+import (
+	"bytes"
+	"io"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+const zshCompletionWrapper = `
+# Wrapper function that delegates to wrapped command's completion when appropriate
+_kubesafe_wrapper() {
+    # words[1] is "kubesafe", words[2] is the wrapped command
+    local wrapped_cmd="${words[2]}"
+
+    # If we have a wrapped command and we're completing after it, try to delegate
+    if [[ -n "$wrapped_cmd" && $CURRENT -gt 2 ]]; then
+        # Check if the wrapped command has a completion function
+        if (( $+functions[_${wrapped_cmd}] )); then
+            # Rebuild words array without kubesafe prefix
+            words=("$wrapped_cmd" "${words[@]:3}")
+            CURRENT=$((CURRENT - 1))
+            _${wrapped_cmd}
+            return
+        fi
+    fi
+
+    # Fall back to standard kubesafe completion
+    _kubesafe
+}
+
+compdef _kubesafe_wrapper kubesafe
+`
+
+const bashCompletionWrapper = `
+# Wrapper function that delegates to wrapped command's completion when appropriate
+_kubesafe_wrapper() {
+    # First positional argument after kubesafe is the wrapped command
+    local wrapped_cmd="${COMP_WORDS[1]}"
+
+    # If we have a wrapped command and we're completing after it, try to delegate
+    if [[ -n "$wrapped_cmd" && $COMP_CWORD -gt 1 ]]; then
+        # Try to find the wrapped command's completion function
+        local completion_func="__start_${wrapped_cmd}"
+        if type "$completion_func" &>/dev/null; then
+            # Build new COMP_WORDS without 'kubesafe' prefix
+            local -a new_words=("${COMP_WORDS[@]:1}")
+            local new_cword=$((COMP_CWORD - 1))
+
+            # Update completion variables and delegate
+            COMP_WORDS=("${new_words[@]}")
+            COMP_CWORD=$new_cword
+            COMP_LINE="${new_words[*]}"
+            COMP_POINT=${#COMP_LINE}
+            $completion_func
+            return
+        fi
+    fi
+
+    # Fall back to standard kubesafe completion
+    __start_kubesafe
+}
+
+complete -o default -F _kubesafe_wrapper kubesafe
+`
+
+const fishCompletionWrapper = `
+# Function to check if we're completing after a wrapped command
+function __kubesafe_using_wrapped_command
+    set -l cmd (commandline -opc)
+    test (count $cmd) -gt 1
+end
+
+# Function to get completions from the wrapped command
+function __kubesafe_complete_wrapped
+    set -l cmd (commandline -opc)
+    if test (count $cmd) -gt 1
+        # Get the wrapped command (second word after kubesafe)
+        set -l wrapped_cmd $cmd[2]
+        # Build the command line as if it started with the wrapped command
+        set -l wrapped_args $cmd[2..-1]
+        # Get the current token being completed
+        set -l current_token (commandline -ct)
+        # Build the fake command line for completion
+        set -l fake_cmdline (string join ' ' $wrapped_args)
+        if test -n "$current_token"
+            set fake_cmdline "$fake_cmdline"
+        end
+        # Get completions from the wrapped command
+        complete -C "$fake_cmdline"
+    end
+end
+
+# Register completion that delegates to wrapped command when appropriate
+complete -c kubesafe -n '__kubesafe_using_wrapped_command' -a '(__kubesafe_complete_wrapped)' -f
+`
+
+func genZshCompletionWithWrapper(cmd *cobra.Command, w io.Writer) error {
+	buf := new(bytes.Buffer)
+	if err := cmd.Root().GenZshCompletion(buf); err != nil {
+		return err
+	}
+	if _, err := w.Write(buf.Bytes()); err != nil {
+		return err
+	}
+	_, err := w.Write([]byte(zshCompletionWrapper))
+	return err
+}
+
+func genBashCompletionWithWrapper(cmd *cobra.Command, w io.Writer) error {
+	buf := new(bytes.Buffer)
+	if err := cmd.Root().GenBashCompletionV2(buf, true); err != nil {
+		return err
+	}
+	if _, err := w.Write(buf.Bytes()); err != nil {
+		return err
+	}
+	_, err := w.Write([]byte(bashCompletionWrapper))
+	return err
+}
+
+func genFishCompletionWithWrapper(cmd *cobra.Command, w io.Writer) error {
+	buf := new(bytes.Buffer)
+	if err := cmd.Root().GenFishCompletion(buf, true); err != nil {
+		return err
+	}
+	if _, err := w.Write(buf.Bytes()); err != nil {
+		return err
+	}
+	_, err := w.Write([]byte(fishCompletionWrapper))
+	return err
+}
+
+func NewCompletionCmd() *cobra.Command {
+	completionCmd := &cobra.Command{
+		Use:   "completion [bash|zsh|fish]",
+		Short: "Generate shell completion scripts",
+		Long: `Generate shell completion scripts for kubesafe.
+
+The generated scripts include support for completing wrapped commands
+when used through kubesafe (e.g., "kubesafe kubectl get <TAB>").
+Completions are delegated to the wrapped command's completion function
+if available.
+
+To load completions:
+
+Bash:
+  $ source <(kubesafe completion bash)
+
+  # To load completions for each session, execute once:
+  # Linux:
+  $ kubesafe completion bash > /etc/bash_completion.d/kubesafe
+  # macOS:
+  $ kubesafe completion bash > $(brew --prefix)/etc/bash_completion.d/kubesafe
+
+  # Note: wrapped command completions must be loaded for delegation to work:
+  $ source <(kubectl completion bash)
+
+Zsh:
+  # If shell completion is not already enabled in your environment,
+  # you will need to enable it. You can execute the following once:
+  $ echo "autoload -U compinit; compinit" >> ~/.zshrc
+
+  # To load completions for each session, add to ~/.zshrc:
+  $ source <(kubesafe completion zsh)
+
+  # Note: wrapped command completions must be loaded for delegation to work:
+  $ source <(kubectl completion zsh)
+
+  # You will need to start a new shell for this setup to take effect.
+
+Fish:
+  $ kubesafe completion fish | source
+
+  # To load completions for each session, execute once:
+  $ kubesafe completion fish > ~/.config/fish/completions/kubesafe.fish
+
+  # Note: wrapped command completions should also be loaded:
+  $ kubectl completion fish | source
+`,
+		DisableFlagsInUseLine: true,
+		ValidArgs:             []string{"bash", "zsh", "fish"},
+		Args:                  cobra.ExactArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			switch args[0] {
+			case "bash":
+				return genBashCompletionWithWrapper(cmd, os.Stdout)
+			case "zsh":
+				return genZshCompletionWithWrapper(cmd, os.Stdout)
+			case "fish":
+				return genFishCompletionWithWrapper(cmd, os.Stdout)
+			}
+			return nil
+		},
+	}
+	return completionCmd
+}