From 9b69228ffcef62099e4a541c3a3c11e9a2341c89 Mon Sep 17 00:00:00 2001
From: knrt10 <kautilya@kinvolk.io>
Date: Fri, 28 Aug 2020 17:37:59 +0530
Subject: [PATCH] Add autocomplete for bash and zsh in lokoctl

Fixes #18

Signed-off-by: knrt10 <kautilya@kinvolk.io>
---
 cli/cmd/completion.go               | 288 ++++++++++++++++++++++++++++
 cli/cmd/component-apply.go          |   7 +
 cli/cmd/component-delete.go         |   7 +
 docs/cli/lokoctl.md                 |   1 +
 docs/cli/lokoctl_completion.md      |  49 +++++
 docs/cli/lokoctl_completion_bash.md |  52 +++++
 docs/cli/lokoctl_completion_zsh.md  |  45 +++++
 7 files changed, 449 insertions(+)
 create mode 100644 cli/cmd/completion.go
 create mode 100644 docs/cli/lokoctl_completion.md
 create mode 100644 docs/cli/lokoctl_completion_bash.md
 create mode 100644 docs/cli/lokoctl_completion_zsh.md

diff --git a/cli/cmd/completion.go b/cli/cmd/completion.go
new file mode 100644
index 000000000..73c3f7f14
--- /dev/null
+++ b/cli/cmd/completion.go
@@ -0,0 +1,288 @@
+// Copyright 2020 The Lokomotive Authors
+//
+// 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 (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+const completionDesc = `  Generate the completion code for lokoctl for the specified shell (Bash or zsh).
+`
+
+const completionExample = `  # Load the lokoctl completion code for Bash into the current shell.
+  source <(lokoctl completion bash)
+
+  # Load the lokoctl completion code for zsh into the current shell.
+  source <(lokoctl completion zsh)
+
+  # Generate a Bash completion file and load it for every shell.
+  lokoctl completion bash > ~/.bash_lokoctl_completion
+  echo "source ~/.bash_lokoctl_completion" >> ~/.bashrc && source ~/.bashrc
+
+  # Set the lokoctl completion code for zsh to autoload on startup.
+  lokoctl completion zsh > "${fpath[1]}/_lokoctl" && exec $SHELL`
+
+const bashCompDesc = `  Generate the completion code for lokoctl for the Bash shell.
+`
+
+const bashExample = `  # If running Bash 3.2 that is included with macOS, install Bash completion using Homebrew.
+  brew install bash-completion
+	
+  # If running Bash 4.1+ on macOS, install Bash completion using homebrew.
+  brew install bash-completion@2
+
+  # Load the lokoctl completion code for Bash into the current shell.
+  source <(lokoctl completion bash)
+
+  # Generate a Bash completion file and load it for every shell.
+  lokoctl completion bash > ~/.bash_lokoctl_completion
+  echo "source ~/.bash_lokoctl_completion" >> ~/.bashrc && source ~/.bashrc
+`
+
+const zshCompDesc = `  Generate the completion code for lokoctl for the zsh shell.
+`
+
+const zshExample = `  # Load the lokoctl completion code for zsh into the current shell.
+  source <(lokoctl completion zsh)
+
+  # Set the lokoctl completion code for zsh to autoload on startup.
+  lokoctl completion zsh > "${fpath[1]}/_lokoctl" && exec $SHELL
+`
+
+const zshInitialization = `#compdef lokoctl
+__lokoctl_bash_source() {
+	alias shopt=':'
+	alias _expand=_bash_expand
+	alias _complete=_bash_comp
+	emulate -L sh
+	setopt kshglob noshglob braceexpand
+	source "$@"
+}
+__lokoctl_type() {
+	# -t is not supported by zsh.
+	if [ "$1" == "-t" ]; then
+		shift
+		# Fake Bash 4 to disable "complete -o nospace". Instead
+		# "compopt +-o nospace" is used in the code to toggle trailing
+		# spaces. We don't support that, but leave trailing spaces on
+		# all the time.
+		if [ "$1" = "__lokoctl_compopt" ]; then
+			echo builtin
+			return 0
+		fi
+	fi
+	type "$@"
+}
+__lokoctl_compgen() {
+	local completions w
+	completions=( $(compgen "$@") ) || return $?
+	# Filter by given word as prefix.
+	while [[ "$1" = -* && "$1" != -- ]]; do
+		shift
+		shift
+	done
+	if [[ "$1" == -- ]]; then
+		shift
+	fi
+	for w in "${completions[@]}"; do
+		if [[ "${w}" = "$1"* ]]; then
+			# Use printf instead of echo because it is possible that
+			# the value to print is -n, which would be interpreted
+			# as a flag to echo.
+			printf "%s\n" "${w}"
+		fi
+	done
+}
+__lokoctl_compopt() {
+	true # Don't do anything. Not supported by bashcompinit in zsh.
+}
+__lokoctl_ltrim_colon_completions()
+{
+	if [[ "$1" == *:* && "$COMP_WORDBREAKS" == *:* ]]; then
+		# Remove colon-word prefix from COMPREPLY items.
+		local colon_word=${1%${1##*:}}
+		local i=${#COMPREPLY[*]}
+		while [[ $((--i)) -ge 0 ]]; do
+			COMPREPLY[$i]=${COMPREPLY[$i]#"$colon_word"}
+		done
+	fi
+}
+__lokoctl_get_comp_words_by_ref() {
+	cur="${COMP_WORDS[COMP_CWORD]}"
+	prev="${COMP_WORDS[${COMP_CWORD}-1]}"
+	words=("${COMP_WORDS[@]}")
+	cword=("${COMP_CWORD[@]}")
+}
+__lokoctl_filedir() {
+	local RET OLD_IFS w qw
+	__debug "_filedir $@ cur=$cur"
+	if [[ "$1" = \~* ]]; then
+		# Somehow does not work. Maybe, zsh does not call this at all.
+		eval echo "$1"
+		return 0
+	fi
+	OLD_IFS="$IFS"
+	IFS=$'\n'
+	if [ "$1" = "-d" ]; then
+		shift
+		RET=( $(compgen -d) )
+	else
+		RET=( $(compgen -f) )
+	fi
+	IFS="$OLD_IFS"
+	IFS="," __debug "RET=${RET[@]} len=${#RET[@]}"
+	for w in ${RET[@]}; do
+		if [[ ! "${w}" = "${cur}"* ]]; then
+			continue
+		fi
+		if eval "[[ \"\${w}\" = *.$1 || -d \"\${w}\" ]]"; then
+			qw="$(__lokoctl_quote "${w}")"
+			if [ -d "${w}" ]; then
+				COMPREPLY+=("${qw}/")
+			else
+				COMPREPLY+=("${qw}")
+			fi
+		fi
+	done
+}
+__lokoctl_quote() {
+	if [[ $1 == \'* || $1 == \"* ]]; then
+		# Leave out first character.
+		printf %q "${1:1}"
+	else
+		printf %q "$1"
+	fi
+}
+autoload -U +X bashcompinit && bashcompinit
+# Use word boundary patterns for BSD or GNU sed.
+LWORD='[[:<:]]'
+RWORD='[[:>:]]'
+if sed --help 2>&1 | grep -q 'GNU\|BusyBox'; then
+	LWORD='\<'
+	RWORD='\>'
+fi
+__lokoctl_convert_bash_to_zsh() {
+	sed \
+	-e 's/declare -F/whence -w/' \
+	-e 's/_get_comp_words_by_ref "\$@"/_get_comp_words_by_ref "\$*"/' \
+	-e 's/local \([a-zA-Z0-9_]*\)=/local \1; \1=/' \
+	-e 's/flags+=("\(--.*\)=")/flags+=("\1"); two_word_flags+=("\1")/' \
+	-e 's/must_have_one_flag+=("\(--.*\)=")/must_have_one_flag+=("\1")/' \
+	-e "s/${LWORD}_filedir${RWORD}/__lokoctl_filedir/g" \
+	-e "s/${LWORD}_get_comp_words_by_ref${RWORD}/__lokoctl_get_comp_words_by_ref/g" \
+	-e "s/${LWORD}__ltrim_colon_completions${RWORD}/__lokoctl_ltrim_colon_completions/g" \
+	-e "s/${LWORD}compgen${RWORD}/__lokoctl_compgen/g" \
+	-e "s/${LWORD}compopt${RWORD}/__lokoctl_compopt/g" \
+	-e "s/${LWORD}declare${RWORD}/builtin declare/g" \
+	-e "s/\\\$(type${RWORD}/\$(__lokoctl_type/g" \
+	-e 's/aliashash\["\(.\{1,\}\)"\]/aliashash[\1]/g' \
+	-e 's/FUNCNAME/funcstack/g' \
+	<<'BASH_COMPLETION_EOF'
+`
+
+const zshTail = `
+BASH_COMPLETION_EOF
+}
+__lokoctl_bash_source <(__lokoctl_convert_bash_to_zsh)
+`
+
+func newCompletionCmd(out io.Writer) *cobra.Command {
+	cmd := &cobra.Command{
+		Use:               "completion",
+		Short:             "Generate the completion code for the specified shell",
+		Long:              completionDesc,
+		Example:           completionExample,
+		Args:              noArgs,
+		ValidArgsFunction: noCompletions, // Disable file completion.
+	}
+
+	bash := &cobra.Command{
+		Use:                   "bash",
+		Short:                 "Generate the completion code for Bash",
+		Long:                  bashCompDesc,
+		Example:               bashExample,
+		Args:                  noArgs,
+		DisableFlagsInUseLine: true,
+		ValidArgsFunction:     noCompletions,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return runCompletionBash(out, cmd)
+		},
+	}
+
+	zsh := &cobra.Command{
+		Use:                   "zsh",
+		Short:                 "Generate the completion code for zsh",
+		Long:                  zshCompDesc,
+		Example:               zshExample,
+		Args:                  noArgs,
+		DisableFlagsInUseLine: true,
+		ValidArgsFunction:     noCompletions,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return runCompletionZsh(out, cmd)
+		},
+	}
+
+	cmd.AddCommand(bash, zsh)
+
+	return cmd
+}
+
+func runCompletionBash(out io.Writer, cmd *cobra.Command) error {
+	return cmd.Root().GenBashCompletion(out)
+}
+
+func runCompletionZsh(out io.Writer, cmd *cobra.Command) error {
+	// TODO: Change the whole process to GenZshCompletion once
+	// cobra releases their new updates.
+	if _, err := out.Write([]byte(zshInitialization)); err != nil {
+		return fmt.Errorf("writing zsh initialization: %w", err)
+	}
+
+	if err := runCompletionBash(out, cmd); err != nil {
+		return fmt.Errorf("running Bash completion: %w", err)
+	}
+
+	if _, err := out.Write([]byte(zshTail)); err != nil {
+		return fmt.Errorf("writing zsh tail: %w", err)
+	}
+
+	return nil
+}
+
+// noCompletions is used to disable file completion.
+func noCompletions(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+	return nil, cobra.ShellCompDirectiveNoFileComp
+}
+
+// noArgs returns an error if any args are included.
+func noArgs(cmd *cobra.Command, args []string) error {
+	if len(args) > 0 {
+		return fmt.Errorf(
+			"%q accepts no arguments\n\nUsage:  %s",
+			cmd.CommandPath(),
+			cmd.UseLine(),
+		)
+	}
+
+	return nil
+}
+
+func init() { //nolint:gochecknoinits
+	RootCmd.AddCommand(newCompletionCmd(os.Stdout))
+}
diff --git a/cli/cmd/component-apply.go b/cli/cmd/component-apply.go
index fb80a4f39..21faf71bf 100644
--- a/cli/cmd/component-apply.go
+++ b/cli/cmd/component-apply.go
@@ -32,6 +32,13 @@ var componentApplyCmd = &cobra.Command{
 Deploys a component if not yet present, otherwise updates it.
 When run with no arguments, all components listed in the configuration are applied.`,
 	Run: runApply,
+	ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		if len(args) != 0 {
+			return nil, cobra.ShellCompDirectiveNoFileComp
+		}
+
+		return components.ListNames(), cobra.ShellCompDirectiveNoFileComp
+	},
 }
 
 func init() {
diff --git a/cli/cmd/component-delete.go b/cli/cmd/component-delete.go
index ab1fe0ebb..240a64be0 100644
--- a/cli/cmd/component-delete.go
+++ b/cli/cmd/component-delete.go
@@ -31,6 +31,13 @@ var componentDeleteCmd = &cobra.Command{
 	Long: `Delete a component.
 When run with no arguments, all components listed in the configuration are deleted.`,
 	Run: runDelete,
+	ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		if len(args) != 0 {
+			return nil, cobra.ShellCompDirectiveNoFileComp
+		}
+
+		return components.ListNames(), cobra.ShellCompDirectiveNoFileComp
+	},
 }
 
 var deleteNamespace bool
diff --git a/docs/cli/lokoctl.md b/docs/cli/lokoctl.md
index 0c9af9377..7fc885ff6 100644
--- a/docs/cli/lokoctl.md
+++ b/docs/cli/lokoctl.md
@@ -21,6 +21,7 @@ Manage Lokomotive clusters
 ### SEE ALSO
 
 * [lokoctl cluster](lokoctl_cluster.md)	 - Manage a cluster
+* [lokoctl completion](lokoctl_completion.md)	 - Generate the completion code for the specified shell
 * [lokoctl component](lokoctl_component.md)	 - Manage components
 * [lokoctl health](lokoctl_health.md)	 - Get the health of a cluster
 * [lokoctl version](lokoctl_version.md)	 - Print version information
diff --git a/docs/cli/lokoctl_completion.md b/docs/cli/lokoctl_completion.md
new file mode 100644
index 000000000..194ab2f48
--- /dev/null
+++ b/docs/cli/lokoctl_completion.md
@@ -0,0 +1,49 @@
+## lokoctl completion
+
+Generate the completion code for the specified shell
+
+### Synopsis
+
+  Generate the completion code for lokoctl for the specified shell (Bash or zsh).
+
+
+### Examples
+
+```
+  # Load the lokoctl completion code for Bash into the current shell.
+  source <(lokoctl completion bash)
+
+  # Load the lokoctl completion code for zsh into the current shell.
+  source <(lokoctl completion zsh)
+
+  # Generate a Bash completion file and load it for every shell.
+  lokoctl completion bash > ~/.bash_lokoctl_completion
+  echo "source ~/.bash_lokoctl_completion" >> ~/.bashrc && source ~/.bashrc
+
+  # Set the lokoctl completion code for zsh to autoload on startup.
+  lokoctl completion zsh > "${fpath[1]}/_lokoctl" && exec $SHELL
+```
+
+### Options
+
+```
+  -h, --help   help for completion
+```
+
+### Options inherited from parent commands
+
+```
+      --kubeconfig-file string   Path to a kubeconfig file. If empty, the following precedence order is used:
+                                   1. Cluster asset dir when a lokocfg file is present in the current directory.
+                                   2. KUBECONFIG environment variable.
+                                   3. ~/.kube/config file.
+      --lokocfg string           Path to lokocfg directory or file (default "./")
+      --lokocfg-vars string      Path to lokocfg.vars file (default "./lokocfg.vars")
+```
+
+### SEE ALSO
+
+* [lokoctl](lokoctl.md)	 - Manage Lokomotive clusters
+* [lokoctl completion bash](lokoctl_completion_bash.md)	 - Generate the completion code for Bash
+* [lokoctl completion zsh](lokoctl_completion_zsh.md)	 - Generate the completion code for zsh
+
diff --git a/docs/cli/lokoctl_completion_bash.md b/docs/cli/lokoctl_completion_bash.md
new file mode 100644
index 000000000..73fdd99bc
--- /dev/null
+++ b/docs/cli/lokoctl_completion_bash.md
@@ -0,0 +1,52 @@
+## lokoctl completion bash
+
+Generate the completion code for Bash
+
+### Synopsis
+
+  Generate the completion code for lokoctl for the Bash shell.
+
+
+```
+lokoctl completion bash
+```
+
+### Examples
+
+```
+  # If running Bash 3.2 that is included with macOS, install Bash completion using Homebrew.
+  brew install bash-completion
+	
+  # If running Bash 4.1+ on macOS, install Bash completion using homebrew.
+  brew install bash-completion@2
+
+  # Load the lokoctl completion code for Bash into the current shell.
+  source <(lokoctl completion bash)
+
+  # Generate a Bash completion file and load it for every shell.
+  lokoctl completion bash > ~/.bash_lokoctl_completion
+  echo "source ~/.bash_lokoctl_completion" >> ~/.bashrc && source ~/.bashrc
+
+```
+
+### Options
+
+```
+  -h, --help   help for bash
+```
+
+### Options inherited from parent commands
+
+```
+      --kubeconfig-file string   Path to a kubeconfig file. If empty, the following precedence order is used:
+                                   1. Cluster asset dir when a lokocfg file is present in the current directory.
+                                   2. KUBECONFIG environment variable.
+                                   3. ~/.kube/config file.
+      --lokocfg string           Path to lokocfg directory or file (default "./")
+      --lokocfg-vars string      Path to lokocfg.vars file (default "./lokocfg.vars")
+```
+
+### SEE ALSO
+
+* [lokoctl completion](lokoctl_completion.md)	 - Generate the completion code for the specified shell
+
diff --git a/docs/cli/lokoctl_completion_zsh.md b/docs/cli/lokoctl_completion_zsh.md
new file mode 100644
index 000000000..22e5b3972
--- /dev/null
+++ b/docs/cli/lokoctl_completion_zsh.md
@@ -0,0 +1,45 @@
+## lokoctl completion zsh
+
+Generate the completion code for zsh
+
+### Synopsis
+
+  Generate the completion code for lokoctl for the zsh shell.
+
+
+```
+lokoctl completion zsh
+```
+
+### Examples
+
+```
+  # Load the lokoctl completion code for zsh into the current shell.
+  source <(lokoctl completion zsh)
+
+  # Set the lokoctl completion code for zsh to autoload on startup.
+  lokoctl completion zsh > "${fpath[1]}/_lokoctl" && exec $SHELL
+
+```
+
+### Options
+
+```
+  -h, --help   help for zsh
+```
+
+### Options inherited from parent commands
+
+```
+      --kubeconfig-file string   Path to a kubeconfig file. If empty, the following precedence order is used:
+                                   1. Cluster asset dir when a lokocfg file is present in the current directory.
+                                   2. KUBECONFIG environment variable.
+                                   3. ~/.kube/config file.
+      --lokocfg string           Path to lokocfg directory or file (default "./")
+      --lokocfg-vars string      Path to lokocfg.vars file (default "./lokocfg.vars")
+```
+
+### SEE ALSO
+
+* [lokoctl completion](lokoctl_completion.md)	 - Generate the completion code for the specified shell
+