From c564903a2cbae0a625803d1b11d95f295f918b08 Mon Sep 17 00:00:00 2001
From: spolisar <22416070+spolisar@users.noreply.github.com>
Date: Tue, 9 Jun 2026 16:48:16 -0400
Subject: [PATCH] feat: add completion shell script generation for bash, zsh,
 and fish

---
 cmd/codecrafters/main.go         |   8 ++
 internal/commands/completions.go | 230 +++++++++++++++++++++++++++++++
 2 files changed, 238 insertions(+)
 create mode 100644 internal/commands/completions.go

diff --git a/cmd/codecrafters/main.go b/cmd/codecrafters/main.go
index a95f447..8a07dbe 100644
--- a/cmd/codecrafters/main.go
+++ b/cmd/codecrafters/main.go
@@ -28,6 +28,7 @@ EXAMPLES
   $ codecrafters submit -m "msg"   # Commit changes & run tests with a custom commit message
   $ codecrafters test              # Run tests without committing changes
   $ codecrafters test --previous   # Run tests for all previous stages and the current stage without committing changes
+  $ codecrafters completion zsh    # Generate shell completions for zsh
 
 COMMANDS
   submit:           Commit changes & run tests
@@ -35,6 +36,7 @@ COMMANDS
   task:             View current stage instructions
   update-buildpack: Update language version
   ping:             Test the connection to a CodeCrafters repository
+  completion:       Generate shell completions for bash, zsh, or fish
   help:             Show usage instructions
 
 VERSION
@@ -111,6 +113,12 @@ func run() error {
 		return commands.UpdateBuildpackCommand()
 	case "ping":
 		return commands.PingCommand()
+	case "completion":
+		if flag.NArg() != 2 {
+			fmt.Print(commands.CompletionUsage())
+			return nil
+		}
+		return commands.CompletionCommand(flag.Arg(1))
 	case "help",
 		"": // no argument
 		flag.Usage()
diff --git a/internal/commands/completions.go b/internal/commands/completions.go
new file mode 100644
index 0000000..42efcfc
--- /dev/null
+++ b/internal/commands/completions.go
@@ -0,0 +1,230 @@
+package commands
+
+import (
+	"fmt"
+	"strings"
+)
+
+const (
+	ShellBash = "bash"
+	ShellZsh  = "zsh"
+	ShellFish = "fish"
+)
+
+func CompletionCommand(shell string) (err error) {
+	var completionScript string
+	switch shell {
+	case ShellBash:
+		completionScript = bashCompletion
+	case ShellZsh:
+		completionScript = zshCompletion
+	case ShellFish:
+		completionScript = fishCompletion
+	case "-help":
+		fallthrough
+	case "--help":
+		fmt.Print(CompletionUsage())
+		return nil
+	default:
+		return fmt.Errorf("unsupported shell %q; supported shells: %s", shell, strings.Join(supportedShells, ", "))
+	}
+	fmt.Print(completionScript)
+
+	return nil
+}
+
+var supportedShells = []string{ShellBash, ShellZsh, ShellFish}
+
+func CompletionUsage() string {
+	return fmt.Sprintf(`Generate shell completions for codecrafters.
+
+USAGE
+  $ codecrafters completion <%s>
+
+INSTALL
+  Bash:
+    $ mkdir -p ~/.local/share/bash-completion/completions
+    $ codecrafters completion bash > ~/.local/share/bash-completion/completions/codecrafters
+    $ echo "source ~/.local/share/bash-completion/completions/codecrafters" >> ~/.bashrc
+
+  Zsh:
+    $ mkdir -p ~/.zsh/completions/
+    $ codecrafters completion zsh > ~/.zsh/completions/_codecrafters
+    $ echo "fpath=(~/.zsh/completions $fpath)" >> ~/.zshrc
+    $ echo "autoload -Uz compinit && compinit" >> ~/.zshrc
+
+  Fish:
+    $ codecrafters completion fish > ~/.config/fish/completions/codecrafters.fish
+`, strings.Join(supportedShells, "|"))
+}
+
+const bashCompletion = `# bash completion for codecrafters
+
+_codecrafters()
+{
+	local cur prev words cword command
+	COMPREPLY=()
+
+	if declare -F _init_completion >/dev/null 2>&1; then
+		_init_completion || return
+	else
+		cur="${COMP_WORDS[COMP_CWORD]}"
+		prev="${COMP_WORDS[COMP_CWORD-1]}"
+		words=("${COMP_WORDS[@]}")
+		cword=$COMP_CWORD
+	fi
+
+	local commands="submit test task update-buildpack ping completion help"
+	local global_flags="--help --version"
+	local shells="bash zsh fish"
+
+	command=""
+	for word in "${words[@]:1:cword-1}"; do
+		case "$word" in
+			submit|test|task|update-buildpack|ping|completion|help)
+				command="$word"
+				break
+				;;
+		esac
+	done
+
+	case "$prev" in
+		-m|--message|--stage|bash|zsh|fish)
+			return 0
+			;;
+	esac
+
+	if [[ -z "$command" ]]; then
+		if [[ "$cur" == -* ]]; then
+			COMPREPLY=( $(compgen -W "$global_flags" -- "$cur") )
+		else
+			COMPREPLY=( $(compgen -W "$commands" -- "$cur") )
+		fi
+		return 0
+	fi
+
+	case "$command" in
+		submit)
+			COMPREPLY=( $(compgen -W "-m --message --help" -- "$cur") )
+			;;
+		test)
+			COMPREPLY=( $(compgen -W "--previous --help" -- "$cur") )
+			;;
+		task)
+			COMPREPLY=( $(compgen -W "--stage --raw --help" -- "$cur") )
+			;;
+		completion)
+			COMPREPLY=( $(compgen -W "$shells" -- "$cur") )
+			;;
+	esac
+}
+
+complete -F _codecrafters codecrafters
+`
+
+const zshCompletion = `#compdef codecrafters
+
+_codecrafters() {
+	local -a commands global_flags submit_flags test_flags test_previous_flag task_flags no_arg_command_flags shells
+
+	commands=(
+		'submit:Commit changes and run tests'
+		'test:Run tests without committing changes'
+		'task:View current stage instructions'
+		'update-buildpack:Update language version'
+		'ping:Test the connection to a CodeCrafters repository'
+		'completion:Generate shell completion script'
+		'help:Show usage instructions'
+	)
+	global_flags=(
+		'--help:show usage instructions'
+		'--version:print version and exit'
+	)
+
+	submit_flags=(
+		'-m:Commit changes and run tests with a custom commit message'
+		'--message:Commit changes and run tests with a custom commit message'
+		'--help:show usage instructions'
+		'-help:show usage instructions'
+	)
+	test_flags=(
+		'--help:show usage instructions'
+		'-help:show usage instructions'
+	)
+	task_flags=(
+		'--stage:view instructions for a specific stage (slug, +N, or -N)'
+		'--raw:print instructions without pretty-printing'
+		'--help:show usage instructions'
+		'-help:show usage instructions'
+	)
+	no_arg_command_flags=(
+		'--help'
+		'-help'
+	)
+	shells=(bash zsh fish)
+
+	if (( CURRENT == 2 )); then
+		if [[ "${words[CURRENT]}" == -* ]]; then
+			_describe -t options 'codecrafters option' global_flags
+			return
+		fi
+
+		_describe -t commands 'codecrafters command' commands
+		return
+	fi
+
+
+	case "${words[2]}" in
+		submit)
+			if [[ "${words[(Ie)-m]}" -ne 0 || "${words[(Ie)--message]}" -ne 0 || "${words[(Ie)-help]}" -ne 0 || "${words[(Ie)--help]}" -ne 0 ]]; then
+				return
+			fi
+			_describe -t options 'submit option' submit_flags
+			;;
+		test)
+			if [[ "${words[(Ie)--previous]}" -ne 0 || "${words[(Ie)-help]}" -ne 0 || "${words[(Ie)--help]}" -ne 0 ]]; then
+				return
+			fi
+			_describe -t options 'test option' test_flags
+			;;
+		task)
+			_describe -t options 'task option' task_flags
+			;;
+		update-buildpack|ping|help)
+			return
+			;;
+		completion)
+			if [[ "${words[(Ie)bash]}" -ne 0 || "${words[(Ie)zsh]}" -ne 0 || "${words[(Ie)fish]}" -ne 0 ]]; then
+				return
+			fi
+
+			if [[ "${words[CURRENT]}" == -* ]]; then
+				_describe -t options 'completion option' no_arg_command_flags
+			else
+				_describe -t shells 'shell' shells
+			fi
+			;;
+	esac
+}
+
+compdef _codecrafters codecrafters
+`
+
+const fishCompletion = `# fish completion for codecrafters
+
+complete -c codecrafters -f
+complete -c codecrafters -n __fish_use_subcommand -a submit -d 'Commit changes and run tests'
+complete -c codecrafters -n __fish_use_subcommand -a test -d 'Run tests without committing changes'
+complete -c codecrafters -n __fish_use_subcommand -a task -d 'View current stage instructions'
+complete -c codecrafters -n __fish_use_subcommand -a update-buildpack -d 'Update language version'
+complete -c codecrafters -n __fish_use_subcommand -a ping -d 'Test the connection to a CodeCrafters repository'
+complete -c codecrafters -n __fish_use_subcommand -a completion -d 'Generate shell completion script'
+complete -c codecrafters -n __fish_use_subcommand -a help -d 'Show usage instructions'
+complete -c codecrafters -n __fish_use_subcommand -l help -d 'show usage instructions'
+complete -c codecrafters -n __fish_use_subcommand -l version -d 'print version and exit'
+complete -c codecrafters -n '__fish_seen_subcommand_from submit' -s m -l message -r -d 'Commit changes and run tests with a custom commit message'
+complete -c codecrafters -n '__fish_seen_subcommand_from test; and not __fish_seen_argument -l previous' -l previous -d 'Run tests for all previous stages and the current stage without committing changes'
+complete -c codecrafters -n '__fish_seen_subcommand_from task' -l stage -r -d 'view instructions for a specific stage (slug, +N, or -N)'
+complete -c codecrafters -n '__fish_seen_subcommand_from task' -l raw -d 'print instructions without pretty-printing'
+complete -c codecrafters -n '__fish_seen_subcommand_from completion; and not __fish_seen_argument -a bash zsh fish' -a 'bash zsh fish'
+`