feat(comp): Bring in Cobra's bash script with desc

This is the bash completion that has been proposed for Cobra in
spf13/cobra#1146

Signed-off-by: Marc Khouzam <marc.khouzam@montreal.ca>

cmd/helm/completion.go

@@ -152,7 +152,7 @@ func newCompletionCmd(out io.Writer) *cobra.Command {
 }
 
 func runCompletionBash(out io.Writer, cmd *cobra.Command) error {
-	err := cmd.Root().GenBashCompletionV2(out, !disableCompDescriptions)
+	err := completion.GenBashCompletion(out, !disableCompDescriptions)
 
 	// In case the user renamed the helm binary (e.g., to be able to run
 	// both helm2 and helm3), we hook the new binary name to the completion function

internal/completion/bash_completions.go

@@ -0,0 +1,286 @@
+package completion
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+
+	"github.com/spf13/cobra"
+)
+
+// GenBashCompletion generates the bash completion script
+func GenBashCompletion(w io.Writer, includeDesc bool) error {
+	compCmd := cobra.ShellCompRequestCmd
+	if !includeDesc {
+		compCmd = cobra.ShellCompNoDescRequestCmd
+	}
+	buf := new(bytes.Buffer)
+	buf.WriteString(fmt.Sprintf(`# Helm's own bash completion
+
+__helm_debug()
+{
+    if [[ -n ${BASH_COMP_DEBUG_FILE:-} ]]; then
+        echo "$*" >> "${BASH_COMP_DEBUG_FILE}"
+    fi
+}
+
+# Macs have bash3 for which the bash-completion package doesn't include
+# _init_completion. This is a minimal version of that function.
+__helm_init_completion()
+{
+    COMPREPLY=()
+    _get_comp_words_by_ref "$@" cur prev words cword
+}
+
+# This function calls the helm program to obtain the completion
+# results and the directive.  It fills the 'out' and 'directive' vars.
+__helm_get_completion_results() {
+    local requestComp lastParam lastChar args
+
+    # Prepare the command to request completions for the program.
+    # Calling ${words[0]} instead of directly helm allows to handle aliases
+    args=("${words[@]:1}")
+    requestComp="${words[0]} %[1]s ${args[*]}"
+
+    lastParam=${words[$((${#words[@]}-1))]}
+    lastChar=${lastParam:$((${#lastParam}-1)):1}
+    __helm_debug "lastParam ${lastParam}, lastChar ${lastChar}"
+
+    if [ -z "${cur}" ] && [ "${lastChar}" != "=" ]; then
+        # If the last parameter is complete (there is a space following it)
+        # We add an extra empty parameter so we can indicate this to the go method.
+        __helm_debug "Adding extra empty parameter"
+        requestComp="${requestComp} ''"
+    fi
+
+    # When completing a flag with an = (e.g., helm -n=<TAB>)
+    # bash focuses on the part after the =, so we need to remove
+    # the flag part from $cur
+    if [[ "${cur}" == -*=* ]]; then
+        cur="${cur#*=}"
+    fi
+
+    __helm_debug "Calling ${requestComp}"
+    # Use eval to handle any environment variables and such
+    out=$(eval "${requestComp}" 2>/dev/null)
+
+    # Extract the directive integer at the very end of the output following a colon (:)
+    directive=${out##*:}
+    # Remove the directive
+    out=${out%%:*}
+    if [ "${directive}" = "${out}" ]; then
+        # There is not directive specified
+        directive=0
+    fi
+    __helm_debug "The completion directive is: ${directive}"
+    __helm_debug "The completions are: ${out[*]}"
+}
+
+__helm_process_completion_results() {
+    local shellCompDirectiveError=%[2]d
+    local shellCompDirectiveNoSpace=%[3]d
+    local shellCompDirectiveNoFileComp=%[4]d
+    local shellCompDirectiveFilterFileExt=%[5]d
+    local shellCompDirectiveFilterDirs=%[6]d
+
+    if [ $((directive & shellCompDirectiveError)) -ne 0 ]; then
+        # Error code.  No completion.
+        __helm_debug "Received error from custom completion go code"
+        return
+    else
+        if [ $((directive & shellCompDirectiveNoSpace)) -ne 0 ]; then
+            if [[ $(type -t compopt) = "builtin" ]]; then
+                __helm_debug "Activating no space"
+                compopt -o nospace
+            else
+                __helm_debug "No space directive not supported in this version of bash"
+            fi
+        fi
+        if [ $((directive & shellCompDirectiveNoFileComp)) -ne 0 ]; then
+            if [[ $(type -t compopt) = "builtin" ]]; then
+                __helm_debug "Activating no file completion"
+                compopt +o default
+            else
+                __helm_debug "No file completion directive not supported in this version of bash"
+            fi
+        fi
+    fi
+
+    if [ $((directive & shellCompDirectiveFilterFileExt)) -ne 0 ]; then
+        # File extension filtering
+        local fullFilter filter filteringCmd
+
+        # Do not use quotes around the $out variable or else newline
+        # characters will be kept.
+        for filter in ${out[*]}; do
+            fullFilter+="$filter|"
+        done
+
+        filteringCmd="_filedir $fullFilter"
+        __helm_debug "File filtering command: $filteringCmd"
+        $filteringCmd
+    elif [ $((directive & shellCompDirectiveFilterDirs)) -ne 0 ]; then
+        # File completion for directories only
+
+        # Use printf to strip any trailing newline
+        local subdir
+        subdir=$(printf "%%s" "${out[0]}")
+        if [ -n "$subdir" ]; then
+            __helm_debug "Listing directories in $subdir"
+            pushd "$subdir" >/dev/null 2>&1 && _filedir -d && popd >/dev/null 2>&1 || return
+        else
+            __helm_debug "Listing directories in ."
+            _filedir -d
+        fi
+    else
+        __helm_handle_standard_completion_case
+    fi
+
+    __helm_handle_special_char "$cur" :
+    __helm_handle_special_char "$cur" =
+}
+
+__helm_handle_standard_completion_case() {
+    local tab comp
+    tab=$(printf '\t')
+
+    local longest=0
+    # Look for the longest completion so that we can format things nicely
+    while IFS='' read -r comp; do
+        # Strip any description before checking the length
+        comp=${comp%%%%$tab*}
+        # Only consider the completions that match
+        comp=$(compgen -W "$comp" -- "$cur")
+        if ((${#comp}>longest)); then
+            longest=${#comp}
+        fi
+    done < <(printf "%%s\n" "${out[@]}")
+
+    local completions=()
+    while IFS='' read -r comp; do
+        if [ -z "$comp" ]; then
+            continue
+        fi
+
+        __helm_debug "Original comp: $comp"
+        comp="$(__helm_format_comp_descriptions "$comp" "$longest")"
+        __helm_debug "Final comp: $comp"
+        completions+=("$comp")
+    done < <(printf "%%s\n" "${out[@]}")
+
+    # Filter completions on the prefix the user specified ($cur)
+    # We do this here because we need to have already escaped any
+    # special characters of descriptions with __helm_format_comp_descriptions
+    while IFS='' read -r comp; do
+        COMPREPLY+=("$comp")
+    done < <(compgen -W "${completions[*]}" -- "$cur")
+
+    # If there is a single completion left, remove the description text
+    if [ ${#COMPREPLY[*]} -eq 1 ]; then
+        __helm_debug "COMPREPLY[0]: ${COMPREPLY[0]}"
+        comp="${COMPREPLY[0]%%%% *}"
+        __helm_debug "Removed description from single completion, which is now: ${comp}"
+        COMPREPLY=()
+        COMPREPLY+=("$comp")
+    fi
+}
+
+__helm_handle_special_char()
+{
+    local comp="$1"
+    local char=$2
+    if [[ "$comp" == *${char}* && "$COMP_WORDBREAKS" == *${char}* ]]; then
+        local word=${comp%%"${comp##*${char}}"}
+        local idx=${#COMPREPLY[*]}
+        while [[ $((--idx)) -ge 0 ]]; do
+            COMPREPLY[$idx]=${COMPREPLY[$idx]#"$word"}
+        done
+    fi
+}
+
+__helm_format_comp_descriptions()
+{
+    local tab
+    tab=$(printf '\t')
+    local comp="$1"
+    local longest=$2
+
+    # Properly format the description string which follows a tab character if there is one
+    if [[ "$comp" == *$tab* ]]; then
+        desc=${comp#*$tab}
+        comp=${comp%%%%$tab*}
+
+        # $COLUMNS stores the current shell width.
+        # Remove an extra 4 because we add 2 spaces and 2 parentheses.
+        maxdesclength=$(( COLUMNS - longest - 4 ))
+
+        # Make sure we can fit a description of at least 8 characters
+        # if we are to align the descriptions.
+        if [[ $maxdesclength -gt 8 ]]; then
+            # Add the proper number of spaces to align the descriptions
+            for ((i = ${#comp} ; i < longest ; i++)); do
+                comp+=" "
+            done
+        else
+            # Don't pad the descriptions so we can fit more text after the completion
+            maxdesclength=$(( COLUMNS - ${#comp} - 4 ))
+        fi
+
+        # If there is enough space for any description text,
+        # truncate the descriptions that are too long for the shell width
+        if [ $maxdesclength -gt 0 ]; then
+            if [ ${#desc} -gt $maxdesclength ]; then
+                desc=${desc:0:$(( maxdesclength - 1 ))}
+                desc+="…"
+            fi
+            comp+="  ($desc)"
+        fi
+    fi
+
+    # Must use printf to escape all special characters
+    printf "%%q" "${comp}"
+}
+
+__start_helm()
+{
+    local cur prev words cword
+
+    COMPREPLY=()
+
+    # Call _init_completion from the bash-completion package
+    # to prepare the arguments properly
+    if declare -F _init_completion >/dev/null 2>&1; then
+        _init_completion -n "=:" || return
+    else
+        __helm_init_completion -n "=:" || return
+    fi
+
+    __helm_debug
+    __helm_debug "========= starting completion logic =========="
+    __helm_debug "cur is ${cur}, words[*] is ${words[*]}, #words[@] is ${#words[@]}, cword is $cword"
+
+    # The user could have moved the cursor backwards on the command-line.
+    # We need to trigger completion from the $cword location, so we need
+    # to truncate the command-line ($words) up to the $cword location.
+    words=("${words[@]:0:$cword+1}")
+    __helm_debug "Truncated words[*]: ${words[*]},"
+
+    local out directive
+    __helm_get_completion_results
+    __helm_process_completion_results
+}
+
+if [[ $(type -t compopt) = "builtin" ]]; then
+    complete -o default -F __start_helm helm
+else
+    complete -o default -o nospace -F __start_helm helm
+fi
+
+# ex: ts=4 sw=4 et filetype=sh
+`, compCmd,
+		cobra.ShellCompDirectiveError, cobra.ShellCompDirectiveNoSpace, cobra.ShellCompDirectiveNoFileComp,
+		cobra.ShellCompDirectiveFilterFileExt, cobra.ShellCompDirectiveFilterDirs))
+
+	_, err := buf.WriteTo(w)
+	return err
+}