feat(comp): Dynamic completion of charts

helm show <subcmd> <TAB>      - completes to chart (ref, path, url)
helm pull <TAB>               - completes to chart (ref, url)

helm install [NAME] <TAB>     - completes to chart (ref, path, url)
helm template [NAME] <TAB>    - completes to chart (ref, path, url)
helm upgrade <TAB>            - completes to release name
helm upgrade <release> <TAB>  - completes to chart (ref, path, url)

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

cmd/helm/root.go

@@ -67,6 +67,11 @@ __helm_override_flags_to_kubectl_flags()
     echo "$1" | sed s/kube-context/context/
 }
 
+__helm_get_repos()
+{
+    eval $(__helm_binary_name) repo list 2>/dev/null | tail +2 | cut -f1
+}
+
 __helm_get_contexts()
 {
     __helm_debug "${FUNCNAME[0]}: c is $c words[c] is ${words[c]}"
@@ -106,6 +111,104 @@ __helm_binary_name()
     echo ${helm_binary}
 }
 
+# This function prevents the zsh shell from adding a space after
+# a completion by adding a second, fake completion
+__helm_zsh_comp_nospace() {
+    __helm_debug "${FUNCNAME[0]}: in is ${in[*]}"
+
+    local out in=("$@")
+
+    # The shell will normally add a space after these completions.
+    # To avoid that we should use "compopt -o nospace".  However, it is not
+    # available in zsh.
+    # Instead, we trick the shell by pretending there is a second, longer match.
+    # We only do this if there is a single choice left for completion
+    # to reduce the times the user could be presented with the fake completion choice.
+
+    out=($(echo ${in[*]} | tr " " "\n" | \grep "^${cur}"))
+    __helm_debug "${FUNCNAME[0]}: out is ${out[*]}"
+
+    [ ${#out[*]} -eq 1 ] && out+=("${out}.")
+
+    __helm_debug "${FUNCNAME[0]}: out is now ${out[*]}"
+
+    echo "${out[*]}"
+}
+
+# $1 = 1 if the completion should include local charts (which means file completion)
+__helm_list_charts()
+{
+    __helm_debug "${FUNCNAME[0]}: c is $c words[c] is ${words[c]}"
+    local repo url file out=() nospace=0 wantFiles=$1
+
+    # Handle completions for repos
+    for repo in $(__helm_get_repos); do
+        if [[ "${cur}" =~ ^${repo}/.* ]]; then
+            # We are doing completion from within a repo
+            out=$(eval $(__helm_binary_name) search repo ${cur} 2>/dev/null | cut -f1 | \grep ^${cur})
+            nospace=0
+        elif [[ ${repo} =~ ^${cur}.* ]]; then
+            # We are completing a repo name
+            out+=(${repo}/)
+            nospace=1
+        fi
+    done
+    __helm_debug "${FUNCNAME[0]}: out after repos is ${out[*]}"
+
+    # Handle completions for url prefixes
+    for url in https:// http:// file://; do
+        if [[ "${cur}" =~ ^${url}.* ]]; then
+            # The user already put in the full url prefix.  Return it
+            # back as a completion to avoid the shell doing path completion
+            out="${cur}"
+            nospace=1
+        elif [[ ${url} =~ ^${cur}.* ]]; then
+            # We are completing a url prefix
+            out+=(${url})
+            nospace=1
+        fi
+    done
+    __helm_debug "${FUNCNAME[0]}: out after urls is ${out[*]}"
+
+    # Handle completion for files.
+    # We only do this if:
+    #   1- There are other completions found (if there are no completions,
+    #      the shell will do file completion itself)
+    #   2- If there is some input from the user (or else we will end up
+    #      lising the entire content of the current directory which will
+    #      be too many choices for the user to find the real repos)
+    if [ $wantFiles -eq 1 ] && [ -n "${out[*]}" ] && [ -n "${cur}" ]; then
+        for file in $(\ls); do
+            if [[ ${file} =~ ^${cur}.* ]]; then
+                # We are completing a file prefix
+                out+=(${file})
+                nospace=1
+            fi
+        done
+    fi
+    __helm_debug "${FUNCNAME[0]}: out after files is ${out[*]}"
+
+    # If the user didn't provide any input to completion,
+    # we provide a hint that a path can also be used
+    [ $wantFiles -eq 1 ] && [ -z "${cur}" ] && out+=(./ /)
+
+    __helm_debug "${FUNCNAME[0]}: out after checking empty input is ${out[*]}"
+
+    if [ $nospace -eq 1 ]; then
+        if [[ -n "${ZSH_VERSION}" ]]; then
+            # Don't let the shell add a space after the completion
+            local tmpout=$(__helm_zsh_comp_nospace "${out[@]}")
+            unset out
+            out=$tmpout
+        elif [[ $(type -t compopt) = "builtin" ]]; then
+            compopt -o nospace
+        fi
+    fi
+
+    __helm_debug "${FUNCNAME[0]}: final out is ${out[*]}"
+    COMPREPLY=( $( compgen -W "${out[*]}" -- "$cur" ) )
+}
+
 __helm_list_releases()
 {
 	__helm_debug "${FUNCNAME[0]}: c is $c words[c] is ${words[c]}"
@@ -123,7 +226,7 @@ __helm_list_repos()
     __helm_debug "${FUNCNAME[0]}: c is $c words[c] is ${words[c]}"
     local out
     # Use eval in case helm_binary_name contains a variable (e.g., $HOME/bin/h3)
-    if out=$(eval $(__helm_binary_name) repo list 2>/dev/null | tail +2 | cut -f1); then
+    if out=$(__helm_get_repos); then
         COMPREPLY=( $( compgen -W "${out[*]}" -- "$cur" ) )
     fi
 }
@@ -138,12 +241,44 @@ __helm_list_plugins()
     fi
 }
 
+__helm_list_charts_after_name() {
+    __helm_debug "${FUNCNAME[0]}: last_command is $last_command"
+    if [[ ${#nouns[@]} -eq 1 ]]; then
+        __helm_list_charts 1
+    fi
+}
+
+__helm_list_releases_then_charts() {
+    __helm_debug "${FUNCNAME[0]}: last_command is $last_command"
+    if [[ ${#nouns[@]} -eq 0 ]]; then
+        __helm_list_releases
+    elif [[ ${#nouns[@]} -eq 1 ]]; then
+        __helm_list_charts 1
+    fi
+}
+
 __helm_custom_func()
 {
     __helm_debug "${FUNCNAME[0]}: last_command is $last_command"
     case ${last_command} in
+        helm_pull)
+            __helm_list_charts 0
+            return
+            ;;
+        helm_show_*)
+            __helm_list_charts 1
+            return
+            ;;
+        helm_install | helm_template)
+            __helm_list_charts_after_name
+            return
+            ;;
+        helm_upgrade)
+            __helm_list_releases_then_charts
+            return
+            ;;
         helm_uninstall | helm_history | helm_status | helm_test |\
-	    helm_upgrade | helm_rollback | helm_get_*)
+        helm_rollback | helm_get_*)
             __helm_list_releases
             return
             ;;