home-manager: add Bash completion

2 files changed, 346 insertions, 0 deletions

diff --git a/home-manager/completion.bash b/home-manager/completion.bash
new file mode 100644
index 00000000000..cb7c0009693
--- /dev/null
+++ b/home-manager/completion.bash
@@ -0,0 +1,343 @@
+#!/bin/env bash
+
+##################################################
+
+# « home-manager » command-line completion
+#
+# © 2019 "Sam Boosalis" <samboosalis@gmail.com>
+#
+# MIT License
+#
+
+##################################################
+# Contributing:
+
+# Compatibility — Bash 3.
+#
+# OSX won't update Bash 3 (last updated circa 2009) to Bash 4,
+# and we'd like this completion script to work on both Linux and Mac.
+#
+# For example, OSX Yosemite (released circa 2014) ships with Bash 3:
+#
+#  $ echo $BASH_VERSION
+#  3.2
+#
+# While Ubuntu LTS 14.04 (a.k.a. Trusty, also released circa 2016)
+# ships with the latest version, Bash 4 (updated circa 2016):
+#
+#  $ echo $BASH_VERSION
+#  4.3
+#
+
+# Testing
+#
+# (1) Invoke « shellcheck »
+#
+#     * source: « https://github.com/koalaman/shellcheck »
+#     * run:    « shellcheck ./share/bash-completion/completions/home-manager »
+#
+# (2) Interpret via Bash 3
+#
+#     * run:    « bash --noprofile --norc ./share/bash-completion/completions/home-manager »
+#
+
+##################################################
+# Examples:
+
+# $ home-manager <TAB>
+#
+# -A
+# -I
+# -f
+# -h
+# -n
+# -v
+# build
+# edit
+# expire-generations
+# generations
+# help
+# news
+# packages
+# remove-generations
+# switch
+
+# $ home-manager e<TAB>
+#
+# edit
+# expire-generations
+
+# $ home-manager remove-generations 20<TAB>
+#
+# 200
+# 201
+# 202
+# 203
+
+##################################################
+# Notes:
+
+# « home-manager » Subcommands:
+#
+#   help
+#   edit
+#   build
+#   switch
+#   generations
+#   remove-generations
+#   expire-generations
+#   packages
+#   news
+
+# « home-manager » Options:
+#
+#   -f FILE
+#   -A ATTRIBUTE
+#   -I PATH
+#   -v
+#   -n
+#   -h
+
+# $ home-manager
+#
+# Usage: /home/sboo/.nix-profile/bin/home-manager [OPTION] COMMAND
+#
+# Options
+#
+#   -f FILE      The home configuration file.
+#                Default is '~/.config/nixpkgs/home.nix'.
+#   -A ATTRIBUTE Optional attribute that selects a configuration
+#                expression in the configuration file.
+#   -I PATH      Add a path to the Nix expression search path.
+#   -v           Verbose output
+#   -n           Do a dry run, only prints what actions would be taken
+#   -h           Print this help
+#
+# Commands
+#
+#   help         Print this help
+#
+#   edit         Open the home configuration in $EDITOR
+#
+#   build        Build configuration into result directory
+#
+#   switch       Build and activate configuration
+#
+#   generations  List all home environment generations
+#
+#   remove-generations ID...
+#       Remove indicated generations. Use 'generations' command to
+#       find suitable generation numbers.
+#
+#   expire-generations TIMESTAMP
+#       Remove generations older than TIMESTAMP where TIMESTAMP is
+#       interpreted as in the -d argument of the date tool. For
+#       example "-30 days" or "2018-01-01".
+#
+#   packages     List all packages installed in home-manager-path
+#
+#   news         Show news entries in a pager
+#
+
+##################################################
+# Dependencies:
+
+command -v home-manager >/dev/null
+command -v grep         >/dev/null
+command -v sed          >/dev/null
+
+##################################################
+# Code:
+
+_home-manager_list-generation-identifiers ()
+
+{
+
+    home-manager generations  |  sed -n -e 's/^................ : id \([[:alnum:]]\+\) -> .*/\1/p'
+
+}
+
+# NOTES
+#
+# (1) the « sed -n -e 's/.../.../p' » invocation:
+#
+#    * the « -e '...' » option takes a Sed Script.
+#    * the « -n » option only prints when « .../p » would print.
+#    * the « s/xxx/yyy/ » Sed Script substitutes « yyy » whenever « xxx » is matched.
+#
+# (2) the « '^................ : id \([[:alnum:]]\+\) -> .*' » regular expression:
+#
+#    * matches « 199 », for example, in the line « 2019-03-13 15:26 : id 199 -> /nix/store/mv619y9pzgsx3kndq0q7fjfvbqqdy5k8-home-manager-generation »
+#
+#
+
+#------------------------------------------------#
+
+# shellcheck disable=SC2120
+_home-manager_list-nix-attributes ()
+
+{
+    local HomeFile
+    local HomeAttrsString
+    # local HomeAttrsArray
+    # local HomeAttr
+
+    if   [ -z "$1" ]
+    then
+        HomeFile=$(readlink -f "$(_home-manager_get-default-home-file)")
+    else
+        HomeFile="$1"
+    fi
+
+    HomeAttrsString=$(nix-instantiate --eval -E "let home = import ${HomeFile}; in (builtins.trace (builtins.toString (builtins.attrNames home)) null)" |& grep '^trace: ')
+    HomeAttrsString="${HomeAttrsString#trace: }"
+
+    echo "${HomeAttrsString}"
+
+    # IFS=" " read -ar HomeAttrsArray <<< "${HomeAttrsString}"
+    #
+    # local HomeAttr
+    # for HomeAttr in "${HomeAttrsArray[@]}"
+    # do
+    #     echo "${HomeAttr}"
+    # done
+
+}
+
+# e.g.:
+#
+#   $ nix-instantiate --eval -E 'let home = import /home/sboo/configuration/configs/nixpkgs/home-attrs.nix; in (builtins.trace (builtins.toString (builtins.attrNames home)) null)' 1>/dev/null
+#   trace: darwin linux
+#
+#   $ _home-manager_list-nix-attributes
+#   linux darwin
+#
+
+#------------------------------------------------#
+
+_home-manager_get-default-home-file ()
+
+{
+    local HomeFileDefault
+
+    HomeFileDefault="$(_home-manager_xdg-get-config-home)/nixpkgs/home.nix"
+
+    echo "${HomeFileDefault}"
+}
+
+# e.g.:
+#
+#   $ _home-manager_get-default-home-file
+#   ~/.config/nixpkgs/home.nix
+#
+
+##################################################
+# XDG-BaseDirs:
+
+_home-manager_xdg-get-config-home () {
+
+    echo "${XDG_CONFIG_HOME:-$HOME/.config}"
+
+}
+
+#------------------------------------------------#
+
+_home-manager_xdg-get-data-home () {
+
+    echo "${XDG_DATA_HOME:-$HOME/.local/share}"
+
+}
+
+
+#------------------------------------------------#
+_home-manager_xdg-get-cache-home () {
+
+    echo "${XDG_CACHE_HOME:-$HOME/.cache}"
+
+}
+
+##################################################
+
+# shellcheck disable=SC2207
+_home-manager_completions ()
+{
+
+    #--------------------------#
+
+    local Subcommands
+    Subcommands=( "help" "edit" "build" "switch" "generations" "remove-generations" "expire-generations" "packages" "news" )
+
+    # ^ « home-manager »'s subcommands.
+
+    #--------------------------#
+
+    local Options
+    Options=( "-f" "-A" "-I" "-h" "-n" "-v" )
+
+    # ^ « home-manager »'s options.
+
+    #--------------------------#
+
+    local CurrentWord
+    CurrentWord="${COMP_WORDS[$COMP_CWORD]}"
+
+    # ^ the word currently being completed
+
+    local PreviousWord
+    if [ "$COMP_CWORD" -ge 1 ]
+    then
+        PreviousWord="${COMP_WORDS[COMP_CWORD-1]}"
+    else
+        PreviousWord=""
+    fi
+
+    # ^ the word to the left of the current word.
+    #
+    #   e.g. in « home-manager -v -f ./<TAB> »:
+    #
+    #       PreviousWord="-f"
+    #       CurrentWord="./"
+
+    #--------------------------#
+
+    COMPREPLY=()
+
+    case "$PreviousWord" in
+
+        "-f")
+
+            COMPREPLY+=( $( compgen -A file -- "$CurrentWord") )
+            ;;
+
+        "-I")
+
+            COMPREPLY+=( $( compgen -A directory -- "$CurrentWord") )
+            ;;
+
+        "-A")
+
+            # shellcheck disable=SC2119
+            COMPREPLY+=( $( compgen -W "$(_home-manager_list-nix-attributes)" -- "$CurrentWord") )
+            ;;
+
+        "remove-generations")
+
+            COMPREPLY+=( $( compgen -W "$(_home-manager_list-generation-identifiers)" -- "$CurrentWord" ) )
+            ;;
+
+        *)
+
+            COMPREPLY+=( $( compgen -W "${Subcommands[*]}" -- "$CurrentWord" ) )
+            COMPREPLY+=( $( compgen -W "${Options[*]}" -- "$CurrentWord" ) )
+            ;;
+
+    esac
+
+    #--------------------------#
+}
+
+##################################################
+
+complete -F _home-manager_completions -o default home-manager
+
+#complete -W "help edit build switch generations remove-generations expire-generations packages news" home-manager
diff --git a/home-manager/default.nix b/home-manager/default.nix
index 82acb2fab63..8b5ae75e0fd 100644
--- a/home-manager/default.nix
+++ b/home-manager/default.nix
@@ -34,4 +34,7 @@ runCommand
       --subst-var-by gnused "${gnused}" \
       --subst-var-by less "${less}" \
       --subst-var-by HOME_MANAGER_PATH '${pathStr}'
+
+    install -D -m755 ${./completion.bash} \
+      $out/share/bash-completion/completions/home-manager
   ''