Add Bash completion script (#60)

* Add completion script
* Add introspection

Makefile

@@ -29,7 +29,7 @@ bats:
 shellcheck:
 	@echo Running shellcheck
 	@shellcheck --version || true
-	@shellcheck -s bash yadm bootstrap test/*.bash
+	@shellcheck -s bash yadm bootstrap test/*.bash completion/yadm.bash_completion
 	@cd test; \
 	for bats_file in *bats; do \
 		sed 's/^@test.*{/function test() {/' "$$bats_file" > "/tmp/$$bats_file.bash"; \

completion/README.md

@@ -0,0 +1,19 @@
+# Prerequisites
+
+**yadm** completion only works if Git completions are also enabled.
+
+# Installation
+
+## Homebrew
+
+If using `homebrew` to install **yadm**, completions should automatically be handled if you also install `brew install bash-completion`. This might require you to include the main completion script in your own bashrc file like this:
+
+```
+[ -f /usr/local/etc/bash_completion ] && source /usr/local/etc/bash_completion
+```
+
+## Manual installation
+Copy the completion script locally, and add this to you bashrc:
+```
+[ -f /full/path/to/yadm.bash_completion ] && source /full/path/to/yadm.bash_completion
+```

completion/yadm.bash_completion

@@ -0,0 +1,85 @@
+# test if git completion is missing, but loader exists, attempt to load
+if ! declare -F _git > /dev/null && declare -F _completion_loader > /dev/null; then
+  _completion_loader git
+fi
+
+# only operate if git completion is present
+if declare -F _git > /dev/null; then
+
+  _yadm() {
+
+    local current=${COMP_WORDS[COMP_CWORD]}
+    local penultimate=${COMP_WORDS[COMP_CWORD-1]}
+    local antepenultimate=${COMP_WORDS[COMP_CWORD-2]}
+
+    local GIT_DIR
+    # shellcheck disable=SC2034
+    GIT_DIR="$(yadm introspect repo 2>/dev/null)"
+
+    case "$penultimate" in
+      bootstrap)
+        COMPREPLY=()
+        return 0
+      ;;
+      config)
+        COMPREPLY=( $(compgen -W "$(yadm introspect configs 2>/dev/null)") )
+        return 0
+		  ;;
+      decrypt)
+        COMPREPLY=( $(compgen -W "-l" -- "$current") )
+        return 0
+		  ;;
+      init)
+        COMPREPLY=( $(compgen -W "-f -w" -- "$current") )
+        return 0
+		  ;;
+      introspect)
+        COMPREPLY=( $(compgen -W "commands configs repo switches" -- "$current") )
+        return 0
+		  ;;
+      help)
+        COMPREPLY=() # no specific help yet
+        return 0
+      ;;
+      list)
+        COMPREPLY=( $(compgen -W "-a" -- "$current") )
+        return 0
+		  ;;
+    esac
+
+    case "$antepenultimate" in
+      clone)
+        COMPREPLY=( $(compgen -W "-f -w --bootstrap --no-bootstrap" -- "$current") )
+        return 0
+		  ;;
+    esac
+
+    # this condition is so files are completed properly for --yadm-xxx options
+    if [[ ! "$penultimate" =~ ^- ]]; then
+      # TODO: somehow solve the problem with [--yadm-xxx option] being
+      #       incompatible with what git expects, namely [--arg=option]
+      _git
+    fi
+    if [[ "$current" =~ ^- ]]; then
+      local matching
+      matching=$(compgen -W "$(yadm introspect switches 2>/dev/null)" -- "$current")
+      __gitcompappend "$matching"
+    fi
+
+    if [ "$COMP_CWORD" == 1 ] || [[ "$antepenultimate" =~ ^- ]] ; then
+      local matching
+      matching=$(compgen -W "$(yadm introspect commands 2>/dev/null)" -- "$current")
+      __gitcompappend "$matching"
+    fi
+
+    # remove duplicates found in COMPREPLY (a native bash way could be better)
+    if [ -n "${COMPREPLY[*]}" ]; then
+      COMPREPLY=($(echo "${COMPREPLY[@]}" | sort -u))
+    fi
+
+  }
+
+	complete -o bashdefault -o default -F _yadm yadm 2>/dev/null \
+		|| complete -o default -F _yadm yadm
+
+fi

test/115_accept_introspect.bats

@@ -0,0 +1,99 @@
+load common
+load_fixtures
+status=;output=; #; populated by bats run()
+
+function count_introspect() {
+  local category="$1"
+  local expected_status="$2"
+  local expected_words="$3"
+  local expected_regex="$4"
+
+  run "${T_YADM_Y[@]}" introspect "$category"
+  local output_words
+  output_words=$(wc -w <<< "$output")
+
+  if [ "$status" -ne "$expected_status" ]; then
+    echo "ERROR: Unexpected exit code (expected $expected_status, got $status)"
+    return 1;
+  fi
+
+  if [ "$output_words" -ne "$expected_words" ]; then
+    echo "ERROR: Unexpected number of output words (expected $expected_words, got $output_words)"
+    return 1;
+  fi
+
+  if [ -n "$expected_regex" ]; then
+    if [[ ! "$output" =~ $expected_regex ]]; then
+      echo "OUTPUT:$output"
+      echo "ERROR: Output does not match regex: $expected_regex"
+      return 1;
+    fi
+  fi
+
+}
+
+@test "Command 'introspect' (no category)" {
+  echo "
+    When 'introspect' command is provided,
+      And no category is provided
+        Produce no output
+        Exit with 0
+  "
+
+  count_introspect "" 0 0
+}
+
+@test "Command 'introspect' (invalid category)" {
+  echo "
+    When 'introspect' command is provided,
+      And an invalid category is provided
+        Produce no output
+        Exit with 0
+  "
+
+  count_introspect "invalid_cat" 0 0
+}
+
+@test "Command 'introspect' (commands)" {
+  echo "
+    When 'introspect' command is provided,
+      And category 'commands' is provided
+        Produce command list
+        Exit with 0
+  "
+
+  count_introspect "commands" 0 15 'version'
+}
+
+@test "Command 'introspect' (configs)" {
+  echo "
+    When 'introspect' command is provided,
+      And category 'configs' is provided
+        Produce switch list
+        Exit with 0
+  "
+
+  count_introspect "configs" 0 11 'yadm\.auto-alt'
+}
+
+@test "Command 'introspect' (repo)" {
+  echo "
+    When 'introspect' command is provided,
+      And category 'repo' is provided
+        Output repo
+        Exit with 0
+  "
+
+  count_introspect "repo" 0 1 "$T_DIR_REPO"
+}
+
+@test "Command 'introspect' (switches)" {
+  echo "
+    When 'introspect' command is provided,
+      And category 'switches' is provided
+        Produce switch list
+        Exit with 0
+  "
+
+  count_introspect "switches" 0 7 '--yadm-dir'
+}

yadm

@@ -57,7 +57,7 @@ function main() {
 
   #; parse command line arguments
   local retval=0
-  internal_commands="^(alt|bootstrap|clean|clone|config|decrypt|encrypt|enter|help|init|list|perms|version)$"
+  internal_commands="^(alt|bootstrap|clean|clone|config|decrypt|encrypt|enter|help|init|introspect|list|perms|version)$"
   if [ -z "$*" ] ; then
     #; no argumnts will result in help()
     help
@@ -338,21 +338,13 @@ function config() {
 
   if [ -z "$*" ] ; then
     #; with no parameters, provide some helpful documentation
+    echo "yadm supports the following configurations:"
+    echo
+    for supported_config in $(introspect_configs); do
+      echo "  ${supported_config}"
+    done
+    echo
     cat << EOF
-yadm supports the following configurations:
-
-  local.class
-  local.hostname
-  local.os
-  local.user
-  yadm.auto-alt
-  yadm.auto-perms
-  yadm.git-program
-  yadm.gpg-perms
-  yadm.gpg-program
-  yadm.gpg-recipient
-  yadm.ssh-perms
-
 Please read the CONFIGURATION section in the man
 page for more details about configurations, and
 how to adjust them.
@@ -558,6 +550,66 @@ function init() {
 
 }
 
+function introspect() {
+  case "$1" in
+    commands|configs|repo|switches)
+      "introspect_$1"
+    ;;
+  esac
+}
+
+function introspect_commands() {
+  cat <<-EOF
+alt
+bootstrap
+clean
+clone
+config
+decrypt
+encrypt
+enter
+gitconfig
+help
+init
+introspect
+list
+perms
+version
+EOF
+}
+
+function introspect_configs() {
+  cat << EOF
+local.class
+local.hostname
+local.os
+local.user
+yadm.auto-alt
+yadm.auto-perms
+yadm.git-program
+yadm.gpg-perms
+yadm.gpg-program
+yadm.gpg-recipient
+yadm.ssh-perms
+EOF
+}
+
+function introspect_repo() {
+  echo "$YADM_REPO"
+}
+
+function introspect_switches() {
+  cat <<-EOF
+--yadm-archive
+--yadm-bootstrap
+--yadm-config
+--yadm-dir
+--yadm-encrypt
+--yadm-repo
+-Y
+EOF
+}
+
 function list() {
 
   require_repo

yadm.1

@@ -49,6 +49,9 @@ list
 .BR yadm " alt
 
 .BR yadm " perms
+
+.BR yadm " introspect
+.I category
 .SH DESCRIPTION
 .B yadm
 is a tool for managing a collection of files across multiple computers,
@@ -242,6 +245,17 @@ Print a list of files managed by
 option will cause all managed files to be listed.
 Otherwise, the list will only include files from the current directory or below.
 .TP
+.BI introspect " category
+Report internal
+.B yadm
+data. Supported categories are
+.IR commands ,
+.IR configs ,
+.IR repo,
+and
+.IR switches .
+The purpose of introspection is to support command line completion.
+.TP
 .B perms
 Update permissions as described in the PERMISSIONS section.
 It is usually unnecessary to run this command, as