shell-completion: zsh: Rework pactl completion

So far the command name has been figured out by looking one or two
items back in the $words array, but I needed a way to figure out the
command given an arbitrary number of parameters. I was implementing
a command for removing devices from the device-manager database, and
the command would take a list of devices. Since the number of devices
that need to be completed can be arbitrarily large, the previous "look
one or two words back" approach didn't work.

This new approach is more verbose, but I think it's also easier to
follow. There's some duplication that would be easy to avoid by
merging some of the commands, but I decided to not do that, to make
it more obvious what the code does.

1 files changed, 229 insertions, 35 deletions

diff --git a/shell-completion/zsh/_pulseaudio b/shell-completion/zsh/_pulseaudio
index 5f66ed916..cbccaf243 100644
--- a/shell-completion/zsh/_pulseaudio
+++ b/shell-completion/zsh/_pulseaudio
@@ -263,50 +263,244 @@ _pactl_completion() {
             'set-sink-formats: set supported formats of a sink'
             'subscribe: subscribe to events'
         )
+
         _describe 'pactl commands' _pactl_commands
     }
 
-    _pactl_list_commands=(
-        'modules: list loaded modules'
-        'sinks: list available sinks'
-        'sources: list available sources'
-        'sink-inputs: list connected sink inputs'
-        'source-outputs: list connected source outputs'
-        'clients: list connected clients'
-        'samples: list samples'
-        'cards: list available cards'
-    )
+    _pactl_command_parameter() {
+        local _command
+
+        _list_parameter() {
+            local -a _objects;
+
+            _objects=(
+                'modules: list loaded modules'
+                'sinks: list available sinks'
+                'sources: list available sources'
+                'sink-inputs: list connected sink inputs'
+                'source-outputs: list connected source outputs'
+                'clients: list connected clients'
+                'samples: list samples'
+                'cards: list available cards'
+            )
+
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after "list".
+                # "pactl list cards short" and "pactl list short cards" are
+                # treated as equivalent by pactl, but here we only support the
+                # first form, so "short" isn't a valid completion.
+                _describe 'objects' _objects
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after "list". As
+                # explained in the previous comment, we only support the
+                # "pactl list cards short" form, so "short" is the only valid
+                # completion here.
+                compadd short
+            fi
+        }
+
+        _play_sample_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after "play-sample".
+                # TODO: Implement sample name completion.
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after "play-sample".
+                # TODO: Implement sink name completion.
+            fi
+        }
+
+        _load_module_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after "load-module".
+                _all_modules
+            else
+                # We're completing the second or later parameter after
+                # "load-module", i.e. the module arguments.
+                # TODO: Implement module argument completion.
+            fi
+        }
+
+        _move_sink_input_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after "move-sink-input".
+                # Even though the function name is "_devices", it actually
+                # completes the sink input index. _devices is magical like
+                # that.
+                _devices
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after
+                # "move-sink-input".
+                _devices
+            fi
+        }
+
+        _move_source_output_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after
+                # "move-source-output". Even though the function name is
+                # "_devices", it actually completes the source output index.
+                # _devices is magical like that.
+                _devices
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after
+                # "move-source-output".
+                _devices
+            fi
+        }
+
+        _suspend_sink_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after "suspend-sink".
+                _devices
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after "suspend-sink".
+                compadd true false
+            fi
+        }
+
+        _suspend_source_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after "suspend-source".
+                _devices
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after "suspend-source".
+                compadd true false
+            fi
+        }
+
+        _set_card_profile_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after
+                # "set-card-profile".
+                _cards
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after
+                # "set-card-profile".
+                _profiles
+            fi
+        }
+
+        _set_sink_port_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after "set-sink-port".
+                _devices
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after "set-sink-port".
+                _ports
+            fi
+        }
+
+        _set_source_port_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after "set-source-port".
+                _devices
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after
+                # "set-source-port".
+                _ports
+            fi
+        }
+
+        _set_sink_mute_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after "set-sink-mute".
+                _devices
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after "set-sink-mute".
+                compadd true false toggle
+            fi
+        }
+
+        _set_source_mute_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after "set-source-mute".
+                _devices
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after
+                # "set-source-mute".
+                compadd true false toggle
+            fi
+        }
+
+        _set_sink_input_mute_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after
+                # "set-sink-input-mute". Even though the function name is
+                # "_devices", it actually completes the sink input index.
+                # _devices is magical like that.
+                _devices
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after
+                # "set-sink-input-mute".
+                compadd true false toggle
+            fi
+        }
+
+        _set_source_output_mute_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after
+                # "set-source-output-mute". Even though the function name is
+                # "_devices", it actually completes the source output index.
+                # _devices is magical like that.
+                _devices
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after
+                # "set-source-output-mute".
+                compadd true false toggle
+            fi
+        }
+
+        _set_port_latency_offset_parameter() {
+            if ((CURRENT == 2)); then
+                # We're completing the first parameter after
+                # "set-port-latency-offset".
+                _cards
+            elif ((CURRENT == 3)); then
+                # We're completing the second parameter after
+                # "set-port-latency-offset".
+                _ports
+            fi
+        }
+
+        _command=$words[1]
+
+        case $_command in
+            stat)                                  if ((CURRENT == 2)); then compadd short; fi;;
+            list)                                  _list_parameter;;
+            upload-sample)                         if ((CURRENT == 2)); then _files; fi;;
+            play-sample)                           _play_sample_parameter;;
+            remove-sample)                         ;; # TODO: Implement sample name completion.
+            load-module)                           _load_module_parameter;;
+            unload-module)                         if ((CURRENT == 2)); then _loaded_modules; fi;;
+            move-sink-input)                       _move_sink_input_parameter;;
+            move-source-output)                    _move_source_output_parameter;;
+            suspend-sink)                          _suspend_sink_parameter;;
+            suspend-source)                        _suspend_source_parameter;;
+            set-card-profile)                      _set_card_profile_parameter;;
+            set-default-sink)                      if ((CURRENT == 2)); then _devices; fi;;
+            set-default-source)                    if ((CURRENT == 2)); then _devices; fi;;
+            set-sink-port)                         _set_sink_port_parameter;;
+            set-source-port)                       _set_source_port_parameter;;
+            set-sink-volume)                       if ((CURRENT == 2)); then _devices; fi;;
+            set-source-volume)                     if ((CURRENT == 2)); then _devices; fi;;
+            set-sink-input-volume)                 if ((CURRENT == 2)); then _devices; fi;;
+            set-source-output-volume)              if ((CURRENT == 2)); then _devices; fi;;
+            set-sink-mute)                         _set_sink_mute_parameter;;
+            set-source-mute)                       _set_source_mute_parameter;;
+            set-sink-input-mute)                   _set_sink_input_mute_parameter;;
+            set-source-output-mute)                _set_source_output_mute_parameter;;
+            set-sink-formats)                      if ((CURRENT == 2)); then _devices; fi;;
+            set-port-latency-offset)               _set_port_latency_offset_parameter;;
+        esac
+    }
 
     _arguments -C -S -A '-*' \
         {-h,--help}'[display help and exit]' \
         '--version[show version and exit]' \
         {-s,--server=}'[name of server to connect to]:host:_hosts' \
         {-n,--client-name=}'[client name to use]:name' \
-        '::pactl command:_pactl_command'
-
-    case $words[$((CURRENT - 1))] in
-        list) _describe 'pactl list commands' _pactl_list_commands;;
-        stat) compadd short;;
-        set-card-profile) _cards;;
-        set-sink-*) _devices;;
-        set-source-*) _devices;;
-        upload-sample) _files;;
-        load-module) _all_modules;;
-        unload-module) _loaded_modules;;
-        suspend-*) _devices;;
-        move-*) _devices;;
-        set-port-latency-offset) _cards;;
-    esac
-
-    case $words[$((CURRENT - 2))] in
-        set-card-profile) _profiles;;
-        set-(sink|source)-port) _ports;;
-        set-port-latency-offset) _ports;;
-        set-*-mute) compadd true false toggle;;
-        suspend-*) compadd true false;;
-        list) compadd short;;
-        move-*) _devices;;
-    esac
+        '::pactl command:_pactl_command' \
+        '*::pactl command parameter:_pactl_command_parameter'
 }
 
 _pacmd_completion() {