Add PowerShell completion generation

I'm not an expert in PowerShell or CLI's, but this developments may help someone else complete it
Should be called like (on Windows):
`script completions PowerShell > $HOME\Documents\PowerShell\Profile.ps1`
or (on Linux or macOS):
`script completions PowerShell > ~/.config/powershell/profile.ps1`
If I understand correctly, where PowerShell saves its configurations

Author: ZettZet

src/cleo/commands/completions/templates.py

@@ -122,4 +122,34 @@
 %(cmds_opts)s"""
 
 
-TEMPLATES = {"bash": BASH_TEMPLATE, "zsh": ZSH_TEMPLATE, "fish": FISH_TEMPLATE}
+POWERSHELL_TEMPLATE = """\
+$%(function)s = {
+    param(
+        [string] $wordToComplete,
+        [System.Management.Automation.Language.Ast] $commandAst,
+        [int] $cursorPosition
+    )
+
+    $options = %(opts)s
+    $commands = %(cmds)s
+
+    if ($wordToComplete -notlike '--*' -and $wordToComplete -notlike "" -and ($commandAst.CommandElements.Count -eq "2")) {
+        return $commands | Where-Object { $_ -like "$wordToComplete*" }
+    }
+
+    $result = $commandAst.CommandElements | Select-Object -Skip 1 | Where-Object { $_ -notlike '--*' }
+    switch ($result -Join " " ) {
+%(cmds_opts)s
+    }
+
+    return $options | Where-Object { $_ -like "$wordToComplete*" }
+}
+
+Register-ArgumentCompleter -Native -CommandName %(script_name)s -ScriptBlock $%(function)s"""
+
+TEMPLATES = {
+    "bash": BASH_TEMPLATE,
+    "zsh": ZSH_TEMPLATE,
+    "fish": FISH_TEMPLATE,
+    "PowerShell": POWERSHELL_TEMPLATE,
+}

src/cleo/commands/completions_command.py

@@ -37,7 +37,7 @@ class CompletionsCommand(Command):
         )
     ]
 
-    SUPPORTED_SHELLS = ("bash", "zsh", "fish")
+    SUPPORTED_SHELLS = ("bash", "zsh", "fish", "PowerShell")
 
     hidden = True
 
@@ -135,6 +135,8 @@ def render(self, shell: str) -> str:
             return self.render_zsh()
         if shell == "fish":
             return self.render_fish()
+        if shell == "PowerShell":
+            return self.render_power_shell()
 
         raise RuntimeError(f"Unrecognized shell: {shell}")
 
@@ -280,9 +282,49 @@ def sanitize(s: str) -> str:
             "cmds_names": " ".join(cmds_names),
         }
 
+    def render_power_shell(self) -> str:
+        script_name, script_path = self._get_script_name_and_path()
+        function = self._generate_function_name(script_name, script_path)
+
+        assert self.application
+        # Global options
+        opts = [
+            f'"--{opt.name}"'
+            for opt in sorted(self.application.definition.options, key=lambda o: o.name)
+        ]
+
+        # Command + options
+        cmds = []
+        cmds_opts = []
+        for cmd in sorted(self.application.all().values(), key=lambda c: c.name or ""):
+            if cmd.hidden or not cmd.enabled or not cmd.name:
+                continue
+
+            command_name = f'"{cmd.name}"'
+            cmds.append(command_name)
+            if len(cmd.definition.options) == 0:
+                continue
+            options = ", ".join(
+                f'"--{opt.name}"'
+                for opt in sorted(cmd.definition.options, key=lambda o: o.name)
+            )
+            cmds_opts += [f"        {command_name} {{ $options += {options}; Break; }}"]
+
+        return TEMPLATES["PowerShell"] % {
+            "function": function,
+            "script_name": script_name,
+            "opts": ", ".join(opts),
+            "cmds": ", ".join(cmds),
+            "cmds_opts": "\n".join(cmds_opts),
+        }
+
     def get_shell_type(self) -> str:
         shell = os.getenv("SHELL")
+
         if not shell:
+            if len(os.getenv("PSModulePath", "").split(os.pathsep)) >= 3:
+                return "PowerShell"
+
             raise RuntimeError(
                 "Could not read SHELL environment variable. "
                 "Please specify your shell type by passing it as the first argument."

tests/commands/completion/fixtures/PowerShell.txt

@@ -0,0 +1,25 @@
+$_my_function = {
+    param(
+        [string] $wordToComplete,
+        [System.Management.Automation.Language.Ast] $commandAst,
+        [int] $cursorPosition
+    )
+
+    $options = "--ansi", "--help", "--no-ansi", "--no-interaction", "--quiet", "--verbose", "--version"
+    $commands = "command:with:colons", "hello", "help", "list", "spaced command"
+
+    if ($wordToComplete -notlike '--*' -and $wordToComplete -notlike "" -and ($commandAst.CommandElements.Count -eq "2")) {
+        return $commands | Where-Object { $_ -like "$wordToComplete*" }
+    }
+
+    $result = $commandAst.CommandElements | Select-Object -Skip 1 | Where-Object { $_ -notlike '--*' }
+    switch ($result -Join " " ) {
+        "command:with:colons" { $options += "--goodbye"; Break; }
+        "hello" { $options += "--dangerous-option", "--option-without-description"; Break; }
+        "spaced command" { $options += "--goodbye"; Break; }
+    }
+
+    return $options | Where-Object { $_ -like "$wordToComplete*" }
+}
+
+Register-ArgumentCompleter -Native -CommandName script -ScriptBlock $_my_function

tests/commands/completion/test_completions_command.py

@@ -96,3 +96,26 @@ def test_fish(mocker: MockerFixture) -> None:
         expected = f.read()
 
     assert expected == tester.io.fetch_output().replace("\r\n", "\n")
+
+
+def test_power_shell(mocker: MockerFixture) -> None:
+    mocker.patch(
+        "cleo.io.inputs.string_input.StringInput.script_name",
+        new_callable=mocker.PropertyMock,
+        return_value="/path/to/my/script",
+    )
+    mocker.patch(
+        "cleo.commands.completions_command.CompletionsCommand._generate_function_name",
+        return_value="_my_function",
+    )
+
+    command = app.find("completions")
+    tester = CommandTester(command)
+    tester.execute("PowerShell")
+
+    with open(
+        os.path.join(os.path.dirname(__file__), "fixtures", "PowerShell.txt")
+    ) as f:
+        expected = f.read()
+
+    assert expected == tester.io.fetch_output().replace("\r\n", "\n")