1 files changed, 142 insertions, 0 deletions
diff --git a/src/shells/powershell.rs b/src/shells/powershell.rs
new file mode 100644
index 0000000..6b09b2e
--- /dev/null
+++ b/src/shells/powershell.rs
@@ -0,0 +1,142 @@
+use std::io::Write;
+
+use clap::builder::StyledStr;
+use clap::*;
+
+use crate::generator::{utils, Generator};
+use crate::INTERNAL_ERROR_MSG;
+
+/// Generate powershell completion file
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub struct PowerShell;
+
+impl Generator for PowerShell {
+    fn file_name(&self, name: &str) -> String {
+        format!("_{name}.ps1")
+    }
+
+    fn generate(&self, cmd: &Command, buf: &mut dyn Write) {
+        let bin_name = cmd
+            .get_bin_name()
+            .expect("crate::generate should have set the bin_name");
+
+        let subcommands_cases = generate_inner(cmd, "");
+
+        let result = format!(
+            r#"
+using namespace System.Management.Automation
+using namespace System.Management.Automation.Language
+
+Register-ArgumentCompleter -Native -CommandName '{bin_name}' -ScriptBlock {{
+    param($wordToComplete, $commandAst, $cursorPosition)
+
+    $commandElements = $commandAst.CommandElements
+    $command = @(
+        '{bin_name}'
+        for ($i = 1; $i -lt $commandElements.Count; $i++) {{
+            $element = $commandElements[$i]
+            if ($element -isnot [StringConstantExpressionAst] -or
+                $element.StringConstantType -ne [StringConstantType]::BareWord -or
+                $element.Value.StartsWith('-') -or
+                $element.Value -eq $wordToComplete) {{
+                break
+        }}
+        $element.Value
+    }}) -join ';'
+
+    $completions = @(switch ($command) {{{subcommands_cases}
+    }})
+
+    $completions.Where{{ $_.CompletionText -like "$wordToComplete*" }} |
+        Sort-Object -Property ListItemText
+}}
+"#
+        );
+
+        w!(buf, result.as_bytes());
+    }
+}
+
+// Escape string inside single quotes
+fn escape_string(string: &str) -> String {
+    string.replace('\'', "''")
+}
+
+fn get_tooltip<T: ToString>(help: Option<&StyledStr>, data: T) -> String {
+    match help {
+        Some(help) => escape_string(&help.to_string()),
+        _ => data.to_string(),
+    }
+}
+
+fn generate_inner(p: &Command, previous_command_name: &str) -> String {
+    debug!("generate_inner");
+
+    let command_name = if previous_command_name.is_empty() {
+        p.get_bin_name().expect(INTERNAL_ERROR_MSG).to_string()
+    } else {
+        format!("{};{}", previous_command_name, &p.get_name())
+    };
+
+    let mut completions = String::new();
+    let preamble = String::from("\n            [CompletionResult]::new(");
+
+    for option in p.get_opts() {
+        generate_aliases(&mut completions, &preamble, option);
+    }
+
+    for flag in utils::flags(p) {
+        generate_aliases(&mut completions, &preamble, &flag);
+    }
+
+    for subcommand in p.get_subcommands() {
+        let data = &subcommand.get_name();
+        let tooltip = get_tooltip(subcommand.get_about(), data);
+
+        completions.push_str(&preamble);
+        completions.push_str(
+            format!("'{data}', '{data}', [CompletionResultType]::ParameterValue, '{tooltip}')")
+                .as_str(),
+        );
+    }
+
+    let mut subcommands_cases = format!(
+        r"
+        '{}' {{{}
+            break
+        }}",
+        &command_name, completions
+    );
+
+    for subcommand in p.get_subcommands() {
+        let subcommand_subcommands_cases = generate_inner(subcommand, &command_name);
+        subcommands_cases.push_str(&subcommand_subcommands_cases);
+    }
+
+    subcommands_cases
+}
+
+fn generate_aliases(completions: &mut String, preamble: &String, arg: &Arg) {
+    use std::fmt::Write as _;
+
+    if let Some(aliases) = arg.get_short_and_visible_aliases() {
+        let tooltip = get_tooltip(arg.get_help(), aliases[0]);
+        for alias in aliases {
+            let _ = write!(
+                completions,
+                "{preamble}'-{alias}', '{alias}{}', [CompletionResultType]::ParameterName, '{tooltip}')",
+                // make PowerShell realize there is a difference between `-s` and `-S`
+                if alias.is_uppercase() { " " } else { "" },
+            );
+        }
+    }
+    if let Some(aliases) = arg.get_long_and_visible_aliases() {
+        let tooltip = get_tooltip(arg.get_help(), aliases[0]);
+        for alias in aliases {
+            let _ = write!(
+                completions,
+                "{preamble}'--{alias}', '{alias}', [CompletionResultType]::ParameterName, '{tooltip}')"
+            );
+        }
+    }
+}