allow multiple extensions (#10593)

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# Description
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Thank you for improving Nushell. Please, check our [contributing
guide](../CONTRIBUTING.md) and talk to the core team before making major
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Description of your pull request goes here. **Provide examples and/or
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This PR allows `open` to handle files with multiple extensions; i.e it
will try to call `from tar.gz`, `from gz` when calling
```nu
open file.tar.gz
```

# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->
No breaking changes.

crates/nu-command/src/filesystem/open.rs

@@ -171,36 +171,35 @@ impl Command for Open {
                         metadata: None,
                         trim_end_newline: false,
                     };
-                    let ext = if raw {
+                    let exts_opt: Option<Vec<String>> = if raw {
                         None
                     } else {
-                        path.extension()
-                            .map(|name| name.to_string_lossy().to_string().to_lowercase())
+                        let path_str = path
+                            .file_name()
+                            .unwrap_or(std::ffi::OsStr::new(path))
+                            .to_string_lossy()
+                            .to_lowercase();
+                        Some(extract_extensions(path_str.as_str()))
                     };
 
-                    if let Some(ext) = ext {
-                        match engine_state.find_decl(format!("from {ext}").as_bytes(), &[]) {
-                            Some(converter_id) => {
-                                let decl = engine_state.get_decl(converter_id);
-                                let command_output = if let Some(block_id) = decl.get_block_id() {
-                                    let block = engine_state.get_block(block_id);
-                                    eval_block(
-                                        engine_state,
-                                        stack,
-                                        block,
-                                        file_contents,
-                                        false,
-                                        false,
-                                    )
-                                } else {
-                                    decl.run(
-                                        engine_state,
-                                        stack,
-                                        &Call::new(call_span),
-                                        file_contents,
-                                    )
-                                };
-                                output.push(command_output.map_err(|inner| {
+                    let converter = exts_opt.and_then(|exts| {
+                        exts.iter().find_map(|ext| {
+                            engine_state
+                                .find_decl(format!("from {}", ext).as_bytes(), &[])
+                                .map(|id| (id, ext.to_string()))
+                        })
+                    });
+
+                    match converter {
+                        Some((converter_id, ext)) => {
+                            let decl = engine_state.get_decl(converter_id);
+                            let command_output = if let Some(block_id) = decl.get_block_id() {
+                                let block = engine_state.get_block(block_id);
+                                eval_block(engine_state, stack, block, file_contents, false, false)
+                            } else {
+                                decl.run(engine_state, stack, &Call::new(call_span), file_contents)
+                            };
+                            output.push(command_output.map_err(|inner| {
                                     ShellError::GenericError(
                                         format!("Error while parsing as {ext}"),
                                         format!("Could not parse '{}' with `from {}`", path.display(), ext),
@@ -209,11 +208,8 @@ impl Command for Open {
                                         vec![inner],
                                     )
                                 })?);
-                            }
-                            None => output.push(file_contents),
                         }
-                    } else {
-                        output.push(file_contents)
+                        None => output.push(file_contents),
                     }
                 }
             }
@@ -265,3 +261,23 @@ fn permission_denied(dir: impl AsRef<Path>) -> bool {
         Ok(_) => false,
     }
 }
+
+fn extract_extensions(filename: &str) -> Vec<String> {
+    let parts: Vec<&str> = filename.split('.').collect();
+    let mut extensions: Vec<String> = Vec::new();
+    let mut current_extension = String::new();
+
+    for part in parts.iter().rev() {
+        if current_extension.is_empty() {
+            current_extension.push_str(part);
+        } else {
+            current_extension = format!("{}.{}", part, current_extension);
+        }
+        extensions.push(current_extension.clone());
+    }
+
+    extensions.pop();
+    extensions.reverse();
+
+    extensions
+}

crates/nu-command/tests/commands/open.rs

@@ -34,6 +34,69 @@ fn parses_file_with_uppercase_extension() {
     })
 }
 
+#[test]
+fn parses_file_with_multiple_extensions() {
+    Playground::setup("open_test_multiple_extensions", |dirs, sandbox| {
+        sandbox.with_files(vec![
+            FileWithContent("file.tar.gz", "this is a tar.gz file"),
+            FileWithContent("file.tar.xz", "this is a tar.xz file"),
+        ]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                hide "from tar.gz" ;
+                hide "from gz" ;
+
+                def "from tar.gz" [] { 'opened tar.gz' } ;
+                def "from gz" [] { 'opened gz' } ;
+                open file.tar.gz
+            "#
+        ));
+
+        assert_eq!(actual.out, "opened tar.gz");
+
+        let actual2 = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                hide "from tar.xz" ;
+                hide "from xz" ;
+                hide "from tar" ;
+
+                def "from tar" [] { 'opened tar' } ;
+                def "from xz" [] { 'opened xz' } ;
+                open file.tar.xz
+            "#
+        ));
+
+        assert_eq!(actual2.out, "opened xz");
+    })
+}
+
+#[test]
+fn parses_dotfile() {
+    Playground::setup("open_test_dotfile", |dirs, sandbox| {
+        sandbox.with_files(vec![FileWithContent(
+            ".gitignore",
+            r#"
+              /target/
+            "#,
+        )]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                hide "from gitignore" ;
+
+                def "from gitignore" [] { 'opened gitignore' } ;
+                open .gitignore
+            "#
+        ));
+
+        assert_eq!(actual.out, "opened gitignore");
+    })
+}
+
 #[test]
 fn parses_csv() {
     Playground::setup("open_test_1", |dirs, sandbox| {