feat(oxfmt): Support .oxfmtrc.json(c) config file (#14398)

Fixes #13611

- Support config file with JSON(C) format
- Automatically find the nearest one from `cwd`
  - Do not merge, just use the first one
  - Search only `.oxfmtrc.json`(not `.jsonc`)
- Use `-c` or `--config` to specify path

Example `.oxfmtrc.json`:

```jsonc
{
  "indentStyle": "space",
  "indentWidth": 2,
  "lineWidth": 80,
  "lineEnding": "lf",
  "quoteStyle": "single",
  "jsxQuoteStyle": "double",
  "quoteProperties": "as-needed",
  "trailingCommas": "all",
  "semicolons": "always",
  "arrowParentheses": "always",
  "bracketSpacing": true,
  "bracketSameLine": false,
  "attributePosition": "auto",
  "expand": "auto",
  "experimentalOperatorPosition": "before",
  "experimentalSortImports": {
    "partitionByNewline": false,
    "partitionByComment": false,
    "sortSideEffects": false,
    "order": "asc",
    "ignoreCase": true
  }
}
```

We may provide tools like `oxfmt-migrate` to convert `.prettierrc`.

Author: leaysgur

Cargo.lock

@@ -24,6 +24,9 @@ pub struct FormatCommand {
     #[bpaf(external, fallback(OutputOptions::DefaultWrite))]
     pub output_options: OutputOptions,
 
+    #[bpaf(external)]
+    pub basic_options: BasicOptions,
+
     #[bpaf(external)]
     pub misc_options: MiscOptions,
 
@@ -49,6 +52,14 @@ pub enum OutputOptions {
     ListDifferent,
 }
 
+/// Basic Options
+#[derive(Debug, Clone, Bpaf)]
+pub struct BasicOptions {
+    /// Path to the configuration file
+    #[bpaf(short, long, argument("PATH"))]
+    pub config: Option<PathBuf>,
+}
+
 /// Miscellaneous
 #[derive(Debug, Clone, Bpaf)]
 pub struct MiscOptions {

apps/oxfmt/src/command.rs

@@ -1,8 +1,15 @@
-use std::{env, io::Write, path::PathBuf, sync::mpsc, time::Instant};
+use std::{
+    env,
+    io::Write,
+    path::{Path, PathBuf},
+    sync::mpsc,
+    time::Instant,
+};
 
 use ignore::overrides::OverrideBuilder;
 
 use oxc_diagnostics::DiagnosticService;
+use oxc_formatter::{FormatOptions, Oxfmtrc};
 
 use crate::{
     cli::{CliRunResult, FormatCommand},
@@ -37,7 +44,19 @@ impl FormatRunner {
         let start_time = Instant::now();
 
         let cwd = self.cwd;
-        let FormatCommand { paths, output_options, misc_options } = self.options;
+        let FormatCommand { paths, output_options, basic_options, misc_options } = self.options;
+
+        // Find and load config
+        let format_options = match load_config(&cwd, basic_options.config.as_ref()) {
+            Ok(options) => options,
+            Err(err) => {
+                print_and_flush_stdout(
+                    stdout,
+                    &format!("Failed to load configuration file.\n{err}\n"),
+                );
+                return CliRunResult::InvalidOptionConfig;
+            }
+        };
 
         // Default to current working directory if no paths are provided
         let paths = if paths.is_empty() { vec![cwd.clone()] } else { paths };
@@ -82,7 +101,7 @@ impl FormatRunner {
         let output_options_clone = output_options.clone();
         // Spawn a thread to run formatting service with streaming entries
         rayon::spawn(move || {
-            let format_service = FormatService::new(cwd, output_options_clone);
+            let format_service = FormatService::new(cwd, output_options_clone, format_options);
             format_service.run_streaming(rx_entry, &tx_error, tx_count);
         });
 
@@ -156,6 +175,40 @@ impl FormatRunner {
     }
 }
 
+const DEFAULT_OXFMTRC: &str = ".oxfmtrc.json";
+
+/// # Errors
+///
+/// Returns error if:
+/// - Config file is specified but not found or invalid
+/// - Config file parsing fails
+fn load_config(cwd: &Path, config: Option<&PathBuf>) -> Result<FormatOptions, String> {
+    // If `--config` is explicitly specified, use that path directly
+    if let Some(config_path) = config {
+        let full_path = if config_path.is_absolute() {
+            PathBuf::from(config_path)
+        } else {
+            cwd.join(config_path)
+        };
+
+        // This will error if the file does not exist or is invalid
+        let oxfmtrc = Oxfmtrc::from_file(&full_path)?;
+        return oxfmtrc.into_format_options();
+    }
+
+    // If `--config` is not specified, search the nearest config file from cwd upwards
+    for dir in cwd.ancestors() {
+        let config_path = dir.join(DEFAULT_OXFMTRC);
+        if config_path.exists() {
+            let oxfmtrc = Oxfmtrc::from_file(&config_path)?;
+            return oxfmtrc.into_format_options();
+        }
+    }
+
+    // No config file found, use defaults
+    Ok(FormatOptions::default())
+}
+
 fn print_and_flush_stdout(stdout: &mut dyn Write, message: &str) {
     use std::io::{Error, ErrorKind};
     fn check_for_writer_error(error: Error) -> Result<(), Error> {

apps/oxfmt/src/format.rs

@@ -13,14 +13,15 @@ use crate::{command::OutputOptions, walk::WalkEntry};
 pub struct FormatService {
     cwd: Box<Path>,
     output_options: OutputOptions,
+    format_options: FormatOptions,
 }
 
 impl FormatService {
-    pub fn new<T>(cwd: T, output_options: OutputOptions) -> Self
+    pub fn new<T>(cwd: T, output_options: OutputOptions, format_options: FormatOptions) -> Self
     where
         T: Into<Box<Path>>,
     {
-        Self { cwd: cwd.into(), output_options }
+        Self { cwd: cwd.into(), output_options, format_options }
     }
 
     /// Process entries as they are received from the channel
@@ -72,9 +73,7 @@ impl FormatService {
             return;
         }
 
-        // TODO: Read and apply config
-        let options = FormatOptions::default();
-        let code = Formatter::new(&allocator, options).build(&ret.program);
+        let code = Formatter::new(&allocator, self.format_options.clone()).build(&ret.program);
 
         let elapsed = start_time.elapsed();
         let is_changed = source_text != code;

apps/oxfmt/src/service.rs

@@ -0,0 +1,3 @@
+{
+  "semicolons": "always"
+}

apps/oxfmt/tests/fixtures/config_file/.oxfmtrc.json

@@ -0,0 +1,3 @@
+{
+  "semicolons": "always"
+}

apps/oxfmt/tests/fixtures/config_file/fmt.json

@@ -0,0 +1,4 @@
+{
+  // Supports JSONC!
+  "semicolons": "always"
+}

apps/oxfmt/tests/fixtures/config_file/fmt.jsonc

@@ -0,0 +1,3 @@
+{
+  "semicolons": "always"
+}

apps/oxfmt/tests/fixtures/config_file/nested/.oxfmtrc.jsonc

@@ -0,0 +1 @@
+const a = 1

apps/oxfmt/tests/fixtures/config_file/nested/deep/test.js

@@ -49,3 +49,29 @@ fn write_mode() {
     let after = "class Foo {}\n";
     Tester::test_write("tests/fixtures/temp.js", before, after);
 }
+
+#[test]
+fn config_file_auto_discovery() {
+    Tester::new()
+        .with_cwd(PathBuf::from("tests/fixtures/config_file"))
+        .test_and_snapshot_multiple(&[&["--check"]]);
+
+    Tester::new()
+        .with_cwd(PathBuf::from("tests/fixtures/config_file/nested"))
+        .test_and_snapshot_multiple(&[&["--check"]]);
+
+    Tester::new()
+        .with_cwd(PathBuf::from("tests/fixtures/config_file/nested/deep"))
+        .test_and_snapshot_multiple(&[&["--check"]]);
+}
+
+#[test]
+fn config_file_explicit() {
+    Tester::new().with_cwd(PathBuf::from("tests/fixtures/config_file")).test_and_snapshot_multiple(
+        &[
+            &["--check", "--config", "./fmt.json"],
+            &["--check", "--config", "./fmt.jsonc"],
+            &["--check", "--config", "NOT_EXISTS.json"],
+        ],
+    );
+}