diff --git a/native/src/lib.rs b/native/src/lib.rs
index 3d4405f8fbf..90382ab90d1 100644
--- a/native/src/lib.rs
+++ b/native/src/lib.rs
@@ -9,24 +9,19 @@ extern crate path_clean;
 extern crate serde;
 extern crate swc;
 
-use anyhow::{Context as _, Error};
+use anyhow::Error;
 use backtrace::Backtrace;
 use neon::prelude::*;
-use path_clean::clean;
-use std::{
-    env,
-    panic::set_hook,
-    path::{Path, PathBuf},
-    sync::Arc,
-};
+use std::{env, panic::set_hook, sync::Arc};
 use swc::{
-    common::{self, errors::Handler, FileName, FilePathMapping, SourceFile, SourceMap},
-    config::{Options, ParseOptions, SourceMapsConfig},
-    ecmascript::ast::Program,
+    common::{self, errors::Handler, FilePathMapping, SourceMap},
     Compiler, TransformOutput,
 };
 
 mod bundle;
+mod parse;
+mod print;
+mod transform;
 
 fn init(_cx: MethodContext<JsUndefined>) -> NeonResult<ArcCompiler> {
     if cfg!(debug_assertions) || env::var("SWC_DEBUG").unwrap_or_else(|_| String::new()) == "1" {
@@ -50,24 +45,7 @@ fn init(_cx: MethodContext<JsUndefined>) -> NeonResult<ArcCompiler> {
     Ok(Arc::new(c))
 }
 
-/// Input to transform
-#[derive(Debug)]
-enum Input {
-    /// json string
-    Program(String),
-    /// Raw source code.
-    Source(Arc<SourceFile>),
-    /// File
-    File(PathBuf),
-}
-
-struct TransformTask {
-    c: Arc<Compiler>,
-    input: Input,
-    options: Options,
-}
-
-fn complete_output<'a>(
+pub fn complete_output<'a>(
     mut cx: impl Context<'a>,
     result: Result<TransformOutput, Error>,
 ) -> JsResult<'a, JsValue> {
@@ -77,439 +55,6 @@ fn complete_output<'a>(
     }
 }
 
-impl Task for TransformTask {
-    type Output = TransformOutput;
-    type Error = Error;
-    type JsEvent = JsValue;
-
-    fn perform(&self) -> Result<Self::Output, Self::Error> {
-        self.c.run(|| match self.input {
-            Input::Program(ref s) => {
-                let program: Program =
-                    serde_json::from_str(&s).expect("failed to deserialize Program");
-                // TODO: Source map
-                self.c.process_js(program, &self.options)
-            }
-
-            Input::File(ref path) => {
-                let fm = self.c.cm.load_file(path).context("failed to read module")?;
-                self.c.process_js_file(fm, &self.options)
-            }
-
-            Input::Source(ref s) => self.c.process_js_file(s.clone(), &self.options),
-        })
-    }
-
-    fn complete(
-        self,
-        cx: TaskContext,
-        result: Result<Self::Output, Self::Error>,
-    ) -> JsResult<Self::JsEvent> {
-        complete_output(cx, result)
-    }
-}
-
-/// returns `compiler, (src / path), options, plugin, callback`
-fn schedule_transform<F>(mut cx: MethodContext<JsCompiler>, op: F) -> JsResult<JsValue>
-where
-    F: FnOnce(&Arc<Compiler>, String, bool, Options) -> TransformTask,
-{
-    let c;
-    let this = cx.this();
-    {
-        let guard = cx.lock();
-        c = this.borrow(&guard).clone();
-    };
-
-    let s = cx.argument::<JsString>(0)?.value();
-    let is_module = cx.argument::<JsBoolean>(1)?;
-    let options_arg = cx.argument::<JsValue>(2)?;
-
-    let options: Options = neon_serde::from_value(&mut cx, options_arg)?;
-    let callback = cx.argument::<JsFunction>(3)?;
-
-    let task = op(&c, s, is_module.value(), options);
-    task.schedule(callback);
-
-    Ok(cx.undefined().upcast())
-}
-
-fn exec_transform<F>(mut cx: MethodContext<JsCompiler>, op: F) -> JsResult<JsValue>
-where
-    F: FnOnce(&Compiler, String, &Options) -> Result<Arc<SourceFile>, Error>,
-{
-    let s = cx.argument::<JsString>(0)?;
-    let is_module = cx.argument::<JsBoolean>(1)?;
-    let options: Options = match cx.argument_opt(2) {
-        Some(v) => neon_serde::from_value(&mut cx, v)?,
-        None => {
-            let obj = cx.empty_object().upcast();
-            neon_serde::from_value(&mut cx, obj)?
-        }
-    };
-
-    let this = cx.this();
-    let output = {
-        let guard = cx.lock();
-        let c = this.borrow(&guard);
-        c.run(|| {
-            if is_module.value() {
-                let program: Program =
-                    serde_json::from_str(&s.value()).expect("failed to deserialize Program");
-                c.process_js(program, &options)
-            } else {
-                let fm = op(&c, s.value(), &options).expect("failed to create fm");
-                c.process_js_file(fm, &options)
-            }
-        })
-    };
-
-    complete_output(cx, output)
-}
-
-fn transform(cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
-    schedule_transform(cx, |c, src, is_module, options| {
-        let input = if is_module {
-            Input::Program(src)
-        } else {
-            Input::Source(c.cm.new_source_file(
-                if options.filename.is_empty() {
-                    FileName::Anon
-                } else {
-                    FileName::Real(options.filename.clone().into())
-                },
-                src,
-            ))
-        };
-
-        TransformTask {
-            c: c.clone(),
-            input,
-            options,
-        }
-    })
-}
-
-fn transform_sync(cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
-    exec_transform(cx, |c, src, options| {
-        Ok(c.cm.new_source_file(
-            if options.filename.is_empty() {
-                FileName::Anon
-            } else {
-                FileName::Real(options.filename.clone().into())
-            },
-            src,
-        ))
-    })
-}
-
-fn transform_file(cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
-    schedule_transform(cx, |c, path, _, options| {
-        let path = clean(&path);
-
-        TransformTask {
-            c: c.clone(),
-            input: Input::File(path.into()),
-            options,
-        }
-    })
-}
-
-fn transform_file_sync(cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
-    exec_transform(cx, |c, path, _| {
-        Ok(c.cm
-            .load_file(Path::new(&path))
-            .expect("failed to load file"))
-    })
-}
-
-// ----- Parsing -----
-
-struct ParseTask {
-    c: Arc<Compiler>,
-    fm: Arc<SourceFile>,
-    options: ParseOptions,
-}
-
-struct ParseFileTask {
-    c: Arc<Compiler>,
-    path: PathBuf,
-    options: ParseOptions,
-}
-
-fn complete_parse<'a>(
-    mut cx: impl Context<'a>,
-    result: Result<Program, Error>,
-    c: &Compiler,
-) -> JsResult<'a, JsValue> {
-    c.run(|| match result {
-        Ok(program) => Ok(cx
-            .string(serde_json::to_string(&program).expect("failed to serialize Program"))
-            .upcast()),
-        Err(err) => cx.throw_error(format!("{:?}", err)),
-    })
-}
-
-impl Task for ParseTask {
-    type Output = Program;
-    type Error = Error;
-    type JsEvent = JsValue;
-
-    fn perform(&self) -> Result<Self::Output, Self::Error> {
-        self.c.run(|| {
-            self.c.parse_js(
-                self.fm.clone(),
-                self.options.target,
-                self.options.syntax,
-                self.options.is_module,
-                self.options.comments,
-            )
-        })
-    }
-
-    fn complete(
-        self,
-        cx: TaskContext,
-        result: Result<Self::Output, Self::Error>,
-    ) -> JsResult<Self::JsEvent> {
-        complete_parse(cx, result, &self.c)
-    }
-}
-
-impl Task for ParseFileTask {
-    type Output = Program;
-    type Error = Error;
-    type JsEvent = JsValue;
-
-    fn perform(&self) -> Result<Self::Output, Self::Error> {
-        self.c.run(|| {
-            let fm = self
-                .c
-                .cm
-                .load_file(&self.path)
-                .context("failed to read module")?;
-
-            self.c.parse_js(
-                fm,
-                self.options.target,
-                self.options.syntax,
-                self.options.is_module,
-                self.options.comments,
-            )
-        })
-    }
-
-    fn complete(
-        self,
-        cx: TaskContext,
-        result: Result<Self::Output, Self::Error>,
-    ) -> JsResult<Self::JsEvent> {
-        complete_parse(cx, result, &self.c)
-    }
-}
-
-fn parse(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
-    let src = cx.argument::<JsString>(0)?;
-    let options_arg = cx.argument::<JsValue>(1)?;
-    let options: ParseOptions = neon_serde::from_value(&mut cx, options_arg)?;
-    let callback = cx.argument::<JsFunction>(2)?;
-
-    let this = cx.this();
-    {
-        let guard = cx.lock();
-        let c = this.borrow(&guard);
-
-        let fm = c.cm.new_source_file(FileName::Anon, src.value());
-
-        ParseTask {
-            c: c.clone(),
-            fm,
-            options,
-        }
-        .schedule(callback);
-    };
-
-    Ok(cx.undefined().upcast())
-}
-
-fn parse_sync(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
-    let c;
-    let this = cx.this();
-    {
-        let guard = cx.lock();
-        let compiler = this.borrow(&guard);
-        c = compiler.clone();
-    }
-    c.run(|| {
-        let src = cx.argument::<JsString>(0)?;
-        let options_arg = cx.argument::<JsValue>(1)?;
-        let options: ParseOptions = neon_serde::from_value(&mut cx, options_arg)?;
-
-        let program = {
-            let fm = c.cm.new_source_file(FileName::Anon, src.value());
-            c.parse_js(
-                fm,
-                options.target,
-                options.syntax,
-                options.is_module,
-                options.comments,
-            )
-        };
-
-        complete_parse(cx, program, &c)
-    })
-}
-
-fn parse_file_sync(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
-    let c;
-    let this = cx.this();
-    {
-        let guard = cx.lock();
-        let compiler = this.borrow(&guard);
-        c = compiler.clone();
-    }
-    c.run(|| {
-        let path = cx.argument::<JsString>(0)?;
-        let options_arg = cx.argument::<JsValue>(1)?;
-        let options: ParseOptions = neon_serde::from_value(&mut cx, options_arg)?;
-
-        let program = {
-            let fm =
-                c.cm.load_file(Path::new(&path.value()))
-                    .expect("failed to read program file");
-
-            c.parse_js(
-                fm,
-                options.target,
-                options.syntax,
-                options.is_module,
-                options.comments,
-            )
-        };
-
-        complete_parse(cx, program, &c)
-    })
-}
-
-fn parse_file(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
-    let path = cx.argument::<JsString>(0)?;
-    let options_arg = cx.argument::<JsValue>(1)?;
-    let options: ParseOptions = neon_serde::from_value(&mut cx, options_arg)?;
-    let callback = cx.argument::<JsFunction>(2)?;
-
-    let this = cx.this();
-    {
-        let guard = cx.lock();
-        let c = this.borrow(&guard);
-
-        ParseFileTask {
-            c: c.clone(),
-            path: path.value().into(),
-            options,
-        }
-        .schedule(callback);
-    };
-
-    Ok(cx.undefined().upcast())
-}
-
-// ----- Printing -----
-
-struct PrintTask {
-    c: Arc<Compiler>,
-    program: Program,
-    options: Options,
-}
-
-impl Task for PrintTask {
-    type Output = TransformOutput;
-    type Error = Error;
-    type JsEvent = JsValue;
-    fn perform(&self) -> Result<Self::Output, Self::Error> {
-        self.c.run(|| {
-            self.c.print(
-                &self.program,
-                self.options
-                    .source_maps
-                    .clone()
-                    .unwrap_or(SourceMapsConfig::Bool(false)),
-                None,
-                self.options
-                    .config
-                    .clone()
-                    .unwrap_or_default()
-                    .minify
-                    .unwrap_or(false),
-            )
-        })
-    }
-
-    fn complete(
-        self,
-        cx: TaskContext,
-        result: Result<Self::Output, Self::Error>,
-    ) -> JsResult<Self::JsEvent> {
-        complete_output(cx, result)
-    }
-}
-
-fn print(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
-    let program = cx.argument::<JsString>(0)?;
-    let program: Program =
-        serde_json::from_str(&program.value()).expect("failed to deserialize Program");
-
-    let options = cx.argument::<JsValue>(1)?;
-    let options: Options = neon_serde::from_value(&mut cx, options)?;
-
-    let callback = cx.argument::<JsFunction>(2)?;
-
-    let this = cx.this();
-    {
-        let guard = cx.lock();
-        let c = this.borrow(&guard);
-
-        PrintTask {
-            c: c.clone(),
-            program,
-            options,
-        }
-        .schedule(callback)
-    }
-
-    Ok(cx.undefined().upcast())
-}
-
-fn print_sync(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
-    let c;
-    let this = cx.this();
-    {
-        let guard = cx.lock();
-        let compiler = this.borrow(&guard);
-        c = compiler.clone();
-    }
-    c.run(|| {
-        let program = cx.argument::<JsString>(0)?;
-        let program: Program =
-            serde_json::from_str(&program.value()).expect("failed to deserialize Program");
-
-        let options = cx.argument::<JsValue>(1)?;
-        let options: Options = neon_serde::from_value(&mut cx, options)?;
-
-        let result = {
-            c.print(
-                &program,
-                options
-                    .source_maps
-                    .clone()
-                    .unwrap_or(SourceMapsConfig::Bool(false)),
-                None,
-                options.config.unwrap_or_default().minify.unwrap_or(false),
-            )
-        };
-        complete_output(cx, result)
-    })
-}
-
 pub type ArcCompiler = Arc<Compiler>;
 
 declare_types! {
@@ -519,43 +64,43 @@ declare_types! {
         }
 
         method transform(cx) {
-            transform(cx)
+            transform::transform(cx)
         }
 
         method transformSync(cx) {
-            transform_sync(cx)
+            transform::transform_sync(cx)
         }
 
         method transformFile(cx) {
-            transform_file(cx)
+            transform::transform_file(cx)
         }
 
         method transformFileSync(cx) {
-            transform_file_sync(cx)
+            transform::transform_file_sync(cx)
         }
 
         method parse(cx) {
-            parse(cx)
+            parse::parse(cx)
         }
 
         method parseSync(cx) {
-            parse_sync(cx)
+            parse::parse_sync(cx)
         }
 
         method parseFile(cx) {
-            parse_file(cx)
+            parse::parse_file(cx)
         }
 
         method parseFileSync(cx) {
-            parse_file_sync(cx)
+            parse::parse_file_sync(cx)
         }
 
         method print(cx) {
-            print(cx)
+            print::print(cx)
         }
 
         method printSync(cx) {
-            print_sync(cx)
+            print::print_sync(cx)
         }
 
         method bundle(cx) {
diff --git a/native/src/parse.rs b/native/src/parse.rs
new file mode 100644
index 00000000000..81d14635f6c
--- /dev/null
+++ b/native/src/parse.rs
@@ -0,0 +1,203 @@
+use crate::JsCompiler;
+use anyhow::{Context as _, Error};
+use neon::prelude::*;
+use std::{
+    path::{Path, PathBuf},
+    sync::Arc,
+};
+use swc::{
+    common::{FileName, SourceFile},
+    config::ParseOptions,
+    ecmascript::ast::Program,
+    Compiler,
+};
+
+// ----- Parsing -----
+
+pub struct ParseTask {
+    pub c: Arc<Compiler>,
+    pub fm: Arc<SourceFile>,
+    pub options: ParseOptions,
+}
+
+pub struct ParseFileTask {
+    pub c: Arc<Compiler>,
+    pub path: PathBuf,
+    pub options: ParseOptions,
+}
+
+pub fn complete_parse<'a>(
+    mut cx: impl Context<'a>,
+    result: Result<Program, Error>,
+    c: &Compiler,
+) -> JsResult<'a, JsValue> {
+    c.run(|| match result {
+        Ok(program) => Ok(cx
+            .string(serde_json::to_string(&program).expect("failed to serialize Program"))
+            .upcast()),
+        Err(err) => cx.throw_error(format!("{:?}", err)),
+    })
+}
+
+impl Task for ParseTask {
+    type Output = Program;
+    type Error = Error;
+    type JsEvent = JsValue;
+
+    fn perform(&self) -> Result<Self::Output, Self::Error> {
+        self.c.run(|| {
+            self.c.parse_js(
+                self.fm.clone(),
+                self.options.target,
+                self.options.syntax,
+                self.options.is_module,
+                self.options.comments,
+            )
+        })
+    }
+
+    fn complete(
+        self,
+        cx: TaskContext,
+        result: Result<Self::Output, Self::Error>,
+    ) -> JsResult<Self::JsEvent> {
+        complete_parse(cx, result, &self.c)
+    }
+}
+
+impl Task for ParseFileTask {
+    type Output = Program;
+    type Error = Error;
+    type JsEvent = JsValue;
+
+    fn perform(&self) -> Result<Self::Output, Self::Error> {
+        self.c.run(|| {
+            let fm = self
+                .c
+                .cm
+                .load_file(&self.path)
+                .context("failed to read module")?;
+
+            self.c.parse_js(
+                fm,
+                self.options.target,
+                self.options.syntax,
+                self.options.is_module,
+                self.options.comments,
+            )
+        })
+    }
+
+    fn complete(
+        self,
+        cx: TaskContext,
+        result: Result<Self::Output, Self::Error>,
+    ) -> JsResult<Self::JsEvent> {
+        complete_parse(cx, result, &self.c)
+    }
+}
+
+pub fn parse(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
+    let src = cx.argument::<JsString>(0)?;
+    let options_arg = cx.argument::<JsValue>(1)?;
+    let options: ParseOptions = neon_serde::from_value(&mut cx, options_arg)?;
+    let callback = cx.argument::<JsFunction>(2)?;
+
+    let this = cx.this();
+    {
+        let guard = cx.lock();
+        let c = this.borrow(&guard);
+
+        let fm = c.cm.new_source_file(FileName::Anon, src.value());
+
+        ParseTask {
+            c: c.clone(),
+            fm,
+            options,
+        }
+        .schedule(callback);
+    };
+
+    Ok(cx.undefined().upcast())
+}
+
+pub fn parse_sync(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
+    let c;
+    let this = cx.this();
+    {
+        let guard = cx.lock();
+        let compiler = this.borrow(&guard);
+        c = compiler.clone();
+    }
+    c.run(|| {
+        let src = cx.argument::<JsString>(0)?;
+        let options_arg = cx.argument::<JsValue>(1)?;
+        let options: ParseOptions = neon_serde::from_value(&mut cx, options_arg)?;
+
+        let program = {
+            let fm = c.cm.new_source_file(FileName::Anon, src.value());
+            c.parse_js(
+                fm,
+                options.target,
+                options.syntax,
+                options.is_module,
+                options.comments,
+            )
+        };
+
+        complete_parse(cx, program, &c)
+    })
+}
+
+pub fn parse_file_sync(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
+    let c;
+    let this = cx.this();
+    {
+        let guard = cx.lock();
+        let compiler = this.borrow(&guard);
+        c = compiler.clone();
+    }
+    c.run(|| {
+        let path = cx.argument::<JsString>(0)?;
+        let options_arg = cx.argument::<JsValue>(1)?;
+        let options: ParseOptions = neon_serde::from_value(&mut cx, options_arg)?;
+
+        let program = {
+            let fm =
+                c.cm.load_file(Path::new(&path.value()))
+                    .expect("failed to read program file");
+
+            c.parse_js(
+                fm,
+                options.target,
+                options.syntax,
+                options.is_module,
+                options.comments,
+            )
+        };
+
+        complete_parse(cx, program, &c)
+    })
+}
+
+pub fn parse_file(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
+    let path = cx.argument::<JsString>(0)?;
+    let options_arg = cx.argument::<JsValue>(1)?;
+    let options: ParseOptions = neon_serde::from_value(&mut cx, options_arg)?;
+    let callback = cx.argument::<JsFunction>(2)?;
+
+    let this = cx.this();
+    {
+        let guard = cx.lock();
+        let c = this.borrow(&guard);
+
+        ParseFileTask {
+            c: c.clone(),
+            path: path.value().into(),
+            options,
+        }
+        .schedule(callback);
+    };
+
+    Ok(cx.undefined().upcast())
+}
diff --git a/native/src/print.rs b/native/src/print.rs
new file mode 100644
index 00000000000..67d6e5c2892
--- /dev/null
+++ b/native/src/print.rs
@@ -0,0 +1,106 @@
+use crate::{complete_output, JsCompiler};
+use anyhow::Error;
+use neon::prelude::*;
+use std::sync::Arc;
+use swc::{
+    config::{Options, SourceMapsConfig},
+    ecmascript::ast::Program,
+    Compiler, TransformOutput,
+};
+
+// ----- Printing -----
+
+pub struct PrintTask {
+    pub c: Arc<Compiler>,
+    pub program: Program,
+    pub options: Options,
+}
+
+impl Task for PrintTask {
+    type Output = TransformOutput;
+    type Error = Error;
+    type JsEvent = JsValue;
+    fn perform(&self) -> Result<Self::Output, Self::Error> {
+        self.c.run(|| {
+            self.c.print(
+                &self.program,
+                self.options
+                    .source_maps
+                    .clone()
+                    .unwrap_or(SourceMapsConfig::Bool(false)),
+                None,
+                self.options
+                    .config
+                    .clone()
+                    .unwrap_or_default()
+                    .minify
+                    .unwrap_or(false),
+            )
+        })
+    }
+
+    fn complete(
+        self,
+        cx: TaskContext,
+        result: Result<Self::Output, Self::Error>,
+    ) -> JsResult<Self::JsEvent> {
+        complete_output(cx, result)
+    }
+}
+
+pub fn print(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
+    let program = cx.argument::<JsString>(0)?;
+    let program: Program =
+        serde_json::from_str(&program.value()).expect("failed to deserialize Program");
+
+    let options = cx.argument::<JsValue>(1)?;
+    let options: Options = neon_serde::from_value(&mut cx, options)?;
+
+    let callback = cx.argument::<JsFunction>(2)?;
+
+    let this = cx.this();
+    {
+        let guard = cx.lock();
+        let c = this.borrow(&guard);
+
+        PrintTask {
+            c: c.clone(),
+            program,
+            options,
+        }
+        .schedule(callback)
+    }
+
+    Ok(cx.undefined().upcast())
+}
+
+pub fn print_sync(mut cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
+    let c;
+    let this = cx.this();
+    {
+        let guard = cx.lock();
+        let compiler = this.borrow(&guard);
+        c = compiler.clone();
+    }
+    c.run(|| {
+        let program = cx.argument::<JsString>(0)?;
+        let program: Program =
+            serde_json::from_str(&program.value()).expect("failed to deserialize Program");
+
+        let options = cx.argument::<JsValue>(1)?;
+        let options: Options = neon_serde::from_value(&mut cx, options)?;
+
+        let result = {
+            c.print(
+                &program,
+                options
+                    .source_maps
+                    .clone()
+                    .unwrap_or(SourceMapsConfig::Bool(false)),
+                None,
+                options.config.unwrap_or_default().minify.unwrap_or(false),
+            )
+        };
+        complete_output(cx, result)
+    })
+}
diff --git a/native/src/transform.rs b/native/src/transform.rs
new file mode 100644
index 00000000000..356e2b5faac
--- /dev/null
+++ b/native/src/transform.rs
@@ -0,0 +1,176 @@
+use crate::{complete_output, JsCompiler};
+use anyhow::{Context as _, Error};
+use neon::prelude::*;
+use path_clean::clean;
+use std::{
+    path::{Path, PathBuf},
+    sync::Arc,
+};
+use swc::{
+    common::{FileName, SourceFile},
+    config::Options,
+    ecmascript::ast::Program,
+    Compiler, TransformOutput,
+};
+/// Input to transform
+#[derive(Debug)]
+pub enum Input {
+    /// json string
+    Program(String),
+    /// Raw source code.
+    Source(Arc<SourceFile>),
+    /// File
+    File(PathBuf),
+}
+
+pub struct TransformTask {
+    pub c: Arc<Compiler>,
+    pub input: Input,
+    pub options: Options,
+}
+
+impl Task for TransformTask {
+    type Output = TransformOutput;
+    type Error = Error;
+    type JsEvent = JsValue;
+
+    fn perform(&self) -> Result<Self::Output, Self::Error> {
+        self.c.run(|| match self.input {
+            Input::Program(ref s) => {
+                let program: Program =
+                    serde_json::from_str(&s).expect("failed to deserialize Program");
+                // TODO: Source map
+                self.c.process_js(program, &self.options)
+            }
+
+            Input::File(ref path) => {
+                let fm = self.c.cm.load_file(path).context("failed to read module")?;
+                self.c.process_js_file(fm, &self.options)
+            }
+
+            Input::Source(ref s) => self.c.process_js_file(s.clone(), &self.options),
+        })
+    }
+
+    fn complete(
+        self,
+        cx: TaskContext,
+        result: Result<Self::Output, Self::Error>,
+    ) -> JsResult<Self::JsEvent> {
+        complete_output(cx, result)
+    }
+}
+
+/// returns `compiler, (src / path), options, plugin, callback`
+pub fn schedule_transform<F>(mut cx: MethodContext<JsCompiler>, op: F) -> JsResult<JsValue>
+where
+    F: FnOnce(&Arc<Compiler>, String, bool, Options) -> TransformTask,
+{
+    let c;
+    let this = cx.this();
+    {
+        let guard = cx.lock();
+        c = this.borrow(&guard).clone();
+    };
+
+    let s = cx.argument::<JsString>(0)?.value();
+    let is_module = cx.argument::<JsBoolean>(1)?;
+    let options_arg = cx.argument::<JsValue>(2)?;
+
+    let options: Options = neon_serde::from_value(&mut cx, options_arg)?;
+    let callback = cx.argument::<JsFunction>(3)?;
+
+    let task = op(&c, s, is_module.value(), options);
+    task.schedule(callback);
+
+    Ok(cx.undefined().upcast())
+}
+
+pub fn exec_transform<F>(mut cx: MethodContext<JsCompiler>, op: F) -> JsResult<JsValue>
+where
+    F: FnOnce(&Compiler, String, &Options) -> Result<Arc<SourceFile>, Error>,
+{
+    let s = cx.argument::<JsString>(0)?;
+    let is_module = cx.argument::<JsBoolean>(1)?;
+    let options: Options = match cx.argument_opt(2) {
+        Some(v) => neon_serde::from_value(&mut cx, v)?,
+        None => {
+            let obj = cx.empty_object().upcast();
+            neon_serde::from_value(&mut cx, obj)?
+        }
+    };
+
+    let this = cx.this();
+    let output = {
+        let guard = cx.lock();
+        let c = this.borrow(&guard);
+        c.run(|| {
+            if is_module.value() {
+                let program: Program =
+                    serde_json::from_str(&s.value()).expect("failed to deserialize Program");
+                c.process_js(program, &options)
+            } else {
+                let fm = op(&c, s.value(), &options).expect("failed to create fm");
+                c.process_js_file(fm, &options)
+            }
+        })
+    };
+
+    complete_output(cx, output)
+}
+
+pub fn transform(cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
+    schedule_transform(cx, |c, src, is_module, options| {
+        let input = if is_module {
+            Input::Program(src)
+        } else {
+            Input::Source(c.cm.new_source_file(
+                if options.filename.is_empty() {
+                    FileName::Anon
+                } else {
+                    FileName::Real(options.filename.clone().into())
+                },
+                src,
+            ))
+        };
+
+        TransformTask {
+            c: c.clone(),
+            input,
+            options,
+        }
+    })
+}
+
+pub fn transform_sync(cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
+    exec_transform(cx, |c, src, options| {
+        Ok(c.cm.new_source_file(
+            if options.filename.is_empty() {
+                FileName::Anon
+            } else {
+                FileName::Real(options.filename.clone().into())
+            },
+            src,
+        ))
+    })
+}
+
+pub fn transform_file(cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
+    schedule_transform(cx, |c, path, _, options| {
+        let path = clean(&path);
+
+        TransformTask {
+            c: c.clone(),
+            input: Input::File(path.into()),
+            options,
+        }
+    })
+}
+
+pub fn transform_file_sync(cx: MethodContext<JsCompiler>) -> JsResult<JsValue> {
+    exec_transform(cx, |c, path, _| {
+        Ok(c.cm
+            .load_file(Path::new(&path))
+            .expect("failed to load file"))
+    })
+}