verilization-lang-scala 0.1.0

use verilization_compiler::{lang, model, util, for_sep};

use model::Named;
use lang::{GeneratorError, Language, OutputHandler};
use std::ffi::OsString;
use std::collections::{HashMap, HashSet};
use std::io::Write;
use std::path::PathBuf;
use num_bigint::BigUint;
use lang::generator::*;
use util::{capitalize_identifier, uncapitalize_identifier};
use num_traits::ToPrimitive;

type PackageMap = HashMap<model::PackageName, model::PackageName>;
const RUNTIME_PACKAGE: &str = "dev.argon.verilization.scala_runtime";


pub struct ScalaOptionsBuilder {
	output_dir: Option<OsString>,
	package_mapping: PackageMap,
	library_mapping: PackageMap,
}

pub struct ScalaOptions {
	pub output_dir: OsString,
	pub package_mapping: PackageMap,
	pub library_mapping: PackageMap,
}

fn make_type_name(name: &str) -> String {
	let mut name = String::from(name);
	capitalize_identifier(&mut name);
	name
}

fn make_field_name(field_name: &str) -> String {
	let mut name = String::from(field_name);
	uncapitalize_identifier(&mut name);
	name
}


fn scala_package_impl<'a>(options: &'a ScalaOptions, package: &model::PackageName) -> Result<&'a model::PackageName, GeneratorError> {
	options.package_mapping.get(&package)
		.or_else(|| options.library_mapping.get(&package))
		.ok_or_else(|| GeneratorError::UnmappedPackage(package.clone()))
}





fn open_scala_file<'output, Output: OutputHandler<'output>>(options: &ScalaOptions, output: &'output mut Output, name: &model::QualifiedName) -> Result<Output::FileHandle, GeneratorError> {
	let java_pkg = scala_package_impl(options, &name.package)?;
	let mut path = PathBuf::from(&options.output_dir);
    for part in &java_pkg.package {
        path.push(part);
    }
	
	path.push(name.name.clone() + ".scala");
	Ok(output.create_file(path)?)
}


pub trait ScalaGenerator<'model, 'opt> : Generator<'model> + GeneratorWithFile {
	fn options(&self) -> &'opt ScalaOptions;
	fn referenced_types(&self) -> model::ReferencedTypeIterator<'model>;


	fn scala_package(&self, package: &model::PackageName) -> Result<&'opt model::PackageName, GeneratorError> {
		scala_package_impl(&self.options(), package)
	}

	fn write_package(&mut self, package: &model::PackageName) -> Result<(), GeneratorError> {
		
		let pkg = self.scala_package(package)?;

		let mut pkg_iter = pkg.package.iter();

		if let Some(part) = pkg_iter.next() {
			write!(self.file(), "package {}", part)?;
			while let Some(part) = pkg_iter.next() {
				write!(self.file(), ".{}", part)?;
			}
			writeln!(self.file())?;
		}

		Ok(())
	}

	fn write_qual_name(&mut self, name: &model::QualifiedName) -> Result<(), GeneratorError> {
		let pkg = self.scala_package(&name.package)?;
		for part in &pkg.package {
			write!(self.file(), "{}.", part)?;
		}
	
		write!(self.file(), "{}", make_type_name(&name.name))?;
	
		Ok(())
	}

	fn write_type_args(&mut self, args: &Vec<LangType<'model>>) -> Result<(), GeneratorError> {
		if !args.is_empty() {
			write!(self.file(), "[")?;
			for_sep!(arg, args, { write!(self.file(), ", ")?; }, {
				self.write_type(arg)?;
			});
			write!(self.file(), "]")?;
		}
	
		Ok(())
	}
	
	
	fn write_type(&mut self, t: &LangType<'model>) -> Result<(), GeneratorError> {
		Ok(match t {
			LangType::Versioned(_, name, version, args, _) => {
				self.write_qual_name(&name)?;
				write!(self.file(), ".V{}", version)?;
				self.write_type_args(args)?;
			},

			LangType::Extern(name, args, _) => {
				self.write_qual_name(name)?;
				self.write_type_args(args)?;
			},

			LangType::TypeParameter(name) => {
				write!(self.file(), "{}", name)?;
			},

			LangType::Converter(from, to) => {
				write!(self.file(), "{}.Converter[", RUNTIME_PACKAGE)?;
				self.write_type(&*from)?;
				write!(self.file(), ", ")?;
				self.write_type(&*to)?;
				write!(self.file(), "]")?;
			},

			LangType::Codec(t) => {
				write!(self.file(), "{}.Codec[", RUNTIME_PACKAGE)?;
				self.write_type(&*t)?;
				write!(self.file(), "]")?;
			},
		})
	}

	fn write_args(&mut self, args: &Vec<LangExpr<'model>>) -> Result<(), GeneratorError> {
		if !args.is_empty() {
			write!(self.file(), "(")?;
			for_sep!(arg, args, { write!(self.file(), ", ")?; }, {
				self.write_expr(&arg)?;
			});
			write!(self.file(), ")")?;
		}

		Ok(())
	}

	fn write_operation_name(&mut self, op: &Operation) -> Result<(), GeneratorError> {
		match op {
			Operation::FromPreviousVersion(prev_ver) => write!(self.file(), "fromV{}", prev_ver)?,
			Operation::FinalTypeConverter => write!(self.file(), "converter")?,
			Operation::TypeCodec => write!(self.file(), "codec")?,
			Operation::FromInteger => write!(self.file(), "fromInteger")?,
			Operation::FromString => write!(self.file(), "fromString")?,
			Operation::FromSequence => write!(self.file(), "fromSequence")?,
			Operation::FromRecord(_) => write!(self.file(), "fromRecord")?,
			Operation::FromCase(name) => write!(self.file(), "fromCase{}", make_type_name(name))?,
		}

		Ok(())
	}

	fn write_expr(&mut self, expr: &LangExpr<'model>) -> Result<(), GeneratorError> {
		match expr {
			LangExpr::Identifier(name) => write!(self.file(), "{}", name)?,
			LangExpr::IntegerLiteral(n) => {
				if let Some(n) = n.to_i32() {
					write!(self.file(), "{}", n)?;
				}
				else if let Some(n) = n.to_i64() {
					write!(self.file(), "{}L", n)?;
				}
				else {
					write!(self.file(), "scala.math.BigInt(\"{}\")", n)?;
				}
			},
			LangExpr::StringLiteral(s) => {
				write!(self.file(), "\"")?;
				for codepoint in s.chars() {
					match codepoint {
						'"' => write!(self.file(), "\\\"")?,
						'\\' => write!(self.file(), "\\\\")?,
						'\n' => write!(self.file(), "\\n")?,
						'\r' => write!(self.file(), "\\r")?,
						_ => write!(self.file(), "{}", codepoint)?,
					}
				}
				write!(self.file(), "\"")?;
			},
			LangExpr::InvokeConverter { converter, value } => {
				self.write_expr(&*converter)?;
				write!(self.file(), ".convert(")?;
				self.write_expr(&*value)?;
				write!(self.file(), ")")?;
			},
			LangExpr::IdentityConverter(t) => {
				write!(self.file(), "{}.Converter.identity[", RUNTIME_PACKAGE)?;
				self.write_type(t)?;
				write!(self.file(), "]")?;
			},
			LangExpr::ReadDiscriminator => write!(self.file(), "{}.Nat.codec.read(reader)", RUNTIME_PACKAGE)?,
			LangExpr::WriteDiscriminator(value) => write!(self.file(), "{}.Nat.codec.write(writer, {})", RUNTIME_PACKAGE, value)?,
			LangExpr::CodecRead { codec } => {
				self.write_expr(&*codec)?;
				write!(self.file(), ".read(reader)")?;
			},
			LangExpr::CodecWrite { codec, value } => {
				self.write_expr(&*codec)?;
				write!(self.file(), ".write(writer, ")?;
				self.write_expr(value)?;
				write!(self.file(), ")")?;
			},
			LangExpr::InvokeOperation(op, target, type_args, args) => {
				match target {
					OperationTarget::VersionedType(name, version) => {
						self.write_qual_name(name)?;
						write!(self.file(), ".V{}.", version)?;
					},
					OperationTarget::ExternType(name) => {
						self.write_qual_name(name)?;
						write!(self.file(), ".")?;
					},
				}
				self.write_operation_name(op)?;
				self.write_type_args(type_args)?;
				match op {
					Operation::FromRecord(field_names) => {
						write!(self.file(), "(")?;
						for_sep!((field_name, arg), field_names.iter().zip(args.iter()), { write!(self.file(), ", ")?; }, {
							write!(self.file(), "{} = ", make_field_name(field_name))?;
							self.write_expr(arg)?;
						});
						write!(self.file(), ")")?;
					},
					_ => self.write_args(args)?,
				}
			},
			LangExpr::InvokeUserConverter { name, prev_ver, version, type_args, args } => {
				self.write_qual_name(name)?;
				write!(self.file(), "_Conversions.v{}ToV{}", prev_ver, version)?;
				self.write_type_args(type_args)?;
				self.write_args(args)?;
			},
			LangExpr::ConstantValue(name, version) => {
				self.write_qual_name(name)?;
				write!(self.file(), ".{}", ScalaLanguage::constant_version_name(version))?;
			},
			LangExpr::CreateStruct(name, version, type_args, fields) => {
				write!(self.file(), "new ")?;
				self.write_qual_name(name)?;
				write!(self.file(), ".V{}", version)?;
				self.write_type_args(type_args)?;
				write!(self.file(), "(")?;
				for_sep!((_, value), fields, { write!(self.file(), ", ")?; }, {
					self.write_expr(value)?;
				});
				write!(self.file(), ")")?;
			},
			LangExpr::CreateEnum(name, version, type_args, field_name, value) => {
				write!(self.file(), "new ")?;
				self.write_qual_name(name)?;
				write!(self.file(), ".V{}.{}", version, make_type_name(field_name))?;
				self.write_type_args(type_args)?;
				write!(self.file(), "(")?;
				self.write_expr(value)?;
				write!(self.file(), ")")?;
			},
			LangExpr::StructField(_, _, field_name, value) => {
				self.write_expr(value)?;
				write!(self.file(), ".{}", make_field_name(field_name))?;
			},
		}

		Ok(())
	}
	
}

impl GeneratorNameMapping for ScalaLanguage {
	fn convert_prev_type_param(param: &str) -> String {
		format!("{}_1", param)
	}

	fn convert_current_type_param(param: &str) -> String {
		format!("{}_2", param)
	}

	fn convert_conv_param_name(param: &str) -> String {
		format!("{}_conv", param)
	}

	fn convert_prev_param_name() -> &'static str {
		"prev"
	}

	fn codec_write_value_name() -> &'static str {
		"value"
	}

	fn codec_codec_param_name(param: &str) -> String {
		format!("{}_codec", param)
	}

	fn constant_version_name(version: &BigUint) -> String {
		format!("v{}", version)
	}
}

struct ScalaConstGenerator<'model, 'opt, 'output, Output: OutputHandler<'output>> {
	file: Output::FileHandle,
	model: &'model model::Verilization,
	options: &'opt ScalaOptions,
	constant: Named<'model, model::Constant>,
	scope: model::Scope<'model>,
}

impl <'model, 'opt, 'output, Output: OutputHandler<'output>> Generator<'model> for ScalaConstGenerator<'model, 'opt, 'output, Output> {
	type Lang = ScalaLanguage;
	
	fn model(&self) -> &'model model::Verilization {
		self.model
	}

	fn scope(&self) -> &model::Scope<'model> {
		&self.scope
	}
}

impl <'model, 'opt, 'output, Output: OutputHandler<'output>> GeneratorWithFile for ScalaConstGenerator<'model, 'opt, 'output, Output> {
	type GeneratorFile = Output::FileHandle;
	fn file(&mut self) -> &mut Self::GeneratorFile {
		&mut self.file
	}
}

impl <'model, 'opt, 'output, Output: OutputHandler<'output>> ScalaGenerator<'model, 'opt> for ScalaConstGenerator<'model, 'opt, 'output, Output> {
	fn options(&self) -> &'opt ScalaOptions {
		self.options
	}

	fn referenced_types(&self) -> model::ReferencedTypeIterator<'model> {
		self.constant.referenced_types()
	}
}

impl <'model, 'opt, 'output, Output: OutputHandler<'output>> ConstGenerator<'model> for ScalaConstGenerator<'model, 'opt, 'output, Output> {
	fn constant(&self) -> Named<'model, model::Constant> {
		self.constant
	}

	fn write_header(&mut self) -> Result<(), GeneratorError> {
        self.write_package(&self.constant.name().package)?;

		writeln!(self.file, "object {} {{", make_type_name(&self.constant.name().name))?;

		Ok(())
	}

	fn write_constant(&mut self, version_name: String, t: LangType<'model>, value: LangExpr<'model>) -> Result<(), GeneratorError> {
		write!(self.file, "\tval {}: ", version_name)?;
		self.write_type(&t)?;
		write!(self.file, " = ")?;
		self.write_expr(&value)?;
		writeln!(self.file)?;

		Ok(())
	}

	fn write_footer(&mut self) -> Result<(), GeneratorError> {
		writeln!(self.file, "}}")?;
		Ok(())
	}
}


impl <'model, 'opt, 'output, Output: OutputHandler<'output>> ScalaConstGenerator<'model, 'opt, 'output, Output> {

	fn open(model: &'model model::Verilization, options: &'opt ScalaOptions, output: &'output mut Output, constant: Named<'model, model::Constant>) -> Result<Self, GeneratorError> {
		let file = open_scala_file(options, output, constant.name())?;
		Ok(ScalaConstGenerator {
			file: file,
			model: model,
			options: options,
			constant: constant,
			scope: constant.scope(),
		})
	}

}

struct ScalaTypeGenerator<'model, 'opt, 'output, Output: OutputHandler<'output>> {
	options: &'opt ScalaOptions,
	model: &'model model::Verilization,
	file: Output::FileHandle,
	type_def: Named<'model, model::VersionedTypeDefinitionData>,
	scope: model::Scope<'model>,
	indentation_level: u32,
}

impl <'model, 'opt, 'output, Output: OutputHandler<'output>> Generator<'model> for ScalaTypeGenerator<'model, 'opt, 'output, Output> {
	type Lang = ScalaLanguage;

	fn model(&self) -> &'model model::Verilization {
		self.model
	}

	fn scope(&self) -> &model::Scope<'model> {
		&self.scope
	}
}

impl <'model, 'opt, 'output, Output: OutputHandler<'output>> GeneratorWithFile for ScalaTypeGenerator<'model, 'opt, 'output, Output> {
	type GeneratorFile = Output::FileHandle;
	fn file(&mut self) -> &mut Self::GeneratorFile {
		&mut self.file
	}
}

impl <'model, 'opt, 'output, Output: OutputHandler<'output>> Indentation for ScalaTypeGenerator<'model, 'opt, 'output, Output> {
	fn indentation_size(&mut self) -> &mut u32 {
		&mut self.indentation_level
	}
}

impl <'model, 'opt, 'output, Output: OutputHandler<'output>> ScalaGenerator<'model, 'opt> for ScalaTypeGenerator<'model, 'opt, 'output, Output> {
	fn options(&self) -> &'opt ScalaOptions {
		self.options
	}

	fn referenced_types(&self) -> model::ReferencedTypeIterator<'model> {
		self.type_def.referenced_types()
	}
}

impl <'model, 'opt, 'output, Output: OutputHandler<'output>> VersionedTypeGenerator<'model> for ScalaTypeGenerator<'model, 'opt, 'output, Output> {
	fn type_def(&self) -> Named<'model, model::VersionedTypeDefinitionData> {
		self.type_def
	}

	fn write_header(&mut self) -> Result<(), GeneratorError> {
		self.write_package(&self.type_def.name().package)?;
		writeln!(self.file, "sealed abstract class {}", make_type_name(&self.type_def.name().name))?;
		writeln!(self.file, "object {} {{", make_type_name(&self.type_def.name().name))?;
		self.indent_increase();
		
		Ok(())
	}

	fn write_version_header(&mut self, t: LangType<'model>) -> Result<(), GeneratorError> {
		match t {
			LangType::Versioned(VersionedTypeKind::Struct, _, version, _, fields) => {
				self.write_indent()?;
				write!(self.file, "final case class V{}", version)?;
				self.write_type_params(&self.type_def().type_params())?;
				writeln!(self.file, "(")?;
				self.indent_increase();

				for field in fields.build()? {
					self.write_indent()?;
					write!(self.file, "{}: ", make_field_name(field.name))?;
					self.write_type(&field.field_type)?;
					writeln!(self.file, ",")?;
				}

				self.indent_decrease();
				self.write_indent()?;
				writeln!(self.file, ") extends {}", self.type_def.name().name)?;

				self.write_indent()?;
				writeln!(self.file, "object V{} {{", version)?;
				self.indent_increase();
			},
			LangType::Versioned(VersionedTypeKind::Enum, _, version, _, fields) => {
				self.write_indent()?;
				write!(self.file, "sealed abstract class V{}", version)?;
				self.write_type_params(&self.type_def().type_params())?;
				writeln!(self.file, " extends {}", self.type_def.name().name)?;

				self.write_indent()?;
				writeln!(self.file, "object V{} {{", version)?;
				self.indent_increase();

				for field in fields.build()? {
					self.write_indent()?;
					write!(self.file, "final case class {}", make_type_name(field.name))?;
					self.write_type_params(&self.type_def().type_params())?;
					write!(self.file, "({}: ", make_field_name(field.name))?;
					self.write_type(&field.field_type)?;
					write!(self.file, ") extends V{}", version)?;
					self.write_type_params(&self.type_def().type_params())?;
					writeln!(self.file)?;
				}
			},
			_ => return Err(GeneratorError::CouldNotGenerateType)
		}

		Ok(())
	}

	fn write_operation(&mut self, operation: OperationInfo<'model>) -> Result<(), GeneratorError> {
		let is_func = !operation.type_params.is_empty() || !operation.params.is_empty();

		self.write_indent()?;
		if is_func {
			write!(self.file, "def ")?;
		}
		else {
			write!(self.file, "val ")?;
		}

		self.write_operation_name(&operation.operation)?;
		self.write_type_params(&operation.type_params)?;
		if is_func {
			write!(self.file, "(")?;
			for_sep!((param_name, param), operation.params, { write!(self.file, ", ")?; }, {
				write!(self.file, "{}: ", param_name)?;
				self.write_type(&param)?;
			});
			write!(self.file, ")")?;
		}
		write!(self.file, ": ")?;
		self.write_type(&operation.result)?;
		write!(self.file, " = ")?;

		self.write_expr_statement(operation.implementation)?;


		Ok(())
	}

	fn write_version_footer(&mut self) -> Result<(), GeneratorError> {
		self.indent_decrease();
		writeln!(self.file, "}}")?;

		Ok(())
	}

	fn write_footer(&mut self) -> Result<(), GeneratorError> {
		self.indent_decrease();
		writeln!(self.file, "}}")?;
		
		Ok(())
	}

}

impl <'model, 'opt, 'output, Output: OutputHandler<'output>> ScalaTypeGenerator<'model, 'opt, 'output, Output> {


	fn open(model: &'model model::Verilization, options: &'opt ScalaOptions, output: &'output mut Output, type_def: Named<'model, model::VersionedTypeDefinitionData>) -> Result<Self, GeneratorError> {
		let file = open_scala_file(options, output, type_def.name())?;
		Ok(ScalaTypeGenerator {
			file: file,
			model: model,
			options: options,
			type_def: type_def,
			scope: type_def.scope(),
			indentation_level: 0,
		})
	}

	fn write_expr_statement(&mut self, stmt: LangExprStmt<'model>) -> Result<(), GeneratorError> {
		match stmt {
			LangExprStmt::Expr(expr) => {
				self.write_expr(&expr)?;
				writeln!(self.file, ";")?;
			},

			LangExprStmt::CreateCodec { t, read, write } => {
				write!(self.file, "new {}.Codec[", RUNTIME_PACKAGE)?;
				self.write_type(&t)?;
				writeln!(self.file, "] {{")?;
				self.indent_increase();


				self.write_indent()?;
				write!(self.file, "override def read[R, E](reader: {}.FormatReader[R, E]): zio.ZIO[R, E, ", RUNTIME_PACKAGE)?;
				self.write_type(&t)?;
				write!(self.file, "] = ")?;
				
				self.write_statement(*read, true)?;

				self.write_indent()?;
				write!(self.file, "override def write[R, E](writer: {}.FormatWriter[R, E], value: ", RUNTIME_PACKAGE)?;
				self.write_type(&t)?;
				write!(self.file, "): zio.ZIO[R, E, Unit] = ")?;

				self.write_statement(*write, true)?;

				self.indent_decrease();
				self.write_indent()?;
				writeln!(self.file, "}}")?;
			},

			LangExprStmt::CreateConverter { from_type, to_type, body } => {
				write!(self.file, "new {}.Converter[", RUNTIME_PACKAGE)?;
				self.write_type(&from_type)?;
				write!(self.file, ", ")?;
				self.write_type(&to_type)?;
				writeln!(self.file, "] {{")?;
				self.indent_increase();


				self.write_indent()?;
				write!(self.file, "override def convert({}: ", ScalaLanguage::convert_prev_param_name())?;
				self.write_type(&from_type)?;
				write!(self.file, "): ")?;
				self.write_type(&to_type)?;
				write!(self.file, " = ")?;

				self.write_statement(*body, false)?;

				self.indent_decrease();
				self.write_indent()?;
				writeln!(self.file, "}};")?;
			},
		}

		Ok(())
	}

	fn record_io_expr(&self, expr: &mut LangExpr<'model>, ops: &mut Vec<(String, LangExpr<'model>)>) {
		let name = format!("value{}", ops.len());
		let old_expr = std::mem::replace(expr, LangExpr::Identifier(name.clone()));
		ops.push((name, old_expr));
	}

	fn gather_io_exprs(&self, expr: &mut LangExpr<'model>, ops: &mut Vec<(String, LangExpr<'model>)>) {
		match expr {
			LangExpr::ReadDiscriminator | LangExpr::WriteDiscriminator(_) => self.record_io_expr(expr, ops),

			LangExpr::CodecRead { codec } => {
				self.gather_io_exprs(codec, ops);
				self.record_io_expr(expr, ops);
			},
			LangExpr::CodecWrite { codec, value } => {
				self.gather_io_exprs(codec, ops);
				self.gather_io_exprs(value, ops);
				self.record_io_expr(expr, ops);
			},



			LangExpr::InvokeConverter { converter, value } => {
				self.gather_io_exprs(converter, ops);
				self.gather_io_exprs(value, ops);
			},

			LangExpr::InvokeOperation(_, _, _, args) => {
				for arg in args {
					self.gather_io_exprs(arg, ops);
				}
			},
			LangExpr::InvokeUserConverter { args, .. } => {
				for arg in args {
					self.gather_io_exprs(arg, ops);
				}
			},
			LangExpr::CreateStruct(_, _, _, fields) => {
				for (_, value) in fields {
					self.gather_io_exprs(value, ops);
				}
			},
			LangExpr::CreateEnum(_, _, _, _, value) => {
				self.gather_io_exprs(value, ops);
			},
			LangExpr::StructField(_, _, _, value) => {
				self.gather_io_exprs(value, ops);
			},
			_ => (),
		}
	}
	
	fn write_statement(&mut self, stmt: LangStmt<'model>, use_io: bool) -> Result<(), GeneratorError> {
		match stmt {
			LangStmt::Expr(mut exprs, mut result_expr) if use_io => {

				let mut io_ops = Vec::new();
				let mut ignored_values = HashSet::new();

				for mut expr in &mut exprs {
					self.gather_io_exprs(&mut expr, &mut io_ops);
					match expr {
						LangExpr::Identifier(name) => { ignored_values.insert(name.clone()); },
						_ => (),
					};
				}
				
				if let Some(result_expr) = &mut result_expr {
					self.gather_io_exprs(result_expr, &mut io_ops);
				}

				if io_ops.is_empty() {
					write!(self.file, "zio.IO.succeed(")?;
					if let Some(result_expr) = result_expr {
						self.write_expr(&result_expr)?;
					}
					else {
						write!(self.file, "()")?;
					}
					writeln!(self.file, ")")?;
				}
				else {
					writeln!(self.file, "for {{")?;
					self.indent_increase();
	
					for (name, expr) in io_ops {
						self.write_indent()?;
						if ignored_values.contains(&name) {
							write!(self.file, "_")?;
						}
						else {
							write!(self.file, "{}", name)?;
						}
						write!(self.file, " <- ")?;
						self.write_expr(&expr)?;
						writeln!(self.file)?;
					}
	
					self.indent_decrease();
					self.write_indent()?;
					write!(self.file, "}} yield ")?;
	
					if let Some(result_expr) = result_expr {
						self.write_expr(&result_expr)?;
					}
					else {
						write!(self.file, "()")?;
					}
	
					writeln!(self.file)?;
				}
			},

			LangStmt::Expr(exprs, result_expr) => {
				writeln!(self.file, "{{")?;
				self.indent_increase();

				for expr in exprs {
					self.write_indent()?;
					self.write_expr(&expr)?;
					writeln!(self.file)?;
				}

				if let Some(result_expr) = result_expr {
					self.write_indent()?;
					self.write_expr(&result_expr)?;
					writeln!(self.file)?;
				}

				self.indent_decrease();
				self.write_indent()?;
				writeln!(self.file, "}}")?;
			},

			LangStmt::MatchEnum { mut value, value_type, cases } => {
				if cases.is_empty() {
					self.write_expr(&value)?;
					writeln!(self.file)?;
					return Ok(())
				}

				let mut io_ops = Vec::new();
				if use_io {
					self.gather_io_exprs(&mut value, &mut io_ops);
				}

				for (name, op) in &io_ops {
					self.write_expr(op)?;
					writeln!(self.file, ".flatMap {{ {} =>", name)?;
					self.indent_increase();
					self.write_indent()?;
				}


				self.write_expr(&value)?;
				writeln!(self.file, " match {{")?;
				self.indent_increase();

				for MatchCase { binding_name, case_name, body } in cases {
					self.write_indent()?;
					write!(self.file, "case ")?;
					match &value_type {
						LangType::Versioned(_, name, version, _, _) => {
							self.write_qual_name(name)?;
							write!(self.file, ".V{}.{}({})", version, make_type_name(&case_name), binding_name)?;
						},
						_ => panic!("Invalid enum type."),
					}
					
					write!(self.file, " => ")?;

					self.write_statement(body, use_io)?;
				}
				
				self.indent_decrease();
				self.write_indent()?;
				writeln!(self.file, "}}")?;



				for _ in &io_ops {
					self.indent_decrease();
					self.write_indent()?;
					writeln!(self.file, "}}")?;
				}
			},

			LangStmt::MatchDiscriminator { mut value, cases } => {
				let mut io_ops = Vec::new();
				if use_io {
					self.gather_io_exprs(&mut value, &mut io_ops);
				}

				for (name, op) in &io_ops {
					self.write_expr(op)?;
					writeln!(self.file, ".flatMap {{ {} =>", name)?;
					self.indent_increase();
					self.write_indent()?;
				}

				self.write_expr(&value)?;
				writeln!(self.file, " match {{")?;
				self.indent_increase();

				for (n, body) in cases {
					self.write_indent()?;
					write!(self.file, "case {}.Util.BigIntValue({}) => ", RUNTIME_PACKAGE, n)?;

					self.write_statement(body, use_io)?;
				}
				
				self.indent_decrease();
				self.write_indent()?;
				writeln!(self.file, "}}")?;

				for _ in &io_ops {
					self.indent_decrease();
					self.write_indent()?;
					writeln!(self.file, "}}")?;
				}
			},
			

		}

		Ok(())
	}

	fn write_type_params(&mut self, params: &Vec<String>) -> Result<(), GeneratorError> {
		if !params.is_empty() {
			write!(self.file, "[")?;
			for_sep!(param, params, { write!(self.file, ", ")?; }, {
				write!(self.file, "{}", param)?;
			});
			write!(self.file, "]")?;
		}
	
		Ok(())
	}
}


pub struct ScalaLanguage {}

impl Language for ScalaLanguage {
	type OptionsBuilder = ScalaOptionsBuilder;
	type Options = ScalaOptions;

    fn name() -> &'static str {
        "scala"
    }

	fn empty_options() -> ScalaOptionsBuilder {
		ScalaOptionsBuilder {
			output_dir: None,
			package_mapping: HashMap::new(),
			library_mapping: HashMap::new(),
		}
	}

	fn add_option(builder: &mut ScalaOptionsBuilder, name: &str, value: OsString) -> Result<(), GeneratorError> {
		if name == "out_dir" {
			if builder.output_dir.is_some() {
				return Err(GeneratorError::InvalidOptions(String::from("Output directory already specified")))
			}

			builder.output_dir = Some(value);
			Ok(())
		}
		else if let Some(pkg) = name.strip_prefix("pkg:") {
			let package = model::PackageName::from_str(pkg);

            let scala_package = model::PackageName::from_str(value.to_str().unwrap());

			if builder.library_mapping.contains_key(&package) || builder.package_mapping.insert(package, scala_package).is_some() {
				return Err(GeneratorError::InvalidOptions(format!("Package already mapped: {}", pkg)))
			}
			Ok(())
		}
		else if let Some(pkg) = name.strip_prefix("lib:") {
			let package = model::PackageName::from_str(pkg);

            let scala_package = model::PackageName::from_str(value.to_str().unwrap());

			if builder.package_mapping.contains_key(&package) || builder.library_mapping.insert(package, scala_package).is_some() {
				return Err(GeneratorError::InvalidOptions(format!("Package already mapped: {}", pkg)))
			}
			Ok(())
		}
		else {
			Err(GeneratorError::InvalidOptions(format!("Unknown option: {}", name)))
		}
	}

	fn finalize_options(builder: Self::OptionsBuilder) -> Result<Self::Options, GeneratorError> {
		Ok(ScalaOptions {
			output_dir: builder.output_dir.ok_or_else(|| GeneratorError::InvalidOptions(String::from("Output directory not specified")))?,
			package_mapping: builder.package_mapping,
			library_mapping: builder.library_mapping,
		})
	}

	fn generate<Output: for<'output> OutputHandler<'output>>(model: &model::Verilization, options: Self::Options, output: &mut Output) -> Result<(), GeneratorError> {
		for constant in model.constants() {
			let mut const_gen = ScalaConstGenerator::open(model, &options, output, constant)?;
			const_gen.generate()?;
		}

		for t in model.types() {
			match t {
				model::NamedTypeDefinition::StructType(t) | model::NamedTypeDefinition::EnumType(t) => {
					let mut type_gen = ScalaTypeGenerator::open(model, &options, output, t)?;
					type_gen.generate()?;		
				},
				model::NamedTypeDefinition::ExternType(_) => (),
			}
		}

		Ok(())
	}

}