// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#ifndef CARBON_TOOLCHAIN_DRIVER_DRIVER_H_
#define CARBON_TOOLCHAIN_DRIVER_DRIVER_H_

#include "common/command_line.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "llvm/Support/raw_ostream.h"

namespace Carbon {

// Command line interface driver.
//
// Provides simple API to parse and run command lines for Carbon.  It is
// generally expected to be used to implement command line tools for working
// with the language.
class Driver {
 public:
  // Constructs a driver with any error or informational output directed to a
  // specified stream.
  Driver(llvm::vfs::FileSystem& fs, llvm::raw_pwrite_stream& output_stream,
         llvm::raw_pwrite_stream& error_stream)
      : fs_(fs), output_stream_(output_stream), error_stream_(error_stream) {
    (void)fs_;
  }

  // Parses the given arguments into both a subcommand to select the operation
  // to perform and any arguments to that subcommand.
  //
  // Returns true if the operation succeeds. If the operation fails, returns
  // false and any information about the failure is printed to the registered
  // error stream (stderr by default).
  auto RunCommand(llvm::ArrayRef<llvm::StringRef> args) -> bool;

 private:
  struct Options;
  struct CompileOptions;

  // Delegates to the command line library to parse the arguments and store the
  // results in a custom `Options` structure that the rest of the driver uses.
  auto ParseArgs(llvm::ArrayRef<llvm::StringRef> args, Options& options)
      -> CommandLine::ParseResult;

  // Does custom validation of the compile-subcommand options structure beyond
  // what the command line parsing library supports.
  auto ValidateCompileOptions(const CompileOptions& options) const -> bool;

  // Implements the compile subcommand of the driver.
  auto Compile(const CompileOptions& options) -> bool;

  llvm::vfs::FileSystem& fs_;
  llvm::raw_pwrite_stream& output_stream_;
  llvm::raw_pwrite_stream& error_stream_;
  llvm::raw_pwrite_stream* vlog_stream_ = nullptr;
};

}  // namespace Carbon

#endif  // CARBON_TOOLCHAIN_DRIVER_DRIVER_H_