// 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_TESTING_FILE_TEST_FILE_TEST_BASE_H_
#define CARBON_TESTING_FILE_TEST_FILE_TEST_BASE_H_

#include <gmock/gmock.h>
#include <gtest/gtest.h>

#include <functional>
#include <mutex>

#include "common/error.h"
#include "common/ostream.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "testing/file_test/autoupdate.h"
#include "testing/file_test/manifest.h"

namespace Carbon::Testing {

// A framework for testing files. See README.md for documentation.
class FileTestBase {
 public:
  // Provided for child class convenience.
  using LineNumberReplacement = FileTestAutoupdater::LineNumberReplacement;
  using CheckLineArray = FileTestAutoupdater::CheckLineArray;

  // The result of Run(), used to detect errors. Failing test files should be
  // named with a `fail_` prefix to indicate an expectation of failure.
  //
  // If per_file_success is empty:
  // - The main file has a `fail_` prefix if !success.
  // - The prefix of split files is unused.
  //
  // If per_file_success is non-empty:
  // - Each file has a `fail_` prefix if !per_file_success[i].second.
  //   - Files may be in per_file_success that aren't part of the main test
  //     file. This allows tracking success in handling files that are
  //     well-known, such as standard libraries. It is still the responsibility
  //     of callers to use a `fail_` prefix if !per_file_success[i].second.
  // - If any file has a `fail_` prefix, success must be false, and the prefix
  //   of the main file is unused.
  // - If no file has a `fail_` prefix, the main file has a `fail_` prefix if
  //   !success.
  struct RunResult {
    bool success;

    // Per-file success results. May be empty.
    llvm::SmallVector<std::pair<std::string, bool>> per_file_success;
  };

  explicit FileTestBase(llvm::StringRef test_name) : test_name_(test_name) {}
  virtual ~FileTestBase() = default;

  // Implemented by children to run the test. The framework will validate the
  // content written to `output_stream` and `error_stream`. Children should use
  // `fs` for file content, and may add more files.
  //
  // If there is a split test file named "STDIN", then its contents will be
  // provided at `input_stream` instead of `fs`. Otherwise, `input_stream` will
  // be null.
  //
  // This cannot be used for test expectations, such as EXPECT_TRUE.
  //
  // The return value should be an error if there was an abnormal error, and
  // RunResult otherwise.
  virtual auto Run(const llvm::SmallVector<llvm::StringRef>& test_args,
                   llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem>& fs,
                   FILE* input_stream, llvm::raw_pwrite_stream& output_stream,
                   llvm::raw_pwrite_stream& error_stream) const
      -> ErrorOr<RunResult> = 0;

  // Returns default arguments. Only called when a file doesn't set ARGS.
  virtual auto GetDefaultArgs() const -> llvm::SmallVector<std::string> = 0;

  // Returns a map of string replacements to implement `%{key}` -> `value` in
  // arguments.
  virtual auto GetArgReplacements() const -> llvm::StringMap<std::string> {
    return {};
  }

  // Returns a regex to match the default file when a line may not be present.
  // May return nullptr if unused. If GetLineNumberReplacements returns an entry
  // with has_file=false, this is required.
  virtual auto GetDefaultFileRE(llvm::ArrayRef<llvm::StringRef> /*filenames*/)
      const -> std::optional<RE2> {
    return std::nullopt;
  }

  // Returns replacement information for line numbers. See LineReplacement for
  // construction.
  virtual auto GetLineNumberReplacements(
      llvm::ArrayRef<llvm::StringRef> filenames) const
      -> llvm::SmallVector<LineNumberReplacement>;

  // Optionally allows children to provide extra replacements for autoupdate.
  virtual auto DoExtraCheckReplacements(std::string& /*check_line*/) const
      -> void {}

  // Optionally allows children to perform tweaks on check lines before
  // they are merged into the output file.
  virtual auto FinalizeCheckLines(CheckLineArray& /*check_lines*/,
                                  bool /*is_stderr*/) const -> void {}

  // Whether to allow running the test in parallel, particularly for autoupdate.
  // This can be overridden to force some tests to be run serially. At any given
  // time, all parallel tests and a single non-parallel test will be allowed to
  // run.
  virtual auto AllowParallelRun() const -> bool { return true; }

  // Modes for GetBazelCommand.
  enum class BazelMode : uint8_t {
    Autoupdate,
    Dump,
    Test,
  };

  // Returns the requested bazel command string for the given execution mode.
  auto GetBazelCommand(BazelMode mode) -> std::string;

  auto test_name() const -> llvm::StringRef { return test_name_; }

 private:
  llvm::StringRef test_name_;
};

// Aggregate a name and factory function for tests using this framework.
struct FileTestFactory {
  // The test fixture name.
  const char* name;

  // A factory function for tests.
  std::function<auto(llvm::StringRef exe_path, llvm::StringRef test_name)
                    ->std::unique_ptr<FileTestBase>>
      factory_fn;
};

// Must be implemented by the individual file_test to initialize tests.
//
// We can't use INSTANTIATE_TEST_CASE_P because of ordering issues between
// container initialization and test instantiation by InitGoogleTest, but this
// also allows us more flexibility in execution.
//
// The `CARBON_FILE_TEST_FACTOR` macro below provides a standard, convenient way
// to implement this function.
extern auto GetFileTestFactory() -> FileTestFactory;

// Provides a standard GetFileTestFactory implementation.
#define CARBON_FILE_TEST_FACTORY(Name)                                       \
  auto GetFileTestFactory() -> FileTestFactory {                             \
    return {#Name, [](llvm::StringRef exe_path, llvm::StringRef test_name) { \
              return std::make_unique<Name>(exe_path, test_name);            \
            }};                                                              \
  }

}  // namespace Carbon::Testing

#endif  // CARBON_TESTING_FILE_TEST_FILE_TEST_BASE_H_
