pound/core/Base/IoFile.h

// Copyright 2025 Xenon Emulator Project. All rights reserved.

#pragma once

#include <filesystem>
#include <span>

#include "Enum.h"
#include "PathUtil.h"

namespace Base::FS {

enum class FileAccessMode {
  /**
   * If the file at path exists, it opens the file for reading.
   * If the file at path does not exist, it fails to open the file.
   */
  Read = 1 << 0,
  /**
   * If the file at path exists, the existing contents of the file are erased.
   * The empty file is then opened for writing.
   * If the file at path does not exist, it creates and opens a new empty file for writing.
   */
  Write = 1 << 1,
  /**
   * If the file at path exists, it opens the file for reading and writing.
   * If the file at path does not exist, it fails to open the file.
   */
  ReadWrite = Read | Write,
  /**
   * If the file at path exists, it opens the file for appending.
   * If the file at path does not exist, it creates and opens a new empty file for appending.
   */
  Append = 1 << 2,
  /**
   * If the file at path exists, it opens the file for both reading and appending.
   * If the file at path does not exist, it creates and opens a new empty file for both
   * reading and appending.
   */
  ReadAppend = Read | Append
};
DECLARE_ENUM_FLAG_OPERATORS(FileAccessMode)

enum class FileMode {
  BinaryMode,
  TextMode
};

enum class FileShareFlag {
  ShareNone,      // Provides exclusive access to the file.
  ShareReadOnly,  // Provides read only shared access to the file.
  ShareWriteOnly, // Provides write only shared access to the file.
  ShareReadWrite  // Provides read and write shared access to the file.
};

enum class SeekOrigin : u32 {
  SetOrigin,       // Seeks from the start of the file.
  CurrentPosition, // Seeks from the current file pointer position.
  End              // Seeks from the end of the file.
};

class IOFile final {
public:
  IOFile();

  explicit IOFile(const std::string& path, FileAccessMode mode,
          FileMode type = FileMode::BinaryMode,
          FileShareFlag flag = FileShareFlag::ShareReadOnly);

  explicit IOFile(std::string_view path, FileAccessMode mode,
          FileMode type = FileMode::BinaryMode,
          FileShareFlag flag = FileShareFlag::ShareReadOnly);
  explicit IOFile(const fs::path &path, FileAccessMode mode,
          FileMode type = FileMode::BinaryMode,
          FileShareFlag flag = FileShareFlag::ShareReadOnly);

  ~IOFile();

  IOFile(const IOFile&) = delete;
  IOFile& operator=(const IOFile&) = delete;

  IOFile(IOFile&& other) noexcept;
  IOFile& operator=(IOFile&& other) noexcept;

  fs::path GetPath() const {
    return filePath;
  }

  FileAccessMode GetAccessMode() const {
    return fileAccessMode;
  }

  FileMode GetType() const {
    return fileType;
  }

  bool IsOpen() const {
    return file != nullptr;
  }

  uptr GetFileMapping();

  int Open(const fs::path& path, FileAccessMode mode,
       FileMode type = FileMode::BinaryMode,
       FileShareFlag flag = FileShareFlag::ShareReadOnly);
  void Close();

  void Unlink();

  bool Flush() const;
  bool Commit() const;

  bool SetSize(u64 size) const;
  u64 GetSize() const;

  bool Seek(s64 offset, SeekOrigin origin = SeekOrigin::SetOrigin) const;
  s64 Tell() const;

  template <typename T>
  size_t Read(T& data) const {
    if constexpr (std::contiguous_iterator<typename T::iterator>) {
      using ContiguousType = typename T::value_type;
      static_assert(std::is_trivially_copyable_v<ContiguousType>,
              "Data type must be trivially copyable.");
      return ReadSpan<ContiguousType>(data);
    } else {
      return ReadObject(data) ? 1 : 0;
    }
  }

  template <typename T>
  size_t Write(const T& data) const {
    if constexpr (std::contiguous_iterator<typename T::iterator>) {
      using ContiguousType = typename T::value_type;
      static_assert(std::is_trivially_copyable_v<ContiguousType>,
              "Data type must be trivially copyable.");
      return WriteSpan<ContiguousType>(data);
    } else {
      static_assert(std::is_trivially_copyable_v<T>, "Data type must be trivially copyable.");
      return WriteObject(data) ? 1 : 0;
    }
  }

  template <typename T>
  size_t ReadSpan(std::span<T> data) const {
    static_assert(std::is_trivially_copyable_v<T>, "Data type must be trivially copyable.");

    if (!IsOpen()) {
      return 0;
    }

    return ReadRaw<T>(data.data(), data.size());
  }

  template <typename T>
  size_t ReadRaw(void* data, size_t size) const {
    return std::fread(data, sizeof(T), size, file);
  }

  template <typename T>
  size_t WriteSpan(std::span<const T> data) const {
    static_assert(std::is_trivially_copyable_v<T>, "Data type must be trivially copyable.");

    if (!IsOpen()) {
      return 0;
    }

    return std::fwrite(data.data(), sizeof(T), data.size(), file);
  }

  template <typename T>
  bool ReadObject(T& object) const {
    static_assert(std::is_trivially_copyable_v<T>, "Data type must be trivially copyable.");
    static_assert(!std::is_pointer_v<T>, "T must not be a pointer to an object.");

    if (!IsOpen()) {
      return false;
    }

    return std::fread(&object, sizeof(T), 1, file) == 1;
  }

  template <typename T>
  size_t WriteRaw(const void* data, size_t size) const {
    return std::fwrite(data, sizeof(T), size, file);
  }

  template <typename T>
  bool WriteObject(const T& object) const {
    static_assert(std::is_trivially_copyable_v<T>, "Data type must be trivially copyable.");
    static_assert(!std::is_pointer_v<T>, "T must not be a pointer to an object.");

    if (!IsOpen()) {
      return false;
    }

    return std::fwrite(&object, sizeof(T), 1, file) == 1;
  }

  std::string ReadString(size_t length) const;

  size_t WriteString(std::span<const char> string) const {
    return WriteSpan(string);
  }

  static size_t WriteBytes(const fs::path path, const auto& data) {
    IOFile out(path, FileAccessMode::Write);
    return out.Write(data);
  }

private:
  fs::path filePath{};
  FileAccessMode fileAccessMode{};
  FileMode fileType{};

  std::FILE *file = nullptr;
  uptr fileMapping = 0;
};

u64 GetDirectorySize(const fs::path &path);

} // namespace Base::FS