#ifndef C10_UTIL_EXCEPTION_H_
#define C10_UTIL_EXCEPTION_H_

#include <c10/macros/Macros.h>
#include <c10/util/Deprecated.h>
#include <c10/util/StringUtil.h>
#include <c10/util/variant.h>

#include <cstddef>
#include <exception>
#include <ostream>
#include <sstream>
#include <string>
#include <vector>

#if defined(_MSC_VER) && _MSC_VER <= 1900
#define __func__ __FUNCTION__
#endif

namespace c10 {

/// The primary ATen error class.
/// Provides a complete error message with source location information via
/// `what()`, and a more concise message via `what_without_backtrace()`.
/// Don't throw this directly; use TORCH_CHECK/TORCH_INTERNAL_ASSERT instead.
///
/// NB: c10::Error is handled specially by the default torch to suppress the
/// backtrace, see torch/csrc/Exceptions.h
class C10_API Error : public std::exception {
  // The actual error message.
  std::string msg_;

  // Context for the message (in order of decreasing specificity).  Context will
  // be automatically formatted appropriately, so it is not necessary to add
  // extra leading/trailing newlines to strings inside this vector
  std::vector<std::string> context_;

  // The C++ backtrace at the point when this exception was raised.  This
  // may be empty if there is no valid backtrace.  (We don't use optional
  // here to reduce the dependencies this file has.)
  std::string backtrace_;

  // These two are derived fields from msg_stack_ and backtrace_, but we need
  // fields for the strings so that we can return a const char* (as the
  // signature of std::exception requires).  Currently, the invariant
  // is that these fields are ALWAYS populated consistently with respect
  // to msg_stack_ and backtrace_.
  std::string what_;
  std::string what_without_backtrace_;

  // This is a little debugging trick: you can stash a relevant pointer
  // in caller, and then when you catch the exception, you can compare
  // against pointers you have on hand to get more information about
  // where the exception came from.  In Caffe2, this is used to figure
  // out which operator raised an exception.
  const void* caller_;

 public:
  // PyTorch-style Error constructor.  NB: the implementation of this
  // is actually in Logging.cpp
  Error(SourceLocation source_location, std::string msg);

  // Caffe2-style error message
  Error(
      const char* file,
      const uint32_t line,
      const char* condition,
      const std::string& msg,
      const std::string& backtrace,
      const void* caller = nullptr);

  // Base constructor
  Error(std::string msg, std::string backtrace, const void* caller = nullptr);

  // Add some new context to the message stack.  The last added context
  // will be formatted at the end of the context list upon printing.
  // WARNING: This method is O(n) in the size of the stack, so don't go
  // wild adding a ridiculous amount of context to error messages.
  void add_context(std::string msg);

  const std::string& msg() const {
    return msg_;
  }

  const std::vector<std::string>& context() const {
    return context_;
  }

  const std::string& backtrace() const {
    return backtrace_;
  }

  /// Returns the complete error message, including the source location.
  /// The returned pointer is invalidated if you call add_context() on
  /// this object.
  const char* what() const noexcept override {
    return what_.c_str();
  }

  const void* caller() const noexcept {
    return caller_;
  }

  /// Returns only the error message string, without source location.
  /// The returned pointer is invalidated if you call add_context() on
  /// this object.
  const char* what_without_backtrace() const noexcept {
    return what_without_backtrace_.c_str();
  }

 private:
  void refresh_what();
  std::string compute_what(bool include_backtrace) const;
};

class C10_API Warning {
 public:
  class C10_API UserWarning {};
  class C10_API DeprecationWarning {};

  using warning_variant_t = c10::variant<UserWarning, DeprecationWarning>;

  Warning(
      warning_variant_t type,
      const SourceLocation& source_location,
      std::string msg,
      bool verbatim);

  Warning(
      warning_variant_t type,
      SourceLocation source_location,
      const char* msg,
      bool verbatim);

  Warning(
      warning_variant_t type,
      SourceLocation source_location,
      ::c10::detail::CompileTimeEmptyString msg,
      bool verbatim);

  // Getters for members
  warning_variant_t type() const;
  const SourceLocation& source_location() const;
  const std::string& msg() const;
  bool verbatim() const;

 private:
  // The type of warning
  warning_variant_t type_;

  // Where the warning happened.
  SourceLocation source_location_;

  // The actual warning message.
  std::string msg_;

  // See note: [Verbatim Warnings]
  bool verbatim_;
};

using UserWarning = Warning::UserWarning;
using DeprecationWarning = Warning::DeprecationWarning;

// Issue a warning with a given message. Dispatched to the current
// warning handler.
void C10_API warn(const Warning& warning);

class C10_API WarningHandler {
 public:
  virtual ~WarningHandler() = default;
  /// The default warning handler. Prints the message to stderr.
  virtual void process(const Warning& warning);
};

namespace WarningUtils {

// Note: [Verbatim Warnings]
// Warnings originating in C++ code can appear out-of-place to Python users:
// a user runs a line in Python, but the warning references a line in C++.
// Some parts of PyTorch, like the JIT, are cognizant of this mismatch
// and take care to map warnings back to the user's program, but most
// of PyTorch simply throws a context-free warning. To allow warning
// handlers to add context where appropriate, warn takes the
// "verbatim" flag. When this is false a warning handler might append
// the C++ warning to a Python warning message that relates the warning
// back to the user's program. Callers who have already accounted for
// context in their warnings should set verbatim to true so their warnings
// appear without modification.

/// Sets the global warning handler. This is not thread-safe, so it should
/// generally be called once during initialization or while holding the GIL
/// for programs that use python.
/// User is responsible for keeping the WarningHandler alive until
/// it is not needed.
C10_API void set_warning_handler(WarningHandler* handler) noexcept(true);
/// Gets the global warning handler.
C10_API WarningHandler* get_warning_handler() noexcept(true);

class C10_API WarningHandlerGuard {
  WarningHandler* prev_handler_;

 public:
  WarningHandlerGuard(WarningHandler* new_handler)
      : prev_handler_(c10::WarningUtils::get_warning_handler()) {
    c10::WarningUtils::set_warning_handler(new_handler);
  }
  ~WarningHandlerGuard() {
    c10::WarningUtils::set_warning_handler(prev_handler_);
  }
};

/// The TORCH_WARN_ONCE macro is difficult to test for. Use
/// setWarnAlways(true) to turn it into TORCH_WARN, which can be
/// tested for more easily.
C10_API void set_warnAlways(bool) noexcept(true);
C10_API bool get_warnAlways(void) noexcept(true);

// A RAII guard that sets warn_always (not thread-local) on
// construction, and sets it back to the original value upon destruction.
struct C10_API WarnAlways {
 public:
  explicit WarnAlways(bool setting = true);
  ~WarnAlways();

 private:
  bool prev_setting;
};

} // namespace WarningUtils

// Used in ATen for out-of-bound indices that can reasonably only be detected
// lazily inside a kernel (See: advanced indexing).  These turn into
// IndexError when they cross to Python.
class C10_API IndexError : public Error {
  using Error::Error;
};

// Used in ATen for invalid values.  These turn into
// ValueError when they cross to Python.
class C10_API ValueError : public Error {
  using Error::Error;
};

// Used in ATen for invalid types.  These turn into
// TypeError when they cross to Python.
class C10_API TypeError : public Error {
  using Error::Error;
};

// Used in ATen for functionality that is not implemented.  These turn into
// NotImplementedError when they cross to Python.
class C10_API NotImplementedError : public Error {
  using Error::Error;
};

// Used in ATen for non finite indices.  These turn into
// ExitException when they cross to Python.
class C10_API EnforceFiniteError : public Error {
  using Error::Error;
};

// Used in Onnxifi backend lowering.  These turn into
// ExitException when they cross to Python.
class C10_API OnnxfiBackendSystemError : public Error {
  using Error::Error;
};

// Used for numerical errors from the linalg module. These
// turn into LinAlgError when they cross into Python.
class C10_API LinAlgError : public Error {
  using Error::Error;
};

class C10_API OutOfMemoryError : public Error {
  using Error::Error;
};

// Used for collective communication library errors from the distributed module.
// These turn into DistBackendError when they cross into Python.
class C10_API DistBackendError : public Error {
  using Error::Error;
};

// A utility function to return an exception std::string by prepending its
// exception type before its what() content
C10_API std::string GetExceptionString(const std::exception& e);

} // namespace c10

// Private helper macro for implementing TORCH_INTERNAL_ASSERT and TORCH_CHECK
//
// Note: In the debug build With MSVC, __LINE__ might be of long type (a.k.a
// int32_t), which is different from the definition of `SourceLocation` that
// requires unsigned int (a.k.a uint32_t) and may cause a compile error with the
// message: error C2397: conversion from 'long' to 'uint32_t' requires a
// narrowing conversion Here the static cast is used to pass the build. if this
// is used inside a lambda the __func__ macro expands to operator(), which isn't
// very useful, but hard to fix in a macro so suppressing the warning.
#define C10_THROW_ERROR(err_type, msg) \
  throw ::c10::err_type(               \
      {__func__, __FILE__, static_cast<uint32_t>(__LINE__)}, msg)

// Private helper macro for workaround MSVC misexpansion of nested macro
// invocations involving __VA_ARGS__.  See
// https://stackoverflow.com/questions/5134523/msvc-doesnt-expand-va-args-correctly
#define C10_EXPAND_MSVC_WORKAROUND(x) x

// On nvcc, C10_UNLIKELY thwarts missing return statement analysis.  In cases
// where the unlikely expression may be a constant, use this macro to ensure
// return statement analysis keeps working (at the cost of not getting the
// likely/unlikely annotation on nvcc).
// https://github.com/pytorch/pytorch/issues/21418
//
// Currently, this is only used in the error reporting macros below.  If you
// want to use it more generally, move me to Macros.h
//
// TODO: Brian Vaughan observed that we might be able to get this to work on
// nvcc by writing some sort of C++ overload that distinguishes constexpr inputs
// from non-constexpr.  Since there isn't any evidence that losing C10_UNLIKELY
// in nvcc is causing us perf problems, this is not yet implemented, but this
// might be an interesting piece of C++ code for an intrepid bootcamper to
// write.
#if defined(__CUDACC__)
#define C10_UNLIKELY_OR_CONST(e) e
#else
#define C10_UNLIKELY_OR_CONST(e) C10_UNLIKELY(e)
#endif

// ----------------------------------------------------------------------------
// Error reporting macros
// ----------------------------------------------------------------------------

#ifdef STRIP_ERROR_MESSAGES
#define TORCH_RETHROW(e, ...) throw
#else
#define TORCH_RETHROW(e, ...)               \
  do {                                      \
    e.add_context(::c10::str(__VA_ARGS__)); \
    throw;                                  \
  } while (false)
#endif

// A utility macro to provide assert()-like functionality; that is, enforcement
// of internal invariants in code.  It supports an arbitrary number of extra
// arguments (evaluated only on failure), which will be printed in the assert