// Copyright 2019 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// -----------------------------------------------------------------------------
// File: status.h
// -----------------------------------------------------------------------------
//
// This header file defines the Abseil `status` library, consisting of:
//
//   * An `absl::Status` class for holding error handling information
//   * A set of canonical `absl::StatusCode` error codes, and associated
//     utilities for generating and propagating status codes.
//   * A set of helper functions for creating status codes and checking their
//     values
//
// Within Google, `absl::Status` is the primary mechanism for gracefully
// handling errors across API boundaries (and in particular across RPC
// boundaries). Some of these errors may be recoverable, but others may not.
// Most functions that can produce a recoverable error should be designed to
// return an `absl::Status` (or `absl::StatusOr`).
//
// Example:
//
// absl::Status myFunction(std::string_view fname, ...) {
//   ...
//   // encounter error
//   if (error condition) {
//     return absl::InvalidArgumentError("bad mode");
//   }
//   // else, return OK
//   return absl::OkStatus();
// }
//
// An `absl::Status` is designed to either return "OK" or one of a number of
// different error codes, corresponding to typical error conditions.
// In almost all cases, when using `absl::Status` you should use the canonical
// error codes (of type `absl::StatusCode`) enumerated in this header file.
// These canonical codes are understood across the codebase and will be
// accepted across all API and RPC boundaries.
#ifndef ABSL_STATUS_STATUS_H_
#define ABSL_STATUS_STATUS_H_

#include <cassert>
#include <functional>
#include <iostream>
#include <memory>
#include <optional>
#include <string>
#include <string_view>

#include "status_internal.h"

namespace absl {

// absl::StatusCode
//
// An `absl::StatusCode` is an enumerated type indicating either no error ("OK")
// or an error condition. In most cases, an `absl::Status` indicates a
// recoverable error, and the purpose of signalling an error is to indicate what
// action to take in response to that error. These error codes map to the proto
// RPC error codes indicated in https://cloud.google.com/apis/design/errors.
//
// The errors listed below are the canonical errors associated with
// `absl::Status` and are used throughout the codebase. As a result, these
// error codes are somewhat generic.
//
// In general, try to return the most specific error that applies if more than
// one error may pertain. For example, prefer `kOutOfRange` over
// `kFailedPrecondition` if both codes apply. Similarly prefer `kNotFound` or
// `kAlreadyExists` over `kFailedPrecondition`.
//
// Because these errors may cross RPC boundaries, these codes are tied to the
// `google.rpc.Code` definitions within
// https://github.com/googleapis/googleapis/blob/master/google/rpc/code.proto
// The string value of these RPC codes is denoted within each enum below.
//
// If your error handling code requires more context, you can attach payloads
// to your status. See `absl::Status::SetPayload()` and
// `absl::Status::GetPayload()` below.
enum class StatusCode : int {
    // StatusCode::kOk
    //
    // kOK (gRPC code "OK") does not indicate an error; this value is returned on
    // success. It is typical to check for this value before proceeding on any
    // given call across an API or RPC boundary. To check this value, use the
    // `absl::Status::ok()` member function rather than inspecting the raw code.
    kOk = 0,

    // StatusCode::kCancelled
    //
    // kCancelled (gRPC code "CANCELLED") indicates the operation was cancelled,
    // typically by the caller.
    kCancelled = 1,

    // StatusCode::kUnknown
    //
    // kUnknown (gRPC code "UNKNOWN") indicates an unknown error occurred. In
    // general, more specific errors should be raised, if possible. Errors raised
    // by APIs that do not return enough error information may be converted to
    // this error.
    kUnknown = 2,

    // StatusCode::kInvalidArgument
    //
    // kInvalidArgument (gRPC code "INVALID_ARGUMENT") indicates the caller
    // specified an invalid argument, such as a malformed filename. Note that use
    // of such errors should be narrowly limited to indicate the invalid nature of
    // the arguments themselves. Errors with validly formed arguments that may
    // cause errors with the state of the receiving system should be denoted with
    // `kFailedPrecondition` instead.
    kInvalidArgument = 3,

    // StatusCode::kDeadlineExceeded
    //
    // kDeadlineExceeded (gRPC code "DEADLINE_EXCEEDED") indicates a deadline
    // expired before the operation could complete. For operations that may change
    // state within a system, this error may be returned even if the operation has
    // completed successfully. For example, a successful response from a server
    // could have been delayed long enough for the deadline to expire.
    kDeadlineExceeded = 4,

    // StatusCode::kNotFound
    //
    // kNotFound (gRPC code "NOT_FOUND") indicates some requested entity (such as
    // a file or directory) was not found.
    //
    // `kNotFound` is useful if a request should be denied for an entire class of
    // users, such as during a gradual feature rollout or undocumented allow list.
    // If a request should be denied for specific sets of users, such as through
    // user-based access control, use `kPermissionDenied` instead.
    kNotFound = 5,

    // StatusCode::kAlreadyExists
    //
    // kAlreadyExists (gRPC code "ALREADY_EXISTS") indicates that the entity a
    // caller attempted to create (such as a file or directory) is already
    // present.
    kAlreadyExists = 6,

    // StatusCode::kPermissionDenied
    //
    // kPermissionDenied (gRPC code "PERMISSION_DENIED") indicates that the caller
    // does not have permission to execute the specified operation. Note that this
    // error is different than an error due to an *un*authenticated user. This
    // error code does not imply the request is valid or the requested entity
    // exists or satisfies any other pre-conditions.
    //
    // `kPermissionDenied` must not be used for rejections caused by exhausting
    // some resource. Instead, use `kResourceExhausted` for those errors.
    // `kPermissionDenied` must not be used if the caller cannot be identified.
    // Instead, use `kUnauthenticated` for those errors.
    kPermissionDenied = 7,

    // StatusCode::kResourceExhausted
    //
    // kResourceExhausted (gRPC code "RESOURCE_EXHAUSTED") indicates some resource
    // has been exhausted, perhaps a per-user quota, or perhaps the entire file
    // system is out of space.
    kResourceExhausted = 8,

    // StatusCode::kFailedPrecondition
    //
    // kFailedPrecondition (gRPC code "FAILED_PRECONDITION") indicates that the
    // operation was rejected because the system is not in a state required for
    // the operation's execution. For example, a directory to be deleted may be
    // non-empty, an "rmdir" operation is applied to a non-directory, etc.
    //
    // Some guidelines that may help a service implementer in deciding between
    // `kFailedPrecondition`, `kAborted`, and `kUnavailable`:
    //
    //  (a) Use `kUnavailable` if the client can retry just the failing call.
    //  (b) Use `kAborted` if the client should retry at a higher transaction
    //      level (such as when a client-specified test-and-set fails, indicating
    //      the client should restart a read-modify-write sequence).
    //  (c) Use `kFailedPrecondition` if the client should not retry until
    //      the system state has been explicitly fixed. For example, if a "rmdir"
    //      fails because the directory is non-empty, `kFailedPrecondition`
    //      should be returned since the client should not retry unless
    //      the files are deleted from the directory.
    kFailedPrecondition = 9,

    // StatusCode::kAborted
    //
    // kAborted (gRPC code "ABORTED") indicates the operation was aborted,
    // typically due to a concurrency issue such as a sequencer check failure or a
    // failed transaction.
    //
    // See the guidelines above for deciding between `kFailedPrecondition`,
    // `kAborted`, and `kUnavailable`.
    kAborted = 10,

    // StatusCode::kOutOfRange
    //
    // kOutOfRange (gRPC code "OUT_OF_RANGE") indicates the operation was
    // attempted past the valid range, such as seeking or reading past an
    // end-of-file.
    //
    // Unlike `kInvalidArgument`, this error indicates a problem that may
    // be fixed if the system state changes. For example, a 32-bit file
    // system will generate `kInvalidArgument` if asked to read at an
    // offset that is not in the range [0,2^32-1], but it will generate
    // `kOutOfRange` if asked to read from an offset past the current
    // file size.
    //
    // There is a fair bit of overlap between `kFailedPrecondition` and
    // `kOutOfRange`.  We recommend using `kOutOfRange` (the more specific
    // error) when it applies so that callers who are iterating through
    // a space can easily look for an `kOutOfRange` error to detect when
    // they are done.
    kOutOfRange = 11,

    // StatusCode::kUnimplemented
    //
    // kUnimplemented (gRPC code "UNIMPLEMENTED") indicates the operation is not
    // implemented or supported in this service. In this case, the operation
    // should not be re-attempted.
    kUnimplemented = 12,

    // StatusCode::kInternal
    //
    // kInternal (gRPC code "INTERNAL") indicates an internal error has occurred
    // and some invariants expected by the underlying system have not been
    // satisfied. This error code is reserved for serious errors.
    kInternal = 13,

    // StatusCode::kUnavailable
    //
    // kUnavailable (gRPC code "UNAVAILABLE") indicates the service is currently
    // unavailable and that this is most likely a transient condition. An error
    // such as this can be corrected by retrying with a backoff scheme. Note that
    // it is not always safe to retry non-idempotent operations.
    //
    // See the guidelines above for deciding between `kFailedPrecondition`,
    // `kAborted`, and `kUnavailable`.
    kUnavailable = 14,

    // StatusCode::kDataLoss
    //
    // kDataLoss (gRPC code "DATA_LOSS") indicates that unrecoverable data loss or
    // corruption has occurred. As this error is serious, proper alerting should
    // be attached to errors such as this.
    kDataLoss = 15,

    // StatusCode::kUnauthenticated
    //
    // kUnauthenticated (gRPC code "UNAUTHENTICATED") indicates that the request
    // does not have valid authentication credentials for the operation. Correct
    // the authentication and try again.
    kUnauthenticated = 16,

    // StatusCode::DoNotUseReservedForFutureExpansionUseDefaultInSwitchInstead_
    //
    // NOTE: this error code entry should not be used and you should not rely on
    // its value, which may change.
    //
    // The purpose of this enumerated value is to force people who handle status
    // codes with `switch()` statements to *not* simply enumerate all possible
    // values, but instead provide a "default:" case. Providing such a default
    // case ensures that code will compile when new codes are added.
    kDoNotUseReservedForFutureExpansionUseDefaultInSwitchInstead_ = 20
};

// StatusCodeToString()
//
// Returns the name for the status code, or "" if it is an unknown value.
std::string StatusCodeToString(StatusCode code);

// operator<<
//
// Streams StatusCodeToString(code) to `os`.
std::ostream& operator<<(std::ostream& os, StatusCode code);

// absl::StatusToStringMode
//
// An `absl::StatusToStringMode` is an enumerated type indicating how
// `absl::Status::ToString()` should construct the output string for a non-ok
// status.
enum class StatusToStringMode : int {
    // ToString will not contain any extra data (such as payloads). It will only
    // contain the error code and message, if any.
    kWithNoExtraData = 0,
    // ToString will contain the payloads.
    kWithPayload = 1 << 0,
    // ToString will include all the extra data this Status has.
    kWithEverything = ~kWithNoExtraData,
    // Default mode used by ToString. Its exact value might change in the future.
    kDefault = kWithPayload,
};

// absl::StatusToStringMode is specified as a bitmask type, which means the
// following operations must be provided:
inline constexpr StatusToStringMode operator&(StatusToStringMode lhs, StatusToStringMode rhs) {
    return static_cast<StatusToStringMode>(static_cast<int>(lhs) & static_cast<int>(rhs));
}
inline constexpr StatusToStringMode operator|(StatusToStringMode lhs, StatusToStringMode rhs) {
    return static_cast<StatusToStringMode>(static_cast<int>(lhs) | static_cast<int>(rhs));
}
inline constexpr StatusToStringMode operator^(StatusToStringMode lhs, StatusToStringMode rhs) {
    return static_cast<StatusToStringMode>(static_cast<int>(lhs) ^ static_cast<int>(rhs));
}
inline constexpr StatusToStringMode operator~(StatusToStringMode arg) {
    return static_cast<StatusToStringMode>(~static_cast<int>(arg));
}
inline StatusToStringMode& operator&=(StatusToStringMode& lhs, StatusToStringMode rhs) {
    lhs = lhs & rhs;
    return lhs;
}
inline StatusToStringMode& operator|=(StatusToStringMode& lhs, StatusToStringMode rhs) {
    lhs = lhs | rhs;
    return lhs;
}
inline StatusToStringMode& operator^=(StatusToStringMode& lhs, StatusToStringMode rhs) {
    lhs = lhs ^ rhs;
    return lhs;
}

// absl::Status
//
// The `absl::Status` class is generally used to gracefully handle errors
// across API boundaries (and in particular across RPC boundaries). Some of
// these errors may be recoverable, but others may not. Most
// functions which can produce a recoverable error should be designed to return
// either an `absl::Status` (or the similar `absl::StatusOr<T>`, which holds
// either an object of type `T` or an error).
//
// API developers should construct their functions to return `absl::OkStatus()`
// upon success, or an `absl::StatusCode` upon another type of error (e.g
// an `absl::StatusCode::kInvalidArgument` error). The API provides convenience
// functions to construct each status code.
//
// Example:
//
// absl::Status myFunction(std::string_view fname, ...) {
//   ...
//   // encounter error
//   if (error condition) {
//     // Construct an absl::StatusCode::kInvalidArgument error
//     return absl::InvalidArgumentError("bad mode");
//   }
//   // else, return OK
//   return absl::OkStatus();
// }
//
// Users handling status error codes should prefer checking for an OK status
// using the `ok()` member function. Handling multiple error codes may justify
// use of switch statement, but only check for error codes you know how to
// handle; do not try to exhaustively match against all canonical error codes.
// Errors that cannot be handled should be logged and/or propagated for higher
// levels to deal with. If you do use a switch statement, make sure that you
// also provide a `default:` switch case, so that code does not break as other
// canonical codes are added to the API.
//
// Example:
//
//   absl::Status result = DoSomething();
//   if (!result.ok()) {
//     LOG(ERROR) << result;
//   }
//
//   // Provide a default if switching on multiple error codes
//   switch (result.code()) {
//     // The user hasn't authenticated. Ask them to reauth
//     case absl::StatusCode::kUnauthenticated:
//       DoReAuth();
//       break;
//     // The user does not have permission. Log an error.
//     case absl::StatusCode::kPermissionDenied:
//       LOG(ERROR) << result;
//       break;
//     // Propagate the error otherwise.
//     default:
//       return true;
//   }
//
// An `absl::Status` can optionally include a payload with more information
// about the error. Typically, this payload serves one of several purposes:
//
//   * It may provide more fine-grained semantic information about the error to
//     facilitate actionable remedies.
//   * It may provide human-readable contexual information that is more
//     appropriate to display to an end user.
//
// Example:
//
//   absl::Status result = DoSomething();
//   // Inform user to retry after 30 seconds
//   // See more error details in googleapis/google/rpc/error_details.proto
//   if (absl::IsResourceExhausted(result)) {
//     google::rpc::RetryInfo info;
//     info.retry_delay().seconds() = 30;
//     // Payloads require a unique key (a URL to ensure no collisions with
//     // other payloads).
//     std::string_view url = "type.googleapis.com/google.rpc.RetryInfo";
//     result.SetPayload(url, info.SerializeAsCord());
//     return result;
//   }
//
// For documentation see https://abseil.io/docs/cpp/guides/status.
//
// Returned Status objects may not be ignored. status_internal.h has a forward
// declaration of the form
// class ABSL_MUST_USE_RESULT Status;
class Status final {
public:
    // Constructors

    // This default constructor creates an OK status with no message or payload.
    // Avoid this constructor and prefer explicit construction of an OK status
    // with `absl::OkStatus()`.
    Status();

    // Creates a status in the canonical error space with the specified
    // `absl::StatusCode` and error message.  If `code == absl::StatusCode::kOk`,  // NOLINT
    // `msg` is ignored and an object identical to an OK status is constructed.
    //
    // The `msg` string must be in UTF-8. The implementation may complain (e.g.,  // NOLINT
    // by printing a warning) if it is not.
    Status(absl::StatusCode code, std::string_view msg);

    Status(const Status&);
    Status& operator=(const Status& x);

    // Move operators

    // The moved-from state is valid but unspecified.
    Status(Status&&) noexcept;
    Status& operator=(Status&&);

    ~Status();

    // Status::Update()
    //
    // Updates the existing status with `new_status` provided that `this->ok()`.
    // If the existing status already contains a non-OK error, this update has no
    // effect and preserves the current data. Note that this behavior may change
    // in the future to augment a current non-ok status with additional
    // information about `new_status`.
    //
    // `Update()` provides a convenient way of keeping track of the first error
    // encountered.
    //
    // Example:
    //   // Instead of "if (overall_status.ok()) overall_status = new_status"
    //   overall_status.Update(new_status);
    //
    void Update(const Status& new_status);
    void Update(Status&& new_status);

    // Status::ok()
    //
    // Returns `true` if `this->ok()`. Prefer checking for an OK status using this
    // member function.
    ABSL_MUST_USE_RESULT bool ok() const;  // NOLINT

    // Status::code()
    //
    // Returns the canonical error code of type `absl::StatusCode` of this status.
    absl::StatusCode code() const;  // NOLINT

    // Status::raw_code()
    //
    // Returns a raw (canonical) error code corresponding to the enum value of
    // `google.rpc.Code` definitions within
    // https://github.com/googleapis/googleapis/blob/master/google/rpc/code.proto.
    // These values could be out of the range of canonical `absl::StatusCode`
    // enum values.
    //
    // NOTE: This function should only be called when converting to an associated
    // wire format. Use `Status::code()` for error handling.
    int raw_code() const;  // NOLINT

    // Status::message()
    //
    // Returns the error message associated with this error code, if available.
    // Note that this message rarely describes the error code.  It is not unusual
    // for the error message to be the empty string. As a result, prefer
    // `Status::ToString()` for debug logging.
    std::string_view message() const;  // NOLINT

    friend bool operator==(const Status&, const Status&);
    friend bool operator!=(const Status&, const Status&);

    // Status::ToString()
    //
    // Returns a string based on the `mode`. By default, it returns combination of
    // the error code name, the message and any associated payload messages. This
    // string is designed simply to be human readable and its exact format should
    // not be load bearing. Do not depend on the exact format of the result of
    // `ToString()` which is subject to change.
    //
    // The printed code name and the message are generally substrings of the
    // result, and the payloads to be printed use the status payload printer
    // mechanism (which is internal).
    std::string ToString(StatusToStringMode mode = StatusToStringMode::kDefault) const;

    // Status::IgnoreError()
    //
    // Ignores any errors. This method does nothing except potentially suppress
    // complaints from any tools that are checking that errors are not dropped on
    // the floor.
    void IgnoreError() const;

    // swap()
    //
    // Swap the contents of one status with another.
    friend void swap(Status& a, Status& b);  // NOLINT

    //----------------------------------------------------------------------------
    // Payload Management APIs
    //----------------------------------------------------------------------------

    // A payload may be attached to a status to provide additional context to an
    // error that may not be satisifed by an existing `absl::StatusCode`.
    // Typically, this payload serves one of several purposes:
    //
    //   * It may provide more fine-grained semantic information about the error
    //     to facilitate actionable remedies.
    //   * It may provide human-readable contexual information that is more
    //     appropriate to display to an end user.
    //
    // A payload consists of a [key,value] pair, where the key is a string
    // referring to a unique "type URL" and the value is an object of type
    // `std::string` to hold the contextual data.
    //
    // The "type URL" should be unique and follow the format of a URL
    // (https://en.wikipedia.org/wiki/URL) and, ideally, provide some
    // documentation or schema on how to interpret its associated data. For
    // example, the default type URL for a protobuf message type is
    // "type.googleapis.com/packagename.messagename". Other custom wire formats
    // should define the format of type URL in a similar practice so as to
    // minimize the chance of conflict between type URLs.
    // Users should ensure that the type URL can be mapped to a concrete
    // C++ type if they want to deserialize the payload and read it effectively.
    //
    // To attach a payload to a status object, call `Status::SetPayload()`,
    // passing it the type URL and an `std::string` of associated data. Similarly,
    // to extract the payload from a status, call `Status::GetPayload()`. You
    // may attach multiple payloads (with differing type URLs) to any given
    // status object, provided that the status is currently exhibiting an error
    // code (i.e. is not OK).

    // Status::GetPayload()
    //
    // Gets the payload of a status given its unique `type_url` key, if present.
    std::optional<std::string> GetPayload(std::string_view type_url) const;

    // Status::SetPayload()
    //
    // Sets the payload for a non-ok status using a `type_url` key, overwriting
    // any existing payload for that `type_url`.
    //
    // NOTE: This function does nothing if the Status is ok.
    void SetPayload(std::string_view type_url, std::string payload);

    // Status::ErasePayload()
    //
    // Erases the payload corresponding to the `type_url` key.  Returns `true` if
    // the payload was present.
    bool ErasePayload(std::string_view type_url);

    // Status::ForEachPayload()
    //
    // Iterates over the stored payloads and calls the
    // `visitor(type_key, payload)` callable for each one.
    //
    // NOTE: The order of calls to `visitor()` is not specified and may change at
    // any time.
    //
    // NOTE: Any mutation on the same 'absl::Status' object during visitation is
    // forbidden and could result in undefined behavior.
    void ForEachPayload(
        const std::function<void(std::string_view, const std::string&)>& visitor) const;

private:
    friend Status CancelledError();

    // Creates a status in the canonical error space with the specified
    // code, and an empty error message.
    explicit Status(absl::StatusCode code);

    static void UnrefNonInlined(uintptr_t rep);
    static void Ref(uintptr_t rep);
    static void Unref(uintptr_t rep);

    // REQUIRES: !ok()
    // Ensures rep_ is not shared with any other Status.
    void PrepareToModify();

    const status_internal::Payloads* GetPayloads() const;
    status_internal::Payloads* GetPayloads();

    // Takes ownership of payload.
    static uintptr_t NewRep(absl::StatusCode code, std::string_view msg,
                            std::unique_ptr<status_internal::Payloads> payload);
    static bool EqualsSlow(const absl::Status& a, const absl::Status& b);

    // MSVC 14.0 limitation requires the const.
    static constexpr const char kMovedFromString[] = "Status accessed after move.";

    static const std::string* EmptyString();
    static const std::string* MovedFromString();

    // Returns whether rep contains an inlined representation.
    // See rep_ for details.
    static bool IsInlined(uintptr_t rep);

    // Indicates whether this Status was the rhs of a move operation. See rep_
    // for details.
    static bool IsMovedFrom(uintptr_t rep);
    static uintptr_t MovedFromRep();

    // Convert between error::Code and the inlined uintptr_t representation used
    // by rep_. See rep_ for details.
    static uintptr_t CodeToInlinedRep(absl::StatusCode code);
    static absl::StatusCode InlinedRepToCode(uintptr_t rep);

    // Converts between StatusRep* and the external uintptr_t representation used
    // by rep_. See rep_ for details.
    static uintptr_t PointerToRep(status_internal::StatusRep* r);
    static status_internal::StatusRep* RepToPointer(uintptr_t r);

    std::string ToStringSlow(StatusToStringMode mode) const;

    // Status supports two different representations.
    //  - When the low bit is off it is an inlined representation.
    //    It uses the canonical error space, no message or payload.
    //    The error code is (rep_ >> 2).
    //    The (rep_ & 2) bit is the "moved from" indicator, used in IsMovedFrom().
    //  - When the low bit is on it is an external representation.
    //    In this case all the data comes from a heap allocated Rep object.
    //    (rep_ - 1) is a status_internal::StatusRep* pointer to that structure.
    uintptr_t rep_;
};

// OkStatus()
//
// Returns an OK status, equivalent to a default constructed instance. Prefer
// usage of `absl::OkStatus()` when constructing such an OK status.
Status OkStatus();

// operator<<()
//
// Prints a human-readable representation of `x` to `os`.
std::ostream& operator<<(std::ostream& os, const Status& x);

// IsAborted()
// IsAlreadyExists()
// IsCancelled()
// IsDataLoss()
// IsDeadlineExceeded()
// IsFailedPrecondition()
// IsInternal()
// IsInvalidArgument()
// IsNotFound()
// IsOutOfRange()
// IsPermissionDenied()
// IsResourceExhausted()
// IsUnauthenticated()
// IsUnavailable()
// IsUnimplemented()
// IsUnknown()
//
// These convenience functions return `true` if a given status matches the
// `absl::StatusCode` error code of its associated function.
ABSL_MUST_USE_RESULT bool IsAborted(const Status& status);
ABSL_MUST_USE_RESULT bool IsAlreadyExists(const Status& status);
ABSL_MUST_USE_RESULT bool IsCancelled(const Status& status);
ABSL_MUST_USE_RESULT bool IsDataLoss(const Status& status);
ABSL_MUST_USE_RESULT bool IsDeadlineExceeded(const Status& status);
ABSL_MUST_USE_RESULT bool IsFailedPrecondition(const Status& status);
ABSL_MUST_USE_RESULT bool IsInternal(const Status& status);
ABSL_MUST_USE_RESULT bool IsInvalidArgument(const Status& status);
ABSL_MUST_USE_RESULT bool IsNotFound(const Status& status);
ABSL_MUST_USE_RESULT bool IsOutOfRange(const Status& status);
ABSL_MUST_USE_RESULT bool IsPermissionDenied(const Status& status);
ABSL_MUST_USE_RESULT bool IsResourceExhausted(const Status& status);
ABSL_MUST_USE_RESULT bool IsUnauthenticated(const Status& status);
ABSL_MUST_USE_RESULT bool IsUnavailable(const Status& status);
ABSL_MUST_USE_RESULT bool IsUnimplemented(const Status& status);
ABSL_MUST_USE_RESULT bool IsUnknown(const Status& status);

// AbortedError()
// AlreadyExistsError()
// CancelledError()
// DataLossError()
// DeadlineExceededError()
// FailedPreconditionError()
// InternalError()
// InvalidArgumentError()
// NotFoundError()
// OutOfRangeError()
// PermissionDeniedError()
// ResourceExhaustedError()
// UnauthenticatedError()
// UnavailableError()
// UnimplementedError()
// UnknownError()
//
// These convenience functions create an `absl::Status` object with an error
// code as indicated by the associated function name, using the error message
// passed in `message`.
Status AbortedError(std::string_view message);
Status AlreadyExistsError(std::string_view message);
Status CancelledError(std::string_view message);
Status DataLossError(std::string_view message);
Status DeadlineExceededError(std::string_view message);
Status FailedPreconditionError(std::string_view message);
Status InternalError(std::string_view message);
Status InvalidArgumentError(std::string_view message);
Status NotFoundError(std::string_view message);
Status OutOfRangeError(std::string_view message);
Status PermissionDeniedError(std::string_view message);
Status ResourceExhaustedError(std::string_view message);
Status UnauthenticatedError(std::string_view message);
Status UnavailableError(std::string_view message);
Status UnimplementedError(std::string_view message);
Status UnknownError(std::string_view message);

//------------------------------------------------------------------------------
// Implementation details follow
//------------------------------------------------------------------------------

inline Status::Status() : rep_(CodeToInlinedRep(absl::StatusCode::kOk)) {
}

inline Status::Status(absl::StatusCode code) : rep_(CodeToInlinedRep(code)) {
}

inline Status::Status(const Status& x) : rep_(x.rep_) {
    Ref(rep_);
}

inline Status& Status::operator=(const Status& x) {
    uintptr_t old_rep = rep_;
    if (x.rep_ != old_rep) {
        Ref(x.rep_);
        rep_ = x.rep_;
        Unref(old_rep);
    }
    return *this;
}

inline Status::Status(Status&& x) noexcept : rep_(x.rep_) {
    x.rep_ = MovedFromRep();
}

inline Status& Status::operator=(Status&& x) {
    uintptr_t old_rep = rep_;
    if (x.rep_ != old_rep) {
        rep_ = x.rep_;
        x.rep_ = MovedFromRep();
        Unref(old_rep);
    }
    return *this;
}

inline void Status::Update(const Status& new_status) {
    if (ok()) {
        *this = new_status;
    }
}

inline void Status::Update(Status&& new_status) {
    if (ok()) {
        *this = std::move(new_status);
    }
}

inline Status::~Status() {
    Unref(rep_);
}

inline bool Status::ok() const {
    return rep_ == CodeToInlinedRep(absl::StatusCode::kOk);
}

inline std::string_view Status::message() const {
    return !IsInlined(rep_)
               ? RepToPointer(rep_)->message
               : (IsMovedFrom(rep_) ? std::string_view(kMovedFromString) : std::string_view());
}

inline bool operator==(const Status& lhs, const Status& rhs) {
    return lhs.rep_ == rhs.rep_ || Status::EqualsSlow(lhs, rhs);
}

inline bool operator!=(const Status& lhs, const Status& rhs) {
    return !(lhs == rhs);
}

inline std::string Status::ToString(StatusToStringMode mode) const {
    return ok() ? "OK" : ToStringSlow(mode);
}

inline void Status::IgnoreError() const {
    // no-op
}

inline void swap(absl::Status& a, absl::Status& b) {
    using std::swap;
    swap(a.rep_, b.rep_);
}

inline const status_internal::Payloads* Status::GetPayloads() const {
    return IsInlined(rep_) ? nullptr : RepToPointer(rep_)->payloads.get();
}

inline status_internal::Payloads* Status::GetPayloads() {
    return IsInlined(rep_) ? nullptr : RepToPointer(rep_)->payloads.get();
}

inline bool Status::IsInlined(uintptr_t rep) {
    return (rep & 1) == 0;
}

inline bool Status::IsMovedFrom(uintptr_t rep) {
    return IsInlined(rep) && (rep & 2) != 0;
}

inline uintptr_t Status::MovedFromRep() {
    return CodeToInlinedRep(absl::StatusCode::kInternal) | 2;
}

inline uintptr_t Status::CodeToInlinedRep(absl::StatusCode code) {
    return static_cast<uintptr_t>(code) << 2;
}

inline absl::StatusCode Status::InlinedRepToCode(uintptr_t rep) {
    assert(IsInlined(rep));
    return static_cast<absl::StatusCode>(rep >> 2);
}

inline status_internal::StatusRep* Status::RepToPointer(uintptr_t rep) {
    assert(!IsInlined(rep));
    return reinterpret_cast<status_internal::StatusRep*>(rep - 1);
}

inline uintptr_t Status::PointerToRep(status_internal::StatusRep* rep) {
    return reinterpret_cast<uintptr_t>(rep) + 1;
}

inline void Status::Ref(uintptr_t rep) {
    if (!IsInlined(rep)) {
        RepToPointer(rep)->ref.fetch_add(1, std::memory_order_relaxed);
    }
}

inline void Status::Unref(uintptr_t rep) {
    if (!IsInlined(rep)) {
        UnrefNonInlined(rep);
    }
}

inline Status OkStatus() {
    return Status();
}

// Creates a `Status` object with the `absl::StatusCode::kCancelled` error code
// and an empty message. It is provided only for efficiency, given that
// message-less kCancelled errors are common in the infrastructure.
inline Status CancelledError() {
    return Status(absl::StatusCode::kCancelled);
}

}  // namespace absl

#endif  // ABSL_STATUS_STATUS_H_