// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_CRDTP_STATUS_H_
#define V8_CRDTP_STATUS_H_

#include <cassert>
#include <cstddef>
#include <limits>
#include <string>

#include "export.h"

namespace v8_crdtp {
// =============================================================================
// Status and Error codes
// =============================================================================

enum class Error {
  OK = 0,

  // JSON parsing errors; checked when parsing / converting from JSON.
  // See json.{h,cc}.
  JSON_PARSER_UNPROCESSED_INPUT_REMAINS = 0x01,
  JSON_PARSER_STACK_LIMIT_EXCEEDED = 0x02,
  JSON_PARSER_NO_INPUT = 0x03,
  JSON_PARSER_INVALID_TOKEN = 0x04,
  JSON_PARSER_INVALID_NUMBER = 0x05,
  JSON_PARSER_INVALID_STRING = 0x06,
  JSON_PARSER_UNEXPECTED_ARRAY_END = 0x07,
  JSON_PARSER_COMMA_OR_ARRAY_END_EXPECTED = 0x08,
  JSON_PARSER_STRING_LITERAL_EXPECTED = 0x09,
  JSON_PARSER_COLON_EXPECTED = 0x0a,
  JSON_PARSER_UNEXPECTED_MAP_END = 0x0b,
  JSON_PARSER_COMMA_OR_MAP_END_EXPECTED = 0x0c,
  JSON_PARSER_VALUE_EXPECTED = 0x0d,

  // CBOR parsing errors; checked when parsing / converting from CBOR.
  CBOR_INVALID_INT32 = 0x0e,
  CBOR_INVALID_DOUBLE = 0x0f,
  CBOR_INVALID_ENVELOPE = 0x10,
  CBOR_ENVELOPE_CONTENTS_LENGTH_MISMATCH = 0x11,
  CBOR_MAP_OR_ARRAY_EXPECTED_IN_ENVELOPE = 0x12,
  CBOR_INVALID_STRING8 = 0x13,
  CBOR_INVALID_STRING16 = 0x14,
  CBOR_INVALID_BINARY = 0x15,
  CBOR_UNSUPPORTED_VALUE = 0x16,
  CBOR_NO_INPUT = 0x17,
  CBOR_INVALID_START_BYTE = 0x18,
  CBOR_UNEXPECTED_EOF_EXPECTED_VALUE = 0x19,
  CBOR_UNEXPECTED_EOF_IN_ARRAY = 0x1a,
  CBOR_UNEXPECTED_EOF_IN_MAP = 0x1b,
  CBOR_INVALID_MAP_KEY = 0x1c,
  CBOR_DUPLICATE_MAP_KEY = 0x1d,
  CBOR_STACK_LIMIT_EXCEEDED = 0x1e,
  CBOR_TRAILING_JUNK = 0x1f,
  CBOR_MAP_START_EXPECTED = 0x20,
  CBOR_MAP_STOP_EXPECTED = 0x21,
  CBOR_ARRAY_START_EXPECTED = 0x22,
  CBOR_ENVELOPE_SIZE_LIMIT_EXCEEDED = 0x23,

  // Message errors are constraints we place on protocol messages coming
  // from a protocol client; these are checked in crdtp::Dispatchable
  // (see dispatch.h) as it performs a shallow parse.
  MESSAGE_MUST_BE_AN_OBJECT = 0x24,
  MESSAGE_MUST_HAVE_INTEGER_ID_PROPERTY = 0x25,
  MESSAGE_MUST_HAVE_STRING_METHOD_PROPERTY = 0x26,
  MESSAGE_MAY_HAVE_STRING_SESSION_ID_PROPERTY = 0x27,
  MESSAGE_MAY_HAVE_OBJECT_PARAMS_PROPERTY = 0x28,
  MESSAGE_HAS_UNKNOWN_PROPERTY = 0x29,

  BINDINGS_MANDATORY_FIELD_MISSING = 0x30,
  BINDINGS_BOOL_VALUE_EXPECTED = 0x31,
  BINDINGS_INT32_VALUE_EXPECTED = 0x32,
  BINDINGS_DOUBLE_VALUE_EXPECTED = 0x33,
  BINDINGS_STRING_VALUE_EXPECTED = 0x34,
  BINDINGS_STRING8_VALUE_EXPECTED = 0x35,
  BINDINGS_BINARY_VALUE_EXPECTED = 0x36,
  BINDINGS_DICTIONARY_VALUE_EXPECTED = 0x37,
};

// A status value with position that can be copied. The default status
// is OK. Usually, error status values should come with a valid position.
struct Status {
  static constexpr size_t npos() { return std::numeric_limits<size_t>::max(); }

  bool ok() const { return error == Error::OK; }

  Error error = Error::OK;
  size_t pos = npos();
  Status(Error error, size_t pos) : error(error), pos(pos) {}
  Status() = default;

  bool IsMessageError() const {
    return error >= Error::MESSAGE_MUST_BE_AN_OBJECT &&
           error <= Error::MESSAGE_HAS_UNKNOWN_PROPERTY;
  }

  // Returns 7 bit US-ASCII string, either "OK" or an error message without
  // position.
  std::string Message() const;

  // Returns a 7 bit US-ASCII string, either "OK" or an error message that
  // includes the position.
  std::string ToASCIIString() const;
};

template <typename T>
class StatusOr {
 public:
  explicit StatusOr(const T& value) : value_(value) {}
  explicit StatusOr(T&& value) : value_(std::move(value)) {}
  explicit StatusOr(const Status& status) : status_(status) {}

  bool ok() const { return status_.ok(); }
  T& operator*() & {
    assert(ok());
    return value_;
  }
  const T& operator*() const& { return value(); }
  T&& operator*() && { return value(); }
  const Status& status() const { return status_; }

  T& value() & { return *this; }
  T&& value() && {
    assert(ok());
    return std::move(value_);
  }
  const T& value() const& { return *this; }

 private:
  Status status_;
  T value_;
};

}  // namespace v8_crdtp

#endif  // V8_CRDTP_STATUS_H_