// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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
//
//   http://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.

#include "kudu/util/jsonreader.h"

#include <ostream>
#include <utility>

#include <cmath>
#include <glog/logging.h>
#include <rapidjson/error/en.h>
#include <rapidjson/rapidjson.h>

#include "kudu/gutil/port.h"
#include "kudu/gutil/strings/substitute.h"

using rapidjson::Value;
using std::string;
using std::vector;
using strings::Substitute;

namespace kudu {

namespace {
const char* const TypeToString(rapidjson::Type t) {
  switch (t) {
    case rapidjson::kNullType:
      return "null";
    case rapidjson::kFalseType:
      return "false";
    case rapidjson::kTrueType:
      return "true";
    case rapidjson::kObjectType:
      return "object";
    case rapidjson::kArrayType:
      return "array";
    case rapidjson::kStringType:
      return "string";
    case rapidjson::kNumberType:
      return "number";
    default:
      LOG(FATAL) << "unexpected type: " << t;
  }
}
} // anonymous namespace

JsonReader::JsonReader(string text) : text_(std::move(text)) {}

JsonReader::~JsonReader() {
}

Status JsonReader::Init() {
  document_.Parse<0>(text_.c_str());
  if (document_.HasParseError()) {
    return Status::Corruption("JSON text is corrupt",
                              rapidjson::GetParseError_En(document_.GetParseError()));
  }
  return Status::OK();
}

Status JsonReader::ExtractBool(const Value* object,
                               const char* field,
                               bool* result) const {
  const Value* val;
  RETURN_NOT_OK(ExtractField(object, field, &val));
  if (PREDICT_FALSE(!val->IsBool())) {
    return Status::InvalidArgument(Substitute(
        "wrong type during field extraction: expected bool but got $0",
        TypeToString(val->GetType())));
  }
  *result = val->GetBool();
  return Status::OK();
}

Status JsonReader::ExtractInt32(const Value* object,
                                const char* field,
                                int32_t* result) const {
  const Value* val;
  RETURN_NOT_OK(ExtractField(object, field, &val));
  if (PREDICT_FALSE(!val->IsInt())) {
    return Status::InvalidArgument(Substitute(
        "wrong type during field extraction: expected int32 but got $0",
        TypeToString(val->GetType())));
  }
  *result = val->GetInt();
  return Status::OK();
}

Status JsonReader::ExtractUint32(const Value* object,
                                 const char* field,
                                 uint32_t* result) const {
  const Value* val;
  RETURN_NOT_OK(ExtractField(object, field, &val));
  if (PREDICT_FALSE(!val->IsUint())) {
    return Status::InvalidArgument(Substitute(
        "wrong type during field extraction: expected uint32 but got $0",
        TypeToString(val->GetType())));
  }
  *result = val->GetUint();
  return Status::OK();
}

Status JsonReader::ExtractInt64(const Value* object,
                                const char* field,
                                int64_t* result) const {
  const Value* val;
  RETURN_NOT_OK(ExtractField(object, field, &val));
  if (PREDICT_FALSE(!val->IsInt64())) {
    return Status::InvalidArgument(Substitute(
        "wrong type during field extraction: expected int64 but got $0",
        TypeToString(val->GetType())));
  }
  *result = val->GetInt64();
  return Status::OK();
}

Status JsonReader::ExtractUint64(const Value* object,
                                 const char* field,
                                 uint64_t* result) const {
  const Value* val;
  RETURN_NOT_OK(ExtractField(object, field, &val));
  if (PREDICT_FALSE(!val->IsUint64())) {
    return Status::InvalidArgument(Substitute(
        "wrong type during field extraction: expected uint64 but got $0",
        TypeToString(val->GetType())));
  }
  *result = val->GetUint64();
  return Status::OK();
}

Status JsonReader::ExtractDouble(const Value* object,
                                 const char* field,
                                 double* result) const {
  const Value* val;
  RETURN_NOT_OK(ExtractField(object, field, &val));
  if (PREDICT_FALSE(!val->IsLosslessDouble())) {
    return Status::InvalidArgument(Substitute(
        "wrong type during field extraction: expected a lossless double type but got $0",
        TypeToString(val->GetType())));
  }
  *result = val->GetDouble();
  return Status::OK();
}

Status JsonReader::ExtractFloat(const Value* object,
                                const char* field,
                                float* result) const {
  const Value* val;
  RETURN_NOT_OK(ExtractField(object, field, &val));
  if (PREDICT_FALSE(!IsLosslessFloatValue(val))) {
    return Status::InvalidArgument(Substitute(
        "wrong type during field extraction: expected a lossless float type but got $0",
        TypeToString(val->GetType())));
  }
  *result = val->GetFloat();
  return Status::OK();
}

Status JsonReader::ExtractString(const Value* object,
                                 const char* field,
                                 string* result) const {
  const Value* val;
  RETURN_NOT_OK(ExtractField(object, field, &val));
  if (PREDICT_FALSE(!val->IsString())) {
    if (val->IsNull()) {
      *result = "";
      return Status::OK();
    }
    return Status::InvalidArgument(Substitute(
        "wrong type during field extraction: expected string but got $0",
        TypeToString(val->GetType())));
  }
  result->assign(val->GetString());
  return Status::OK();
}

Status JsonReader::ExtractObject(const Value* object,
                                 const char* field,
                                 const Value** result) const {
  const Value* val;
  RETURN_NOT_OK(ExtractField(object, field, &val));
  if (PREDICT_FALSE(!val->IsObject())) {
    return Status::InvalidArgument(Substitute(
        "wrong type during field extraction: expected object but got $0",
        TypeToString(val->GetType())));
  }
  *result = val;
  return Status::OK();
}

Status JsonReader::ExtractObjectArray(const Value* object,
                                      const char* field,
                                      vector<const Value*>* result) const {
  const Value* val;
  RETURN_NOT_OK(ExtractField(object, field, &val));
  if (PREDICT_FALSE(!val->IsArray())) {
    return Status::InvalidArgument(Substitute(
        "wrong type during field extraction: expected object array but got $0",
        TypeToString(val->GetType())));
  }
  for (Value::ConstValueIterator iter = val->Begin(); iter != val->End(); ++iter) {
    result->push_back(iter);
  }
  return Status::OK();
}

Status JsonReader::ExtractField(const Value* object,
                                const char* field,
                                const Value** result) const {
  if (field && PREDICT_FALSE(!object->HasMember(field))) {
    return Status::NotFound("Missing field", field);
  }
  *result = field ? &(*object)[field] : object;
  return Status::OK();
}

bool JsonReader::IsLosslessFloatValue(const Value* value) const {
  if (!value->IsLosslessDouble()) {
    return false;
  }
  double a = value->GetDouble();
  double b = static_cast<double>(static_cast<float>(a));
  return fabs(a-b) <= 1e-7;
}

} // namespace kudu