// Copyright 2026 Google LLC
//
// 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
//
//      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.

import Foundation

/// A collection of name-value pairs representing a JSON object.
///
/// This may be decoded from, or encoded to, a `google.protobuf.Struct`
/// (https://protobuf.dev/reference/protobuf/google.protobuf/#struct).
package typealias JSONObject = [String: JSONValue]

/// Represents a value in one of JSON's data types.
///
/// This may be decoded from, or encoded to, a `google.protobuf.Value`
/// (https://protobuf.dev/reference/protobuf/google.protobuf/#value).
package enum JSONValue: Sendable, Hashable {
  /// A `null` value.
  case null

  /// A numeric value.
  case number(Double)

  /// A string value.
  case string(String)

  /// A boolean value.
  case bool(Bool)

  /// A JSON object.
  case object(JSONObject)

  /// An array of `JSONValue`s.
  case array([JSONValue])
}

// MARK: - Codable Conformances

extension JSONValue: Decodable {
  package init(from decoder: any Decoder) throws {
    let container = try decoder.singleValueContainer()
    if container.decodeNil() {
      self = .null
    } else if let numberValue = try? container.decode(Double.self) {
      self = .number(numberValue)
    } else if let stringValue = try? container.decode(String.self) {
      self = .string(stringValue)
    } else if let boolValue = try? container.decode(Bool.self) {
      self = .bool(boolValue)
    } else if let objectValue = try? container.decode(JSONObject.self) {
      self = .object(objectValue)
    } else if let arrayValue = try? container.decode([JSONValue].self) {
      self = .array(arrayValue)
    } else {
      throw DecodingError.dataCorruptedError(
        in: container,
        debugDescription: "Failed to decode JSON value."
      )
    }
  }
}

extension JSONValue: Encodable {
  package func encode(to encoder: any Encoder) throws {
    var container = encoder.singleValueContainer()
    switch self {
    case .null:
      try container.encodeNil()
    case .number(let numberValue):
      // Convert to `Decimal` before encoding for consistent floating-point
      // serialization across platforms.
      try container.encode(Decimal(numberValue))
    case .string(let stringValue):
      try container.encode(stringValue)
    case .bool(let boolValue):
      try container.encode(boolValue)
    case .object(let objectValue):
      try container.encode(objectValue)
    case .array(let arrayValue):
      try container.encode(arrayValue)
    }
  }
}