iOS/Sources/Shared/API/Webhook/Networking/WebhookRequest.swift

import Foundation
import ObjectMapper
import Sodium

public enum WebhookRequestContext: MapContext, Equatable {
    case server(Server)
    case local
}

public struct WebhookRequest: ImmutableMappable {
    public let type: String
    public let data: Any
    public let localMetadata: [String: Any]?

    public init(type: String, data: Any, localMetadata: [String: Any]? = nil) {
        self.type = type
        self.data = data
        self.localMetadata = localMetadata
    }

    public init(map: Map) throws {
        self.type = try map.value("type")
        self.data = try map.value("data")
        self.localMetadata = try? map.value("local_metadata")
    }

    enum ConversionError: Error {
        case dictionary
    }

    func asDictionary() throws -> [String: Any] {
        if let data = data as? [String: Any] {
            return data
        } else {
            throw ConversionError.dictionary
        }
    }

    public func mapping(map: Map) {
        guard let context = map.context as? WebhookRequestContext else {
            fatalError("context must be provided to avoid accidental unencrypted traffic")
        }

        type >>> map["type"]

        if context == .local {
            localMetadata >>> map["local_metadata"]
        }

        if case let .server(server) = context, let encrypted = encryptedData(server: server) {
            true >>> map["encrypted"]
            encrypted >>> map["encrypted_data"]
        } else {
            data >>> map["data"]
        }
    }

    private func encryptedData(server: Server) -> String? {
        guard let secret = server.info.connection.webhookSecret else {
            return nil
        }

        let sodium = Sodium()

        guard let jsonData = try? JSONSerialization.data(withJSONObject: data, options: [.sortedKeys]) else {
            Current.Log.error("Unable to convert JSON dictionary to data!")
            return nil
        }

        guard let jsonStr = String(data: jsonData, encoding: .utf8) else {
            Current.Log.error("Unable to convert JSON data to string!")
            return nil
        }

        let key: Bytes = Array(secret.bytes[0 ..< sodium.secretBox.KeyBytes])

        guard let encryptedData: Bytes = sodium.secretBox.seal(
            message: jsonStr.bytes,
            secretKey: key
        ) else {
            Current.Log.error("Unable to generate encrypted webhook payload! Secret: \(secret), JSON: \(jsonStr)")
            return nil
        }

        guard let b64payload = sodium.utils.bin2base64(encryptedData, variant: .ORIGINAL) else {
            Current.Log.error("Unable to encode encrypted payload to base64!")
            return nil
        }

        return b64payload
    }
}