import Foundation
import Apollo

extension Result {
    var value: Success? { do { return try get() } catch { return nil } }
    var error: Failure? { do { _ = try get();return nil } catch { return error as? Failure } }
}

extension Network.Service {
    class GraphQL: Common.Service.Provider {
        #warning("shared should be removed or init make private")
        static let shared = GraphQL()
        private var _client: ApolloClient!
        private var _paycashClient: ApolloClient!
        init() { }
    }
}

extension Network.Service.GraphQL {
    @discardableResult
    func fetch<Query:GraphQLQuery>(query: Query, completion: @escaping (Result<Query.Data, Error>) -> Void ) -> Cancellable {
        client.fetch(query: query, cachePolicy: .fetchIgnoringCacheCompletely) {
            if let data = $0.value?.data {
                completion(.success(data))
            } else if let error = $0.error {
                completion(.failure(error))
            } else {
                completion(.failure(NSError.error(L10n.Common.Alert.error)))
            }
        }
    }
    @discardableResult
    func fetchV2<Query:GraphQLQuery>(query: Query, completion: @escaping (Result<Query.Data, Error>) -> Void ) -> Cancellable {
        paycashClient.fetch(query: query, cachePolicy: .fetchIgnoringCacheCompletely) {
            if let data = $0.value?.data {
                completion(.success(data))
            } else if let error = $0.error {
                completion(.failure(error))
            } else {
                completion(.failure(NSError.error(L10n.Common.Alert.error)))
            }
        }
    }
    @discardableResult
    func perform<Mutation:GraphQLMutation>(mutation: Mutation, completion: ((Result<Mutation.Data, Error>) -> Void)? = nil) -> Cancellable {
        client.perform(mutation: mutation) {
            guard let completion = completion else { return }
            if let data = $0.value?.data {
                completion(.success(data))
            } else if let error = $0.error {
                completion(.failure(error))
            } else {
                completion(.failure(NSError.error(L10n.Common.Alert.error)))
            }
        }
    }
}

extension Network.Service.GraphQL {
    fileprivate var client: ApolloClient {
        if _client == nil {
            _client = ApolloClient(url: URL(string: Network.servers.current.graphql)!)
        }
        return _client
    }
    fileprivate var paycashClient: ApolloClient {
        if _paycashClient == nil {
            _paycashClient = ApolloClient(url: URL(string: Network.servers.current.paycashQraphql)!)
        }
        return _paycashClient
    }
}

//extension Network.Service.GraphQL: HTTPNetworkTransportPreflightDelegate {
//    func networkTransport(_ networkTransport: HTTPNetworkTransport, shouldSend request: URLRequest) -> Bool { true }
//    func networkTransport(_ networkTransport: HTTPNetworkTransport, willSend request: inout URLRequest) {}
//}
//