Sources/SPTDataLoaderSwift/ResponseSerializer.swift

// Copyright 2015-2023 Spotify AB
//
// 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 protocol that provides response type serialization.
public protocol ResponseSerializer {
    /// The serialized instance type to be returned.
    associatedtype Output

    /// Serializes a response into the associated type.
    /// - Parameter response: The `SPTDataLoaderResponse` received for a request.
    /// - Throws: An `Error` resulting from failed serialization.
    /// - Returns: A serialized instance of the associated type.
    func serialize(response: SPTDataLoaderResponse) throws -> Output
}

struct DataResponseSerializer: ResponseSerializer {
    func serialize(response: SPTDataLoaderResponse) throws -> Data {
        guard let data = response.body else {
            throw ResponseSerializationError.dataNotFound
        }

        return data
    }
}

struct DecodableResponseSerializer<Value: Decodable>: ResponseSerializer {
    let decoder: ResponseDecoder

    func serialize(response: SPTDataLoaderResponse) throws -> Value {
        guard let data = response.body else {
            throw ResponseSerializationError.dataNotFound
        }

        return try decoder.decode(Value.self, from: data)
    }
}

struct JSONResponseSerializer: ResponseSerializer {
    let options: JSONSerialization.ReadingOptions

    func serialize(response: SPTDataLoaderResponse) throws -> Any {
        guard let data = response.body else {
            throw ResponseSerializationError.dataNotFound
        }

        return try JSONSerialization.jsonObject(with: data, options: options)
    }
}