//
//  Copyright (c) 2022 Touch Instinct
//
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//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
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//
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//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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//

import Foundation

private final class MapAsyncOperation<Output, Failure: Error>: DependendAsyncOperation<Output, Failure> {
    public init<DependencyOutput, DependencyFailure: Error>(dependency: AsyncOperation<DependencyOutput, DependencyFailure>,
                                                            mapOutput: @escaping (DependencyOutput) -> Result<Output, Failure>,
                                                            mapFailure: @escaping (DependencyFailure) -> Failure) {

        super.init(dependency: dependency) {
            $0.mapError(mapFailure).flatMap(mapOutput)
        }
    }
}

public extension AsyncOperation {
    func map<NewOutput, NewFailure: Error>(mapOutput: @escaping (Output) -> Result<NewOutput, NewFailure>,
                                           mapFailure: @escaping (Failure) -> NewFailure)
    -> AsyncOperation<NewOutput, NewFailure> {

        MapAsyncOperation(dependency: self,
                          mapOutput: mapOutput,
                          mapFailure: mapFailure)
    }

    func map<NewOutput>(mapOutput: @escaping (Output) -> NewOutput) -> AsyncOperation<NewOutput, Failure> {
        MapAsyncOperation(dependency: self,
                          mapOutput: { .success(mapOutput($0)) },
                          mapFailure: { $0 })
    }
}