import Foundation
import SwiftSignalKit
import Postbox

public typealias EngineTempBox = TempBox
public typealias EngineTempBoxFile = TempBoxFile

public final class EngineMediaResource: Equatable {
    public enum CacheTimeout {
        case `default`
        case shortLived
    }

    public struct ByteRange {
        public enum Priority {
            case `default`
            case elevated
            case maximum
        }

        public var range: Range<Int>
        public var priority: Priority

        public init(range: Range<Int>, priority: Priority) {
            self.range = range
            self.priority = priority
        }
    }

    public final class Fetch {
        public enum Result {
            case moveTempFile(file: TempBoxFile)
        }

        public enum Error {
            case generic
        }

        public let signal: () -> Signal<Result, Error>

        public init(_ signal: @escaping () -> Signal<Result, Error>) {
            self.signal = signal
        }
    }

    public final class ResourceData {
        public let path: String
        public let availableSize: Int
        public let isComplete: Bool

        public init(
            path: String,
            availableSize: Int,
            isComplete: Bool
        ) {
            self.path = path
            self.availableSize = availableSize
            self.isComplete = isComplete
        }
    }

    public struct Id: Equatable, Hashable {
        public var stringRepresentation: String

        public init(_ stringRepresentation: String) {
            self.stringRepresentation = stringRepresentation
        }

        public init(_ id: MediaResourceId) {
            self.stringRepresentation = id.stringRepresentation
        }
    }

    private let resource: MediaResource

    public init(_ resource: MediaResource) {
        self.resource = resource
    }

    public func _asResource() -> MediaResource {
        return self.resource
    }

    public var id: Id {
        return Id(self.resource.id)
    }

    public static func ==(lhs: EngineMediaResource, rhs: EngineMediaResource) -> Bool {
        return lhs.resource.isEqual(to: rhs.resource)
    }
}

public extension EngineMediaResource.ResourceData {
    convenience init(_ data: MediaResourceData) {
        self.init(path: data.path, availableSize: data.size, isComplete: data.complete)
    }
}

public extension TelegramEngine {
    final class Resources {
        private let account: Account

        init(account: Account) {
            self.account = account
        }

        public func preUpload(id: Int64, encrypt: Bool, tag: MediaResourceFetchTag?, source: Signal<MediaResourceData, NoError>, onComplete: (()->Void)? = nil) {
            return self.account.messageMediaPreuploadManager.add(network: self.account.network, postbox: self.account.postbox, id: id, encrypt: encrypt, tag: tag, source: source, onComplete: onComplete)
        }

        public func collectCacheUsageStats(peerId: PeerId? = nil, additionalCachePaths: [String] = [], logFilesPath: String? = nil) -> Signal<CacheUsageStatsResult, NoError> {
            return _internal_collectCacheUsageStats(account: self.account, peerId: peerId, additionalCachePaths: additionalCachePaths, logFilesPath: logFilesPath)
        }

        public func clearCachedMediaResources(mediaResourceIds: Set<MediaResourceId>) -> Signal<Void, NoError> {
            return _internal_clearCachedMediaResources(account: self.account, mediaResourceIds: mediaResourceIds)
        }

        public func data(id: EngineMediaResource.Id, attemptSynchronously: Bool = false) -> Signal<EngineMediaResource.ResourceData, NoError> {
            return self.account.postbox.mediaBox.resourceData(
                id: MediaResourceId(id.stringRepresentation),
                pathExtension: nil,
                option: .complete(waitUntilFetchStatus: false),
                attemptSynchronously: attemptSynchronously
            )
            |> map { data in
                return EngineMediaResource.ResourceData(data)
            }
        }

        public func custom(id: String, fetch: EngineMediaResource.Fetch, cacheTimeout: EngineMediaResource.CacheTimeout = .default, attemptSynchronously: Bool = false) -> Signal<EngineMediaResource.ResourceData, NoError> {
            let mappedKeepDuration: CachedMediaRepresentationKeepDuration
            switch cacheTimeout {
            case .default:
                mappedKeepDuration = .general
            case .shortLived:
                mappedKeepDuration = .shortLived
            }
            return self.account.postbox.mediaBox.customResourceData(
                id: id,
                baseResourceId: nil,
                pathExtension: nil,
                complete: true,
                fetch: {
                    return Signal { subscriber in
                        return fetch.signal().start(next: { result in
                            let mappedResult: CachedMediaResourceRepresentationResult
                            switch result {
                            case let .moveTempFile(file):
                                mappedResult = .tempFile(file)
                            }
                            subscriber.putNext(mappedResult)
                        }, completed: {
                            subscriber.putCompletion()
                        })
                    }
                },
                keepDuration: mappedKeepDuration,
                attemptSynchronously: attemptSynchronously
            )
            |> map { data in
                return EngineMediaResource.ResourceData(data)
            }
        }

        public func httpData(url: String) -> Signal<Data, EngineMediaResource.Fetch.Error> {
            return fetchHttpResource(url: url)
            |> mapError { _ -> EngineMediaResource.Fetch.Error in
                return .generic
            }
            |> mapToSignal { value -> Signal<Data, EngineMediaResource.Fetch.Error> in
                switch value {
                case let .dataPart(_, data, _, _):
                    return .single(data)
                default:
                    return .complete()
                }
            }
        }

        public func cancelAllFetches(id: String) {
            preconditionFailure()
        }
    }
}