//Copyright 2019 Soroush Khanlou
//
//Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
//
//The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
//
//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

import Foundation

class SerialInputStream: InputStream {

    let inputStreams: [InputStream]

    private var currentIndex: Int
    private var _streamStatus: Stream.Status
    private var _streamError: Error?
    private var _delegate: StreamDelegate?

    init(inputStreams: [InputStream]) {
        self.inputStreams = inputStreams
        self.currentIndex = 0
        self._streamStatus = .notOpen
        self._streamError = nil
        super.init(data: Data()) //required because `init()` is not marked as a designated initializer
    }

    override var streamStatus: Stream.Status {
        return _streamStatus
    }

    override var streamError: Error? {
        return _streamError
    }

    override var delegate: StreamDelegate? {
        get {
            return _delegate
        }
        set {
            _delegate = newValue
        }
    }

    override func read(_ buffer: UnsafeMutablePointer<UInt8>, maxLength: Int) -> Int {
        if _streamStatus == .closed{
            return 0
        }

        var totalNumberOfBytesRead = 0

        while totalNumberOfBytesRead < maxLength {
            if currentIndex == inputStreams.count {
                self.close()
                break
            }

            let currentInputStream = inputStreams[currentIndex]

            if currentInputStream.streamStatus != .open {
                currentInputStream.open()
            }

            if !currentInputStream.hasBytesAvailable {
                self.currentIndex += 1
                continue
            }

            let remainingLength = maxLength - totalNumberOfBytesRead

            let numberOfBytesRead = currentInputStream.read(&buffer[totalNumberOfBytesRead], maxLength: remainingLength)

            if numberOfBytesRead == 0 {
                self.currentIndex += 1
                continue
            }

            if numberOfBytesRead == -1 {
                self._streamError = currentInputStream.streamError
                self._streamStatus = .error
                return -1
            }

            totalNumberOfBytesRead += numberOfBytesRead
        }

        return totalNumberOfBytesRead
    }

    override func getBuffer(_ buffer: UnsafeMutablePointer<UnsafeMutablePointer<UInt8>?>, length len: UnsafeMutablePointer<Int>) -> Bool {
        return false
    }

    override var hasBytesAvailable: Bool {
        return true
    }

    override func open() {
        guard self._streamStatus == .open else {
            return
        }
        self._streamStatus = .open
    }

    override func close() {
        self._streamStatus = .closed
    }

    override func property(forKey key: Stream.PropertyKey) -> Any? {
        return nil
    }

    override func setProperty(_ property: Any?, forKey key: Stream.PropertyKey) -> Bool {
        return false
    }

    override func schedule(in aRunLoop: RunLoop, forMode mode: RunLoop.Mode) {

    }

    override func remove(from aRunLoop: RunLoop, forMode mode: RunLoop.Mode) {

    }

}