//
//  Socket+File.swift
//  Swifter
//
//  Copyright (c) 2014-2016 Damian Kołakowski. All rights reserved.
//

#if os(Linux)
    import Glibc
#else
    import Foundation
#endif


#if os(iOS) || os(tvOS) || os (Linux)
    
    struct sf_hdtr { }
    
    private func sendfileImpl(source: Int32, _ target: Int32, _: off_t, _: UnsafeMutablePointer<off_t>, _: UnsafeMutablePointer<sf_hdtr>?, _: Int32) -> Int32 {
        var buffer = [UInt8](repeating: 0, count: 1024)
        while true {
            let readResult = read(source, &buffer, buffer.count)
            guard readResult > 0 else {
                return Int32(readResult)
            }
            var writeCounter = 0
            while writeCounter < readResult {
                let writeResult = write(target, &buffer + writeCounter, readResult - writeCounter)
                guard writeResult > 0 else {
                    return Int32(writeResult)
                }
                writeCounter = writeCounter + writeResult
            }
        }
    }
    
#else
    
    private let sendfileImpl = sendfile
    
#endif

#if os(iOS) || os(tvOS) || os (Linux)

extension Socket {
    
    public func writeFile(file: String.File) throws -> Void {
        var offset: off_t = 0
        let result = sendfileImpl(source: fileno(file.pointer), self.socketFileDescriptor, 0, &offset, nil, 0)
        if result == -1 {
            throw SocketError.writeFailed("sendfile: " + Process.lastErrno)
        }
    }
    
}

#endif