TemporaryFile.swift

// Working around Foundation deficiencies when trying to append to a file
// (and without run loops, delegates, and other BS).
// Why is this so complicated?

import Foundation


public final class TemporaryFile {
    public let handle: NSFileHandle //IUO until Swift 2.2
    public let url: NSURL

    /// Creates a temporary file with a random name in the given directory
    public init(inDirectory: NSURL) throws {
        self.url = inDirectory.URLByAppendingPathComponent(NSUUID().UUIDString)
        let data = NSData()
        do {
            try data.writeToURL(self.url, options: NSDataWritingOptions())
            self.handle = try NSFileHandle(forWritingToURL: self.url)
        } catch {
            self.handle = NSFileHandle()
            throw error
        }
    }

    /// Creates a temporary file with a random name in the temporary files directory
    public convenience init() throws {
        try self.init(inDirectory: NSURL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true))
    }

    public func write(data: NSData) {
        self.handle.writeData(data)
    }

    public func write(buffer: [UInt8]) {
        buffer.withUnsafeBufferPointer { (ptr) -> Void in
            let data = NSData(bytes: UnsafePointer<Void>(ptr.baseAddress), length: ptr.count)
            self.write(data)
        }
    }

    public func moveTo(destination: NSURL) throws {
        try NSFileManager.defaultManager().moveItemAtURL(self.url, toURL: destination)
    }

    /// Returns a memory-mapped `NSData` of the file contents. Used for testing.
    public func read() throws -> NSData {
        return try NSData(contentsOfURL: self.url, options: NSDataReadingOptions.DataReadingMappedIfSafe)
    }
}