/**
 * Tae Won Ha - http://taewon.de - @hataewon
 * See LICENSE
 */

import Cocoa

fileprivate let workspace = NSWorkspace.shared
fileprivate let iconsCache = NSCache<NSURL, NSImage>()

class FileUtils {
  
  fileprivate static let keysToGet: [URLResourceKey] = [
    .isDirectoryKey,
    .isHiddenKey,
    .isAliasFileKey,
    .isSymbolicLinkKey
  ]
  
  fileprivate static let scanOptions: FileManager.DirectoryEnumerationOptions = [
    .skipsSubdirectoryDescendants,
    .skipsPackageDescendants
  ]
  
  fileprivate static let fileManager = FileManager.default

  static let userHomeUrl = URL(fileURLWithPath: NSHomeDirectory(), isDirectory: true)
  
  static func directDescendants(of url: URL) -> [URL] {
    guard let childUrls = try? self.fileManager.contentsOfDirectory(
      at: url, includingPropertiesForKeys: self.keysToGet, options: self.scanOptions
    ) else {
      // FIXME error handling
      return []
    }
    
    return childUrls
  }
  
  static func fileExists(at url: URL) -> Bool {
    guard url.isFileURL else {
      return false
    }

    let path = url.path
    return self.fileManager.fileExists(atPath: path)
  }

  static func commonParent(of urls: [URL]) -> URL {
    guard urls.count > 0 else {
      return URL(fileURLWithPath: "/", isDirectory: true)
    }

    let pathComps = urls.map { $0.deletingLastPathComponent().pathComponents }
    let min = pathComps.map { $0.count }.min()!
    let pathCompsOnlyMin = pathComps.map { $0[0..<min] }
    let commonIdx = (0..<min).reversed().reduce(min - 1) { (result, idx) in
      if Set(pathCompsOnlyMin.map { $0[idx] }).count > 1 {
        return idx - 1
      } else {
        return result
      }
    }

    let result = pathCompsOnlyMin[0]
    let possibleParent = NSURL.fileURL(withPathComponents: Array(result[0...commonIdx]))!

    return possibleParent.isDir ? possibleParent : possibleParent.parent
  }

  static func icon(forType type: String) -> NSImage {
    return workspace.icon(forFileType: type)
  }

  static func icon(forUrl url: URL) -> NSImage? {
    if let cached = iconsCache.object(forKey: url as NSURL) {
      return cached
    }

    let path = url.path
    let icon = workspace.icon(forFile: path)
    icon.size = CGSize(width: 16, height: 16)
    iconsCache.setObject(icon, forKey: url as NSURL)

    return icon
  }
}