//
//  OneDriveFileProvider.swift
//  FileProvider
//
//  Created by Amir Abbas Mousavian.
//  Copyright © 2017 Mousavian. Distributed under MIT license.
//

import Foundation
import CoreGraphics

/**
 Allows accessing to OneDrive stored files, either hosted on Microsoft servers or business coprporate one.
 This provider doesn't cache or save files internally, however you can set `useCache` and `cache` properties
 to use Foundation `NSURLCache` system.
 
 - Note: Uploading files and data are limited to 100MB, for now.
 */
open class OneDriveFileProvider: FileProviderBasicRemote {
    open class var type: String { return "OneDrive" }
    open let baseURL: URL?
    /// Drive name for user, default is `root`. Changing its value will effect on new operations.
    open var drive: String
    /// Generated storage url from server url and drive name
    open var currentPath: String
    
    open var dispatch_queue: DispatchQueue
    open var operation_queue: OperationQueue {
        willSet {
            assert(_session == nil, "It's not effective to change dispatch_queue property after session is initialized.")
        }
    }
    
    open weak var delegate: FileProviderDelegate?
    open var credential: URLCredential? {
        didSet {
            sessionDelegate?.credential = self.credential
        }
    }
    open private(set) var cache: URLCache?
    public var useCache: Bool
    public var validatingCache: Bool
   
    fileprivate var _session: URLSession?
    fileprivate var sessionDelegate: SessionDelegate?
    public var session: URLSession {
        get {
            if _session == nil {
                self.sessionDelegate = SessionDelegate(fileProvider: self)
                let queue = OperationQueue()
                //queue.underlyingQueue = dispatch_queue
                let config = URLSessionConfiguration.default
                config.urlCache = cache
                config.requestCachePolicy = .returnCacheDataElseLoad
                _session = URLSession(configuration: config, delegate: sessionDelegate as URLSessionDelegate?, delegateQueue: queue)
                _session?.sessionDescription = UUID().uuidString
                initEmptySessionHandler(_session!.sessionDescription!)
            }
            return _session!
        }
        
        set {
            assert(newValue.delegate is SessionDelegate, "session instances should have a SessionDelegate instance as delegate.")
            _session = newValue
            if session.sessionDescription?.isEmpty ?? true {
                _session?.sessionDescription = UUID().uuidString
            }
            self.sessionDelegate = newValue.delegate as? SessionDelegate
            initEmptySessionHandler(_session!.sessionDescription!)
        }
    }
    
    /**
     Initializer for Onedrive provider with given client ID and Token.
     These parameters must be retrieved via [Authentication for the OneDrive API](https://dev.onedrive.com/auth/readme.htm).
     
     There are libraries like [p2/OAuth2](https://github.com/p2/OAuth2) or [OAuthSwift](https://github.com/OAuthSwift/OAuthSwift) which can facilate the procedure to retrieve token.
     The latter is easier to use and prefered. Also you can use [auth0/Lock](https://github.com/auth0/Lock.iOS-OSX) which provides graphical user interface.
     
     - Parameters:
       - credential: a `URLCredential` object with Client ID set as `user` and Token set as `password`.
       - serverURL: server url, Set it if you are trying to connect OneDrive Business server, otherwise leave it
         `nil` to connect to OneDrive Personal uses.
       - drive: drive name for user on server, default value is `root`.
       - cache: A URLCache to cache downloaded files and contents.
     */
    public init(credential: URLCredential?, serverURL: URL? = nil, drive: String = "root", cache: URLCache? = nil) {
        let baseURL = serverURL?.absoluteURL ?? URL(string: "https://api.onedrive.com/")!
        self.baseURL = baseURL.path.hasSuffix("/") ? baseURL : baseURL.appendingPathComponent("")
        self.drive = drive
        self.currentPath = ""
        self.useCache = false
        self.validatingCache = true
        self.cache = cache
        self.credential = credential
        dispatch_queue = DispatchQueue(label: "FileProvider.\(type(of: self).type)", attributes: .concurrent)
        operation_queue = OperationQueue()
        operation_queue.name = "FileProvider.\(type(of: self).type).Operation"
    }
    
    public required convenience init?(coder aDecoder: NSCoder) {
        self.init(credential: aDecoder.decodeObject(forKey: "credential") as? URLCredential,
                  serverURL: aDecoder.decodeObject(forKey: "baseURL") as? URL,
                  drive: aDecoder.decodeObject(forKey: "drive") as? String ?? "root")
        self.currentPath   = aDecoder.decodeObject(forKey: "currentPath") as? String ?? ""
        self.useCache = aDecoder.decodeBool(forKey: "useCache")
        self.validatingCache = aDecoder.decodeBool(forKey: "validatingCache")
    }
    
    open func encode(with aCoder: NSCoder) {
        aCoder.encode(self.credential, forKey: "credential")
        aCoder.encode(self.baseURL, forKey: "baseURL")
        aCoder.encode(self.drive, forKey: "drive")
        aCoder.encode(self.currentPath, forKey: "currentPath")
        aCoder.encode(self.useCache, forKey: "useCache")
        aCoder.encode(self.validatingCache, forKey: "validatingCache")
    }
    
    public static var supportsSecureCoding: Bool {
        return true
    }
    
    open func copy(with zone: NSZone? = nil) -> Any {
        let copy = OneDriveFileProvider(credential: self.credential, serverURL: self.baseURL, drive: self.drive, cache: self.cache)
        copy.currentPath = self.currentPath
        copy.delegate = self.delegate
        copy.fileOperationDelegate = self.fileOperationDelegate
        copy.useCache = self.useCache
        copy.validatingCache = self.validatingCache
        return copy
    }
    
    deinit {
        if let sessionuuid = _session?.sessionDescription {
            removeSessionHandler(for: sessionuuid)
        }
        
        if fileProviderCancelTasksOnInvalidating {
            _session?.invalidateAndCancel()
        } else {
            _session?.finishTasksAndInvalidate()
        }
    }
    
    open func contentsOfDirectory(path: String, completionHandler: @escaping ((_ contents: [FileObject], _ error: Error?) -> Void)) {
        list(path) { (contents, cursor, error) in
            completionHandler(contents, error)
        }
    }
    
    open func attributesOfItem(path: String, completionHandler: @escaping ((_ attributes: FileObject?, _ error: Error?) -> Void)) {
        var request = URLRequest(url: url(of: path))
        request.httpMethod = "GET"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
            var serverError: FileProviderOneDriveError?
            var fileObject: OneDriveFileObject?
            if let response = response as? HTTPURLResponse {
                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
                serverError = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
                if let json = data?.deserializeJSON(), let file = OneDriveFileObject(baseURL: self.baseURL, drive: self.drive, json: json) {
                    fileObject = file
                }
            }
            completionHandler(fileObject, serverError ?? error)
        }) 
        task.resume()
    }
    
    open func storageProperties(completionHandler: @escaping ((_ total: Int64, _ used: Int64) -> Void)) {
        var request = URLRequest(url: url())
        request.httpMethod = "GET"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
            var totalSize: Int64 = -1
            var usedSize: Int64 = 0
            if let json = data?.deserializeJSON() {
                totalSize = (json["total"] as? NSNumber)?.int64Value ?? -1
                usedSize = (json["used"] as? NSNumber)?.int64Value ?? 0
            }
            completionHandler(totalSize, usedSize)
        }) 
        task.resume()
    }
    
    open func searchFiles(path: String, recursive: Bool, query: NSPredicate, foundItemHandler: ((FileObject) -> Void)?, completionHandler: @escaping ((_ files: [FileObject], _ error: Error?) -> Void)) {
        var foundFiles = [OneDriveFileObject]()
        var queryStr: String?
        queryStr = query.findValue(forKey: "name") as? String ?? query.findAllValues(forKey: nil).flatMap { $0.value as? String }.first
        guard let finalQueryStr = queryStr else { return }
        search(path, query: finalQueryStr, foundItem: { (file) in
            if query.evaluate(with: file.mapPredicate()) {
                foundFiles.append(file)
                foundItemHandler?(file)
            }
        }, completionHandler: { (error) in
            completionHandler(foundFiles, error)
        })
    }
    
    open func url(of path: String? = nil, modifier: String? = nil) -> URL {
        var rpath: String
        if let path = path {
            rpath = path
        } else {
            rpath = self.currentPath
        }
        
        if rpath.hasPrefix("/") {
            rpath.remove(at: rpath.startIndex)
        }
        if rpath.isEmpty {
            if let modifier = modifier {
                return baseURL!.appendingPathComponent("drive/\(drive)/\(modifier)")
            }
            return baseURL!.appendingPathComponent("drive/\(drive)")
        }
        let driveURL = baseURL!.appendingPathComponent("drive/\(drive):/")
        rpath = (rpath.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed) ?? rpath)
        rpath = rpath.trimmingCharacters(in: pathTrimSet)
        if let modifier = modifier {
            rpath = rpath + ":/" + modifier
        }
        return URL(string: rpath, relativeTo: driveURL) ?? driveURL
    }
    
    open func isReachable(completionHandler: @escaping (Bool) -> Void) {
        var request = URLRequest(url: url())
        request.httpMethod = "HEAD"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
            let status = (response as? HTTPURLResponse)?.statusCode ?? 400
            completionHandler(status == 200)
        })
        task.resume()
    }
    
    open weak var fileOperationDelegate: FileOperationDelegate?
}

extension OneDriveFileProvider: FileProviderOperations {
    
    
    open func create(folder folderName: String, at atPath: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let path = (atPath as NSString).appendingPathComponent(folderName) + "/"
        return doOperation(.create(path: path), completionHandler: completionHandler)
    }
    
    open func moveItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        return doOperation(.move(source: path, destination: toPath), completionHandler: completionHandler)
    }
    
    open func copyItem(path: String, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        return doOperation(.copy(source: path, destination: toPath), completionHandler: completionHandler)
    }
    
    open func removeItem(path: String, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        return doOperation(.remove(path: path), completionHandler: completionHandler)
    }
    
    fileprivate func doOperation(_ operation: FileOperationType, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: operation) ?? true == true else {
            return nil
        }
        guard let sourcePath = operation.source else { return nil }
        let destPath = operation.destination
        var request = URLRequest(url: url(of: sourcePath))
        switch operation {
        case .create:
            request.httpMethod = "CREATE"
        case .copy:
            request.httpMethod = "POST"
        case .move:
            request.httpMethod = "PATCH"
        case .remove:
            request.httpMethod = "DELETE"
        default: // modify, link, fetch
            return nil
        }
        
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        var requestDictionary = [String: AnyObject]()
        if let dest = correctPath(destPath) as NSString? {
            request.setValue("application/json", forHTTPHeaderField: "Content-Type")
            requestDictionary["parentReference"] = ("/drive/\(drive):" + dest.deletingLastPathComponent) as NSString
            requestDictionary["name"] = dest.lastPathComponent as NSString
            request.httpBody = Data(jsonDictionary: requestDictionary)
        }
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
            var serverError: FileProviderOneDriveError?
            if let response = response as? HTTPURLResponse, response.statusCode >= 300, let code = FileProviderHTTPErrorCode(rawValue: response.statusCode) {
                 serverError = FileProviderOneDriveError(code: code, path: sourcePath, errorDescription: String(data: data ?? Data(), encoding: .utf8))
            }
            completionHandler?(serverError ?? error)
            self.delegateNotify(operation, error: serverError ?? error)
        })
        task.taskDescription = operation.json
        task.resume()
        return RemoteOperationHandle(operationType: operation, tasks: [task])
    }
    
    open func copyItem(localFile: URL, to toPath: String, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        // check file is not a folder
        guard (try? localFile.resourceValues(forKeys: [.fileResourceTypeKey]))?.fileResourceType ?? .unknown == .regular else {
            dispatch_queue.async {
                completionHandler?(self.throwError(localFile.path, code: URLError.fileIsDirectory))
            }
            return nil
        }
        
        let opType = FileOperationType.copy(source: localFile.absoluteString, destination: toPath)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
        }
        return upload_simple(toPath, localFile: localFile, overwrite: overwrite, operation: opType, completionHandler: completionHandler)
    }
    
    open func copyItem(path: String, toLocalURL destURL: URL, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.copy(source: path, destination: destURL.absoluteString)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
        }
        var request = URLRequest(url: self.url(of: path, modifier: "content"))
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        let task = session.downloadTask(with: request)
        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = completionHandler
        downloadCompletionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { tempURL in
            guard let httpResponse = task.response as? HTTPURLResponse , httpResponse.statusCode < 300 else {
                let code = FileProviderHTTPErrorCode(rawValue: (task.response as? HTTPURLResponse)?.statusCode ?? -1)
                let errorData : Data? = nil //Data(contentsOf: cacheURL) // TODO: Figure out how to get error response data for the error description
                let serverError : FileProviderOneDriveError? = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: errorData ?? Data(), encoding: .utf8)) : nil
                completionHandler?(serverError)
                return
            }
            do {
                try FileManager.default.moveItem(at: tempURL, to: destURL)
                completionHandler?(nil)
            } catch let e {
                completionHandler?(e)
            }
        }
        task.taskDescription = opType.json
        task.resume()
        return RemoteOperationHandle(operationType: opType, tasks: [task])
    }
}

extension OneDriveFileProvider: FileProviderReadWrite {
    open func contents(path: String, offset: Int64, length: Int, completionHandler: @escaping ((_ contents: Data?, _ error: Error?) -> Void)) -> OperationHandle? {
        if length == 0 || offset < 0 {
            dispatch_queue.async {
                completionHandler(Data(), nil)
            }
            return nil
        }
        
        let opType = FileOperationType.fetch(path: path)
        var request = URLRequest(url: self.url(of: path, modifier: "content"))
        request.httpMethod = "GET"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        if length > 0 {
            request.setValue("bytes=\(offset)-\(offset + Int64(length) - 1)", forHTTPHeaderField: "Range")
        } else if offset > 0 && length < 0 {
            request.setValue("bytes=\(offset)-", forHTTPHeaderField: "Range")
        }
        let task = session.downloadTask(with: request)
        completionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { error in
            completionHandler(nil, error)
        }
        downloadCompletionHandlersForTasks[session.sessionDescription!]?[task.taskIdentifier] = { tempURL in
            guard let httpResponse = task.response as? HTTPURLResponse , httpResponse.statusCode < 300 else {
                let code = FileProviderHTTPErrorCode(rawValue: (task.response as? HTTPURLResponse)?.statusCode ?? -1)
                let errorData : Data? = nil //Data(contentsOf: cacheURL) // TODO: Figure out how to get error response data for the error description
                let serverError : FileProviderOneDriveError? = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: errorData ?? Data(), encoding: .utf8)) : nil
                completionHandler(nil, serverError)
                return
            }
            do {
                let data = try Data(contentsOf: tempURL)
                completionHandler(data, nil)
            } catch let e {
                completionHandler(nil, e)
            }
        }
        task.taskDescription = opType.json
        task.resume()
        return RemoteOperationHandle(operationType: opType, tasks: [task])
    }
    
    open func writeContents(path: String, contents data: Data?, atomically: Bool, overwrite: Bool, completionHandler: SimpleCompletionHandler) -> OperationHandle? {
        let opType = FileOperationType.modify(path: path)
        guard fileOperationDelegate?.fileProvider(self, shouldDoOperation: opType) ?? true == true else {
            return nil
        }
        // FIXME: remove 150MB restriction
        return upload_simple(path, data: data ?? Data(), overwrite: overwrite, operation: opType, completionHandler: completionHandler)
    }
    
    fileprivate func registerNotifcation(path: String, eventHandler: (() -> Void)) {
        /* There is two ways to monitor folders changing in OneDrive. Either using webooks
         * which means you have to implement a server to translate it to push notifications
         * or using apiv2 list_folder/longpoll method. The second one is implemeted here.
         * Tough webhooks are much more efficient, longpoll is much simpler to implement!
         * You can implemnt your own webhook service and replace this method accordingly.
         */
        NotImplemented()
    }
    fileprivate func unregisterNotifcation(path: String) {
        NotImplemented()
    }
    
    /**
     Genrates a public url to a file to be shared with other users and can be downloaded without authentication.
     
     - Parameters:
       - to: path of file, including file/directory name.
       - completionHandler: a closure with result of directory entries or error.
         `link`: a url returned by OneDrive to share.
         `attribute`: `nil` for OneDrive.
         `expiration`: `nil` for OneDrive, as it doesn't expires.
         `error`: Error returned by OneDrive.
     */
    open func publicLink(to path: String, completionHandler: @escaping ((_ link: URL?, _ attribute: OneDriveFileObject?, _ expiration: Date?, _ error: Error?) -> Void)) {
        var request = URLRequest(url: self.url(of: path, modifier: "action.createLink"))
        request.httpMethod = "POST"
        let requestDictionary: [String: AnyObject] = ["type": "view" as NSString]
        request.httpBody = Data(jsonDictionary: requestDictionary)
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
            var serverError: FileProviderOneDriveError?
            var link: URL?
            if let response = response as? HTTPURLResponse {
                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
                serverError = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
                if let json = data?.deserializeJSON() {
                    if let linkDic = json["link"] as? NSDictionary, let linkStr = linkDic["webUrl"] as? String {
                        link = URL(string: linkStr)
                    }
                }
            }
            
            completionHandler(link, nil, nil, serverError ?? error)
        })
        task.resume()
    }
}


extension OneDriveFileProvider: ExtendedFileProvider {
    open func thumbnailOfFileSupported(path: String) -> Bool {
        return true
    }
    
    open func propertiesOfFileSupported(path: String) -> Bool {
        let fileExt = (path as NSString).pathExtension.lowercased()
        switch fileExt {
        case "jpg", "jpeg", "bmp", "gif", "png", "tif", "tiff":
            return true
        case "mp3", "aac", "m4a", "wma":
            return true
        case "mp4", "mpg", "3gp", "mov", "avi", "wmv":
            return true
        default:
            return false
        }
    }
    
    open func thumbnailOfFile(path: String, dimension: CGSize?, completionHandler: @escaping ((_ image: ImageClass?, _ error: Error?) -> Void)) {
        let url: URL
        if let dimension = dimension {
            url = self.url(of: path, modifier: "thumbnails/0/=c\(dimension.width)x\(dimension.height)/content")
        } else {
            url =  self.url(of: path, modifier: "thumbnails/0/small/content")
        }
        
        var request = URLRequest(url: url)
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        let task = self.session.dataTask(with: request, completionHandler: { (data, response, error) in
            var image: ImageClass? = nil
            if let code = (response as? HTTPURLResponse)?.statusCode , code >= 300, let rCode = FileProviderHTTPErrorCode(rawValue: code) {
                let responseError = FileProviderOneDriveError(code: rCode, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8))
                completionHandler(nil, responseError)
                return
            }
            if let data = data {
                image = ImageClass(data: data)
            }
            completionHandler(image, error)
        })
        task.resume()
    }
    
    open func propertiesOfFile(path: String, completionHandler: @escaping ((_ propertiesDictionary: [String : Any], _ keys: [String], _ error: Error?) -> Void)) {
        var request = URLRequest(url: url(of: path))
        request.httpMethod = "GET"
        request.setValue("Bearer \(credential?.password ?? "")", forHTTPHeaderField: "Authorization")
        let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
            var serverError: FileProviderOneDriveError?
            var dic = [String: Any]()
            var keys = [String]()
            if let response = response as? HTTPURLResponse {
                let code = FileProviderHTTPErrorCode(rawValue: response.statusCode)
                serverError = code != nil ? FileProviderOneDriveError(code: code!, path: path, errorDescription: String(data: data ?? Data(), encoding: .utf8)) : nil
                if let json = data?.deserializeJSON() {
                    (dic, keys) = self.mapMediaInfo(json)
                }
            }
            completionHandler(dic, keys, serverError ?? error)
        })
        task.resume()
    }
}

extension OneDriveFileProvider: FileProvider { }