import PreloadFile from '../generic/preload_file';
import {BaseFileSystem, FileSystem, BFSOneArgCallback, BFSCallback, FileSystemOptions} from '../core/file_system';
import {FileFlag} from '../core/file_flag';
import {default as Stats, FileType} from '../core/node_fs_stats';
import {ApiError, ErrorCode} from '../core/api_error';
import {File} from '../core/file';
import {arrayBuffer2Buffer, buffer2ArrayBuffer} from '../core/util';
import {Dropbox} from 'dropbox_bridge';
import setImmediate from '../generic/setImmediate';
import {dirname} from 'path';
type DropboxClient = DropboxTypes.Dropbox;

/**
 * Dropbox paths do not begin with a /, they just begin with a folder at the root node.
 * Here, we strip the `/`.
 * @param p An absolute path
 */
function FixPath(p: string): string {
  if (p === '/') {
    return '';
  } else {
    return p;
  }
}

/**
 * HACK: Dropbox errors are FUBAR'd sometimes.
 * @url https://github.com/dropbox/dropbox-sdk-js/issues/146
 * @param e
 */
function ExtractTheFuckingError<T>(e: DropboxTypes.Error<T>): T {
  const obj = <any> e.error;
  if (obj['.tag']) {
    // Everything is OK.
    return obj;
  } else if (obj['error']) {
    // Terrible nested object bug.
    const obj2 = obj.error;
    if (obj2['.tag']) {
      return obj2;
    } else if (obj2['reason'] && obj2['reason']['.tag']) {
      return obj2.reason;
    } else {
      return obj2;
    }
  } else if (typeof(obj) === 'string') {
    // Might be a fucking JSON object error.
    try {
      const obj2 = JSON.parse(obj);
      if (obj2['error'] && obj2['error']['reason'] && obj2['error']['reason']['.tag']) {
        return obj2.error.reason;
      }
    } catch (e) {
      // Nope. Give up.

    }
  }
  return <any> obj;
}

/**
 * Returns a user-facing error message given an error.
 *
 * HACK: Dropbox error messages sometimes lack a `user_message` field.
 * Sometimes, they are even strings. Ugh.
 * @url https://github.com/dropbox/dropbox-sdk-js/issues/146
 * @url https://github.com/dropbox/dropbox-sdk-js/issues/145
 * @url https://github.com/dropbox/dropbox-sdk-js/issues/144
 * @param err An error.
 */
function GetErrorMessage(err: DropboxTypes.Error<any>): string {
  if (err['user_message']) {
    return err.user_message.text;
  } else if (err['error_summary']) {
    return err.error_summary;
  } else if (typeof(err.error) === "string") {
    return err.error;
  } else if (typeof(err.error) === "object") {
    // DROPBOX BUG: Sometimes, error is a nested error.
    return GetErrorMessage(err.error);
  } else {
    throw new Error(`Dropbox's servers gave us a garbage error message: ${JSON.stringify(err)}`);
  }
}

function LookupErrorToError(err: DropboxTypes.files.LookupError, p: string, msg: string): ApiError {
  switch (err['.tag']) {
    case 'malformed_path':
      return new ApiError(ErrorCode.EBADF, msg, p);
    case 'not_found':
      return ApiError.ENOENT(p);
    case 'not_file':
      return ApiError.EISDIR(p);
    case 'not_folder':
      return ApiError.ENOTDIR(p);
    case 'restricted_content':
      return ApiError.EPERM(p);
    case 'other':
    default:
      return new ApiError(ErrorCode.EIO, msg, p);
  }
}

function WriteErrorToError(err: DropboxTypes.files.WriteError, p: string, msg: string): ApiError {
  switch (err['.tag']) {
    case 'malformed_path':
    case 'disallowed_name':
      return new ApiError(ErrorCode.EBADF, msg, p);
    case 'conflict':
    case 'no_write_permission':
    case 'team_folder':
      return ApiError.EPERM(p);
    case 'insufficient_space':
      return new ApiError(ErrorCode.ENOSPC, msg);
    case 'other':
    default:
      return new ApiError(ErrorCode.EIO, msg, p);
  }
}

function FilesDeleteWrapped(client: DropboxClient, p: string, cb: BFSOneArgCallback): void {
  const arg: DropboxTypes.files.DeleteArg = {
    path: FixPath(p)
  };
  client.filesDeleteV2(arg)
    .then(() => {
      cb();
    }).catch((e: DropboxTypes.Error<DropboxTypes.files.DeleteError>) => {
      const err = ExtractTheFuckingError(e);
      switch (err['.tag']) {
        case 'path_lookup':
          cb(LookupErrorToError((<DropboxTypes.files.DeleteErrorPathLookup> err).path_lookup, p, GetErrorMessage(e)));
          break;
        case 'path_write':
          cb(WriteErrorToError((<DropboxTypes.files.DeleteErrorPathWrite> err).path_write, p, GetErrorMessage(e)));
          break;
        case 'too_many_write_operations':
          setTimeout(() => FilesDeleteWrapped(client, p, cb), 500 + (300 * (Math.random())));
          break;
        case 'other':
        default:
          cb(new ApiError(ErrorCode.EIO, GetErrorMessage(e), p));
          break;
      }
    });
}

export class DropboxFile extends PreloadFile<DropboxFileSystem> implements File {
  constructor(_fs: DropboxFileSystem, _path: string, _flag: FileFlag, _stat: Stats, contents?: Buffer) {
    super(_fs, _path, _flag, _stat, contents);
  }

  public sync(cb: BFSOneArgCallback): void {
    this._fs._syncFile(this.getPath(), this.getBuffer(), cb);
  }

  public close(cb: BFSOneArgCallback): void {
    this.sync(cb);
  }
}

/**
 * Options for the Dropbox file system.
 */
export interface DropboxFileSystemOptions {
  // An *authenticated* Dropbox client from the 2.x JS SDK.
  client: DropboxTypes.Dropbox;
}

/**
 * A read/write file system backed by Dropbox cloud storage.
 *
 * Uses the Dropbox V2 API, and the 2.x JS SDK.
 */
export default class DropboxFileSystem extends BaseFileSystem implements FileSystem {
  public static readonly Name = "DropboxV2";

  public static readonly Options: FileSystemOptions = {
    client: {
      type: "object",
      description: "An *authenticated* Dropbox client. Must be from the 2.5.x JS SDK."
    }
  };

  /**
   * Creates a new DropboxFileSystem instance with the given options.
   * Must be given an *authenticated* Dropbox client from 2.x JS SDK.
   */
  public static Create(opts: DropboxFileSystemOptions, cb: BFSCallback<DropboxFileSystem>): void {
    cb(null, new DropboxFileSystem(opts.client));
  }

  public static isAvailable(): boolean {
    // Checks if the Dropbox library is loaded.
    return typeof Dropbox !== 'undefined';
  }

  private _client: DropboxTypes.Dropbox;

  private constructor(client: DropboxTypes.Dropbox) {
    super();
    this._client = client;
  }

  public getName(): string {
    return DropboxFileSystem.Name;
  }

  public isReadOnly(): boolean {
    return false;
  }

  // Dropbox doesn't support symlinks, properties, or synchronous calls
  // TODO: does it???

  public supportsSymlinks(): boolean {
    return false;
  }

  public supportsProps(): boolean {
    return false;
  }

  public supportsSynch(): boolean {
    return false;
  }

  /**
   * Deletes *everything* in the file system. Mainly intended for unit testing!
   * @param mainCb Called when operation completes.
   */
  public empty(mainCb: BFSOneArgCallback): void {
    this.readdir('/', (e, paths?) => {
      if (paths) {
        const next = (e?: ApiError) => {
          if (paths.length === 0) {
            mainCb();
          } else {
            FilesDeleteWrapped(this._client, <string> paths.shift(), next);
          }
        };
        next();
      } else {
        mainCb(e);
      }
    });
  }

  public rename(oldPath: string, newPath: string, cb: BFSOneArgCallback): void {
    // Dropbox doesn't let you rename things over existing things, but POSIX does.
    // So, we need to see if newPath exists...
    this.stat(newPath, false, (e, stats?) => {
      const rename = () => {
        const relocationArg: DropboxTypes.files.RelocationArg = {
          from_path: FixPath(oldPath),
          to_path: FixPath(newPath)
        };
        this._client.filesMoveV2(relocationArg)
          .then(() => cb())
          .catch(function(e: DropboxTypes.Error<DropboxTypes.files.RelocationError>) {
            const err = ExtractTheFuckingError(e);
            switch (err['.tag']) {
              case 'from_lookup':
                cb(LookupErrorToError((<DropboxTypes.files.RelocationErrorFromLookup> err).from_lookup, oldPath, GetErrorMessage(e)));
                break;
              case 'from_write':
                cb(WriteErrorToError((<DropboxTypes.files.RelocationErrorFromWrite> err).from_write, oldPath, GetErrorMessage(e)));
                break;
              case 'to':
                cb(WriteErrorToError((<DropboxTypes.files.RelocationErrorTo> err).to, newPath, GetErrorMessage(e)));
                break;
              case 'cant_copy_shared_folder':
              case 'cant_nest_shared_folder':
                cb(new ApiError(ErrorCode.EPERM, GetErrorMessage(e), oldPath));
                break;
              case 'cant_move_folder_into_itself':
              case 'duplicated_or_nested_paths':
                cb(new ApiError(ErrorCode.EBADF, GetErrorMessage(e), oldPath));
                break;
              case 'too_many_files':
                cb(new ApiError(ErrorCode.ENOSPC, GetErrorMessage(e), oldPath));
                break;
              case 'other':
              default:
                cb(new ApiError(ErrorCode.EIO, GetErrorMessage(e), oldPath));
                break;
            }
        });
      };
      if (e) {
        // Doesn't exist. Proceed!
        rename();
      } else if (oldPath === newPath) {
        // NOP if the path exists. Error if it doesn't exist.
        if (e) {
          cb(ApiError.ENOENT(newPath));
        } else {
          cb();
        }
      } else if (stats && stats.isDirectory()) {
        // Exists, is a directory. Cannot rename over an existing directory.
        cb(ApiError.EISDIR(newPath));
      } else {
        // Exists, is a file, and differs from oldPath. Delete and rename.
        this.unlink(newPath, (e) => {
          if (e) {
            cb(e);
          } else {
            rename();
          }
        });
      }
    });
  }

  public stat(path: string, isLstat: boolean, cb: BFSCallback<Stats>): void {
    if (path === '/') {
      // Dropbox doesn't support querying the root directory.
      setImmediate(function() {
        cb(null, new Stats(FileType.DIRECTORY, 4096));
      });
      return;
    }
    const arg: DropboxTypes.files.GetMetadataArg = {
      path: FixPath(path)
    };
    this._client.filesGetMetadata(arg).then((ref) => {
      switch (ref['.tag']) {
        case 'file':
          const fileMetadata = <DropboxTypes.files.FileMetadata> ref;
          // TODO: Parse time fields.
          cb(null, new Stats(FileType.FILE, fileMetadata.size));
          break;
        case 'folder':
          cb(null, new Stats(FileType.DIRECTORY, 4096));
          break;
        case 'deleted':
          cb(ApiError.ENOENT(path));
          break;
        default:
          // Unknown.
          break;
      }
    }).catch((e: DropboxTypes.Error<DropboxTypes.files.GetMetadataError>) => {
      const err = ExtractTheFuckingError(e);
      switch (err['.tag']) {
        case 'path':
          cb(LookupErrorToError(err.path, path, GetErrorMessage(e)));
          break;
        default:
          cb(new ApiError(ErrorCode.EIO, GetErrorMessage(e), path));
          break;
      }
    });
  }

  public openFile(path: string, flags: FileFlag, cb: BFSCallback<File>): void {
    const downloadArg: DropboxTypes.files.DownloadArg = {
      path: FixPath(path)
    };
    this._client.filesDownload(downloadArg).then((res) => {
      const b: Blob = (<any> res).fileBlob;
      const fr = new FileReader();
      fr.onload = () => {
        const ab = fr.result as ArrayBuffer;
        cb(null, new DropboxFile(this, path, flags, new Stats(FileType.FILE, ab.byteLength), arrayBuffer2Buffer(ab)));
      };
      fr.readAsArrayBuffer(b);
    }).catch((e: DropboxTypes.Error<DropboxTypes.files.DownloadError>) => {
      const err = ExtractTheFuckingError(e);
      switch (err['.tag']) {
        case 'path':
          const dpError = <DropboxTypes.files.DownloadErrorPath> err;
          cb(LookupErrorToError(dpError.path, path, GetErrorMessage(e)));
          break;
        case 'other':
        default:
          cb(new ApiError(ErrorCode.EIO, GetErrorMessage(e), path));
          break;
      }
    });
  }

  public createFile(p: string, flags: FileFlag, mode: number, cb: BFSCallback<File>): void {
    const fileData = Buffer.alloc(0);
    const blob = new Blob([buffer2ArrayBuffer(fileData) as ArrayBuffer], {type: "octet/stream"});
    const commitInfo: DropboxTypes.files.CommitInfo = {
      contents: blob,
      path: FixPath(p)
    };
    this._client.filesUpload(commitInfo).then((metadata) => {
      cb(null, new DropboxFile(this, p, flags, new Stats(FileType.FILE, 0), fileData));
    }).catch((e: DropboxTypes.Error<DropboxTypes.files.UploadError>) => {
      const err = ExtractTheFuckingError(e);
      // HACK: Casting to 'any' since tag can be 'too_many_write_operations'.
      switch (<string> err['.tag']) {
        case 'path':
          const upError = <DropboxTypes.files.UploadErrorPath> err;
          cb(WriteErrorToError((upError as any).path.reason, p, GetErrorMessage(e)));
          break;
        case 'too_many_write_operations':
          // Retry in (500, 800) ms.
          setTimeout(() => this.createFile(p, flags, mode, cb), 500 + (300 * (Math.random())));
          break;
        case 'other':
        default:
          cb(new ApiError(ErrorCode.EIO, GetErrorMessage(e), p));
          break;
      }
    });
  }

  /**
   * Delete a file
   */
  public unlink(path: string, cb: BFSOneArgCallback): void {
    // Must be a file. Check first.
    this.stat(path, false, (e, stat) => {
      if (stat) {
        if (stat.isDirectory()) {
          cb(ApiError.EISDIR(path));
        } else {
          FilesDeleteWrapped(this._client, path, cb);
        }
      } else {
        cb(e);
      }
    });
  }

  /**
   * Delete a directory
   */
  public rmdir(path: string, cb: BFSOneArgCallback): void {
    this.readdir(path, (e, paths) => {
      if (paths) {
        if (paths.length > 0) {
          cb(ApiError.ENOTEMPTY(path));
        } else {
          FilesDeleteWrapped(this._client, path, cb);
        }
      } else {
        cb(e);
      }
    });
  }

  /**
   * Create a directory
   */
  public mkdir(p: string, mode: number, cb: BFSOneArgCallback): void {
    // Dropbox's create_folder is recursive. Check if parent exists.
    const parent = dirname(p);
    this.stat(parent, false, (e, stats?) => {
      if (e) {
        cb(e);
      } else if (stats && !stats.isDirectory()) {
        cb(ApiError.ENOTDIR(parent));
      } else {
        const arg: DropboxTypes.files.CreateFolderArg = {
          path: FixPath(p)
        };
        this._client.filesCreateFolderV2(arg).then(() => cb()).catch((e: DropboxTypes.Error<DropboxTypes.files.CreateFolderError>) => {
          const err = ExtractTheFuckingError(e);
          if ((<string> err['.tag']) === "too_many_write_operations") {
            // Retry in a bit.
            setTimeout(() => this.mkdir(p, mode, cb), 500 + (300 * (Math.random())));
          } else {
            cb(WriteErrorToError(ExtractTheFuckingError(e).path, p, GetErrorMessage(e)));
          }
        });
      }
    });
  }

  /**
   * Get the names of the files in a directory
   */
  public readdir(path: string, cb: BFSCallback<string[]>): void {
    const arg: DropboxTypes.files.ListFolderArg = {
      path: FixPath(path)
    };
    this._client.filesListFolder(arg).then((res) => {
      ContinueReadingDir(this._client, path, res, [], cb);
    }).catch((e: DropboxTypes.Error<DropboxTypes.files.ListFolderError>) => {
      ProcessListFolderError(e, path, cb);
    });
  }

  /**
   * (Internal) Syncs file to Dropbox.
   */
  public _syncFile(p: string, d: Buffer, cb: BFSOneArgCallback): void {
    const blob = new Blob([buffer2ArrayBuffer(d) as ArrayBuffer], {type: "octet/stream"});
    const arg: DropboxTypes.files.CommitInfo = {
      contents: blob,
      path: FixPath(p),
      mode: {
        '.tag': 'overwrite'
      }
    };
    this._client.filesUpload(arg).then(() => {
      cb();
    }).catch((e: DropboxTypes.Error<DropboxTypes.files.UploadError>) => {
      const err = ExtractTheFuckingError(e);
      switch (<string> err['.tag']) {
        case 'path':
          const upError = <DropboxTypes.files.UploadErrorPath> err;
          cb(WriteErrorToError((upError as any).path.reason, p, GetErrorMessage(e)));
          break;
        case 'too_many_write_operations':
          setTimeout(() => this._syncFile(p, d, cb), 500 + (300 * (Math.random())));
          break;
        case 'other':
        default:
          cb(new ApiError(ErrorCode.EIO, GetErrorMessage(e), p));
          break;
      }
    });
  }
}

function ProcessListFolderError(e: DropboxTypes.Error<DropboxTypes.files.ListFolderError>, path: string, cb: BFSCallback<string[]>): void {
  const err = ExtractTheFuckingError(e);
  switch (err['.tag']) {
    case 'path':
      const pathError = <DropboxTypes.files.ListFolderErrorPath> err;
      cb(LookupErrorToError(pathError.path, path, GetErrorMessage(e)));
      break;
    case 'other':
    default:
      cb(new ApiError(ErrorCode.EIO, GetErrorMessage(e), path));
      break;
  }
}

function ContinueReadingDir(client: DropboxClient, path: string, res: DropboxTypes.files.ListFolderResult, previousEntries: string[], cb: BFSCallback<string[]>): void {
  const newEntries = <string[]> res.entries.map((e) => e.path_display).filter((p) => !!p);
  const entries = previousEntries.concat(newEntries);
  if (!res.has_more) {
    cb(null, entries);
  } else {
    const arg: DropboxTypes.files.ListFolderContinueArg = {
      cursor: res.cursor
    };
    client.filesListFolderContinue(arg).then((res) => {
      ContinueReadingDir(client, path, res, entries, cb);
    }).catch((e: DropboxTypes.Error<DropboxTypes.files.ListFolderError>) => {
      ProcessListFolderError(e, path, cb);
    });
  }
}