/**
 * file.js: Transport for outputting to a local log file.
 *
 * (C) 2010 Charlie Robbins
 * MIT LICENCE
 */

'use strict';

const fs = require('fs');
const path = require('path');
const asyncSeries = require('async/series');
const zlib = require('zlib');
const { MESSAGE } = require('triple-beam');
const { Stream, PassThrough } = require('readable-stream');
const TransportStream = require('winston-transport');
const debug = require('diagnostics')('winston:file');
const os = require('os');
const tailFile = require('../tail-file');

/**
 * Transport for outputting to a local log file.
 * @type {File}
 * @extends {TransportStream}
 */
module.exports = class File extends TransportStream {
  /**
   * Constructor function for the File transport object responsible for
   * persisting log messages and metadata to one or more files.
   * @param {Object} options - Options for this instance.
   */
  constructor(options = {}) {
    super(options);

    // Expose the name of this Transport on the prototype.
    this.name = 'file';

    // Helper function which throws an `Error` in the event that any of the
    // rest of the arguments is present in `options`.
    function throwIf(target, ...args) {
      args.slice(1).forEach(name => {
        if (options[name]) {
          throw new Error(`Cannot set ${name} and ${target} together`);
        }
      });
    }

    // Setup the base stream that always gets piped to to handle buffering.
    this._stream = new PassThrough();
    this._stream.setMaxListeners(30);

    // Bind this context for listener methods.
    this._onError = this._onError.bind(this);

    if (options.filename || options.dirname) {
      throwIf('filename or dirname', 'stream');
      this._basename = this.filename = options.filename
        ? path.basename(options.filename)
        : 'winston.log';

      this.dirname = options.dirname || path.dirname(options.filename);
      this.options = options.options || { flags: 'a' };
    } else if (options.stream) {
      // eslint-disable-next-line no-console
      console.warn('options.stream will be removed in winston@4. Use winston.transports.Stream');
      throwIf('stream', 'filename', 'maxsize');
      this._dest = this._stream.pipe(this._setupStream(options.stream));
      // We need to listen for drain events when write() returns false. This
      // can make node mad at times.
    } else {
      throw new Error('Cannot log to file without filename or stream.');
    }

    this.maxsize = options.maxsize || null;
    this.rotationFormat = options.rotationFormat || false;
    this.zippedArchive = options.zippedArchive || false;
    this.maxFiles = options.maxFiles || null;
    this.eol = options.eol || os.EOL;
    this.tailable = options.tailable || false;

    // Internal state variables representing the number of files this instance
    // has created and the current size (in bytes) of the current logfile.
    this._size = 0;
    this._pendingSize = 0;
    this._created = 0;
    this._drain = false;
    this._opening = false;

    this.open();
  }

  /**
   * Core logging method exposed to Winston. Metadata is optional.
   * @param {Object} info - TODO: add param description.
   * @param {Function} callback - TODO: add param description.
   * @returns {undefined}
   */
  log(info, callback = () => {}) {
    // Remark: (jcrugzz) What is necessary about this callback(null, true) now
    // when thinking about 3.x? Should silent be handled in the base
    // TransportStream _write method?
    if (this.silent) {
      callback();
      return true;
    }

    // Output stream buffer is full and has asked us to wait for the drain event
    if (this._drain) {
      this._stream.once('drain', () => {
        this._drain = false;
        this.log(info, callback);
      });
      return;
    }

    // Grab the raw string and append the expected EOL.
    const output = `${info[MESSAGE]}${this.eol}`;
    const bytes = Buffer.byteLength(output);

    // After we have written to the PassThrough check to see if we need
    // to rotate to the next file.
    //
    // Remark: This gets called too early and does not depict when data
    // has been actually flushed to disk.
    function logged() {
      this._size += bytes;
      this._pendingSize -= bytes;

      debug('logged %s %s', this._size, output);
      this.emit('logged', info);

      // Do not attempt to rotate files while opening
      if (this._opening) {
        return;
      }

      // Check to see if we need to end the stream and create a new one.
      if (!this._needsNewFile()) {
        return;
      }

      // End the current stream, ensure it flushes and create a new one.
      // This could potentially be optimized to not run a stat call but its
      // the safest way since we are supporting `maxFiles`.
      this._endStream(() => this._rotateFile());
    }

    // Keep track of the pending bytes being written while files are opening
    // in order to properly rotate the PassThrough this._stream when the file
    // eventually does open.
    this._pendingSize += bytes;
    if (this._opening
      && !this.rotatedWhileOpening
      && this._needsNewFile(this._size + this._pendingSize)) {
      this.rotatedWhileOpening = true;
    }

    const written = this._stream.write(output, logged.bind(this));
    if (!written) {
      this._drain = true;
      this._stream.once('drain', () => {
        this._drain = false;
        callback();
      });
    } else {
      callback(); // eslint-disable-line callback-return
    }

    debug('written', written, this._drain);

    return written;
  }

  /**
   * Query the transport. Options object is optional.
   * @param {Object} options - Loggly-like query options for this instance.
   * @param {function} callback - Continuation to respond to when complete.
   * TODO: Refactor me.
   */
  query(options, callback) {
    if (typeof options === 'function') {
      callback = options;
      options = {};
    }

    options = this.normalizeQuery(options);
    const file = path.join(this.dirname, this.filename);
    let buff = '';
    let results = [];
    let row = 0;

    const stream = fs.createReadStream(file, {
      encoding: 'utf8'
    });

    stream.on('error', err => {
      if (stream.readable) {
        stream.destroy();
      }
      if (!callback) {
        return;
      }

      return err.code !== 'ENOENT' ? callback(err) : callback(null, results);
    });

    stream.on('data', data => {
      data = (buff + data).split(/\n+/);
      const l = data.length - 1;
      let i = 0;

      for (; i < l; i++) {
        if (!options.start || row >= options.start) {
          add(data[i]);
        }
        row++;
      }

      buff = data[l];
    });

    stream.on('close', () => {
      if (buff) {
        add(buff, true);
      }
      if (options.order === 'desc') {
        results = results.reverse();
      }

      // eslint-disable-next-line callback-return
      if (callback) callback(null, results);
    });

    function add(buff, attempt) {
      try {
        const log = JSON.parse(buff);
        if (check(log)) {
          push(log);
        }
      } catch (e) {
        if (!attempt) {
          stream.emit('error', e);
        }
      }
    }

    function push(log) {
      if (
        options.rows &&
        results.length >= options.rows &&
        options.order !== 'desc'
      ) {
        if (stream.readable) {
          stream.destroy();
        }
        return;
      }

      if (options.fields) {
        log = options.fields.reduce((obj, key) => {
          obj[key] = log[key];
          return obj;
        }, {});
      }

      if (options.order === 'desc') {
        if (results.length >= options.rows) {
          results.shift();
        }
      }
      results.push(log);
    }

    function check(log) {
      if (!log) {
        return;
      }

      if (typeof log !== 'object') {
        return;
      }

      const time = new Date(log.timestamp);
      if (
        (options.from && time < options.from) ||
        (options.until && time > options.until) ||
        (options.level && options.level !== log.level)
      ) {
        return;
      }

      return true;
    }
  }

  /**
   * Returns a log stream for this transport. Options object is optional.
   * @param {Object} options - Stream options for this instance.
   * @returns {Stream} - TODO: add return description.
   * TODO: Refactor me.
   */
  stream(options = {}) {
    const file = path.join(this.dirname, this.filename);
    const stream = new Stream();
    const tail = {
      file,
      start: options.start
    };

    stream.destroy = tailFile(tail, (err, line) => {
      if (err) {
        return stream.emit('error', err);
      }

      try {
        stream.emit('data', line);
        line = JSON.parse(line);
        stream.emit('log', line);
      } catch (e) {
        stream.emit('error', e);
      }
    });

    return stream;
  }

  /**
   * Checks to see the filesize of.
   * @returns {undefined}
   */
  open() {
    // If we do not have a filename then we were passed a stream and
    // don't need to keep track of size.
    if (!this.filename) return;
    if (this._opening) return;

    this._opening = true;

    // Stat the target file to get the size and create the stream.
    this.stat((err, size) => {
      if (err) {
        return this.emit('error', err);
      }

      debug('stat done: %s { size: %s }', this.filename, size);
      this._size = size;
      this._dest = this._createStream(this._stream);
      this._opening = false;
    });
  }

  /**
   * Stat the file and assess information in order to create the proper stream.
   * @param {function} callback - TODO: add param description.
   * @returns {undefined}
   */
  stat(callback) {
    const target = this._getFile();
    const fullpath = path.join(this.dirname, target);

    fs.stat(fullpath, (err, stat) => {
      if (err && err.code === 'ENOENT') {
        debug('ENOENT ok', fullpath);
        // Update internally tracked filename with the new target name.
        this.filename = target;
        return callback(null, 0);
      }

      if (err) {
        debug(`err ${err.code} ${fullpath}`);
        return callback(err);
      }

      if (!stat || this._needsNewFile(stat.size)) {
        // If `stats.size` is greater than the `maxsize` for this
        // instance then try again.
        return this._incFile(() => this.stat(callback));
      }

      // Once we have figured out what the filename is, set it
      // and return the size.
      this.filename = target;
      callback(null, stat.size);
    });
  }

  /**
   * Closes the stream associated with this instance.
   * @param {function} cb - TODO: add param description.
   * @returns {undefined}
   */
  close(cb) {
    if (!this._stream) {
      return;
    }

    this._stream.end(() => {
      if (cb) {
        cb(); // eslint-disable-line callback-return
      }
      this.emit('flush');
      this.emit('closed');
    });
  }

  /**
   * TODO: add method description.
   * @param {number} size - TODO: add param description.
   * @returns {undefined}
   */
  _needsNewFile(size) {
    size = size || this._size;
    return this.maxsize && size >= this.maxsize;
  }

  /**
   * TODO: add method description.
   * @param {Error} err - TODO: add param description.
   * @returns {undefined}
   */
  _onError(err) {
    this.emit('error', err);
  }

  /**
   * TODO: add method description.
   * @param {Stream} stream - TODO: add param description.
   * @returns {mixed} - TODO: add return description.
   */
  _setupStream(stream) {
    stream.on('error', this._onError);

    return stream;
  }

  /**
   * TODO: add method description.
   * @param {Stream} stream - TODO: add param description.
   * @returns {mixed} - TODO: add return description.
   */
  _cleanupStream(stream) {
    stream.removeListener('error', this._onError);

    return stream;
  }

  /**
   * TODO: add method description.
   */
  _rotateFile() {
    this._incFile(() => this.open());
  }

  /**
   * Unpipe from the stream that has been marked as full and end it so it
   * flushes to disk.
   *
   * @param {function} callback - Callback for when the current file has closed.
   * @private
   */
  _endStream(callback) {
    this._stream.unpipe(this._dest);
    this._dest.end(() => {
      this._cleanupStream(this._dest);
      callback();
    });
  }

  /**
   * Returns the WritableStream for the active file on this instance. If we
   * should gzip the file then a zlib stream is returned.
   *
   * @param {ReadableStream} source – PassThrough to pipe to the file when open.
   * @returns {WritableStream} Stream that writes to disk for the active file.
   */
  _createStream(source) {
    const fullpath = path.join(this.dirname, this.filename);

    debug('create stream start', fullpath, this.options);
    const dest = fs.createWriteStream(fullpath, this.options)
      // TODO: What should we do with errors here?
      .on('error', err => debug(err))
      .on('close', () => debug('close', dest.path, dest.bytesWritten))
      .on('open', () => {
        debug('file open ok', fullpath);
        this.emit('open', fullpath);
        source.pipe(dest);

        // If rotation occured during the open operation then we immediately
        // start writing to a new PassThrough, begin opening the next file
        // and cleanup the previous source and dest once the source has drained.
        if (this.rotatedWhileOpening) {
          this._stream = new PassThrough();
          this._stream.setMaxListeners(30);
          this._rotateFile();
          this.rotatedWhileOpening = false;
          this._cleanupStream(dest);
          source.end();
        }
      });

    debug('create stream ok', fullpath);
    if (this.zippedArchive) {
      const gzip = zlib.createGzip();
      gzip.pipe(dest);
      return gzip;
    }

    return dest;
  }

  /**
   * TODO: add method description.
   * @param {function} callback - TODO: add param description.
   * @returns {undefined}
   */
  _incFile(callback) {
    debug('_incFile', this.filename);
    const ext = path.extname(this._basename);
    const basename = path.basename(this._basename, ext);

    if (!this.tailable) {
      this._created += 1;
      this._checkMaxFilesIncrementing(ext, basename, callback);
    } else {
      this._checkMaxFilesTailable(ext, basename, callback);
    }
  }

  /**
   * Gets the next filename to use for this instance in the case that log
   * filesizes are being capped.
   * @returns {string} - TODO: add return description.
   * @private
   */
  _getFile() {
    const ext = path.extname(this._basename);
    const basename = path.basename(this._basename, ext);
    const isRotation = this.rotationFormat
      ? this.rotationFormat()
      : this._created;

    // Caveat emptor (indexzero): rotationFormat() was broken by design When
    // combined with max files because the set of files to unlink is never
    // stored.
    const target = !this.tailable && this._created
      ? `${basename}${isRotation}${ext}`
      : `${basename}${ext}`;

    return this.zippedArchive
      ? `${target}.gz`
      : target;
  }

  /**
   * Increment the number of files created or checked by this instance.
   * @param {mixed} ext - TODO: add param description.
   * @param {mixed} basename - TODO: add param description.
   * @param {mixed} callback - TODO: add param description.
   * @returns {undefined}
   * @private
   */
  _checkMaxFilesIncrementing(ext, basename, callback) {
    // Check for maxFiles option and delete file.
    if (!this.maxFiles || this._created < this.maxFiles) {
      return setImmediate(callback);
    }

    const oldest = this._created - this.maxFiles;
    const isOldest = oldest !== 0 ? oldest : '';
    const isZipped = this.zippedArchive ? '.gz' : '';
    const filePath = `${basename}${isOldest}${ext}${isZipped}`;
    const target = path.join(this.dirname, filePath);

    fs.unlink(target, callback);
  }

  /**
   * Roll files forward based on integer, up to maxFiles. e.g. if base if
   * file.log and it becomes oversized, roll to file1.log, and allow file.log
   * to be re-used. If file is oversized again, roll file1.log to file2.log,
   * roll file.log to file1.log, and so on.
   * @param {mixed} ext - TODO: add param description.
   * @param {mixed} basename - TODO: add param description.
   * @param {mixed} callback - TODO: add param description.
   * @returns {undefined}
   * @private
   */
  _checkMaxFilesTailable(ext, basename, callback) {
    const tasks = [];
    if (!this.maxFiles) {
      return;
    }

    // const isZipped = this.zippedArchive ? '.gz' : '';
    const isZipped = this.zippedArchive ? '.gz' : '';
    for (let x = this.maxFiles - 1; x > 0; x--) {
      tasks.push(function (i) {
        return cb => {
          let fileName = `${basename}${(i - 1)}${ext}${isZipped}`;
          const tmppath = path.join(this.dirname, fileName);

          fs.exists(tmppath, exists => {
            if (!exists) {
              return cb(null);
            }

            fileName = `${basename}${i}${ext}${isZipped}`;
            fs.rename(tmppath, path.join(this.dirname, fileName), cb);
          });
        };
      }.bind(this, x));
    }

    asyncSeries(tasks, () => {
      fs.rename(
        path.join(this.dirname, `${basename}${ext}`),
        path.join(this.dirname, `${basename}1${ext}`),
        callback
      );
    });
  }
};
