/**
 *                  WHITEBOPHIR SERVER
 *********************************************************
 * @licstart  The following is the entire license notice for the
 *  JavaScript code in this page.
 *
 * Copyright (C) 2013-2014  Ophir LOJKINE
 *
 *
 * The JavaScript code in this page is free software: you can
 * redistribute it and/or modify it under the terms of the GNU
 * General Public License (GNU GPL) as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option)
 * any later version.  The code is distributed WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU GPL for more details.
 *
 * As additional permission under GNU GPL version 3 section 7, you
 * may distribute non-source (e.g., minimized or compacted) forms of
 * that code without the copy of the GNU GPL normally required by
 * section 4, provided you include this license notice and a URL
 * through which recipients can access the Corresponding Source.
 *
 * @licend
 * @module boardData
 */

var fs = require("./fs_promises.js"),
  log = require("./log.js").log,
  path = require("path"),
  config = require("./configuration.js");

/**
 * Represents a board.
 * @class
 * @constructor
 * @param {string} name
 */
var BoardData = function (name) {
  this.name = name;
  /** @type {{[name: string]: {[object_id:string]: any}}} */
  this.board = {};
  this.file = path.join(
    config.HISTORY_DIR,
    "board-" + encodeURIComponent(name) + ".json"
  );
  this.lastSaveDate = Date.now();
  this.users = new Set();
};

/** Adds data to the board */
BoardData.prototype.set = function (id, data) {
  //KISS
  data.time = Date.now();
  this.validate(data);
  this.board[id] = data;
  this.delaySave();
};

/** Adds a child to an element that is already in the board
 * @param {string} id - Identifier of the parent element.
 * @param {object} child - Object containing the the values to update.
 * @param {boolean} [create=true] - Whether to create an empty parent if it doesn't exist
 * @returns {boolean} - True if the child was added, else false
 */
BoardData.prototype.addChild = function (parentId, child) {
  var obj = this.board[parentId];
  if (typeof obj !== "object") return false;
  if (Array.isArray(obj._children)) obj._children.push(child);
  else obj._children = [child];

  this.validate(obj);
  this.delaySave();
  return true;
};

/** Update the data in the board
 * @param {string} id - Identifier of the data to update.
 * @param {object} data - Object containing the values to update.
 * @param {boolean} create - True if the object should be created if it's not currently in the DB.
 */
BoardData.prototype.update = function (id, data, create) {
  delete data.type;
  delete data.tool;

  var obj = this.board[id];
  if (typeof obj === "object") {
    for (var i in data) {
      obj[i] = data[i];
    }
  } else if (create || obj !== undefined) {
    this.board[id] = data;
  }
  this.delaySave();
};

/** Removes data from the board
 * @param {string} id - Identifier of the data to delete.
 */
BoardData.prototype.delete = function (id) {
  //KISS
  delete this.board[id];
  this.delaySave();
};

/** Reads data from the board
 * @param {string} id - Identifier of the element to get.
 * @returns {object} The element with the given id, or undefined if no element has this id
 */
BoardData.prototype.get = function (id, children) {
  return this.board[id];
};

/** Reads data from the board
 * @param {string} [id] - Identifier of the first element to get.
 * @param {BoardData~processData} callback - Function to be called with each piece of data read
 */
BoardData.prototype.getAll = function (id) {
  var results = [];
  for (var i in this.board) {
    if (!id || i > id) {
      results.push(this.board[i]);
    }
  }
  return results;
};

/**
 * This callback is displayed as part of the BoardData class.
 * Describes a function that processes data that comes from the board
 * @callback BoardData~processData
 * @param {object} data
 */

/** Delays the triggering of auto-save by SAVE_INTERVAL seconds
 */
BoardData.prototype.delaySave = function (file) {
  if (this.saveTimeoutId !== undefined) clearTimeout(this.saveTimeoutId);
  this.saveTimeoutId = setTimeout(this.save.bind(this), config.SAVE_INTERVAL);
  if (Date.now() - this.lastSaveDate > config.MAX_SAVE_DELAY)
    setTimeout(this.save.bind(this), 0);
};

/** Saves the data in the board to a file.
 * @param {string} [file=this.file] - Path to the file where the board data will be saved.
 */
BoardData.prototype.save = async function (file) {
  this.lastSaveDate = Date.now();
  this.clean();
  if (!file) file = this.file;
  var tmp_file = backupFileName(file);
  var board_txt = JSON.stringify(this.board);
  if (board_txt === "{}") {
    // empty board
    try {
      await fs.promises.unlink(file);
      log("removed empty board", { name: this.name });
    } catch (err) {
      if (err.code !== "ENOENT") {
        // If the file already wasn't saved, this is not an error
        log("board deletion error", { err: err.toString() });
      }
    }
  } else {
    try {
      await fs.promises.writeFile(tmp_file, board_txt);
      await fs.promises.rename(tmp_file, file);
      log("saved board", {
        name: this.name,
        size: board_txt.length,
        delay_ms: Date.now() - this.lastSaveDate,
      });
    } catch (err) {
      log("board saving error", {
        err: err.toString(),
        tmp_file: tmp_file,
      });
      return;
    }
  }
};

/** Remove old elements from the board */
BoardData.prototype.clean = function cleanBoard() {
  var board = this.board;
  var ids = Object.keys(board);
  if (ids.length > config.MAX_ITEM_COUNT) {
    var toDestroy = ids
      .sort(function (x, y) {
        return (board[x].time | 0) - (board[y].time | 0);
      })
      .slice(0, -config.MAX_ITEM_COUNT);
    for (var i = 0; i < toDestroy.length; i++) delete board[toDestroy[i]];
    log("cleaned board", { removed: toDestroy.length, board: this.name });
  }
};

/** Reformats an item if necessary in order to make it follow the boards' policy
 * @param {object} item The object to edit
 * @param {object} parent The parent of the object to edit
 */
BoardData.prototype.validate = function validate(item, parent) {
  if (item.hasOwnProperty("size")) {
    item.size = parseInt(item.size) || 1;
    item.size = Math.min(Math.max(item.size, 1), 50);
  }
  if (item.hasOwnProperty("x") || item.hasOwnProperty("y")) {
    item.x = parseFloat(item.x) || 0;
    item.x = Math.min(Math.max(item.x, 0), config.MAX_BOARD_SIZE);
    item.x = Math.round(10 * item.x) / 10;
    item.y = parseFloat(item.y) || 0;
    item.y = Math.min(Math.max(item.y, 0), config.MAX_BOARD_SIZE);
    item.y = Math.round(10 * item.y) / 10;
  }
  if (item.hasOwnProperty("opacity")) {
    item.opacity = Math.min(Math.max(item.opacity, 0.1), 1) || 1;
    if (item.opacity === 1) delete item.opacity;
  }
  if (item.hasOwnProperty("_children")) {
    if (!Array.isArray(item._children)) item._children = [];
    if (item._children.length > config.MAX_CHILDREN)
      item._children.length = config.MAX_CHILDREN;
    for (var i = 0; i < item._children.length; i++) {
      this.validate(item._children[i]);
    }
  }
};

/** Load the data in the board from a file.
 * @param {string} name - name of the board
 */
BoardData.load = async function loadBoard(name) {
  var boardData = new BoardData(name),
    data;
  try {
    data = await fs.promises.readFile(boardData.file);
    boardData.board = JSON.parse(data);
    for (id in boardData.board) boardData.validate(boardData.board[id]);
    log("disk load", { board: boardData.name });
  } catch (e) {
    log("empty board creation", {
      board: boardData.name,
      // If the file doesn't exist, this is not an error
      error: e.code !== "ENOENT" && e.toString(),
    });
    boardData.board = {};
    if (data) {
      // There was an error loading the board, but some data was still read
      var backup = backupFileName(boardData.file);
      log("Writing the corrupted file to " + backup);
      try {
        await fs.promises.writeFile(backup, data);
      } catch (err) {
        log("Error writing " + backup + ": " + err);
      }
    }
  }
  return boardData;
};

/**
 * Given a board file name, return a name to use for temporary data saving.
 * @param {string} baseName
 */
function backupFileName(baseName) {
  var date = new Date().toISOString().replace(/:/g, "");
  return baseName + "." + date + ".bak";
}

module.exports.BoardData = BoardData;