goog.provide('ascii.State');

/** @const */ var MAX_GRID_SIZE = 1000;
/** @const */ var SPECIAL_VALUE = '+';

/** @const */ var SPECIAL_LINE_H = '\u2014';
/** @const */ var SPECIAL_LINE_V = '|';

/**
 * An individual cell within the diagram and it's current value.
 *
 * @constructor
 */
ascii.Cell = function() {
  /** @type {?string} */ this.value = null;
  /** @type {?string} */ this.scratchValue = null;
};

/** @return {?string} */
ascii.Cell.prototype.getDrawValue = function() {
  return (this.scratchValue != null ? this.scratchValue : this.value);
};

/**
 * Holds the entire state of the diagram as a 2D array of cells.
 *
 * @constructor
 */
ascii.State = function() {
  /** @type {Array.<Array.<ascii.Cell>>} */
  this.cells = new Array(MAX_GRID_SIZE);
  /** @type {Array.<ascii.Cell>} */
  this.scratchCells = new Array();

  for (var i = 0; i < this.cells.length; i++) {
    this.cells[i] = new Array(MAX_GRID_SIZE);
    for (var j = 0; j < this.cells[i].length; j++) {
      this.cells[i][j] = new ascii.Cell();
    }
  }
};

/**
 * Returns the cell at the given coordinates.
 *
 * @param {ascii.Vector} vector
 * @return {ascii.Cell}
 */
ascii.State.prototype.getCell = function(vector) {
  return this.cells[vector.x][vector.y];
};

/**
 * Sets the cells value at the given position. Probably shouldn't
 * be used directly in many cases. Used drawValue instead.
 *
 * @param {ascii.Vector} position
 * @param {?string} value
 */
ascii.State.prototype.setValue = function(position, value) {
  this.getCell(position).value = value;
};
    
/**
 * Sets the cells scratch (uncommitted) value at the given position.
 *
 * @param {ascii.Vector} position
 * @param {?string} value
 */
ascii.State.prototype.drawValue = function(position, value) {
  var cell = this.getCell(position);
  this.scratchCells.push(cell);
  cell.scratchValue = value;
};

/**
 * Sets the cells scratch value to be the special value.
 *
 * @param {ascii.Vector} position
 */
ascii.State.prototype.drawSpecial = function(position) {
  this.drawValue(position, SPECIAL_VALUE);
};

/**
 * Clears the current drawing scratchpad.
 */
ascii.State.prototype.clearDraw = function() {
  for (var i in this.scratchCells) {
    this.scratchCells[i].scratchValue = null;
  }
  this.scratchCells.length = 0;
};

/**
 * Returns true if the cell at the given position is special.
 *
 * @param {ascii.Vector} position
 * @return {boolean}
 */
ascii.State.prototype.isSpecial = function(position) {
  var cell = this.getCell(position);
  var value =  cell.scratchValue != null ? cell.scratchValue : cell.value;
  return value == SPECIAL_VALUE;
};

/**
 * Returns the draw value of a cell at the given position.
 *
 * @param {ascii.Vector} position
 * @return {?string}
 */
ascii.State.prototype.getDrawValue = function(position) {
  var cell = this.getCell(position);
  var value =  cell.scratchValue != null ? cell.scratchValue : cell.value;
  if (value != SPECIAL_VALUE) {
    return value;
  }

  // Magic time.
  var left = this.isSpecial(position.add(new ascii.Vector(-1, 0)));
  var right = this.isSpecial(position.add(new ascii.Vector(1, 0)));
  var up = this.isSpecial(position.add(new ascii.Vector(0, -1)));
  var down = this.isSpecial(position.add(new ascii.Vector(0, 1)));
  
  if (left && right && !up && !down) {
    return SPECIAL_LINE_H;
  }
  if (!left && !right && up && down) {
    return SPECIAL_LINE_V;
  }
  if (left && right && up && down) {
    return SPECIAL_LINE_H;
  }
  return SPECIAL_VALUE;
};

/**
 * Ends the current draw, commiting anything currently drawn the scratchpad.
 */
ascii.State.prototype.commitDraw = function() {
  for (var i in this.scratchCells) {
    this.scratchCells[i].value = this.scratchCells[i].getDrawValue();
    this.scratchCells[i].scratchValue = null;
  }
};