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"use strict"; |
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var _ = require('lodash'), |
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Promise = require("bluebird"); |
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// Expose `Move` |
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module.exports = Move; |
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var cardinalPoints = ['N','E','S','W']; |
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/** |
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* Set up Move with `mower` and `grid` |
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* which is responsible for moving mowers |
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* |
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* @param {Object} mower |
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* @param {String} grid |
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* @api public |
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*/ |
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function Move(mower, grid){ |
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this.mower = mower; |
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this.grid = grid; |
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} |
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/** |
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* Call the movement method from an instruction |
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* |
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* @param {String} instruction |
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* @api public |
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*/ |
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Move.prototype.runInstruction = function(instruction) { |
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var self = this; |
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return new Promise(function(resolve, reject) { |
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switch(instruction) { |
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case 'A': |
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self.goForward(); |
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break; |
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case 'G': |
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case 'D': |
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self.turn(instruction); |
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break; |
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default: |
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reject( new Error('Invalid instruction: '+instruction) ); |
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} |
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resolve(self.mower.position); |
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}); |
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}; |
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/** |
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* Update mower's position if not occupied |
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* |
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* @param {Object} newPosition |
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* @api public |
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*/ |
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Move.prototype.updatePosition = function(newPosition) { |
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this.mower.position = newPosition; |
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this.grid.setItemPosition(this.mower.id, newPosition); // save new position in grid object |
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}; |
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/** |
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* Return false if the given position is occupied or not allowed |
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* |
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* @param {Object} position |
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* @return {Boolean} |
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* @api public |
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*/ |
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Move.prototype.isNextPositionAllowed = function(position) { |
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var nextCellOccupation = this.grid.getCellOccupation(position); |
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return (nextCellOccupation === null || nextCellOccupation === this.mower.id) && |
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(position.x >= 0 && position.x <= this.grid.width && position.y >= 0 && position.y <= this.grid.heigth); |
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}; |
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/** |
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* Move a mower forward. |
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* The direction is the actual cardinal. |
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* |
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* @api public |
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*/ |
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Move.prototype.goForward = function() { |
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var actualPosition = _.clone(this.mower.position), |
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nextPosition = getNextPositionForward(actualPosition); |
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if(this.isNextPositionAllowed(nextPosition)) { |
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this.updatePosition(nextPosition); |
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} |
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}; |
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/** |
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* Move a mower to the left or the right. |
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* |
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* @param {String} instruction |
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* @api public |
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*/ |
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Move.prototype.turn = function(instruction) { |
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var mower = this.mower, |
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newPosition = _.clone(mower.position), |
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cardinalIndex = _.findIndex(cardinalPoints, function(c) { return c === mower.position.c; }), |
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newCardinalIndex = cardinalIndex; |
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switch(instruction) { |
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case 'D': |
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newCardinalIndex = cardinalIndex+1 > cardinalPoints.length-1 ? 0 : cardinalIndex+1; |
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break; |
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case 'G': |
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newCardinalIndex = cardinalIndex-1 < 0 ? cardinalPoints.length-1 : cardinalIndex-1; |
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break; |
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default: |
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throw new Error('Invalid instruction: '+mower.position.c); |
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} |
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newPosition.c = cardinalPoints[newCardinalIndex]; |
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this.updatePosition(newPosition); |
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}; |
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119
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/** |
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* Move a mower forward. |
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* The direction is the actual cardinal. |
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* |
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* @api protected |
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*/ |
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127
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function getNextPositionForward(position) { |
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var valueToAdd = position.c==='N'||position.c==='E' ? 1 : -1; |
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var propToChange = position.c==='W'||position.c==='E'?'x':'y'; |
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position[propToChange] = position[propToChange]+valueToAdd; |
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return position; |
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} |
Huljo /
MowItNow
