chart.js

var Bar = require('./bar');

var defaults = {
    xlabel: null,
    ylabel: null,
    width: 80,
    height: 40,
    step: 4,
    lmargin: 10,
    direction: 'y',
    xmin: 0,
    ymin: 0
};

var Chart = module.exports = function(config) {
    var charm = this.charm = config.charm;
    if (!charm){
        charm = this.charm = require('charm')(process);
        this.charm.on('^C', process.exit);
    }
    this.xlabel = config.xlabel;
    this.ylabel = config.ylabel;
    this.direction = config.direction || defaults.direction;
    this.width = config.width || defaults.width;
    this.height = config.height || defaults.height;
    this.lmargin = config.lmargin || defaults.lmargin;
    this.step = config.step || defaults.step;
    this.bars = [];
    this.xmin = config.xmin || defaults.xmin;
    this.xmax = config.xmax || this.width;
    this.ymin = config.ymin || defaults.ymin;
    this.ymax = config.ymax || this.height;
    this.max_size = 0;
};

Chart.prototype.bucketize = function(data, min, max) {
    var numBuckets = 0;
    if (this.direction === 'x') {
        numBuckets = Math.floor(this.height/this.step);
    } else {
        numBuckets = Math.floor(this.width/this.step);
    }
    data.sort(function(a, b) {
        return a - b;
    });
    if (!max) max = data[data.length-1];
    if (!min) min = data[0];
    var bucketWidth = (max - min)/numBuckets;
    var size = 0;
    var bucket_ct = 0;
    var i = 0;
    for (var j = 0; j < numBuckets; j++) {
        while (data[i] < min+bucketWidth*(j+1)) {
            size++;
            i++;
        }
	var opts = {size: size};
        this.addBar(opts);
        size = 0;
    }
};

Chart.prototype.addBar = function(opts) {
    if (arguments.length == 2) {
        opts = {size: arguments[0], color: arguments[1]};
    } else if (typeof opts == 'number') {
        opts = {size: opts};
    }
    if (opts.size > this.max_size) this.max_size = opts.size;
    this.bars.push(new Bar(this, opts));
    return this;
};

Chart.prototype.drawAxes = function() {
    var charm = this.charm;
    var i = 0;
    // draw y axis
    for (i = 0; i < this.height; i++) {
        charm.write('\n');
        charm.right(this.lmargin);
        charm.write('|');
    }

    // At the bottom of the terminal weird things happen with vertical spacing.
    // Scroll a couple lines down then come back up before drawing the bottom axis
    charm.write('\n\n');
    charm.up(2);
    charm.right(this.lmargin+1);
        // The cursor is now at the origin of the graph

    // draw x axis
    charm.push();

    charm.write('\n');
    charm.right(this.lmargin);
    for (i = this.lmargin-1; i < this.width+this.lmargin-1; i++) {
        charm.write('-');
    }
    charm.pop();
};

Chart.prototype.labelAxes = function() {
    var charm = this.charm;
    // label y axis
    if (this.ylabel) {
        charm.push();
        var yminstr = String(this.ymin);
        charm.left(yminstr.length+2);
        charm.write(yminstr);
        // move all the way to the left of the screen on the x axis
        charm.left(this.lmargin-2);

        // move half way up the y axis
        charm.up(this.height/2);
        charm.write(this.ylabel);
        charm.up(this.height/2);

        // move to the top of the y axis
        var ymaxstr = this.direction === 'y' ? String(this.max_size) : String(this.ymax);
        charm.left(ymaxstr.length);
        charm.write(ymaxstr);
        charm.pop();
    }

    // label x axis
    if (this.xlabel) {
        charm.push();
        charm.write('\n\n');
        charm.right(this.lmargin+1);
        charm.write(String(this.xmin));
        charm.right(this.width/2 - String(this.xmin).length);
        charm.write(this.xlabel);
        charm.right(this.width/2 - this.xlabel.length);
        var xmaxstr = this.direction === 'x' ? String(this.max_size) : String(this.xmax);
        charm.write(xmaxstr);
        charm.pop();

    }
};

Chart.prototype.drawBars = function() {
    // set scale based on max_size
    if (this.direction === 'x') {
        this.scale = this.width/this.max_size;
    } else {
        this.scale = this.height/this.max_size;
    }

    var charm = this.charm;
    for (var i = 0; i < this.bars.length; i++) {
        if (this.direction === 'x') {
            if (i != 0) charm.up(this.step);
        } else {
            if (i != 0) charm.right(this.step);
        }
        charm.push();
        this.bars[i].draw(this.scale);
        charm.pop();
    }
    if (this.direction === 'x') charm.down(this.step*this.bars.length+1);
    charm.write('\n\n\n');
    if (this.direction === 'y') charm.write('\n');
};

Chart.prototype.draw = function() {
    this.drawAxes();
    this.labelAxes();
    this.drawBars();
    this.charm.write('\n\n');
};