/**
 * Gets temperature data from Yahoo RSS feed and displays it in a meter
 * as well as numerically.
 *
 * Copyright (C) 2012-2013 Mithat Konar
 */

// Constants:
// change the URL to get the desired location and units
// (see http://developer.yahoo.com/weather/).
final String URL = "http://weather.yahooapis.com/forecastrss?w=12781882&u=f";
 
// path in XML data to current conditions:
final String ELEMENT_CONDITION="channel/item/yweather:condition";
 
// attribute name in element above for current temperature:
final String ATTRIBUTE_CONDITION_TEMPERATURE = "temp";
 
// path in XML data to element that holds units of measurement:
final String ELEMENT_UNITS = "channel/yweather:units";
 
// attribute name in element above that holds units for temperature:
final String ATTRIBUTE_UNIT_TEMPERATURE = "temperature";
 
// misc.
final int BORDER=10;

// Functions:
void setup() {
  size(200, 100);
  smooth(); 

  try {
    XML weather = loadXML(URL);  // instantiate an XML object from URL
    XML condition = weather.getChild(ELEMENT_CONDITION);  // pull current cond.
    XML units = weather.getChild(ELEMENT_UNITS);  // pull units data
    
    background(#296783);
    
    int temperature = condition.getInt(ATTRIBUTE_CONDITION_TEMPERATURE);
    drawDigitalTemp(temperature, units.getString(ATTRIBUTE_UNIT_TEMPERATURE),
                    width/2, height/2);
    drawMeter(temperature, -40, 120, 10, height-2*BORDER, width-10-BORDER, BORDER);
  }
  catch (Exception e) {
    println("Problem loading " + URL);
    println(e);
    
    // Turn the canvas red with a big 'X' in it to indicate error.
    background(#ff0000);
    strokeWeight(5);
    line(BORDER, BORDER, width-BORDER, height-BORDER);
    line(BORDER, height-BORDER, width-BORDER, BORDER);
  }

  println("Exiting app.");
}

/**
 * Render a temperature numerically at a given canvas location.
 *
 * @param temperature the temperature to be drawn (int)
 * @param units       the units of measure used for temperatre (String)
 * @param x           the horizontal location of the display (int)
 * @param y           the vertical location of the display (int)
 *
 * @return void
 */
void drawDigitalTemp(int temperature, String units, int x, int y)
{
  PFont font;
  font = loadFont("Monospaced.bold-48.vlw"); 
  textFont(font, 48);
  textAlign(CENTER, CENTER);
  fill(#ffffff);
  text(temperature + "\u00b0" + units, x, y);
}

/**
 * Render a value on a vertical meter.
 *
 * @param val      the value to be drawn (float)
 * @param minimum  val's value that corresponds to no deflection (float)
 * @param minimum  val's value that corresponds to maximum deflection (float)
 * @param w        the width of the meter (int)
 * @param h        the height of the meter (int)
 * @param x        the horizontal location of the meter (int)
 * @param y        the vertical location of the meter (int)
 *
 * @return void
 */
void drawMeter(float val, float minimum, float maximum, int w, int h, int x, int y)
{
  // calculate height of indicator in pixels
  float barHeight=map(val, minimum, maximum, 0, h);

  // draw the indicator
  strokeWeight(1);
  stroke(#ff0000);
  fill(#e00000);
  rect(x, y+(h-barHeight), w, barHeight);

  // draw the frame
  noFill();
  stroke(#1F4D62);
  rect(x, y, w, h);
}