var usgs_dir = 'http://earthquake.usgs.gov/earthquakes/dyfi/events/nc/'
  , usgs_evt = '71676251' // 2011-11-05 3.2 quake near Piedmont, CA, USA
  , usgs_csv = '/us/cdi_zip.txt'
  , usgs_url = usgs_dir + usgs_evt + usgs_csv
  ;

var path = d3.geo.path()
    .projection(d3.geo.albersUsa()
    .scale(1400)
    .translate([680, 360]));

var svg = d3.select("#body").append("svg:svg")
    .attr("class", "YlOrRd")
    .attr("width",  960)
    .attr("height", 500)
    .append('svg:g')
      .attr("transform", "scale(1.9) translate(-100 -198)")
      ;

var zipcodes = svg.append("svg:g")
    .attr("id", "ca-zipcodes");

var states = svg.append("svg:g")
    .attr("id", "states");

load_csv(usgs_url, show, { header_cb: parse_header, line_cb: parse_line });

function parse_header(name, n) {
  return ({ '# Columns: ZIP/Location': 'zip'
          , 'CDI':                     'cdi'
          , 'No. of responses':        'responses'
          , 'Epicentral distance':     'dist'
          , 'Latitude':                'lat'
          , 'Longitude':               'lng'
          , 'Suspect?':                'suspect'
          , 'City':                    'city'
          , 'State':                   'state'
          })[name];
}

function parse_line(val, n) {
  return ([ String // zip
          , String // cdi
          , Number // responses
          , Number // dist
          , Number // lat
          , Number // lng
          , Number // suspect
          , String // city
          , String // state
          ])[n](val);
}

function show(csv) {
  function sum(arr) { return d3.sum(arr, function(d){ return d.responses; }); }
  function padded_zip(d) { return pad(d.zip); }
  var pad = d3.format("05d")
    , data = d3.nest().key(padded_zip).rollup(sum).map(csv)
    , max = d3.max(d3.values(data))
    , quantize = d3.scale.linear().domain([0, max]).rangeRound([0, 8]);

  window.data = data; // for ease of inspection

  d3.json("zips-ca.json", function(json) {
    zipcodes.selectAll("path")
        .data(json.features)
      .enter().append("svg:path")
        .attr("class", function(d) {
          return "q" + quantize(data[pad(d.id)] || 0) + "-9";
        })
        .attr("d", path)
      .append("svg:title")
        .text(function(d) {
           var no = data[pad(d.id)] || 0;
           return d.id + ": " + no + " responses";
        });
  });
}

d3.json("us-ca.json", function(json) {
  states.selectAll("path")
      .data(json.features)
    .enter().append("svg:path")
      .attr("d", path);
});

d3.select("select").on("change", function() {
  d3.selectAll("svg").attr("class", this.value);
});