#!/usr/bin/python

import sys, math, cairo
from xml.etree import ElementTree

WIDTH, HEIGHT, DOTSIZE = 1024, 768, 3

if len(sys.argv) > 1:
  osm_filename = sys.argv[1]
else:
  osm_filename = 'osm.xml'

tree = ElementTree.parse(osm_filename)
root = tree.getroot()
if root.tag != 'osm':
  print "%s is not an osm XML file" % osm_filename
  sys.exit(1)

# Parse XML
box = {}
nodes = {}
ways = {}
for elem in root:
  if elem.tag == "bounds":
    box['minlat'] = float(elem.attrib['minlat'])
    box['minlon'] = float(elem.attrib['minlon'])
    box['maxlat'] = float(elem.attrib['maxlat'])
    box['maxlon'] = float(elem.attrib['maxlon'])

  #
  #
  #
  elif elem.tag == "node":
    # <node id="241468971" lat="48.7557063" lon="2.2961071" ...>
    node = {}
    id = int(elem.attrib['id'])
    node['visible'] = (True if elem.attrib['visible'] == "true" else False)
    node['lat'] = float(elem.attrib['lat'])
    node['lon'] = float(elem.attrib['lon'])
    node['tags'] = []
    for children in elem:
      if children.tag == "tag":
        # <tag k="created_by" v="JOSM" />
        node['tags'].append((children.attrib['k'], children.attrib['v']))
      else:
        print "Unknown sub xml tag \"%s\" for node" % ElementTree.tostring(elem)

    nodes[id] = node

  #
  #
  #
  elif elem.tag == "way":
    # <way id="22493122" visible="true" ...>
    way = {}
    id = int(elem.attrib['id'])
    if elem.attrib['visible'] != "true":
      continue
    way['tags'] = []
    way['nodes'] = []
    way['road'] = 0

    for children in elem:
      if children.tag == "tag":
        # <tag k="created_by" v="JOSM" />
        way['tags'].append((children.attrib['k'], children.attrib['v']))
        if children.attrib['k'] == "highway":
          way['road'] = 1
      elif children.tag == "nd":
        # <nd ref="233273784"/>
        way['nodes'].append(int(children.attrib['ref']))

      else:
        print "Unknown sub xml tag \"%s\" for way" % ElementTree.tostring(elem)

    ways[id] = way

  #
  #
  #
  else:
    print "Unknown xml tag \"%s\"" % ElementTree.tostring(elem)

def map_longitude_to_screen_coor(longitude):
  return ((longitude - box['minlon']) * (WIDTH)) / (box['maxlon'] - box['minlon'])

def map_latitude_to_screen_coor(latitude):
  return ((latitude - box['minlat']) * (HEIGHT)) / (box['maxlat'] - box['minlat'])

# Use cairo to make the graphic

surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, WIDTH, HEIGHT)
#surface = cairo.PSSurface("example.ps", WIDTH, HEIGHT)
#surface = cairo.PSSurface("example.pdf", WIDTH, HEIGHT)
#surface = cairo.SVGSurface("example.svg", WIDTH, HEIGHT)
cr = cairo.Context(surface)

# Plot dot
cr.set_source_rgba(1.0, 0.1, 0.1, 0.8)
for way_id in ways:
  for node_id in ways[way_id]['nodes']:
    lat = map_latitude_to_screen_coor(nodes[node_id]['lat'])
    lon = map_longitude_to_screen_coor(nodes[node_id]['lon'])
    cr.arc(lat, lon, 3, 0, 2 * math.pi)
    cr.fill()

# Plot line
for way_id in ways:
  first = 1
  for node_id in ways[way_id]['nodes']:
    lat = map_latitude_to_screen_coor(nodes[node_id]['lat'])
    lon = map_longitude_to_screen_coor(nodes[node_id]['lon'])
    if first:
      first = 0
      cr.move_to(lat, lon)
    else:
      cr.line_to(lat, lon)
  if ways[way_id]['road'] == 1:
    cr.set_source_rgba(0.1, 0.4, 1.0, 1.0)
    cr.stroke ()
  else:
    cr.set_source_rgba(0.1, 0.6, 0.0, 0.5)
    cr.fill()

cr.stroke ()

surface.write_to_png ("example.png")