#!/usr/bin/env python

# Handle GPX files in various ways.

# Copyright 2009 by Akkana Peck. Share and enjoy under the GPL v2 or later.

import sys, xml.dom.minidom

class TrackFile :

    """Parsing and handling of GPS track files.
    Currently only GPX format is supported.
    """

    def __init__(self) :
        pass

    def findBounds(self, trkpts) :
        minlon = 361
        maxlon = -361
        minlat = 91
        maxlat = -91
        for pt in trkpts :
            lat = float(pt.getAttribute("lat"))
            lon = float(pt.getAttribute("lon"))
            if lat > maxlat : maxlat = lat
            if lat < minlat : minlat = lat
            if lon > maxlon : maxlon = lon
            if lon < minlon : minlon = lon

        return ( minlon, minlat, maxlon, maxlat )

    def readTrackFile(self, _filename, opts) :

        self.filename = _filename
        self.points = []

        if (opts.debug) :
            print "Reading track file", self.filename
        dom = xml.dom.minidom.parse(self.filename)

        # Find the track segments
        timenode = dom.getElementsByTagName("time")
        tracks = dom.getElementsByTagName("trk")
        print "Found", len(tracks), "tracks"
        for trk in tracks :
            name = self.getVal(trk, "name")
            trkpts = trk.getElementsByTagName("trkpt")
            trksegs = trk.getElementsByTagName("trkseg")

            if opts.list or opts.write :
                print "\n", name, "has", len(trkpts), "track points",
                if len(trksegs) > 1 :
                    print "in", len(trksegs), "segments",

            if not opts.write :
                print ''    # to print a newline
                continue

            if (len(trkpts) <=  0) :
                print "-- not writing"
                continue

            outfilename = name + ".gpx"
            if opts.prompt :
                while True :     # Python has no do ... while loop
                    outfilename = raw_input("\nFilename (" + outfilename + "): ")
                    if outfilename != "" : break
            if outfilename[-4:] != ".gpx" :
                outfilename = outfilename + ".gpx"

            ( minlon, minlat, maxlon, maxlat ) = self.findBounds(trkpts)

            fp = open(outfilename, "w")
            fp.write('<?xml version="1.0" encoding="UTF-8"?>\n')
            fp.write('<gpx version="1.0" creator="GPXMgr: http://www.shallowsky.com/software/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.topografix.com/GPX/1/0" xsi:schemaLocation="http://www.topografix.com/GPX/1/0 http://www.topografix.com/GPX/1/0/gpx.xsd">\n')
            if len(timenode) > 0 :
                timenode[0].writexml(fp)
            fp.write('\n')

            # write bounds
            fp.write('<bounds minlat="' + str(minlat) + \
                      '" minlon="' + str(minlon) + \
                      '" maxlat="' + str(maxlat) + \
                      '" maxlon="' + str(maxlon) + '"/>')

            trk.writexml(fp)
            fp.write('\n</gpx>\n')
            fp.close()
            print "-- wrote", outfilename

#         trkpts = dom.getElementsByTagName("trkpt")
#         for i in range (0, len(trkpts), 1) :
#             self.handleTrackPoint(trkpts[i])

    @staticmethod
    def getVal(parent, name) :
        nodeList = parent.getElementsByTagName(name)
        if len(nodeList) < 1 :
            return "No " + name + " element"
        children = nodeList[0].childNodes
        if len(children) < 1 :
            return "No " + name + " children"
        node = children[0]
        if node.nodeType != node.TEXT_NODE:
            return name + " isn't a text node"
        return node.data

if __name__ == "__main__" :
    from optparse import OptionParser
    usage = "Usage: %prog [options] gpx_file(s)"
    version = "%prog 0.1: analyze or split GPX files with multiple tracks.\n\
Copyright 2009 by Akkana Peck; share and enjoy under the GPL v2 or later."
    parser = OptionParser(usage=usage, version=version)
    parser.add_option("-l", "--list",
                      action="store_true", dest="list",
                      help="list the tracks available -- don't write anything")
    parser.add_option("-w", "--write",
                      action="store_true", dest="write",
                      help="split into multiple track files")
    parser.add_option("-p", "--prompt",
                      action="store_true", dest="prompt",
                      help="prompt for each filename before writing")
    parser.add_option("-d", "--debug",
                      action="store_true", dest="debug")
    (options, args) = parser.parse_args()

    for arg in args :
        trkfile = TrackFile()
        trkfile.readTrackFile(arg, options)