#!/usr/bin/env python
# -*- coding: utf-8
"""
@module  g.proj.identify
@brief   Module for automatic identification of EPSG from definition of projection in WKT format.

(C) 2014-2015 by the GRASS Development Team
This program is free software under the GNU General Public License
(>=v2). Read the file COPYING that comes with GRASS for details.

@author Matej Krejci <matejkrejci gmail.com> (GSoC 2015)
"""

#%module
#% description: Autoidentifies EPSG code from WKT CRS definition.
#% keyword: general
#% keyword: projection
#% keyword: EPSG
#% keyword: WKT
#% keyword: .prj
#%end

#%option G_OPT_F_INPUT
#% key: wkt
#% description: Name of input file with WKT definition
#% required: no
#%end

#%option
#% key: epsg
#% type: integer
#% description: Input EPSG code
#% required: no
#%end

#%flag
#% key: p
#% description: Print projection info in Proj4 format
#%end

#%flag
#% key: w
#% description: Print projection info in WKT format
#%end

#%flag
#% key: s
#% description: Save as default EPSG in the current location
#%end

from grass.script import core as grass
from grass.pygrass.modules import Module
from subprocess import PIPE
from osgeo import osr
import os


def writeEPSGtoPEMANENT(epsg):
    env = grass.gisenv()
    gisdbase = env['GISDBASE']
    location = env['LOCATION_NAME']
    path = os.path.join(gisdbase, location, "PERMANENT","PROJ_EPSG")
    if os.path.isfile(path): #if already file exist
        if os.getenv('GRASS_OVERWRITE', False):
            try:
                io = open(path,'w')
                io.write("epsg: %s"%epsg )
                io.close()
                grass.message("EPSG code have been written to <%s>" % path)
            except IOError as e:
                grass.error("I/O error({0}): {1}".format(e.errno, e.strerror))

        else:
            grass.message("EPSG file already exist <%s>" % path)
    else:
        try:
            io = open(path,'w')
            io.write("epsg: %s"%epsg)
            io.close()
            grass.message("EPSG code have been written to <%s>" % path)
        except IOError as e:
            grass.error("I/O error({0}): {1}".format(e.errno, e.strerror))

def isPermanent():
    env = grass.gisenv()
    if env['MAPSET'] == "PERMANENT":
        return True
    return False

def grassEpsg():
    proj=Module('g.proj',
               flags='p',
               quiet=True,
               stdout_=PIPE)
    proj=proj.outputs.stdout
    lines=proj.splitlines()
    for e,line in enumerate(lines):
        if 'EPSG' in line:
            epsg=lines[e+1].split(':')[1].replace(' ','')
            print('epsg=%s' % epsg)
            if flags['s']:
                if isPermanent():
                    writeEPSGtoPEMANENT(epsg)
                else:
                    grass.warning("Unable to access PERMANENT mapset")
            return
    try:
        proj=Module('g.proj',
               flags='wf',
               quiet=True,
               stdout_=PIPE)
        proj=proj.outputs.stdout
        wkt2standards(proj)
    except:
        grass.error('WKT input error')

def wkt2standards(prj_txt):
    srs = osr.SpatialReference()
    srs.ImportFromESRI([prj_txt])
    if flags['w']:
        print('wkt=%s' % srs.ExportToWkt())
    if flags['p']:
        print('proj4=%s' % srs.ExportToProj4())
    srs.AutoIdentifyEPSG()
    try :
        int(srs.GetAuthorityCode(None))
        epsg=srs.GetAuthorityCode(None)
        print('epsg=%s' % epsg)
        if flags['s']:
            if isPermanent():
                writeEPSGtoPEMANENT(epsg)
            else:
                grass.warning("Unable to access PERMANENT mapset")
    except:
        grass.error('EPSG code cannot be identified')

def epsg2standards(epsg):
    srs = osr.SpatialReference()
    srs.ImportFromEPSG(int(epsg))
    if flags['w']:
        print('wkt=%s' % srs.ExportToWkt())
    if flags['p']:
        print('proj4=%s' % srs.ExportToProj4())

def main():
    epsg=options['epsg']
    pathwkt=options['wkt']
    if epsg and pathwkt:
        grass.error('Only one type of conversions can be processed concurrently')

    if epsg:
        epsg2standards(epsg)
    else:
        if pathwkt:
            try:
                io= open(pathwkt,'r')
                wkt=io.read().rstrip()
                wkt2standards(wkt)
            except IOError as e:
                grass.error('Unable to open file <%s>: %s'%(e.errno, e.strerror))
        else:
            grassEpsg()

if __name__ == "__main__":
    options, flags = grass.parser()
    main()