#!/usr/bin/env python
# -*- coding: UTF-8 -*-

from os.path import exists, join, isabs, abspath
from os import listdir, environ
from sys import exit
from subprocess import call
from datetime import datetime
from time import sleep
from sys import stderr

# Default values which can be overwritten.
default = {
    'MAX_DAYS': '100',
    'DIFF': 'sporadic',
    'MAX_MERGE': '7',
    'COMPRESSION_LEVEL': '1',
    'BASE_URL': 'http://planet.openstreetmap.org/replication/',
    'IMPORT_QUEUE': 'import_queue',
    'IMPORT_DONE': 'import_done',
    'BASE_PBF': 'base_pbf',
    'TIME': 120,
}

for key in default.keys():
    if key in environ:
        default[key] = environ[key]

# Folders
folders = ['IMPORT_QUEUE', 'IMPORT_DONE', 'BASE_PBF']
for folder in folders:
    if not isabs(default[folder]):
        # Get the absolute path.
        default[folder] = abspath(default[folder])

    # Test the folder
    if not exists(default[folder]):
        print >> stderr, 'The folder %s does not exist.' % default[folder]
        exit()

# Test files
state_file = None
osm_file = None
poly_file = None
for f in listdir(default['BASE_PBF']):
    if f.endswith('.state.txt'):
        state_file = join(default['BASE_PBF'], f)

    if f.endswith('.osm.pbf'):
        osm_file = join(default['BASE_PBF'], f)

    if f.endswith('.poly'):
        poly_file = join(default['BASE_PBF'], f)

if not state_file:
    print >> stderr, 'State file *.state.txt is missing in %s' % default['BASE_PBF']
    exit()

if not osm_file:
    print >> stderr, 'OSM file *.osm.pbf is missing in %s' % default['BASE_PBF']
    exit()

if not poly_file:
    print 'No *.poly detected in %s' % default['BASE_PBF']
else:
    print '%s detected for clipping.' % poly_file

while True:
    # Check if diff to be imported is empty. If not, take the latest diff.
    diff_to_be_imported = sorted(listdir(default['IMPORT_QUEUE']))
    if len(diff_to_be_imported):
        print "Timestamp from the lastest not imported diff."
        timestamp = diff_to_be_imported[-1].split('.')[0]
    else:
        # Check if imported diff is empty. If not, take the latest diff.
        imported_diff = sorted(listdir(default['IMPORT_DONE']))
        if len(imported_diff):
            print "Timestamp from the lastest imported diff."
            timestamp = imported_diff[-1].split('.')[0]

        else:
            # Take the timestamp from original file.
            print "Timestamp from the original state file."
            state_file_settings = {}
            with open(state_file) as a_file:
                for line in a_file:
                    if '=' in line:
                        name, value = line.partition("=")[::2]
                        state_file_settings[name] = value

            timestamp = state_file_settings['timestamp'].strip()

    # Removing some \ in the timestamp.
    timestamp = timestamp.replace('\\', '')

    # Save time
    current_time = datetime.utcnow().strftime('%Y-%m-%dT%H:%M:%SZ')
    print 'Old time     : %s' % timestamp
    print 'Current time : %s' % current_time

    # Destination
    file_name = '%s.osc.gz' % current_time
    file_path = join(default['IMPORT_QUEUE'], file_name)

    # Command
    command = ['osmupdate', '-v']
    if poly_file:
        command.append('-B=%s' % poly_file)
    command += ['--max-days=' + default['MAX_DAYS']]
    command += [default['DIFF']]
    command += ['--max-merge=' + default['MAX_MERGE']]
    command += ['--compression-level=' + default['COMPRESSION_LEVEL']]
    command += ['--base-url=' + default['BASE_URL']]
    command.append(timestamp)
    command.append(file_path)

    if call(command) != 0:
        print >> stderr, 'An error occured in osmupdate.'

    # Sleep
    print 'Sleeping for %s seconds.' % default['TIME']
    sleep(default['TIME'])