import argparse
import array
import logging
import numpy
import os
import six
import sys
import ujson as json

from bisect import bisect_left
from leveldb import LevelDB
from itertools import izip, groupby

this_dir = os.path.realpath(os.path.dirname(__file__))
sys.path.append(os.path.realpath(os.path.join(os.pardir, os.pardir)))

from geodata.coordinates.conversion import latlon_to_decimal
from geodata.file_utils import ensure_dir
from geodata.osm.extract import *
from geodata.encoding import safe_decode, safe_encode

DEFAULT_INTERSECTIONS_FILENAME = 'intersections.json'


class OSMIntersectionReader(object):
    def __init__(self, filename, db_dir):
        self.filename = filename

        self.node_ids = array.array('l')

        self.logger = logging.getLogger('osm.intersections')

        # Store these in a LevelDB
        ensure_dir(db_dir)
        ways_dir = os.path.join(db_dir, 'ways')
        ensure_dir(ways_dir)
        nodes_dir = os.path.join(db_dir, 'nodes')
        ensure_dir(nodes_dir)
        self.way_props = LevelDB(ways_dir)
        self.node_props = LevelDB(nodes_dir)

        # These form a graph and should always have the same length
        self.intersection_edges_nodes = array.array('l')
        self.intersection_edges_ways = array.array('l')

    def binary_search(self, a, x):
        '''Locate the leftmost value exactly equal to x'''
        i = bisect_left(a, x)
        if i != len(a) and a[i] == x:
            return i
        return None

    def intersections(self):
        '''
        Generator which yields tuples like:

        (node_id, lat, lon, {way_id: way_props})
        '''
        i = 0

        node_ids = array.array('l')
        node_counts = array.array('i')

        for element_id, props, deps in parse_osm(self.filename, dependencies=True):
            props = {safe_decode(k): safe_decode(v) for k, v in six.iteritems(props)}
            if element_id.startswith('node'):
                node_id = long(element_id.split(':')[-1])
                node_ids.append(node_id)
                node_counts.append(0)
                self.node_props.Put(safe_encode(node_id), json.dumps(props))
            elif element_id.startswith('way'):
                # Don't care about the ordering of the nodes, and want uniques e.g. for circular roads
                deps = set(deps)

                # Get node indices by binary search
                for node_id in deps:
                    try:
                        node_index = self.binary_search(node_ids, node_id)
                    except ValueError:
                        continue
                    if node_index is None:
                        continue
                    node_counts[node_index] += 1

            if i % 1000 == 0 and i > 0:
                self.logger.info('doing {}s, at {}'.format(element_id.split(':')[0], i))
            i += 1

        for i, count in enumerate(node_counts):
            if count > 1:
                self.node_ids.append(node_ids[i])

        del node_ids
        del node_counts

        i = 0

        for element_id, props, deps in parse_osm(self.filename, dependencies=True):
            if element_id.startswith('node'):
                node_id = long(element_id.split(':')[-1])
                node_index = self.binary_search(self.node_ids, node_id)
            elif element_id.startswith('way'):
                props = {safe_decode(k): safe_decode(v) for k, v in six.iteritems(props)}
                way_id = long(element_id.split(':')[-1])
                props['id'] = way_id
                for node_id in deps:
                    node_index = self.binary_search(self.node_ids, node_id)
                    if node_index is not None:
                        self.intersection_edges_nodes.append(node_id)
                        self.intersection_edges_ways.append(way_id)
                        self.way_props.Put(safe_encode(way_id), json.dumps(props))

            if i % 1000 == 0 and i > 0:
                self.logger.info('second pass, doing {}s, at {}'.format(element_id.split(':')[0], i))
            i += 1

        i = 0

        indices = numpy.argsort(self.intersection_edges_nodes)
        self.intersection_edges_nodes = numpy.fromiter((self.intersection_edges_nodes[i] for i in indices), dtype=numpy.uint64)
        self.intersection_edges_ways = numpy.fromiter((self.intersection_edges_ways[i] for i in indices), dtype=numpy.uint64)
        del indices

        idx = 0

        # Need to make a copy here otherwise will change dictionary size during iteration
        for node_id, g in groupby(self.intersection_edges_nodes):
            group_len = sum((1 for j in g))

            node_props = json.loads(self.node_props.Get(safe_encode(node_id)))

            way_indices = self.intersection_edges_ways[idx:idx + group_len]
            all_ways = [json.loads(self.way_props.Get(safe_encode(w))) for w in way_indices]
            way_names = set()
            ways = []
            for way in all_ways:
                if way['name'] in way_names:
                    continue
                ways.append(way)
                way_names.add(way['name'])

            idx += group_len

            if i % 1000 == 0 and i > 0:
                self.logger.info('checking intersections, did {}'.format(i))
            i += 1

            if len(ways) > 1:
                node_index = self.binary_search(self.node_ids, node_id)
                yield self.node_ids[node_index], node_props, ways

    def create_intersections(self, outfile):
        out = open(outfile, 'w')
        for node_id, node_props, ways in self.intersections():
            d = {'id': safe_encode(node_id),
                 'node': node_props,
                 'ways': ways}
            out.write(json.dumps(d) + six.u('\n'))

    @classmethod
    def read_intersections(cls, infile):
        f = open(infile)
        for line in f:
            data = json.loads(line.rstrip())
            yield data['id'], data['node'], data['ways']


if __name__ == '__main__':
    parser = argparse.ArgumentParser()

    parser.add_argument('-i', '--input',
                        required=True,
                        help='Path to planet-ways-latlons.osm')

    parser.add_argument('--db-dir',
                        required=True,
                        help='Path to temporary db')

    parser.add_argument('-o', '--out-dir',
                        default=os.getcwd(),
                        required=True,
                        help='Output directory')

    args = parser.parse_args()

    logging.basicConfig(level=logging.INFO)

    reader = OSMIntersectionReader(args.input, args.db_dir)
    reader.create_intersections(os.path.join(args.out_dir, DEFAULT_INTERSECTIONS_FILENAME))