#!/usr/bin/python
"""
Expire meta tiles from a OSM change file by resetting their modified time.
"""

import argparse
import os.path as ospath
import osmium as o
import pyproj

EXPIRY_TIME = 946681200 # 2000-01-01 00:00:00
# width/height of the spherical mercator projection
SIZE = 40075016.6855784

proj_wsg84 = pyproj.Proj(init='epsg:4326')
proj_merc = pyproj.Proj(init='epsg:3857')

class TileCollector(o.SimpleHandler):

    def __init__(self, node_cache, zoom):
        super(TileCollector, self).__init__()
        self.node_cache = o.index.create_map("dense_file_array," + node_cache)
        self.done_nodes = set()
        self.tile_set = set()
        self.zoom = zoom

    def add_tile_from_node(self, location):
        if not location.valid():
            return

        lat = max(-85, min(85.0, location.lat))
        x, y = pyproj.transform(proj_wsg84, proj_merc, location.lon, lat)

        # renormalise into unit space [0,1]
        x = 0.5 + x / SIZE
        y = 0.5 - y / SIZE
        # transform into tile space
        x = x * 2**self.zoom
        y = y * 2**self.zoom
        # chop of the fractional parts
        self.tile_set.add((int(x), int(y), self.zoom))

    def node(self, node):
        # we put all the nodes into the hash, as it doesn't matter whether the node was
        # added, deleted or modified - the tile will need updating anyway.
        self.done_nodes.add(node.id)
        self.add_tile_from_node(node.location)

    def way(self, way):
        for n in way.nodes:
            if not n.ref in self.done_nodes:
                self.done_nodes.add(n.ref)
                try:
                    self.add_tile_from_node(self.node_cache.get(n.ref))
                except o.NotFoundError:
                    pass # no coordinate


def xyz_to_meta(x, y, z, meta_size):
    """ Return the file name of a meta tile.
        This must match the definition of xyz to meta in mod_tile.
    """
    # mask off the final few bits
    x = x & ~(meta_size - 1)
    y = y & ~(meta_size - 1)

    # generate the path
    path = None
    for i in range(0, 5):
        part = str(((x & 0x0f) << 4) | (y & 0x0f))
        x = x >> 4
        y = y >> 4
        if path is None:
            path = (part + ".meta")
        else:
            path = ospath.join(part, path)

    return ospath.join(str(z), path)


def expire_meta(meta):
    """Expire the meta tile by setting the modified time back.
    """
    if ospath.exists(meta):
        print("Expiring " + meta)
        os.utime(meta, (EXPIRY_TIME, EXPIRY_TIME))


def expire_meta_tiles(options):
    proc = TileCollector(options.node_cache, options.max_zoom)
    proc.apply_file(options.inputfile)

    tile_set = proc.tile_set

    # turn all the tiles into expires, putting them in the set
    # so that we don't expire things multiple times
    for z in range(options.min_zoom, options.max_zoom + 1):
        meta_set = set()
        new_set = set()
        for xy in tile_set:
            meta = xyz_to_meta(xy[0], xy[1], xy[2], options.meta_size)

            for tile_dir in options.tile_dir:
                meta_set.add(ospath.join(tile_dir, meta))

            # add the parent into the set for the next round
            new_set.add((int(xy[0]/2), int(xy[1]/2), xy[2] - 1))

        # expire all meta tiles
        for meta in meta_set:
            expire_meta(meta)

        # continue with parent tiles
        tile_set = new_set

if __name__ == '__main__':

    parser = argparse.ArgumentParser(description=__doc__,
                                     formatter_class=argparse.RawDescriptionHelpFormatter,
                                     usage='%(prog)s [options] <inputfile>')
    parser.add_argument('--min', action='store', dest='min_zoom', default=13,
                        type=int,
                        help='Minimum zoom for expiry.')
    parser.add_argument('--max', action='store', dest='max_zoom', default=20,
                        type=int,
                        help='Maximum zoom for expiry.')
    parser.add_argument('-t', action='append', dest='tile_dir', default=None,
                        required=True,
                        help='Tile directory (repeat for multiple directories).')
    parser.add_argument('--meta-tile-size', action='store', dest='meta_size',
                        default=8, type=int,
                        help='The size of the meta tile blocks.')
    parser.add_argument('--node-cache', action='store', dest='node_cache',
                        default='/store/database/nodes',
                        help='osm2pgsql flatnode file.')
    parser.add_argument('inputfile',
                        help='OSC input file.')

    options = parser.parse_args()

    expire_meta_tiles(options)