import asyncpg
import io
import os

import logging
import tornado
import tornado.web
from tornado.log import enable_pretty_logging
import mercantile
import pyproj
import yaml
import sys
import itertools

log = logging.getLogger('tornado.application')

def GetTM2Source(file):
    with open(file,'r') as stream:
        tm2source = yaml.load(stream)
    return tm2source

def GenerateFunction(layers):
    queries = []
    function = "CREATE OR REPLACE FUNCTION gettile(geometry, numeric, numeric, numeric) RETURNS SETOF bytea AS $$"
    for layer in layers['Layer']:
        layer_query = layer['Datasource']['table'].strip()
        layer_query = layer_query[1:len(layer_query)-6]			# Remove enough characters to remove first and last () and "AS t"
        layer_query = layer_query.replace("geometry", "ST_AsMVTGeom(geometry,!bbox!,4096,0,true) AS mvtgeometry")
        base_query = "SELECT ST_ASMVT('"+layer['id']+"', 4096, 'mvtgeometry', tile) FROM ("+layer_query+" WHERE ST_AsMVTGeom(geometry, !bbox!,4096,0,true) IS NOT NULL) AS tile"
        queries.append(base_query.replace("!bbox!","$1").replace("!scale_denominator!","$2").replace("!pixel_width!","$3").replace("!pixel_height!","$4"))
    function = function + " UNION ALL ".join(queries) + ";$$ LANGUAGE SQL"
    print(function)
    return(function)

dsn = 'postgresql://'+os.getenv('POSTGRES_USER','openmaptiles')+':'+os.getenv('POSTGRES_PASSWORD','openmaptiles')+'@'+os.getenv('POSTGRES_HOST','postgres')+':'+os.getenv('POSTGRES_PORT','5432')+'/'+os.getenv('POSTGRES_DB','openmaptiles')

def bounds(zoom,x,y):
    inProj = pyproj.Proj(init='epsg:4326')
    outProj = pyproj.Proj(init='epsg:3857')
    lnglatbbox = mercantile.bounds(x,y,zoom)
    ws = (pyproj.transform(inProj,outProj,lnglatbbox[0],lnglatbbox[1]))
    en = (pyproj.transform(inProj,outProj,lnglatbbox[2],lnglatbbox[3]))
    return {'w':ws[0],'s':ws[1],'e':en[0],'n':en[1]}

def zoom_to_scale_denom(zoom):						# For !scale_denominator!
    # From https://github.com/openstreetmap/mapnik-stylesheets/blob/master/zoom-to-scale.txt
    map_width_in_metres = 40075016.68557849
    tile_width_in_pixels = 256.0
    standardized_pixel_size = 0.00028
    map_width_in_pixels = tile_width_in_pixels*(2.0**zoom)
    return str(map_width_in_metres/(map_width_in_pixels * standardized_pixel_size))

def replace_tokens(query,s,w,n,e,scale_denom):
    return query.replace("!bbox!","ST_MakeBox2D(ST_Point("+w+", "+s+"), ST_Point("+e+", "+n+"))").replace("!scale_denominator!",scale_denom).replace("!pixel_width!","256").replace("!pixel_height!","256")

async def get_mvt(connection,zoom,x,y):
    try:								# Sanitize the inputs
        sani_zoom,sani_x,sani_y = float(zoom),float(x),float(y)
        del zoom,x,y
    except:
        print('suspicious')
        return 1

    scale_denom = zoom_to_scale_denom(sani_zoom)
    tilebounds = bounds(sani_zoom,sani_x,sani_y)
    s,w,n,e = str(tilebounds['s']),str(tilebounds['w']),str(tilebounds['n']),str(tilebounds['e'])
    final_query = "SELECT gettile(!bbox!, !scale_denominator!, !pixel_width!, !pixel_height!);"
    sent_query = replace_tokens(final_query,s,w,n,e,scale_denom)
    log.info(sent_query)
    response = await connection.fetch(sent_query)
    layers = filter(None,list(itertools.chain.from_iterable(response)))
    final_tile = b''
    for layer in layers:
        final_tile = final_tile + io.BytesIO(layer).getvalue()
    return final_tile

class GetTile(tornado.web.RequestHandler):
    def initialize(self, pool):
        self.pool = pool

    async def get(self, zoom,x,y):
        self.set_header("Content-Type", "application/x-protobuf")
        self.set_header("Content-Disposition", "attachment")
        self.set_header("Access-Control-Allow-Origin", "*")
        async with self.pool.acquire() as connection:
                response = await get_mvt(connection, zoom,x,y)
                self.write(response)

async def get_pool():
    pool = await asyncpg.create_pool(dsn = dsn)
    layers = GetTM2Source(os.getenv("MAPPING_FILE", "/mapping/data.yml"))
    # Make this prepared statement from the tm2source
    create_function = GenerateFunction(layers)
    async with pool.acquire() as connection:
        await connection.execute(create_function)
    return pool

def m():
        enable_pretty_logging()
        io_loop = tornado.ioloop.IOLoop.current()
        pool = io_loop.run_sync(get_pool)
        application = tornado.web.Application([(r"/tiles/([0-9]+)/([0-9]+)/([0-9]+).pbf", GetTile, dict(pool=pool))])
        print("Postserve started..")
        application.listen(int(os.getenv("LISTEN_PORT", "8080")))
        io_loop.start()

if __name__ == "__main__":
    m()