#!/usr/bin/env python
"""
This is a simple vector tile server that returns a PBF tile for  /tiles/{z}/{x}/{y}.pbf  requests

Use these environment variables to configure PostgreSQL access:
   POSTGRES_HOST, POSTGRES_PORT, POSTGRES_DB, POSTGRES_PASSWORD

Usage:
  server <prepared-sql-file> [--fname <name>] [--port <port>]
  server --help
  server --version

  <prepared-sql-file>       SQL file generated by generate-sqltomvt script with the --prepared flag

Options:
  --fname=<name>            Name of the generated function [default: gettile]
  -p --port=<port>          Serve on this port [default: 8080]
  --help                    Show this screen.
  --version                 Show version.
"""
import tornado.ioloop
import tornado.web
import io
import os
from docopt import docopt
from sqlalchemy import create_engine, inspect
from sqlalchemy.orm import sessionmaker


class GetTile(tornado.web.RequestHandler):
    def initialize(self, session, query):
        self.db_session = session
        self.db_query = query

    def get(self, z, x, y):
        z, x, y = int(z), int(x), int(y)
        try:
            result = self.db_session.execute(self.db_query, params=dict(z=z, x=x, y=y)).fetchall()
            if result:
                self.set_header("Content-Type", "application/x-protobuf")
                self.set_header("Content-Disposition", "attachment")
                self.set_header("Access-Control-Allow-Origin", "*")
                value = io.BytesIO(result[0][0]).getvalue()
                self.write(value)
                print('{0},{1},{2} returned {3} bytes'.format(z, x, y, len(value)))
            else:
                self.clear()
                self.set_status(404)
                print('Got NULL result for {0},{1},{2}'.format(z, x, y))
        except Exception as err:
            print('{0},{1},{2} threw an exception {3}'.format(z, x, y, err))
            raise

def main(args):
    sqlfile = args['<prepared-sql-file>']
    with open(sqlfile, 'r') as stream:
        prepared = stream.read()

    pghost = os.getenv('POSTGRES_HOST', 'localhost') + ':' + os.getenv('POSTGRES_PORT', '5432')
    pgdb = os.getenv('POSTGRES_DB', 'openmaptiles')
    pgcreds = os.getenv('POSTGRES_USER', 'openmaptiles') + ':' + os.getenv('POSTGRES_PASSWORD', 'openmaptiles')
    engine = create_engine('postgresql://' + pgcreds + '@' + pghost + '/' + pgdb)

    print('Connecting to PostgreSQL at {0}, db={1}'.format(pghost, pgdb))
    inspector = inspect(engine)
    session = sessionmaker(bind=engine)()
    session.execute(prepared)

    query = "EXECUTE {0}(:z, :x, :y)".format(args['--fname'])
    print('Loaded {0}, will use "{1}" to get vector tiles.'.format(sqlfile, query))

    port = int(args['--port'])
    application = tornado.web.Application([(
        r"/tiles/([0-9]+)/([0-9]+)/([0-9]+).pbf",
        GetTile,
        dict(session=session, query=query)
    )])
    application.listen(port)

    print("Postserve started, listening on 0.0.0.0:{0}".format(port))
    tornado.ioloop.IOLoop.instance().start()


if __name__ == "__main__":
    main(docopt(__doc__, version="1.0"))