/* select osm_id,highway, st_length(way) as len, max_degree(way), st_numpoints(way) from
   planet_osm_line where highway is not null and oneway <> 'no' and junction is null
   and st_isring(way) and st_length(way) < 1000  and
   highway in ('primary','secondary','tertiary','trunk','residential','unclassified');
*/

DROP FUNCTION IF EXISTS max_degree(way geometry);
CREATE OR REPLACE FUNCTION max_degree(way geometry)
  RETURNS numeric
  AS
  $$
  DECLARE
     i              numeric;
     result         float;
     curAngle       float;
     angle          float;
     azimuth1       float;
     azimuth2       float;
     intNumPoints   numeric;
     point1         geometry;
     point2         geometry;
     point3         geometry;
BEGIN

   IF geometrytype(way) <> 'LINESTRING' THEN
     RETURN 9999;
   END IF;

   result := 0;

   intNumPoints := ST_NumPoints(way);

   FOR i in 2..intNumPoints LOOP
      point1 := ST_PointN(way, i-1);
      point2 := ST_PointN(way, i);
      IF i + 1 <= intNumPoints THEN
         point3 := ST_PointN(way, i+1);
      ELSE
         point3 := ST_PointN(way, 1);
      END IF;

      azimuth1 := degrees(ST_Azimuth(point1, point2));
      azimuth2 := degrees(ST_Azimuth(point2, point3));

      angle := abs(round((azimuth1 - azimuth2)::decimal, 2));

      IF angle < (360 - angle) THEN
         curAngle := angle;
      ELSE
         curAngle := 360 - angle;
      END IF;

      IF curAngle > result THEN
        result := curAngle;
      END IF;

   END LOOP;

   RETURN result;

END
$$ LANGUAGE 'plpgsql' IMMUTABLE;


/* RAISE NOTICE 'Index %, Angle %, A1 %, A2 %', i, curAngle, azimuth1, azimuth2; */