topology.sql.in

-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-- 
-- $Id$
--
-- PostGIS - Spatial Types for PostgreSQL
-- http://postgis.refractions.net
--
-- Copyright (C) 2010, 2011 Sandro Santilli <strk@keybit.net>
-- Copyright (C) 2005 Refractions Research Inc.
--
-- This is free software; you can redistribute and/or modify it under
-- the terms of the GNU General Public Licence. See the COPYING file.
--
-- Author: Sandro Santilli <strk@keybit.net>
--  
-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
--
-- STATUS:
--
--  All objects are created in the 'topology' schema.
--
--  We have PostGIS-specific objects and SQL/MM objects.
--  PostGIS-specific objects have no prefix, SQL/MM ones
--  have the ``ST_' prefix.
--  
-- [PostGIS-specific]
--
-- TABLE topology
--  Table storing topology info (name, srid, precision)
--
-- TYPE TopoGeometry
--  Complex type storing topology_id, layer_id, geometry type
--  and topogeometry id.
--
-- DOMAIN TopoElement
--  An array of two elements: element_id and element_type.
--  In fact, an array of integers.
--
-- DOMAIN TopoElementArray
--  An array of element_id,element_type values.
--  In fact, a bidimensional array of integers:
--  '{{id,type}, {id,type}, ...}'
--
-- FUNCTION CreateTopology(name, [srid], [precision])
--  Initialize a new topology (creating schema with
--  edge,face,node,relation) and add a record into
--  the topology.topology table.
--  TODO: add triggers (or rules, or whatever) enforcing
--        precision to the edge and node tables.
--  
-- FUNCTION DropTopology(name)
--    Delete a topology removing reference from the
--    topology.topology table
--
-- FUNCTION GetTopologyId(name)
-- FUNCTION GetTopologySRID(name)
-- FUNCTION GetTopologyName(id)
--    Return info about a Topology
--
-- FUNCTION AddTopoGeometryColumn(toponame, schema, table, column, geomtype)
--    Add a TopoGeometry column to a table, making it a topology layer.
--    Returns created layer id.
--
-- FUNCTION DropTopoGeometryColumn(schema, table, column)
--    Drop a TopoGeometry column, unregister the associated layer,
--    cleanup the relation table.
--
-- FUNCTION CreateTopoGeom(toponame, geomtype, layer_id, topo_objects)
--    Create a TopoGeometry object from existing Topology elements.
--    The "topo_objects" parameter is of TopoElementArray type.
--
-- FUNCTION GetTopoGeomElementArray(toponame, layer_id, topogeom_id)
-- FUNCTION GetTopoGeomElementArray(TopoGeometry)
--    Returns a TopoElementArray object containing the topological
--    elements of the given TopoGeometry.
--
-- FUNCTION GetTopoGeomElements(toponame, layer_id, topogeom_id)
-- FUNCTION GetTopoGeomElements(TopoGeometry)
--    Returns a set of TopoElement objects containing the
--    topological elements of the given TopoGeometry (primitive
--    elements)
--
-- FUNCTION ValidateTopology(toponame)
--    Run validity checks on the topology, returning, for each
--    detected error, a 3-columns row containing error string
--    and references to involved topo elements: error, id1, id2
--
-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
--
-- Overloaded functions for TopoGeometry inputs
--
-- FUNCTION intersects(TopoGeometry, TopoGeometry)
-- FUNCTION equals(TopoGeometry, TopoGeometry)
--
-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
--
-- FUNCTION TopoGeo_AddPoint(toponame, point)
--    Add a Point geometry to the topology
--    TODO: accept a topology/layer id
--          rework to use existing node if existent
--
-- FUNCTION TopoGeo_AddLinestring(toponame, line)
--    Add a LineString geometry to the topology
--    TODO: accept a topology/layer id
--          rework to use existing nodes/edges
--          splitting them if required
--
-- FUNCTION TopoGeo_AddPolygon(toponame, polygon)
--    Add a Polygon geometry to the topology
--    TODO: implement
--
-- TYPE GetFaceEdges_ReturnType
--    Complex type used to return tuples from ST_GetFaceEdges
--
-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
--
-- [SQL/MM]
--
--   ST_InitTopoGeo
--    Done, can be modified to include explicit sequences or
--    more constraints. Very noisy due to implicit index creations
--    for primary keys and sequences for serial fields...
--  
--   ST_CreateTopoGeo
--    Complete
--  
--   ST_AddIsoNode
--    Complete
--  
--   ST_RemoveIsoNode
--    Complete
--  
--   ST_MoveIsoNode
--    Complete
--  
--   ST_AddIsoEdge
--    Complete
--
--   ST_RemoveIsoEdge
--    Complete, exceptions untested
--  
--   ST_ChangeEdgeGeom
--    Complete
--
--   ST_NewEdgesSplit
--    Complete
--    Also updates the Relation table
--
--   ST_ModEdgeSplit
--    Complete
--    Also updates the Relation table
--
--   ST_AddEdgeNewFaces
--    Complete
--    Also updates the Relation table
--
--   ST_AddEdgeModFace
--    Complete
--    Also updates the Relation table
--  
--   ST_GetFaceEdges
--    Complete
--
--   ST_ModEdgeHeal
--    Complete
--    Also updates the Relation table
--
--   ST_NewEdgeHeal
--    Complete
--    Also updates the Relation table
--  
--   ST_GetFaceGeometry
--    Implemented using ST_BuildArea()
--  
--   ST_RemEdgeNewFace
--    Complete
--    Also updates the Relation table
--  
--   ST_RemEdgeModFace
--    Complete
--    Also updates the Relation table
--  
--   ST_ValidateTopoGeo
--    Unimplemented (probably a wrapper around ValidateTopology)
--  
--  

-- Uninstalling previous installation isn't really a good habit ...
-- Let people decide about that
-- DROP SCHEMA topology CASCADE;

#include "../postgis/sqldefines.h"


CREATE SCHEMA topology;

-- Doing everything outside of a transaction helps
-- upgrading in the best case.
BEGIN;

--={ ----------------------------------------------------------------
--  POSTGIS-SPECIFIC block
--
--  This part contains function NOT in the SQL/MM specification
--
---------------------------------------------------------------------

--
-- Topology table.
-- Stores id,name,precision and SRID of topologies.
--
CREATE TABLE topology.topology (
  id SERIAL NOT NULL PRIMARY KEY,
  name VARCHAR NOT NULL UNIQUE,
  SRID INTEGER NOT NULL,
  precision FLOAT8 NOT NULL,
  hasz BOOLEAN NOT NULL DEFAULT false
);

--{ LayerTrigger()
--
-- Layer integrity trigger
--
CREATE OR REPLACE FUNCTION topology.LayerTrigger()
  RETURNS trigger
AS
$$
DECLARE
  rec RECORD;
  ok BOOL;
  toponame varchar;
  query TEXT;
BEGIN

  --RAISE NOTICE 'LayerTrigger called % % at % level', TG_WHEN, TG_OP, TG_LEVEL;


  IF TG_OP = 'INSERT' THEN
    RAISE EXCEPTION 'LayerTrigger not meant to be called on INSERT';
  ELSIF TG_OP = 'UPDATE' THEN
    RAISE EXCEPTION 'The topology.layer table cannot be updated';
  END IF;


  -- Check for existance of any feature column referencing
  -- this layer
  FOR rec IN SELECT * FROM pg_namespace n, pg_class c, pg_attribute a
    WHERE text(n.nspname) = OLD.schema_name
    AND c.relnamespace = n.oid
    AND text(c.relname) = OLD.table_name
    AND a.attrelid = c.oid
    AND text(a.attname) = OLD.feature_column
  LOOP
    query = 'SELECT * '
      || ' FROM ' || quote_ident(OLD.schema_name)
      || '.' || quote_ident(OLD.table_name)
      || ' WHERE layer_id('
      || quote_ident(OLD.feature_column)||') '
      || '=' || OLD.layer_id
      || ' LIMIT 1';
    --RAISE NOTICE '%', query;
    FOR rec IN EXECUTE query
    LOOP
      RAISE NOTICE 'A feature referencing layer % of topology % still exists in %.%.%', OLD.layer_id, OLD.topology_id, OLD.schema_name, OLD.table_name, OLD.feature_column;
      RETURN NULL;
    END LOOP;
  END LOOP;


  -- Get topology name
  SELECT name FROM topology.topology INTO toponame
    WHERE id = OLD.topology_id;

  IF toponame IS NULL THEN
    RAISE NOTICE 'Could not find name of topology with id %',
      OLD.layer_id;
  END IF;

  -- Check if any record in the relation table references this layer
  FOR rec IN SELECT * FROM pg_namespace
    WHERE text(nspname) = toponame
  LOOP
    query = 'SELECT * '
      || ' FROM ' || quote_ident(toponame)
      || '.relation '
      || ' WHERE layer_id = '|| OLD.layer_id
      || ' LIMIT 1';
    --RAISE NOTICE '%', query;
    FOR rec IN EXECUTE query
    LOOP
      RAISE NOTICE 'A record in %.relation still references layer %', toponame, OLD.layer_id;
      RETURN NULL;
    END LOOP;
  END LOOP;

  RETURN OLD;
END;
$$
LANGUAGE 'plpgsql' VOLATILE STRICT;
--} LayerTrigger()


--{
-- Layer table.
-- Stores topology layer informations
--
CREATE TABLE topology.layer (
  topology_id INTEGER NOT NULL
    REFERENCES topology.topology(id),
  layer_id integer NOT NULL,
  schema_name VARCHAR NOT NULL,
  table_name VARCHAR NOT NULL,
  feature_column VARCHAR NOT NULL,
  feature_type integer NOT NULL,
  level INTEGER NOT NULL DEFAULT 0,
  child_id INTEGER DEFAULT NULL,
  UNIQUE(schema_name, table_name, feature_column),
  PRIMARY KEY(topology_id, layer_id)
);

CREATE TRIGGER layer_integrity_checks BEFORE UPDATE OR DELETE
ON topology.layer FOR EACH ROW EXECUTE PROCEDURE topology.LayerTrigger();

--} Layer table.

--
-- Type returned by ValidateTopology 
--
CREATE TYPE topology.ValidateTopology_ReturnType AS (
  error varchar,
  id1 integer,
  id2 integer
);

--
-- TopoGeometry type
--
CREATE TYPE topology.TopoGeometry AS (
  topology_id integer,
  layer_id integer,
  id integer,
  type integer -- 1: [multi]point, 2: [multi]line,
               -- 3: [multi]polygon, 4: collection
);

--
-- TopoElement domain
-- 
-- This is an array of two elements: element_id and element_type.
--
-- When used to define _simple_ TopoGeometries,
-- element_type can be:
--  0: a node
--  1: an edge
--  2: a face
-- and element_id will be the node, edge or face identifier
--
-- When used to define _hierarchical_ TopoGeometries,
-- element_type will be the child layer identifier and
-- element_id will be composing TopoGoemetry identifier
--
CREATE DOMAIN topology.TopoElement AS integer[]
  CONSTRAINT DIMENSIONS CHECK (
    array_upper(VALUE, 2) IS NULL
    AND array_upper(VALUE, 1) = 2
  );
ALTER DOMAIN topology.TopoElement ADD
        CONSTRAINT lower_dimension CHECK (
    array_lower(VALUE, 1) = 1
  );
ALTER DOMAIN topology.TopoElement DROP CONSTRAINT 
#if POSTGIS_PGSQL_VERSION >= 92
  IF EXISTS
#endif
  type_range;
ALTER DOMAIN topology.TopoElement ADD
        CONSTRAINT type_range CHECK (
    VALUE[2] > 0 
  );

--
-- TopoElementArray domain
--
CREATE DOMAIN topology.TopoElementArray AS integer[][]
  CONSTRAINT DIMENSIONS CHECK (
    array_upper(VALUE, 2) IS NOT NULL
    AND array_upper(VALUE, 2) = 2
    AND array_upper(VALUE, 3) IS NULL
  );

--{ RelationTrigger()
--
-- Relation integrity trigger
--
CREATE OR REPLACE FUNCTION topology.RelationTrigger()
  RETURNS trigger
AS
$$
DECLARE
  toponame varchar;
  topoid integer;
  plyr RECORD; -- parent layer
  rec RECORD;
  ok BOOL;

BEGIN
  IF TG_NARGS != 2 THEN
    RAISE EXCEPTION 'RelationTrigger called with wrong number of arguments';
  END IF;

  topoid = TG_ARGV[0];
  toponame = TG_ARGV[1];

  --RAISE NOTICE 'RelationTrigger called % % on %.relation for a %', TG_WHEN, TG_OP, toponame, TG_LEVEL;


  IF TG_OP = 'DELETE' THEN
    RAISE EXCEPTION 'RelationTrigger not meant to be called on DELETE';
  END IF;

  -- Get layer info (and verify it exists)
  ok = false;
  FOR plyr IN EXECUTE 'SELECT * FROM topology.layer '
    || 'WHERE '
    || ' topology_id = ' || topoid
    || ' AND'
    || ' layer_id = ' || NEW.layer_id
  LOOP
    ok = true;
    EXIT;
  END LOOP;
  IF NOT ok THEN
    RAISE EXCEPTION 'Layer % does not exist in topology %',
      NEW.layer_id, topoid;
    RETURN NULL;
  END IF;

  IF plyr.level > 0 THEN -- this is hierarchical layer

    -- ElementType must be the layer child id
    IF NEW.element_type != plyr.child_id THEN
      RAISE EXCEPTION 'Type of elements in layer % must be set to its child layer id %', plyr.layer_id, plyr.child_id;
      RETURN NULL;
    END IF;

    -- ElementId must be an existent TopoGeometry in child layer
    ok = false;
    FOR rec IN EXECUTE 'SELECT topogeo_id FROM '
      || quote_ident(toponame) || '.relation '
      || ' WHERE layer_id = ' || plyr.child_id 
      || ' AND topogeo_id = ' || NEW.element_id
    LOOP
      ok = true;
      EXIT;
    END LOOP;
    IF NOT ok THEN
      RAISE EXCEPTION 'TopoGeometry % does not exist in the child layer %', NEW.element_id, plyr.child_id;
      RETURN NULL;
    END IF;

  ELSE -- this is a basic layer

    -- ElementType must be compatible with layer type
    IF plyr.feature_type != 4
      AND plyr.feature_type != NEW.element_type
    THEN
      RAISE EXCEPTION 'Element of type % is not compatible with layer of type %', NEW.element_type, plyr.feature_type;
      RETURN NULL;
    END IF;

    --
    -- Now lets see if the element is consistent, which
    -- is it exists in the topology tables.
    --

    --
    -- Element is a Node
    --
    IF NEW.element_type = 1 
    THEN
      ok = false;
      FOR rec IN EXECUTE 'SELECT node_id FROM '
        || quote_ident(toponame) || '.node '
        || ' WHERE node_id = ' || NEW.element_id
      LOOP
        ok = true;
        EXIT;
      END LOOP;
      IF NOT ok THEN
        RAISE EXCEPTION 'Node % does not exist in topology %', NEW.element_id, toponame;
        RETURN NULL;
      END IF;

    --
    -- Element is an Edge
    --
    ELSIF NEW.element_type = 2 
    THEN
      ok = false;
      FOR rec IN EXECUTE 'SELECT edge_id FROM '
        || quote_ident(toponame) || '.edge_data '
        || ' WHERE edge_id = ' || abs(NEW.element_id)
      LOOP
        ok = true;
        EXIT;
      END LOOP;
      IF NOT ok THEN
        RAISE EXCEPTION 'Edge % does not exist in topology %', NEW.element_id, toponame;
        RETURN NULL;
      END IF;

    --
    -- Element is a Face
    --
    ELSIF NEW.element_type = 3 
    THEN
      IF NEW.element_id = 0 THEN
        RAISE EXCEPTION 'Face % cannot be associated with any feature', NEW.element_id;
        RETURN NULL;
      END IF;
      ok = false;
      FOR rec IN EXECUTE 'SELECT face_id FROM '
        || quote_ident(toponame) || '.face '
        || ' WHERE face_id = ' || NEW.element_id
      LOOP
        ok = true;
        EXIT;
      END LOOP;
      IF NOT ok THEN
        RAISE EXCEPTION 'Face % does not exist in topology %', NEW.element_id, toponame;
        RETURN NULL;
      END IF;
    END IF;

  END IF;
  
  RETURN NEW;
END;
$$
LANGUAGE 'plpgsql' VOLATILE STRICT;
--} RelationTrigger()

--{
--  AddTopoGeometryColumn(toponame, schema, table, colum, type, [child])
--
--  Add a TopoGeometry column to a table, making it a topology layer.
--  Returns created layer id.
--
--
CREATE OR REPLACE FUNCTION topology.AddTopoGeometryColumn(toponame varchar, schema varchar, tbl varchar, col varchar, ltype varchar, child integer)
  RETURNS integer
AS
$$
DECLARE
  intltype integer;
  newlevel integer;
  topoid integer;
  rec RECORD;
  newlayer_id integer;
  query text;
BEGIN

        -- Get topology id
        SELECT id FROM topology.topology into topoid
                WHERE name = toponame;

  IF topoid IS NULL THEN
    RAISE EXCEPTION 'Topology % does not exist', toponame;
  END IF;

  IF ltype ILIKE '%POINT%' OR ltype ILIKE 'PUNTAL' THEN
    intltype = 1;
  ELSIF ltype ILIKE '%LINE%' OR ltype ILIKE 'LINEAL' THEN
    intltype = 2;
  ELSIF ltype ILIKE '%POLYGON%' OR ltype ILIKE 'AREAL' THEN
    intltype = 3;
  ELSIF ltype ILIKE '%COLLECTION%' OR ltype ILIKE 'GEOMETRY' THEN
    intltype = 4;
  ELSE
    RAISE EXCEPTION 'Layer type must be one of POINT,LINE,POLYGON,COLLECTION';
  END IF;

  --
  -- Add new TopoGeometry column in schema.table
  --
  EXECUTE 'ALTER TABLE ' || quote_ident(schema)
    || '.' || quote_ident(tbl) 
    || ' ADD COLUMN ' || quote_ident(col)
    || ' topology.TopoGeometry;';


  --
  -- See if child id exists and extract its level
  --
  IF child IS NOT NULL THEN
    SELECT level + 1 FROM topology.layer
      WHERE layer_id = child
      INTO newlevel;
    IF newlevel IS NULL THEN
      RAISE EXCEPTION 'Child layer % does not exist in topology "%"', child, toponame;
    END IF;
  END IF;

  --
  -- Get new layer id from sequence
  --
  EXECUTE 'SELECT nextval(' ||
    quote_literal(
      quote_ident(toponame) || '.layer_id_seq'
    ) || ')' INTO STRICT newlayer_id;

  EXECUTE 'INSERT INTO ' 
    || 'topology.layer(topology_id, '
    || 'layer_id, level, child_id, schema_name, '
    || 'table_name, feature_column, feature_type) '
    || 'VALUES ('
    || topoid || ','
    || newlayer_id || ',' || COALESCE(newlevel, 0) || ','
    || COALESCE(child::text, 'NULL') || ','
    || quote_literal(schema) || ','
    || quote_literal(tbl) || ','
    || quote_literal(col) || ','
    || intltype || ');';


  --
  -- Create a sequence for TopoGeometries in this new layer
  --
  EXECUTE 'CREATE SEQUENCE ' || quote_ident(toponame)
    || '.topogeo_s_' || newlayer_id;

  --
  -- Add constraints on TopoGeom column
  --
  EXECUTE 'ALTER TABLE ' || quote_ident(schema)
    || '.' || quote_ident(tbl) 
    || ' ADD CONSTRAINT "check_topogeom_' || col || '" CHECK ('
    || 'topology_id(' || quote_ident(col) || ') = ' || topoid
    || ' AND '
    || 'layer_id(' || quote_ident(col) || ') = ' || newlayer_id
    || ' AND '
    || 'type(' || quote_ident(col) || ') = ' || intltype
    || ');';

  --
  -- Add dependency of the feature column on the topology schema
  --
  query = 'INSERT INTO pg_catalog.pg_depend SELECT '
    || 'fcat.oid, fobj.oid, fsub.attnum, tcat.oid, '
    || 'tobj.oid, 0, ''n'' '
    || 'FROM pg_class fcat, pg_namespace fnsp, '
    || ' pg_class fobj, pg_attribute fsub, '
    || ' pg_class tcat, pg_namespace tobj '
    || ' WHERE fcat.relname = ''pg_class'' '
    || ' AND fnsp.nspname = ' || quote_literal(schema)
    || ' AND fobj.relnamespace = fnsp.oid '
    || ' AND fobj.relname = ' || quote_literal(tbl)
    || ' AND fsub.attrelid = fobj.oid '
    || ' AND fsub.attname = ' || quote_literal(col)
    || ' AND tcat.relname = ''pg_namespace'' '
    || ' AND tobj.nspname = ' || quote_literal(toponame);

--
-- The only reason to add this dependency is to avoid
-- simple drop of a feature column. Still, drop cascade
-- will remove both the feature column and the sequence
-- corrupting the topology anyway ...
--
#if 0
  --
  -- Add dependency of the topogeom sequence on the feature column 
  -- This is a dirty hack ...
  --
  query = 'INSERT INTO pg_catalog.pg_depend SELECT '
    || 'scat.oid, sobj.oid, 0, fcat.oid, '
    || 'fobj.oid, fsub.attnum, ''n'' '
    || 'FROM pg_class fcat, pg_namespace fnsp, '
    || ' pg_class fobj, pg_attribute fsub, '
    || ' pg_class scat, pg_class sobj, '
    || ' pg_namespace snsp '
    || ' WHERE fcat.relname = ''pg_class'' '
    || ' AND fnsp.nspname = ' || quote_literal(schema)
    || ' AND fobj.relnamespace = fnsp.oid '
    || ' AND fobj.relname = ' || quote_literal(tbl)
    || ' AND fsub.attrelid = fobj.oid '
    || ' AND fsub.attname = ' || quote_literal(col)
    || ' AND scat.relname = ''pg_class'' '
    || ' AND snsp.nspname = ' || quote_literal(toponame)
    || ' AND sobj.relnamespace = snsp.oid ' 
    || ' AND sobj.relname = '
    || ' ''topogeo_s_' || newlayer_id || ''' ';

  RAISE NOTICE '%', query;
  EXECUTE query;
#endif

  RETURN newlayer_id;
END;
$$
LANGUAGE 'plpgsql' VOLATILE;
--}{ AddTopoGeometryColumn

CREATE OR REPLACE FUNCTION topology.AddTopoGeometryColumn(varchar, varchar, varchar, varchar, varchar)
  RETURNS integer
AS
$$
  SELECT topology.AddTopoGeometryColumn($1, $2, $3, $4, $5, NULL);
$$
LANGUAGE 'sql' VOLATILE;

--
--} AddTopoGeometryColumn

--{
--  DropTopoGeometryColumn(schema, table, colum)
--
--  Drop a TopoGeometry column, unregister the associated layer,
--  cleanup the relation table.
--
--
CREATE OR REPLACE FUNCTION topology.DropTopoGeometryColumn(schema varchar, tbl varchar, col varchar)
  RETURNS text
AS
$$
DECLARE
  rec RECORD;
  lyrinfo RECORD;
  ok BOOL;
  result text;
BEGIN

        -- Get layer and topology info
  ok = false;
  FOR rec IN EXECUTE 'SELECT t.name as toponame, l.* FROM '
    || 'topology.topology t, topology.layer l '
    || ' WHERE l.topology_id = t.id'
    || ' AND l.schema_name = ' || quote_literal(schema)
    || ' AND l.table_name = ' || quote_literal(tbl)
    || ' AND l.feature_column = ' || quote_literal(col)
  LOOP
    ok = true;
    lyrinfo = rec;
  END LOOP;

  -- Layer not found
  IF NOT ok THEN
    RAISE EXCEPTION 'No layer registered on %.%.%',
      schema,tbl,col;
  END IF;
    
  -- Clean up the topology schema
  FOR rec IN SELECT * FROM pg_namespace
    WHERE text(nspname) = lyrinfo.toponame
  LOOP
    -- Cleanup the relation table
    EXECUTE 'DELETE FROM ' || quote_ident(lyrinfo.toponame)
      || '.relation '
      || ' WHERE '
      || 'layer_id = ' || lyrinfo.layer_id;

    -- Drop the sequence for topogeoms in this layer
    EXECUTE 'DROP SEQUENCE ' || quote_ident(lyrinfo.toponame)
      || '.topogeo_s_' || lyrinfo.layer_id;

  END LOOP;

  ok = false;
  FOR rec IN SELECT * FROM pg_namespace n, pg_class c, pg_attribute a
    WHERE text(n.nspname) = schema
    AND c.relnamespace = n.oid
    AND text(c.relname) = tbl
    AND a.attrelid = c.oid
    AND text(a.attname) = col
  LOOP
    ok = true;
    EXIT;
  END LOOP;


  IF ok THEN
    -- Set feature column to NULL to bypass referential integrity
    -- checks
    EXECUTE 'UPDATE ' || quote_ident(schema) || '.'
      || quote_ident(tbl)
      || ' SET ' || quote_ident(col)
      || ' = NULL';
  END IF;

  -- Delete the layer record
  EXECUTE 'DELETE FROM topology.layer '
    || ' WHERE topology_id = ' || lyrinfo.topology_id
    || ' AND layer_id = ' || lyrinfo.layer_id;

  IF ok THEN
    -- Drop the layer column
    EXECUTE 'ALTER TABLE ' || quote_ident(schema) || '.'
      || quote_ident(tbl)
      || ' DROP ' || quote_ident(col)
      || ' cascade';
  END IF;

  result = 'Layer ' || lyrinfo.layer_id || ' ('
    || schema || '.' || tbl || '.' || col
    || ') dropped';

  RETURN result;
END;
$$
LANGUAGE 'plpgsql' VOLATILE;
--
--} DropTopoGeometryColumn


--{
-- CreateTopoGeom(topology_name, topogeom_type, layer_id, elements)
--
-- Create a TopoGeometry object from Topology elements.
-- The elements parameter is a two-dimensional array. 
-- Every element of the array is either a Topology element represented by
-- (id, type) or a TopoGeometry element represented by (id, layer).
-- The actual semantic depends on the TopoGeometry layer, either at
-- level 0 (elements are topological primitives) or higer (elements
-- are TopoGeoms from child layer).
-- 
-- @param toponame Topology name
--
-- @param tg_type Spatial type of geometry
--          1:[multi]point (puntal)
--          2:[multi]line  (lineal)
--          3:[multi]poly  (areal)
--          4:collection   (mixed)
--
-- @param layer_id Layer identifier
--
-- @param tg_objs Array of components
-- 
-- Return a topology.TopoGeometry object.
--
CREATE OR REPLACE FUNCTION topology.CreateTopoGeom(toponame varchar, tg_type integer, layer_id integer, tg_objs topology.TopoElementArray)
  RETURNS topology.TopoGeometry
AS
$$
DECLARE
  i integer;
  dims varchar;
  outerdims varchar;
  innerdims varchar;
  obj_type integer;
  obj_id integer;
  ret topology.TopoGeometry;
  rec RECORD;
  layertype integer;
  layerlevel integer;
  layerchild integer;
BEGIN

  IF tg_type < 1 OR tg_type > 4 THEN
    RAISE EXCEPTION 'Invalid TopoGeometry type % (must be in the range 1..4)', tg_type;
  END IF;

  -- Get topology id into return TopoGeometry
  SELECT id FROM topology.topology into ret.topology_id
    WHERE name = toponame;

  --
  -- Get layer info
  --
  layertype := NULL;
  FOR rec IN EXECUTE 'SELECT * FROM topology.layer'
    || ' WHERE topology_id = ' || ret.topology_id
    || ' AND layer_id = ' || layer_id
  LOOP
    layertype = rec.feature_type;
    layerlevel = rec.level;
    layerchild = rec.child_id;
  END LOOP;

  -- Check for existence of given layer id
  IF layertype IS NULL THEN
    RAISE EXCEPTION 'No layer with id % is registered with topology %', layer_id, toponame;
  END IF;

  -- Verify compatibility between layer geometry type and
  -- TopoGeom requested geometry type
  IF layertype != 4 and layertype != tg_type THEN
    RAISE EXCEPTION 'A Layer of type % cannot contain a TopoGeometry of type %', layertype, tg_type;
  END IF;

  -- Set layer id and type in return object
  ret.layer_id = layer_id;
  ret.type = tg_type;

  --
  -- Get new TopoGeo id from sequence
  --
  FOR rec IN EXECUTE 'SELECT nextval(' ||
    quote_literal(
      quote_ident(toponame) || '.topogeo_s_' || layer_id
    ) || ')'
  LOOP
    ret.id = rec.nextval;
  END LOOP;

  -- Loop over outer dimension
  i = array_lower(tg_objs, 1);
  LOOP
    obj_id = tg_objs[i][1];
    obj_type = tg_objs[i][2];

    -- Elements of type 0 represent emptiness, just skip them
    IF obj_type = 0 THEN
      IF obj_id != 0 THEN
        RAISE EXCEPTION 'Malformed empty topo element {0,%} -- id must be 0 as well', obj_id;
      END IF;
    ELSE
      IF layerlevel = 0 THEN -- array specifies lower-level objects
        IF tg_type != 4 and tg_type != obj_type THEN
          RAISE EXCEPTION 'A TopoGeometry of type % cannot contain topology elements of type %', tg_type, obj_type;
        END IF;
      ELSE -- array specifies lower-level topogeometries
        IF obj_type != layerchild THEN
          RAISE EXCEPTION 'TopoGeom element layer do not match TopoGeom child layer';
        END IF;
        -- TODO: verify that the referred TopoGeometry really
        -- exists in the relation table ?
      END IF;

      --RAISE NOTICE 'obj:% type:% id:%', i, obj_type, obj_id;

      --
      -- Insert record into the Relation table
      --
      EXECUTE 'INSERT INTO '||quote_ident(toponame)
        || '.relation(topogeo_id, layer_id, '
        || 'element_id,element_type) '
        || ' VALUES ('||ret.id
        ||','||ret.layer_id
        || ',' || obj_id || ',' || obj_type || ');';
    END IF;

    i = i+1;
    IF i > array_upper(tg_objs, 1) THEN
      EXIT;
    END IF;
  END LOOP;

  RETURN ret;

END
$$
LANGUAGE 'plpgsql' VOLATILE STRICT;
--} CreateTopoGeom(toponame,topogeom_type, layer_id, TopoElementArray)

--{
-- CreateTopoGeom(topology_name, topogeom_type, layer_id) - creates the empty topogeom
CREATE OR REPLACE FUNCTION topology.CreateTopoGeom(toponame varchar, tg_type integer, layer_id integer)
  RETURNS topology.TopoGeometry
AS
$$
  SELECT topology.CreateTopoGeom($1,$2,$3,'{{0,0}}');
$$ LANGUAGE 'sql' VOLATILE STRICT;
--} CreateTopoGeom(toponame, topogeom_type, layer_id)

--{
-- GetTopologyName(topology_id)
--
-- TODO: rewrite in SQL ?
--
CREATE OR REPLACE FUNCTION topology.GetTopologyName(topoid integer)
  RETURNS varchar
AS
$$
DECLARE
  ret varchar;
BEGIN
        SELECT name FROM topology.topology into ret
                WHERE id = topoid;
  RETURN ret;
END
$$
LANGUAGE 'plpgsql' STABLE STRICT;
--} GetTopologyName(topoid)

--{
-- GetTopologyId(toponame)
--
-- TODO: rewrite in SQL ?
--
CREATE OR REPLACE FUNCTION topology.GetTopologyId(toponame varchar)
  RETURNS integer
AS
$$
DECLARE
  ret integer;
BEGIN
        SELECT id FROM topology.topology into ret
                WHERE name = toponame;
  RETURN ret;
END
$$
LANGUAGE 'plpgsql' STABLE STRICT;
--} GetTopologyId(toponame)

--{
-- GetTopologySRID(toponame)
--
CREATE OR REPLACE FUNCTION topology.GetTopologySRID(toponame varchar)
  RETURNS integer
AS $$
  SELECT SRID FROM topology.topology WHERE name = $1;
$$ LANGUAGE 'sql' STABLE STRICT;
--} GetTopologySRID(toponame)
  


--{
-- GetTopoGeomElementArray(toponame, layer_id, topogeom_id)
-- GetTopoGeomElementArray(TopoGeometry)
--
-- Returns a set of element_id,element_type
--
CREATE OR REPLACE FUNCTION topology.GetTopoGeomElementArray(toponame varchar, layer_id integer, tgid integer)
  RETURNS topology.TopoElementArray
AS
$$
DECLARE
  rec RECORD;
  tg_objs varchar := '{';
  i integer;
  query text;
BEGIN

  query = 'SELECT * FROM topology.GetTopoGeomElements('
    || quote_literal(toponame) || ','
    || quote_literal(layer_id) || ','
    || quote_literal(tgid)
    || ') as obj ORDER BY obj';

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Query: %', query;
#endif

  -- TODO: why not using array_agg here ?

  i = 1;
  FOR rec IN EXECUTE query
  LOOP
    IF i > 1 THEN
      tg_objs = tg_objs || ',';
    END IF;
    tg_objs = tg_objs || '{'
      || rec.obj[1] || ',' || rec.obj[2]
      || '}';
    i = i+1;
  END LOOP;

  tg_objs = tg_objs || '}';

  RETURN tg_objs;
END;
$$
LANGUAGE 'plpgsql' STABLE STRICT;

CREATE OR REPLACE FUNCTION topology.GetTopoGeomElementArray(tg topology.TopoGeometry)
  RETURNS topology.TopoElementArray
AS
$$
DECLARE
  toponame varchar;
BEGIN
  toponame = topology.GetTopologyName(tg.topology_id);
  RETURN topology.GetTopoGeomElementArray(toponame, tg.layer_id, tg.id);
END;
$$
LANGUAGE 'plpgsql' STABLE STRICT;

--} GetTopoGeomElementArray()

--{
-- GetTopoGeomElements(toponame, layer_id, topogeom_id)
-- GetTopoGeomElements(TopoGeometry)
--
-- Returns a set of element_id,element_type
--
CREATE OR REPLACE FUNCTION topology.GetTopoGeomElements(toponame varchar, layerid integer, tgid integer)
  RETURNS SETOF topology.TopoElement
AS
$$
DECLARE
  ret topology.TopoElement;
  rec RECORD;
  rec2 RECORD;
  query text;
  query2 text;
  lyr RECORD;
  ok bool;
BEGIN

  -- Get layer info
  ok = false;
  FOR rec IN EXECUTE 'SELECT * FROM '
    || ' topology.layer '
    || ' WHERE layer_id = ' || layerid
  LOOP
    lyr = rec;
    ok = true;
  END LOOP;

  IF NOT ok THEN
    RAISE EXCEPTION 'Layer % does not exist', layerid;
  END IF;


  query = 'SELECT abs(element_id) as element_id, element_type FROM '
    || quote_ident(toponame) || '.relation WHERE '
    || ' layer_id = ' || layerid
    || ' AND topogeo_id = ' || quote_literal(tgid)
    || ' ORDER BY element_type, element_id';

  --RAISE NOTICE 'Query: %', query;

  FOR rec IN EXECUTE query
  LOOP
    IF lyr.level > 0 THEN
      query2 = 'SELECT * from topology.GetTopoGeomElements('
        || quote_literal(toponame) || ','
        || rec.element_type
        || ','
        || rec.element_id
        || ') as ret;';
      --RAISE NOTICE 'Query2: %', query2;
      FOR rec2 IN EXECUTE query2
      LOOP
        RETURN NEXT rec2.ret;
      END LOOP;
    ELSE
      ret = '{' || rec.element_id || ',' || rec.element_type || '}';
      RETURN NEXT ret;
    END IF;
  
  END LOOP;

  RETURN;
END;
$$
LANGUAGE 'plpgsql' STABLE STRICT;

CREATE OR REPLACE FUNCTION topology.GetTopoGeomElements(tg topology.TopoGeometry)
  RETURNS SETOF topology.TopoElement
AS
$$
DECLARE
  toponame varchar;
  rec RECORD;
BEGIN
  toponame = topology.GetTopologyName(tg.topology_id);
  FOR rec IN SELECT * FROM topology.GetTopoGeomElements(toponame,
    tg.layer_id,tg.id) as ret
  LOOP
    RETURN NEXT rec.ret;
  END LOOP;
  RETURN;
END;
$$
LANGUAGE 'plpgsql' STABLE STRICT;

--} GetTopoGeomElements()

--{
-- Geometry(TopoGeometry)
--
-- Construct a Geometry from a TopoGeometry.
-- 
-- }{
CREATE OR REPLACE FUNCTION topology.Geometry(topogeom topology.TopoGeometry)
  RETURNS Geometry
AS $$
DECLARE
  toponame varchar;
  geom geometry;
  rec RECORD;
  plyr RECORD;
  clyr RECORD;
  sql TEXT;
BEGIN

  -- Get topology name
  SELECT name FROM topology.topology
  WHERE id = topogeom.topology_id
  INTO toponame;
  IF toponame IS NULL THEN
    RAISE EXCEPTION 'Invalid TopoGeometry (unexistent topology id %)', topogeom.topology_id;
  END IF;

  -- Get layer info
  SELECT * FROM topology.layer
    WHERE topology_id = topogeom.topology_id
    AND layer_id = topogeom.layer_id
    INTO plyr;
  IF plyr IS NULL THEN
    RAISE EXCEPTION 'Could not find TopoGeometry layer % in topology %', topogeom.layer_id, topogeom.topology_id;
  END IF;

  --
  -- If this feature layer is on any level > 0 we will
  -- compute the topological union of all child features
  -- in fact recursing.
  --
  IF plyr.level > 0 THEN -- {

    -- Get child layer info
    SELECT * FROM topology.layer WHERE layer_id = plyr.child_id
      AND topology_id = topogeom.topology_id
      INTO clyr;
    IF clyr IS NULL THEN
      RAISE EXCEPTION 'Invalid layer % in topology % (unexistent child layer %)', topogeom.layer_id, topogeom.topology_id, plyr.child_id;
    END IF;

    sql := 'SELECT st_multi(st_union(topology.Geometry('
      || quote_ident(clyr.feature_column)
      || '))) as geom FROM '
      || quote_ident(clyr.schema_name) || '.'
      || quote_ident(clyr.table_name)
      || ', ' || quote_ident(toponame) || '.relation pr'
      || ' WHERE '
      || ' pr.topogeo_id = ' || topogeom.id
      || ' AND '
      || ' pr.layer_id = ' || topogeom.layer_id
      || ' AND '
      || ' id('||quote_ident(clyr.feature_column)
      || ') = pr.element_id '
      || ' AND '
      || 'layer_id('||quote_ident(clyr.feature_column)
      || ') = pr.element_type ';
    --RAISE DEBUG '%', query;
    EXECUTE sql INTO geom;
      
  ELSIF topogeom.type = 3 THEN -- [multi]polygon -- }{

    sql := 'SELECT st_multi(st_union('
      || 'topology.ST_GetFaceGeometry('
      || quote_literal(toponame) || ','
      || 'element_id))) as g FROM ' 
      || quote_ident(toponame)
      || '.relation WHERE topogeo_id = '
      || topogeom.id || ' AND layer_id = '
      || topogeom.layer_id || ' AND element_type = 3 ';
    EXECUTE sql INTO geom;

  ELSIF topogeom.type = 2 THEN -- [multi]line -- }{

    sql := 
      'SELECT st_multi(ST_LineMerge(ST_Collect(e.geom))) as g FROM '
      || quote_ident(toponame) || '.edge e, '
      || quote_ident(toponame) || '.relation r '
      || ' WHERE r.topogeo_id = ' || topogeom.id
      || ' AND r.layer_id = ' || topogeom.layer_id
      || ' AND r.element_type = 2 '
      || ' AND abs(r.element_id) = e.edge_id';
    EXECUTE sql INTO geom;
  
  ELSIF topogeom.type = 1 THEN -- [multi]point -- }{

    sql :=
      'SELECT st_multi(st_union(n.geom)) as g FROM '
      || quote_ident(toponame) || '.node n, '
      || quote_ident(toponame) || '.relation r '
      || ' WHERE r.topogeo_id = ' || topogeom.id
      || ' AND r.layer_id = ' || topogeom.layer_id
      || ' AND r.element_type = 1 '
      || ' AND r.element_id = n.node_id';
    EXECUTE sql INTO geom;

  ELSIF topogeom.type = 4 THEN -- mixed collection -- }{

    sql := 'WITH areas AS ( SELECT ST_Union('
      || 'topology.ST_GetFaceGeometry('
      || quote_literal(toponame) || ','
      || 'element_id)) as g FROM ' 
      || quote_ident(toponame)
      || '.relation WHERE topogeo_id = '
      || topogeom.id || ' AND layer_id = '
      || topogeom.layer_id || ' AND element_type = 3), '
      || 'lines AS ( SELECT ST_LineMerge(ST_Collect(e.geom)) as g FROM '
      || quote_ident(toponame) || '.edge e, '
      || quote_ident(toponame) || '.relation r '
      || ' WHERE r.topogeo_id = ' || topogeom.id
      || ' AND r.layer_id = ' || topogeom.layer_id
      || ' AND r.element_type = 2 '
      || ' AND abs(r.element_id) = e.edge_id ), '
      || ' points as ( SELECT st_union(n.geom) as g FROM '
      || quote_ident(toponame) || '.node n, '
      || quote_ident(toponame) || '.relation r '
      || ' WHERE r.topogeo_id = ' || topogeom.id
      || ' AND r.layer_id = ' || topogeom.layer_id
      || ' AND r.element_type = 1 '
      || ' AND r.element_id = n.node_id ), '
      || ' un as ( SELECT g FROM areas UNION ALL SELECT g FROM lines '
      || '          UNION ALL SELECT g FROM points ) '
      || 'SELECT ST_Multi(ST_Collect(g)) FROM un';
    EXECUTE sql INTO geom;

  ELSE -- }{

    RAISE EXCEPTION 'Invalid TopoGeometries (unknown type %)', topogeom.type;

  END IF; -- }

  IF geom IS NULL THEN
    IF topogeom.type = 3 THEN -- [multi]polygon
      geom := 'MULTIPOLYGON EMPTY';
    ELSIF topogeom.type = 2 THEN -- [multi]line
      geom := 'MULTILINESTRING EMPTY';
    ELSIF topogeom.type = 1 THEN -- [multi]point
      geom := 'MULTIPOINT EMPTY';
    ELSE
      geom := 'GEOMETRYCOLLECTION EMPTY';
    END IF;
  END IF;

  RETURN geom;
END
$$
LANGUAGE 'plpgsql' VOLATILE STRICT;
--} Geometry(TopoGeometry)

-- 7.3+ explicit cast 
CREATE CAST (topology.TopoGeometry AS Geometry) WITH FUNCTION topology.Geometry(topology.TopoGeometry) AS IMPLICIT;

--{
--  ValidateTopology(toponame)
--
--  Return a Set of ValidateTopology_ReturnType containing
--  informations on all topology inconsistencies
--
CREATE OR REPLACE FUNCTION topology.ValidateTopology(toponame varchar)
  RETURNS setof topology.ValidateTopology_ReturnType
AS
$$
DECLARE
  retrec topology.ValidateTopology_ReturnType;
  rec RECORD;
  rec2 RECORD;
  i integer;
  invalid_edges integer[];
  invalid_faces integer[];
  sql text;
BEGIN

  -- Check for coincident nodes
  FOR rec IN EXECUTE 'SELECT a.node_id as id1, b.node_id as id2 FROM '
    || quote_ident(toponame) || '.node a, '
    || quote_ident(toponame) || '.node b '
    || 'WHERE a.node_id < b.node_id '
    || ' AND ST_DWithin(a.geom, b.geom, 0)' -- NOTE: see #1625 and #1789
  LOOP
    retrec.error = 'coincident nodes';
    retrec.id1 = rec.id1;
    retrec.id2 = rec.id2;
    RETURN NEXT retrec;
  END LOOP;

  -- Check for edge crossed nodes
  -- TODO: do this in the single edge loop
  FOR rec IN EXECUTE 'SELECT n.node_id as id1, e.edge_id as id2 FROM '
    || quote_ident(toponame) || '.node n, '
    || quote_ident(toponame) || '.edge e '
    || 'WHERE e.start_node != n.node_id '
    || 'AND e.end_node != n.node_id '
    || 'AND ST_Within(n.geom, e.geom)'
  LOOP
    retrec.error = 'edge crosses node';
    retrec.id1 = rec.id1;
    retrec.id2 = rec.id2;
    RETURN NEXT retrec;
  END LOOP;

  -- Scan all edges 
  FOR rec IN EXECUTE 'SELECT e.geom, e.edge_id as id1, e.left_face, e.right_face FROM '
    || quote_ident(toponame) || '.edge e ORDER BY edge_id'
  LOOP

    -- Any invalid edge becomes a cancer for higher level complexes
    IF NOT ST_IsValid(rec.geom) THEN

      retrec.error = 'invalid edge';
      retrec.id1 = rec.id1;
      retrec.id2 = NULL;
      RETURN NEXT retrec;
      invalid_edges := array_append(invalid_edges, rec.id1);

      IF invalid_faces IS NULL OR NOT rec.left_face = ANY ( invalid_faces )
      THEN
        invalid_faces := array_append(invalid_faces, rec.left_face);
      END IF;

      IF rec.right_face != rec.left_face AND ( invalid_faces IS NULL OR
            NOT rec.right_face = ANY ( invalid_faces ) )
      THEN
        invalid_faces := array_append(invalid_faces, rec.right_face);
      END IF;

      CONTINUE;

    END IF;

    IF NOT ST_IsSimple(rec.geom) THEN
      retrec.error = 'edge not simple';
      retrec.id1 = rec.id1;
      retrec.id2 = NULL;
      RETURN NEXT retrec;
    END IF;

  END LOOP;

  -- Check for edge crossing
  sql := 'SELECT e1.edge_id as id1, e2.edge_id as id2, '
    || ' e1.geom as g1, e2.geom as g2, '
    || 'ST_Relate(e1.geom, e2.geom) as im FROM '
    || quote_ident(toponame) || '.edge e1, '
    || quote_ident(toponame) || '.edge e2 '
    || 'WHERE e1.edge_id < e2.edge_id '
    || ' AND e1.geom && e2.geom ';
  IF invalid_edges IS NOT NULL THEN
    sql := sql || ' AND NOT e1.edge_id = ANY ('
               || quote_literal(invalid_edges) || ')'
               || ' AND NOT e2.edge_id = ANY ('
               || quote_literal(invalid_edges) || ')';
  END IF;

  FOR rec IN EXECUTE sql
  LOOP
    IF ST_RelateMatch(rec.im, 'FF1F**1*2') THEN
      CONTINUE; -- no interior intersection
    END IF;

    --
    -- Closed lines have no boundary, so endpoint
    -- intersection would be considered interior
    -- See http://trac.osgeo.org/postgis/ticket/770
    -- See also full explanation in topology.AddEdge
    --

    IF ST_RelateMatch(rec.im, 'FF10F01F2') THEN
      -- first line (g1) is open, second (g2) is closed
      -- first boundary has puntual intersection with second interior
      --
      -- compute intersection, check it equals second endpoint
      IF ST_Equals(ST_Intersection(rec.g2, rec.g1),
                   ST_StartPoint(rec.g2))
      THEN
        CONTINUE;
      END IF;
    END IF;

    IF ST_RelateMatch(rec.im, 'F01FFF102') THEN
      -- second line (g2) is open, first (g1) is closed
      -- second boundary has puntual intersection with first interior
      -- 
      -- compute intersection, check it equals first endpoint
      IF ST_Equals(ST_Intersection(rec.g2, rec.g1),
                   ST_StartPoint(rec.g1))
      THEN
        CONTINUE;
      END IF;
    END IF;

    IF ST_RelateMatch(rec.im, '0F1FFF1F2') THEN
      -- both lines are closed (boundary intersects nothing)
      -- they have puntual intersection between interiors
      -- 
      -- compute intersection, check it's a single point
      -- and equals first StartPoint _and_ second StartPoint
      IF ST_Equals(ST_Intersection(rec.g1, rec.g2),
                   ST_StartPoint(rec.g1)) AND
         ST_Equals(ST_StartPoint(rec.g1), ST_StartPoint(rec.g2))
      THEN
        CONTINUE;
      END IF;
    END IF;

    retrec.error = 'edge crosses edge';
    retrec.id1 = rec.id1;
    retrec.id2 = rec.id2;
    RETURN NEXT retrec;
  END LOOP;

  -- Check for edge start_node geometry mis-match
  -- TODO: move this in the first edge table scan 
  FOR rec IN EXECUTE 'SELECT e.edge_id as id1, n.node_id as id2 FROM '
    || quote_ident(toponame) || '.edge e, '
    || quote_ident(toponame) || '.node n '
    || 'WHERE e.start_node = n.node_id '
    || 'AND NOT ST_Equals(ST_StartPoint(e.geom), n.geom)'
  LOOP
    retrec.error = 'edge start node geometry mis-match';
    retrec.id1 = rec.id1;
    retrec.id2 = rec.id2;
    RETURN NEXT retrec;
  END LOOP;

  -- Check for edge end_node geometry mis-match
  -- TODO: move this in the first edge table scan 
  FOR rec IN EXECUTE 'SELECT e.edge_id as id1, n.node_id as id2 FROM '
    || quote_ident(toponame) || '.edge e, '
    || quote_ident(toponame) || '.node n '
    || 'WHERE e.end_node = n.node_id '
    || 'AND NOT ST_Equals(ST_EndPoint(e.geom), n.geom)'
  LOOP
    retrec.error = 'edge end node geometry mis-match';
    retrec.id1 = rec.id1;
    retrec.id2 = rec.id2;
    RETURN NEXT retrec;
  END LOOP;

  -- Check for faces w/out edges
  FOR rec IN EXECUTE 'SELECT face_id as id1 FROM '
    || quote_ident(toponame) || '.face '
    || 'WHERE face_id > 0 EXCEPT ( SELECT left_face FROM '
    || quote_ident(toponame) || '.edge '
    || ' UNION SELECT right_face FROM '
    || quote_ident(toponame) || '.edge '
    || ')'
  LOOP
    retrec.error = 'face without edges';
    retrec.id1 = rec.id1;
    retrec.id2 = NULL;
    RETURN NEXT retrec;
  END LOOP;

  -- Now create a temporary table to construct all face geometries
  -- for checking their consistency

  sql := 'CREATE TEMP TABLE face_check ON COMMIT DROP AS '
    || 'SELECT face_id, topology.ST_GetFaceGeometry('
    || quote_literal(toponame) || ', face_id) as geom, mbr FROM '
    || quote_ident(toponame) || '.face WHERE face_id > 0';
  IF invalid_faces IS NOT NULL THEN
    sql := sql || ' AND NOT face_id = ANY ('
               || quote_literal(invalid_faces) || ')';
  END IF;
  EXECUTE sql;

  -- Build a gist index on geom
  EXECUTE 'CREATE INDEX "face_check_gist" ON '
    || 'face_check USING gist (geom);';

  -- Build a btree index on id
  EXECUTE 'CREATE INDEX "face_check_bt" ON ' 
    || 'face_check (face_id);';

  -- Scan the table looking for NULL geometries
  FOR rec IN EXECUTE
    'SELECT f1.face_id FROM '
    || 'face_check f1 WHERE f1.geom IS NULL'
  LOOP
    -- Face missing !
    retrec.error := 'face has no rings';
    retrec.id1 := rec.face_id;
    retrec.id2 := NULL;
    RETURN NEXT retrec;
  END LOOP;


  -- Scan the table looking for overlap or containment
  -- TODO: also check for MBR consistency
  FOR rec IN EXECUTE
    'SELECT f1.geom, f1.face_id as id1, f2.face_id as id2, '
    || ' ST_Relate(f1.geom, f2.geom) as im'
    || ' FROM '
    || 'face_check f1, '
    || 'face_check f2 '
    || 'WHERE f1.face_id < f2.face_id'
    || ' AND f1.geom && f2.geom'
  LOOP

    -- Face overlap
    IF ST_RelateMatch(rec.im, 'T*T***T**') THEN
    retrec.error = 'face overlaps face';
    retrec.id1 = rec.id1;
    retrec.id2 = rec.id2;
    RETURN NEXT retrec;
    END IF;

    -- Face 1 is within face 2 
    IF ST_RelateMatch(rec.im, 'T*F**F***') THEN
    retrec.error = 'face within face';
    retrec.id1 = rec.id1;
    retrec.id2 = rec.id2;
    RETURN NEXT retrec;
    END IF;

    -- Face 1 contains face 2
    IF ST_RelateMatch(rec.im, 'T*****FF*') THEN
    retrec.error = 'face within face';
    retrec.id1 = rec.id2;
    retrec.id2 = rec.id1;
    RETURN NEXT retrec;
    END IF;

  END LOOP;

#if 0
  -- Check SRID consistency
  FOR rec in EXECUTE
    'SELECT count(*) FROM ( getSRID(geom) FROM '
    || quote_ident(toponame) || '.edge '
    || ' UNION '
    'SELECT getSRID(geom) FROM '
    || quote_ident(toponame) || '.node )'
  LOOP
    IF rec.count > 1 THEN
      retrec.error = 'mixed SRIDs';
      retrec.id1 = NULL;
      retrec.id2 = NULL;
      RETURN NEXT retrec;
    END IF;
  END LOOP;
#endif

  DROP TABLE face_check;

  RETURN;
END
$$
LANGUAGE 'plpgsql' VOLATILE STRICT;
-- } ValidateTopology(toponame)

--{
--  CreateTopology(name, SRID, precision, hasZ)
--
-- Create a topology schema, add a topology info record
-- in the topology.topology relation, return it's numeric
-- id. 
--
CREATE OR REPLACE FUNCTION topology.CreateTopology(atopology varchar, srid integer, prec float8, hasZ boolean)
RETURNS integer
AS
$$
DECLARE
  rec RECORD;
  topology_id integer;
  ndims integer;
BEGIN

--  FOR rec IN SELECT * FROM pg_namespace WHERE text(nspname) = atopology
--  LOOP
--    RAISE EXCEPTION 'SQL/MM Spatial exception - schema already exists';
--  END LOOP;

  ndims = 2;
  IF hasZ THEN ndims = 3; END IF;

  ------ Fetch next id for the new topology
  FOR rec IN SELECT nextval('topology.topology_id_seq')
  LOOP
    topology_id = rec.nextval;
  END LOOP;


  EXECUTE 'CREATE SCHEMA ' || quote_ident(atopology);

  -------------{ face CREATION
  EXECUTE 
  'CREATE TABLE ' || quote_ident(atopology) || '.face ('
  || 'face_id SERIAL,'
  || ' CONSTRAINT face_primary_key PRIMARY KEY(face_id)'
  || ');';

  -- Add mbr column to the face table 
  EXECUTE
  'SELECT AddGeometryColumn('||quote_literal(atopology)
  ||',''face'',''mbr'','||quote_literal(srid)
  ||',''POLYGON'',2)'; -- 2d only mbr is good enough

  -------------} END OF face CREATION


  --------------{ node CREATION

  EXECUTE 
  'CREATE TABLE ' || quote_ident(atopology) || '.node ('
  || 'node_id SERIAL,'
  --|| 'geom GEOMETRY,'
  || 'containing_face INTEGER,'

  || 'CONSTRAINT node_primary_key PRIMARY KEY(node_id),'

  --|| 'CONSTRAINT node_geometry_type CHECK '
  --|| '( GeometryType(geom) = ''POINT'' ),'

  || 'CONSTRAINT face_exists FOREIGN KEY(containing_face) '
  || 'REFERENCES ' || quote_ident(atopology) || '.face(face_id)'

  || ');';

  -- Add geometry column to the node table 
  EXECUTE
  'SELECT AddGeometryColumn('||quote_literal(atopology)
  ||',''node'',''geom'','||quote_literal(srid)
  ||',''POINT'',' || ndims || ')';

  --------------} END OF node CREATION

  --------------{ edge CREATION

  -- edge_data table
  EXECUTE 
  'CREATE TABLE ' || quote_ident(atopology) || '.edge_data ('
  || 'edge_id SERIAL NOT NULL PRIMARY KEY,'
  || 'start_node INTEGER NOT NULL,'
  || 'end_node INTEGER NOT NULL,'
  || 'next_left_edge INTEGER NOT NULL,'
  || 'abs_next_left_edge INTEGER NOT NULL,'
  || 'next_right_edge INTEGER NOT NULL,'
  || 'abs_next_right_edge INTEGER NOT NULL,'
  || 'left_face INTEGER NOT NULL,'
  || 'right_face INTEGER NOT NULL,'
  --|| 'geom GEOMETRY NOT NULL,'

  --|| 'CONSTRAINT edge_geometry_type CHECK '
  --|| '( GeometryType(geom) = ''LINESTRING'' ),'

  || 'CONSTRAINT start_node_exists FOREIGN KEY(start_node)'
  || ' REFERENCES ' || quote_ident(atopology) || '.node(node_id),'

  || 'CONSTRAINT end_node_exists FOREIGN KEY(end_node) '
  || ' REFERENCES ' || quote_ident(atopology) || '.node(node_id),'

  || 'CONSTRAINT left_face_exists FOREIGN KEY(left_face) '
  || 'REFERENCES ' || quote_ident(atopology) || '.face(face_id),'

  || 'CONSTRAINT right_face_exists FOREIGN KEY(right_face) '
  || 'REFERENCES ' || quote_ident(atopology) || '.face(face_id),'

  || 'CONSTRAINT next_left_edge_exists FOREIGN KEY(abs_next_left_edge)'
  || ' REFERENCES ' || quote_ident(atopology)
  || '.edge_data(edge_id)'
  || ' DEFERRABLE INITIALLY DEFERRED,'

  || 'CONSTRAINT next_right_edge_exists '
  || 'FOREIGN KEY(abs_next_right_edge)'
  || ' REFERENCES ' || quote_ident(atopology)
  || '.edge_data(edge_id) '
  || ' DEFERRABLE INITIALLY DEFERRED'
  || ');';

  -- Add geometry column to the edge_data table 
  EXECUTE
  'SELECT AddGeometryColumn('||quote_literal(atopology)
  ||',''edge_data'',''geom'','||quote_literal(srid)
  ||',''LINESTRING'',' || ndims || ')';


  -- edge standard view (select rule)
  EXECUTE 'CREATE VIEW ' || quote_ident(atopology)
    || '.edge AS SELECT '
    || ' edge_id, start_node, end_node, next_left_edge, '
    || ' next_right_edge, '
    || ' left_face, right_face, geom FROM '
    || quote_ident(atopology) || '.edge_data';

  -- edge standard view description
  EXECUTE 'COMMENT ON VIEW ' || quote_ident(atopology)
    || '.edge IS '
    || '''Contains edge topology primitives''';
  EXECUTE 'COMMENT ON COLUMN ' || quote_ident(atopology)
    || '.edge.edge_id IS '
    || '''Unique identifier of the edge''';
  EXECUTE 'COMMENT ON COLUMN ' || quote_ident(atopology)
    || '.edge.start_node IS '
    || '''Unique identifier of the node at the start of the edge''';
  EXECUTE 'COMMENT ON COLUMN ' || quote_ident(atopology)
    || '.edge.end_node IS '
    || '''Unique identifier of the node at the end of the edge''';
  EXECUTE 'COMMENT ON COLUMN ' || quote_ident(atopology)
    || '.edge.next_left_edge IS '
    || '''Unique identifier of the next edge of the face on the left (when looking in the direction from START_NODE to END_NODE), moving counterclockwise around the face boundary''';
  EXECUTE 'COMMENT ON COLUMN ' || quote_ident(atopology)
    || '.edge.next_right_edge IS '
    || '''Unique identifier of the next edge of the face on the right (when looking in the direction from START_NODE to END_NODE), moving counterclockwise around the face boundary''';
  EXECUTE 'COMMENT ON COLUMN ' || quote_ident(atopology)
    || '.edge.left_face IS '
    || '''Unique identifier of the face on the left side of the edge when looking in the direction from START_NODE to END_NODE''';
  EXECUTE 'COMMENT ON COLUMN ' || quote_ident(atopology)
    || '.edge.right_face IS '
    || '''Unique identifier of the face on the right side of the edge when looking in the direction from START_NODE to END_NODE''';
  EXECUTE 'COMMENT ON COLUMN ' || quote_ident(atopology)
    || '.edge.geom IS '
    || '''The geometry of the edge''';

  -- edge standard view (insert rule)
  EXECUTE 'CREATE RULE edge_insert_rule AS ON INSERT '
          || 'TO ' || quote_ident(atopology)
    || '.edge DO INSTEAD '
                || ' INSERT into ' || quote_ident(atopology)
    || '.edge_data '
                || ' VALUES (NEW.edge_id, NEW.start_node, NEW.end_node, '
    || ' NEW.next_left_edge, abs(NEW.next_left_edge), '
    || ' NEW.next_right_edge, abs(NEW.next_right_edge), '
    || ' NEW.left_face, NEW.right_face, NEW.geom);';

  --------------} END OF edge CREATION

  --------------{ layer sequence 
  EXECUTE 'CREATE SEQUENCE '
    || quote_ident(atopology) || '.layer_id_seq;';
  --------------} layer sequence

  --------------{ relation CREATION
  --
  EXECUTE 
  'CREATE TABLE ' || quote_ident(atopology) || '.relation ('
  || ' topogeo_id integer NOT NULL, '
  || ' layer_id integer NOT NULL, ' 
  || ' element_id integer NOT NULL, '
  || ' element_type integer NOT NULL, '
  || ' UNIQUE(layer_id,topogeo_id,element_id,element_type));';

  EXECUTE 
  'CREATE TRIGGER relation_integrity_checks '
  ||'BEFORE UPDATE OR INSERT ON '
  || quote_ident(atopology) || '.relation FOR EACH ROW '
  || ' EXECUTE PROCEDURE topology.RelationTrigger('
  ||topology_id||','||quote_literal(atopology)||')';
  --------------} END OF relation CREATION

  
  ------- Default (world) face
  EXECUTE 'INSERT INTO ' || quote_ident(atopology) || '.face(face_id) VALUES(0);';

  ------- GiST index on face
  EXECUTE 'CREATE INDEX face_gist ON '
    || quote_ident(atopology)
    || '.face using gist (mbr);';

  ------- GiST index on node
  EXECUTE 'CREATE INDEX node_gist ON '
    || quote_ident(atopology)
    || '.node using gist (geom);';

  ------- GiST index on edge
  EXECUTE 'CREATE INDEX edge_gist ON '
    || quote_ident(atopology)
    || '.edge_data using gist (geom);';

  ------- Indexes on left_face and right_face of edge_data
  ------- NOTE: these indexes speed up GetFaceGeometry (and thus
  -------       TopoGeometry::Geometry) by a factor of 10 !
  -------       See http://trac.osgeo.org/postgis/ticket/806
  EXECUTE 'CREATE INDEX edge_left_face_idx ON '
    || quote_ident(atopology)
    || '.edge_data (left_face);';
  EXECUTE 'CREATE INDEX edge_right_face_idx ON '
    || quote_ident(atopology)
    || '.edge_data (right_face);';

  ------- Indexes on start_node and end_node of edge_data
  ------- NOTE: this indexes speed up node deletion
  -------       by a factor of 1000 !
  -------       See http://trac.osgeo.org/postgis/ticket/2082
  EXECUTE 'CREATE INDEX edge_start_node_idx ON '
    || quote_ident(atopology)
    || '.edge_data (start_node);';
  EXECUTE 'CREATE INDEX edge_end_node_idx ON '
    || quote_ident(atopology)
    || '.edge_data (end_node);';

  -- TODO: consider also adding an index on node.containing_face 

  ------- Add record to the "topology" metadata table
  EXECUTE 'INSERT INTO topology.topology '
    || '(id, name, srid, precision, hasZ) VALUES ('
    || quote_literal(topology_id) || ','
    || quote_literal(atopology) || ','
    || quote_literal(srid) || ',' || quote_literal(prec)
    || ',' || hasZ
    || ')';

  RETURN topology_id;
END
$$
LANGUAGE 'plpgsql' VOLATILE STRICT;

--} CreateTopology

--{ CreateTopology wrappers for unspecified srid or precision or hasZ

--  CreateTopology(name, SRID, precision) -- hasZ = false
CREATE OR REPLACE FUNCTION topology.CreateTopology(toponame varchar, srid integer, prec float8)
RETURNS integer AS
' SELECT topology.CreateTopology($1, $2, $3, false);'
LANGUAGE 'sql' VOLATILE STRICT;

--  CreateTopology(name, SRID) -- precision = 0
CREATE OR REPLACE FUNCTION topology.CreateTopology(varchar, integer)
RETURNS integer AS
' SELECT topology.CreateTopology($1, $2, 0); '
LANGUAGE 'sql' VOLATILE STRICT;

--  CreateTopology(name) -- srid = unknown, precision = 0
CREATE OR REPLACE FUNCTION topology.CreateTopology(varchar)
RETURNS integer AS
$$ SELECT topology.CreateTopology($1, ST_SRID('POINT EMPTY'::geometry), 0); $$
LANGUAGE 'sql' VOLATILE STRICT;

--} CreateTopology

--{
--  DropTopology(name)
--
-- Drops a topology schema getting rid of every dependent object.
--
CREATE OR REPLACE FUNCTION topology.DropTopology(atopology varchar)
RETURNS text
AS
$$
DECLARE
  topoid integer;
  rec RECORD;
BEGIN

  -- Get topology id
        SELECT id FROM topology.topology into topoid
                WHERE name = atopology;


  IF topoid IS NOT NULL THEN

    RAISE NOTICE 'Dropping all layers from topology % (%)',
      atopology, topoid;

    -- Drop all layers in the topology
    FOR rec IN EXECUTE 'SELECT * FROM topology.layer WHERE '
      || ' topology_id = ' || topoid
    LOOP

      EXECUTE 'SELECT topology.DropTopoGeometryColumn('
        || quote_literal(rec.schema_name)
        || ','
        || quote_literal(rec.table_name)
        || ','
        || quote_literal(rec.feature_column)
        || ')';
    END LOOP;

    -- Delete record from topology.topology
    EXECUTE 'DELETE FROM topology.topology WHERE id = '
      || topoid;

  END IF;


  -- Drop the schema (if it exists)
  FOR rec IN SELECT * FROM pg_namespace WHERE text(nspname) = atopology
  LOOP
    EXECUTE 'DROP SCHEMA '||quote_ident(atopology)||' CASCADE';
  END LOOP;

  RETURN 'Topology ' || quote_literal(atopology) || ' dropped';
END
$$
LANGUAGE 'plpgsql' VOLATILE STRICT;
--} DropTopology

#include "sql/manage/TopologySummary.sql.in"
#include "sql/manage/CopyTopology.sql.in"

-- Spatial predicates
#include "sql/predicates.sql.in"

--  Querying
#include "sql/query/getnodebypoint.sql.in"
#include "sql/query/getedgebypoint.sql.in"
#include "sql/query/getfacebypoint.sql.in"

--  Populating
#include "sql/populate.sql.in"
#include "sql/polygonize.sql.in"

--  TopoElement
#include "sql/topoelement/topoelement_agg.sql.in"

--  TopoGeometry
#include "sql/topogeometry/type.sql.in"
#include "sql/topogeometry/cleartopogeom.sql.in"
#include "sql/topogeometry/simplify.sql.in"
#include "sql/topogeometry/totopogeom.sql.in"

--  Exports
#include "sql/export/gml.sql.in"
#include "sql/export/TopoJSON.sql.in"

--=}  POSTGIS-SPECIFIC block

--  SQL/MM block
#include "sql/sqlmm.sql.in"

-- The following files needs getfaceedges_returntype, defined in sqlmm.sql
#include "sql/query/GetRingEdges.sql.in"
#include "sql/query/GetNodeEdges.sql.in"

--general management --
#include "sql/manage/ManageHelper.sql.in"

CREATE OR REPLACE FUNCTION postgis_topology_scripts_installed() RETURNS text
	AS _POSTGIS_SQL_SELECT_POSTGIS_SCRIPTS_VERSION
	LANGUAGE 'sql' IMMUTABLE;

-- Make sure topology is in database search path --
SELECT topology.AddToSearchPath('topology');

COMMIT;