-- Creates a new group
CREATE OR REPLACE
FUNCTION cartodb.CDB_Group_CreateGroup(group_name text)
    RETURNS VOID AS $$
DECLARE
    group_role TEXT;
BEGIN
    group_role := cartodb._CDB_Group_GroupRole(group_name);
    EXECUTE format('CREATE ROLE "%s" NOLOGIN;', group_role);
    PERFORM cartodb._CDB_Group_CreateGroup_API(current_database(), group_name, group_role);
END
$$ LANGUAGE PLPGSQL VOLATILE;

-- Drops group and everything that role owns
-- TODO: LIMITATION: in order to drop a role all its owned objects must be dropped before.
-- Right now this is done with DROP OWNED, which can only be done by a superadmin.
-- Not even the role creator can drop the role and the objects it owns.
-- All group owned objects by the group are permissions.
CREATE OR REPLACE
FUNCTION cartodb.CDB_Group_DropGroup(group_name text)
    RETURNS VOID AS $$
DECLARE
    group_role TEXT;
BEGIN
    group_role := cartodb._CDB_Group_GroupRole(group_name);
    EXECUTE format('DROP OWNED BY "%s"', group_role);
    EXECUTE format('DROP ROLE IF EXISTS "%s"', group_role);
    PERFORM cartodb._CDB_Group_DropGroup_API(current_database(), group_name);
END
$$ LANGUAGE PLPGSQL VOLATILE;

-- Renames a group
CREATE OR REPLACE
FUNCTION cartodb.CDB_Group_RenameGroup(old_group_name text, new_group_name text)
    RETURNS VOID AS $$
DECLARE
    old_group_role TEXT;
    new_group_role TEXT;
BEGIN
    old_group_role = cartodb._CDB_Group_GroupRole(old_group_name);
    new_group_role = cartodb._CDB_Group_GroupRole(new_group_name);
    EXECUTE format('ALTER ROLE "%s" RENAME TO "%s"', old_group_role, new_group_role);
    PERFORM cartodb._CDB_Group_RenameGroup_API(current_database(), old_group_name, new_group_name, new_group_role);
END
$$ LANGUAGE PLPGSQL VOLATILE;

-- Adds a user to a group
CREATE OR REPLACE
FUNCTION cartodb.CDB_Group_AddMember(group_name text, username text)
    RETURNS VOID AS $$
DECLARE
    group_role TEXT;
    user_role TEXT;
BEGIN
    group_role := cartodb._CDB_Group_GroupRole(group_name);
    user_role := cartodb._CDB_User_RoleFromUsername(username);
    IF(group_role IS NULL OR user_role IS NULL)
    THEN
      RAISE EXCEPTION 'Group role (%) and user role (%) must be already existing', group_role, user_role;
    END IF;
    EXECUTE format('GRANT "%s" TO "%s"', group_role, user_role);
    PERFORM cartodb._CDB_Group_AddMember_API(current_database(), group_name, username);
END
$$ LANGUAGE PLPGSQL VOLATILE;

-- Removes a user from a group
CREATE OR REPLACE
FUNCTION cartodb.CDB_Group_RemoveMember(group_name text, username text)
    RETURNS VOID AS $$
DECLARE
    group_role TEXT;
    user_role TEXT;
BEGIN
    group_role := cartodb._CDB_Group_GroupRole(group_name);
    user_role := cartodb._CDB_User_RoleFromUsername(username);
    EXECUTE format('REVOKE "%s" FROM "%s"', group_role, user_role);
    PERFORM cartodb._CDB_Group_RemoveMember_API(current_database(), group_name, username);
END
$$ LANGUAGE PLPGSQL VOLATILE;

-- Grants table read permission to a group
CREATE OR REPLACE
FUNCTION cartodb.CDB_Group_Table_GrantRead(group_name text, username text, table_name text)
    RETURNS VOID AS $$
DECLARE
    group_role TEXT;
BEGIN
    group_role := cartodb._CDB_Group_GroupRole(group_name);
    EXECUTE format('GRANT USAGE ON SCHEMA "%s" TO "%s"', username, group_role);
    EXECUTE format('GRANT SELECT ON TABLE "%s"."%s" TO "%s"', username, table_name, group_role );
END
$$ LANGUAGE PLPGSQL VOLATILE;

-- Grants table write permission to a group
CREATE OR REPLACE
FUNCTION cartodb.CDB_Group_Table_GrantReadWrite(group_name text, username text, table_name text)
    RETURNS VOID AS $$
DECLARE
    group_role TEXT;
BEGIN
    group_role := cartodb._CDB_Group_GroupRole(group_name);
    EXECUTE format('GRANT USAGE ON SCHEMA "%s" TO "%s"', username, group_role);
    EXECUTE format('GRANT SELECT, INSERT, UPDATE, DELETE ON TABLE "%s"."%s" TO "%s"', username, table_name, group_role);
END
$$ LANGUAGE PLPGSQL VOLATILE;

-- Revokes all permissions on a table from a group
CREATE OR REPLACE
FUNCTION cartodb.CDB_Group_Table_RevokeAll(group_name text, username text, table_name text)
    RETURNS VOID AS $$
DECLARE
    group_role TEXT;
BEGIN
    group_role := cartodb._CDB_Group_GroupRole(group_name);
    EXECUTE format('REVOKE ALL ON TABLE "%s"."%s" FROM "%s"', username, table_name, group_role);
END
$$ LANGUAGE PLPGSQL VOLATILE;

-----------------------
-- Private functions
-----------------------
-- Given a group name returns a role. group_name must be a valid PostgreSQL idenfifier. See http://www.postgresql.org/docs/9.2/static/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS
CREATE OR REPLACE
FUNCTION cartodb._CDB_Group_GroupRole(group_name text)
    RETURNS TEXT AS $$
DECLARE
    group_role TEXT;
    prefix TEXT;
    max_length constant INTEGER := 63;
BEGIN
    prefix = format('%s_g_', cartodb._CDB_Group_ShortDatabaseName());
    group_role := format('%s%s', prefix, group_name);
    IF LENGTH(group_role) > max_length
    THEN
        RAISE EXCEPTION 'Group name must be shorter. It can''t have more than % characters, but it is longer (%): %', max_length - LENGTH(prefix), length(group_name), group_name;
    END IF;
    RETURN group_role;
END
$$ LANGUAGE PLPGSQL IMMUTABLE;

-- Returns the first owner of the schema matching username. Organization user schemas must have one only owner.
CREATE OR REPLACE
FUNCTION cartodb._CDB_User_RoleFromUsername(username text)
    RETURNS TEXT AS $$
DECLARE
    user_role TEXT;
BEGIN
    -- This was preferred, but non-superadmins won't get results
    --EXECUTE 'SELECT SCHEMA_OWNER FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_NAME = $1 LIMIT 1' INTO user_role USING username;
    EXECUTE 'SELECT pg_get_userbyid(nspowner) FROM pg_namespace WHERE nspname = $1;' INTO user_role USING username;
    RETURN user_role;
END
$$ LANGUAGE PLPGSQL IMMUTABLE;

-- Database names are too long, we need a shorter version for composing role names
CREATE OR REPLACE
FUNCTION cartodb._CDB_Group_ShortDatabaseName()
    RETURNS TEXT AS $$
DECLARE
    short_database_name TEXT;
BEGIN
    EXECUTE 'SELECT md5(current_database())' INTO short_database_name;
    RETURN short_database_name;
END
$$ LANGUAGE PLPGSQL IMMUTABLE;