/*
Copyright 2012 The Camlistore Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package postgres

const requiredSchemaVersion = 1

func SchemaVersion() int {
	return requiredSchemaVersion
}

// TODO(mpl): use hstore
func SQLCreateTables() []string {
	return []string{
		`CREATE TABLE rows (
 k VARCHAR(255) NOT NULL PRIMARY KEY,
 v VARCHAR(255))`,

		`CREATE TABLE meta (
 metakey VARCHAR(255) NOT NULL PRIMARY KEY,
 value VARCHAR(255) NOT NULL)`,
	}
}

func SQLDefineReplace() []string {
	return []string{
		// The first 3 statements here are a work around that allows us to issue
		// the "CREATE LANGUAGE plpsql;" statement only if the language doesn't
		// already exist.
		`CREATE OR REPLACE FUNCTION create_language_plpgsql() RETURNS INTEGER AS
$$
CREATE LANGUAGE plpgsql;
SELECT 1;
$$
LANGUAGE SQL;`,

		`SELECT CASE WHEN NOT
(
	SELECT  TRUE AS exists
	FROM    pg_language
	WHERE   lanname = 'plpgsql'
	UNION
	SELECT  FALSE AS exists
	ORDER BY exists DESC
	LIMIT 1
)
THEN
    create_language_plpgsql()
ELSE
	0
END AS plpgsql_created;`,

		`DROP FUNCTION create_language_plpgsql();`,

		`CREATE OR REPLACE FUNCTION replaceinto(key TEXT, value TEXT) RETURNS VOID AS
$$
BEGIN
    LOOP
        UPDATE rows SET v = value WHERE k = key;
        IF found THEN
            RETURN;
        END IF;
        BEGIN
            INSERT INTO rows(k,v) VALUES (key, value);
            RETURN;
        EXCEPTION WHEN unique_violation THEN
        END;
    END LOOP;
END;
$$
LANGUAGE plpgsql;`,
		`CREATE OR REPLACE FUNCTION replaceintometa(key TEXT, val TEXT) RETURNS VOID AS
$$
BEGIN
    LOOP
        UPDATE meta SET value = val WHERE metakey = key;
        IF found THEN
            RETURN;
        END IF;
        BEGIN
            INSERT INTO meta(metakey,value) VALUES (key, val);
            RETURN;
        EXCEPTION WHEN unique_violation THEN
        END;
    END LOOP;
END;
$$
LANGUAGE plpgsql;`,
	}
}