// Package sql define database sql statement
package sql

// RecursiveSQL define topologic table recursive query statement
var RecursiveSQL = `WITH RECURSIVE recursive_tree as (
	SELECT uuid_from,uuid_to,flag
	FROM "topologic"
	WHERE uuid_from = ?
	UNION ALL
	SELECT t.uuid_from,t.uuid_to,t.flag
	FROM "topologic" t
	JOIN recursive_tree rt ON t.uuid_from = rt.uuid_to
	)
	SELECT * FROM recursive_tree;`

// RecursiveTopologicByStartSQL returns every directed edge reachable from the
// supplied start component. It tracks the visited node path inside PostgreSQL
// so cycles in topologic data cannot recurse forever.
var RecursiveTopologicByStartSQL = `WITH RECURSIVE recursive_tree as (
	SELECT uuid_from, uuid_to, flag, ARRAY[uuid_from, uuid_to] AS path
	FROM "topologic"
	WHERE uuid_from = ?
	UNION ALL
	SELECT t.uuid_from, t.uuid_to, t.flag, rt.path || t.uuid_to
	FROM "topologic" t
	JOIN recursive_tree rt ON t.uuid_from = rt.uuid_to
	WHERE NOT t.uuid_to = ANY(rt.path)
)
SELECT uuid_from, uuid_to, flag FROM recursive_tree;`