From 3f1cbe1e8fa5257ba7de858a1a34048f141712ce Mon Sep 17 00:00:00 2001
From: Gaurav Gahlot <gauravgahlot0107@gmail.com>
Date: Thu, 11 Feb 2021 16:53:56 +0530
Subject: [PATCH] migration - 202102111035-template-revisions

Fixes: https://github.com/tinkerbell/tink/issues/413

The migration introduces template revisions. A template can have multiple
revisions, which are stored in the 'template_revisions' table.

The migration also transforms the existing templates to the new
template-revisions structure. Therefore ensuring that end users do not
face any issues with the introduction of revisions.

Signed-off-by: Gaurav Gahlot <gauravgahlot0107@gmail.com>
---
 .../202102111035-template-revisions.go        | 60 +++++++++++++++++++
 db/migration/migration.go                     |  1 +
 2 files changed, 61 insertions(+)
 create mode 100644 db/migration/202102111035-template-revisions.go

diff --git a/db/migration/202102111035-template-revisions.go b/db/migration/202102111035-template-revisions.go
new file mode 100644
index 000000000..2fb0aa853
--- /dev/null
+++ b/db/migration/202102111035-template-revisions.go
@@ -0,0 +1,60 @@
+package migration
+
+import migrate "github.com/rubenv/sql-migrate"
+
+// Get202102111035 introduces template revisions.
+//
+// Fixes: https://github.com/tinkerbell/tink/issues/413
+//
+// The migration introduces template revisions. A template can have multiple
+// revisions, which are stored in the 'template_revisions' table.
+//
+// The migration also transforms the existing templates to the new
+// template-revisions structure. Therefore ensuring that end users do not
+// face any issues with the introduction of revisions.
+func Get202102111035() *migrate.Migration {
+	return &migrate.Migration{
+		Id: "202102111035-template-revisions",
+		Up: []string{`
+CREATE TABLE IF NOT EXISTS template_revisions(
+	template_id UUID
+	, revision SMALLINT DEFAULT 1
+	, data BYTEA
+        , created_at TIMESTAMPTZ DEFAULT now()
+        , deleted_at TIMESTAMPTZ
+	, PRIMARY KEY(template_id, revision)
+);
+
+CREATE INDEX IF NOT EXISTS idx_template_revisions_template_id ON template_revisions (template_id);
+
+ALTER TABLE template ADD COLUMN revision INT DEFAULT 1;
+
+CREATE OR REPLACE FUNCTION migrate_to_template_revisions()
+RETURNS void AS $$
+DECLARE
+	template_count integer;
+	revisions_count integer;
+BEGIN
+	SELECT COUNT(id) INTO template_count
+	FROM template WHERE deleted_at IS NULL;
+
+	INSERT INTO template_revisions(template_id, data, created_at)
+	SELECT id, data, created_at
+	FROM template
+	WHERE template.deleted_at IS NULL;
+
+	SELECT COUNT(template_id) INTO revisions_count
+	FROM template_revisions WHERE deleted_at IS NULL;
+
+	IF revisions_count != template_count THEN
+		RAISE EXCEPTION 'failed to migrate templates'; 
+	END IF;
+	
+	ALTER TABLE template DROP COLUMN data;
+END;
+$$ LANGUAGE plpgsql;
+
+SELECT migrate_to_template_revisions();
+		`},
+	}
+}
diff --git a/db/migration/migration.go b/db/migration/migration.go
index a921f577d..8c4e02a74 100644
--- a/db/migration/migration.go
+++ b/db/migration/migration.go
@@ -11,6 +11,7 @@ var migrations = []func() *migrate.Migration{
 	Get202012041103,
 	Get202012091055,
 	Get2020121691335,
+	Get202102111035,
 }
 
 func GetMigrations() *migrate.MemoryMigrationSource {