From 57728681b6138e53bc3a3da09e996701571675d8 Mon Sep 17 00:00:00 2001
From: wqy <wqyuyu@outlook.com>
Date: Sat, 3 Sep 2022 17:29:50 +0800
Subject: [PATCH] Implement redo by PL/pgSQL

---
 script/script/api/create/1.title.sql   |  2 +-
 script/script/api/create/operation.sql | 22 ++++++++++++++++++++++
 script/script/api/drop/operation.sql   |  2 ++
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/script/script/api/create/1.title.sql b/script/script/api/create/1.title.sql
index abbf5e6..fb81579 100644
--- a/script/script/api/create/1.title.sql
+++ b/script/script/api/create/1.title.sql
@@ -9,7 +9,7 @@ begin
 end;
 $$ language plpgsql;
 
--- update_title()
+-- set_title()
 create function tj.set_title(new_title text) returns void as
 $$
 declare
diff --git a/script/script/api/create/operation.sql b/script/script/api/create/operation.sql
index ebb5edf..ad56cdf 100644
--- a/script/script/api/create/operation.sql
+++ b/script/script/api/create/operation.sql
@@ -84,4 +84,26 @@ declare
 begin
     perform tj.execute_undo(true);
 end;
+$$ language plpgsql;
+
+create function tj.redo() returns void as
+$$
+declare
+    curr_id int;
+    child_id int;
+    redo_sql text;
+begin
+    select id into curr_id from tj.current_operation;
+
+    select redo_child into child_id from tj.operation where id = curr_id;
+    if child_id = null then
+        return;
+    end if;
+
+    select redo into redo_sql from tj.operation where id = child_id;
+
+    execute redo_sql;
+
+    update tj.current_operation set id = child_id where id = curr_id;
+end;
 $$ language plpgsql;
\ No newline at end of file
diff --git a/script/script/api/drop/operation.sql b/script/script/api/drop/operation.sql
index 951fa22..1692da5 100644
--- a/script/script/api/drop/operation.sql
+++ b/script/script/api/drop/operation.sql
@@ -1,3 +1,5 @@
+drop function if exists tj.redo;
+
 drop function if exists tj.discard_undo;
 drop function if exists tj.undo;
 drop function if exists tj.execute_undo;