From 6d0870b35a4e959dcdb9244b1b7d8375e66a1e84 Mon Sep 17 00:00:00 2001
From: Daniel Cachapa <cachapa@gmail.com>
Date: Fri, 16 Feb 2024 22:52:39 +0100
Subject: [PATCH] Add support for inserts from select queries

---
 CHANGELOG.md                  |  4 +++
 lib/src/timestamped_crdt.dart | 50 +++++++++++++++++++++++++++++------
 pubspec.yaml                  |  2 +-
 3 files changed, 47 insertions(+), 9 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f3a8d5a..e52ecea 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 2.1.7
+
+- Add support for inserts from select queries
+
 ## 2.1.6
 
 - Upgrade sqlparser
diff --git a/lib/src/timestamped_crdt.dart b/lib/src/timestamped_crdt.dart
index d069bd6..f637c87 100644
--- a/lib/src/timestamped_crdt.dart
+++ b/lib/src/timestamped_crdt.dart
@@ -10,7 +10,48 @@ abstract class TimestampedCrdt extends BaseCrdt {
   @override
   Future<void> _insert(InsertStatement statement, List<Object?>? args,
       [Hlc? hlc]) async {
+    // Force explicit column description in insert statements
+    assert(statement.targetColumns.isNotEmpty,
+        'Unsupported statement: target columns must be explicitly stated.\n${statement.toSql()}');
+    // Disallow star select statements
+    assert(
+        statement.source is! SelectInsertSource ||
+            ((statement.source as SelectInsertSource).stmt as SelectStatement)
+                .columns
+                .whereType<StarResultColumn>()
+                .isEmpty,
+        'Unsupported statement: select columns must be explicitly stated.\n${statement.toSql()}');
+
     final argCount = args?.length ?? 0;
+    final source = switch (statement.source) {
+      ValuesSource s => ValuesSource([
+          Tuple(expressions: [
+            ...s.values.first.expressions,
+            NumberedVariable(argCount + 1),
+            NumberedVariable(argCount + 2),
+            NumberedVariable(argCount + 3),
+          ])
+        ]),
+      SelectInsertSource s => SelectInsertSource(SelectStatement(
+          withClause: (s.stmt as SelectStatement).withClause,
+          distinct: (s.stmt as SelectStatement).distinct,
+          columns: [
+            ...(s.stmt as SelectStatement).columns,
+            ExpressionResultColumn(expression: NumberedVariable(argCount + 1)),
+            ExpressionResultColumn(expression: NumberedVariable(argCount + 2)),
+            ExpressionResultColumn(expression: NumberedVariable(argCount + 3)),
+          ],
+          from: (s.stmt as SelectStatement).from,
+          where: (s.stmt as SelectStatement).where,
+          groupBy: (s.stmt as SelectStatement).groupBy,
+          windowDeclarations: (s.stmt as SelectStatement).windowDeclarations,
+          orderBy: (s.stmt as SelectStatement).orderBy,
+          limit: (s.stmt as SelectStatement).limit,
+        )),
+      _ => throw UnimplementedError(
+          'Unsupported data source: ${statement.source.runtimeType}, please file an issue in the sql_crdt project.')
+    };
+
     final newStatement = InsertStatement(
       mode: statement.mode,
       upsert: statement.upsert,
@@ -23,14 +64,7 @@ abstract class TimestampedCrdt extends BaseCrdt {
         Reference(columnName: 'node_id'),
         Reference(columnName: 'modified'),
       ],
-      source: ValuesSource([
-        Tuple(expressions: [
-          ...(statement.source as ValuesSource).values.first.expressions,
-          NumberedVariable(argCount + 1),
-          NumberedVariable(argCount + 2),
-          NumberedVariable(argCount + 3),
-        ])
-      ]),
+      source: source,
     );
 
     // Touch
diff --git a/pubspec.yaml b/pubspec.yaml
index 6ab2247..71b3f2a 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: sql_crdt
 description: Base package for Conflict-free Replicated Data Types (CRDTs) using SQL databases
-version: 2.1.6
+version: 2.1.7
 homepage: https://github.com/cachapa/sql_crdt
 repository: https://github.com/cachapa/sql_crdt
 issue_tracker: https://github.com/cachapa/sql_crdt/issues