refactor: sql-tools (#19717)

server/src/sql-tools/comparers/column.comparer.ts

@@ -0,0 +1,82 @@
+import { getColumnType, isDefaultEqual } from 'src/sql-tools/helpers';
+import { Comparer, DatabaseColumn, Reason, SchemaDiff } from 'src/sql-tools/types';
+
+export const compareColumns: Comparer<DatabaseColumn> = {
+  onMissing: (source) => [
+    {
+      type: 'ColumnAdd',
+      column: source,
+      reason: Reason.MissingInTarget,
+    },
+  ],
+  onExtra: (target) => [
+    {
+      type: 'ColumnDrop',
+      tableName: target.tableName,
+      columnName: target.name,
+      reason: Reason.MissingInSource,
+    },
+  ],
+  onCompare: (source, target) => {
+    const sourceType = getColumnType(source);
+    const targetType = getColumnType(target);
+
+    const isTypeChanged = sourceType !== targetType;
+
+    if (isTypeChanged) {
+      // TODO: convert between types via UPDATE when possible
+      return dropAndRecreateColumn(source, target, `column type is different (${sourceType} vs ${targetType})`);
+    }
+
+    const items: SchemaDiff[] = [];
+    if (source.nullable !== target.nullable) {
+      items.push({
+        type: 'ColumnAlter',
+        tableName: source.tableName,
+        columnName: source.name,
+        changes: {
+          nullable: source.nullable,
+        },
+        reason: `nullable is different (${source.nullable} vs ${target.nullable})`,
+      });
+    }
+
+    if (!isDefaultEqual(source, target)) {
+      items.push({
+        type: 'ColumnAlter',
+        tableName: source.tableName,
+        columnName: source.name,
+        changes: {
+          default: String(source.default),
+        },
+        reason: `default is different (${source.default} vs ${target.default})`,
+      });
+    }
+
+    if (source.comment !== target.comment) {
+      items.push({
+        type: 'ColumnAlter',
+        tableName: source.tableName,
+        columnName: source.name,
+        changes: {
+          comment: String(source.comment),
+        },
+        reason: `comment is different (${source.comment} vs ${target.comment})`,
+      });
+    }
+
+    return items;
+  },
+};
+
+const dropAndRecreateColumn = (source: DatabaseColumn, target: DatabaseColumn, reason: string): SchemaDiff[] => {
+  return [
+    {
+      type: 'ColumnDrop',
+      tableName: target.tableName,
+      columnName: target.name,
+      reason,
+    },
+    { type: 'ColumnAdd', column: source, reason },
+  ];
+};