From b7706f9a4284ae638096a028162093623350508d Mon Sep 17 00:00:00 2001
From: Timo Hocker <t-hocker@web.de>
Date: Sun, 19 Apr 2020 18:49:07 +0200
Subject: [PATCH] implementing patches

---
 lib/snippets/database/classes/Database.ts     |  9 ++++++
 lib/snippets/database/classes/PatchAction.ts  |  5 ++++
 lib/snippets/database/classes/Table.ts        |  9 ++++++
 .../database/patch_actions/RenameColumn.ts    | 28 +++++++++++++++----
 4 files changed, 45 insertions(+), 6 deletions(-)
 create mode 100644 lib/snippets/database/classes/PatchAction.ts

diff --git a/lib/snippets/database/classes/Database.ts b/lib/snippets/database/classes/Database.ts
index 254447e..386d388 100644
--- a/lib/snippets/database/classes/Database.ts
+++ b/lib/snippets/database/classes/Database.ts
@@ -2,4 +2,13 @@ import { Table } from './Table';
 
 export class Database {
   public tables: Array<Table> = [];
+
+  public get_table (name: string): Table|null {
+    for (const table of this.tables) {
+      if (table.name === name)
+        return table;
+    }
+
+    return null;
+  }
 }
diff --git a/lib/snippets/database/classes/PatchAction.ts b/lib/snippets/database/classes/PatchAction.ts
new file mode 100644
index 0000000..aa91222
--- /dev/null
+++ b/lib/snippets/database/classes/PatchAction.ts
@@ -0,0 +1,5 @@
+import { Database } from './Database';
+
+export interface PatchAction {
+  apply(db: Database): void;
+}
diff --git a/lib/snippets/database/classes/Table.ts b/lib/snippets/database/classes/Table.ts
index d05cfaa..94abde1 100644
--- a/lib/snippets/database/classes/Table.ts
+++ b/lib/snippets/database/classes/Table.ts
@@ -7,4 +7,13 @@ export class Table {
   public constructor (name: string) {
     this.name = name;
   }
+
+  public get_column (name: string): Column|null {
+    for (const col of this.columns) {
+      if (col.name === name)
+        return col;
+    }
+
+    return null;
+  }
 }
diff --git a/lib/snippets/database/patch_actions/RenameColumn.ts b/lib/snippets/database/patch_actions/RenameColumn.ts
index 09e4a50..19f6773 100644
--- a/lib/snippets/database/patch_actions/RenameColumn.ts
+++ b/lib/snippets/database/patch_actions/RenameColumn.ts
@@ -1,26 +1,42 @@
 import { Serializable } from '../classes/Serializable';
+import { PatchAction } from '../classes/PatchAction';
+import { Database } from '../classes/Database';
 
-export class RenameColumn implements Serializable {
+export class RenameColumn implements Serializable, PatchAction {
+  public table: string;
   public column: string;
   public new_name: string;
 
-  public constructor (column: string, new_name = null) {
-    if (new_name === null) {
-      const regex = /(?<column>[a-z_]+) (?<new_name>[a-z_]+)/iu;
+  public constructor (
+    column: string,
+    new_name: string|null = null,
+    table: string|null = null
+  ) {
+    if (new_name === null || table === null) {
+      const regex
+      = /(?<table>[a-z_]+) (?<column>[a-z_]+) (?<new_name>[a-z_]+)/iu;
       const res = regex.exec (column);
       if (res === null || typeof res.groups === 'undefined')
         throw new Error ('invalid string to deserialize');
 
       this.column = res.groups.column;
       this.new_name = res.groups.new_name;
+      this.table = res.groups.table;
       return;
     }
 
     this.column = column;
-    this.new_name = new_name as unknown as string;
+    this.table = table;
+    this.new_name = new_name;
   }
 
   public serialize (): string {
-    return `${this.column} ${this.new_name}`;
+    return `${this.table} ${this.column} ${this.new_name}`;
+  }
+
+  public apply (db: Database): void {
+    const table = db.get_table (this.table);
+    const column = table?.get_column(this.column);
+    column?.name = this.new_name;
   }
 }