added ability to revert (#21)

src/domain/Script.ts

@@ -2,44 +2,56 @@ import { BaseEntity } from '@/infrastructure/Entity/BaseEntity';
 import { IScript } from './IScript';
 
 export class Script extends BaseEntity<string> implements IScript {
-    private static ensureNoEmptyLines(name: string, code: string): void {
-        if (code.split('\n').some((line) => line.trim().length === 0)) {
-            throw Error(`Script has empty lines "${name}"`);
-        }
-    }
-
-    private static ensureCodeHasUniqueLines(name: string, code: string): void {
-        const lines = code.split('\n')
-            .filter((line) => this.mayBeUniqueLine(line));
-        if (lines.length === 0) {
-            return;
-        }
-        const duplicateLines = lines.filter((e, i, a) => a.indexOf(e) !== i);
-        if (duplicateLines.length !== 0) {
-            throw Error(`Duplicates detected in script "${name}":\n ${duplicateLines.join('\n')}`);
-        }
-    }
-
-    private static mayBeUniqueLine(codeLine: string): boolean {
-        const trimmed = codeLine.trim();
-        if (trimmed === ')' || trimmed === '(') { // "(" and ")" are used often in batch code
-            return false;
-        }
-        return true;
-    }
-
     constructor(
-        public name: string,
-        public code: string,
-        public documentationUrls: ReadonlyArray<string>,
-        public isRecommended: boolean) {
+        public readonly name: string,
+        public readonly code: string,
+        public readonly revertCode: string,
+        public readonly documentationUrls: ReadonlyArray<string>,
+        public readonly isRecommended: boolean) {
         super(name);
-        if (code == null || code.length === 0) {
-            throw new Error('Code is empty or null');
+        validateCode(name, code);
+        if (revertCode) {
+            validateCode(name, revertCode);
+            if (code === revertCode) {
+                throw new Error(`${name}: Code itself and its reverting code cannot be the same`);
+            }
         }
-        Script.ensureCodeHasUniqueLines(name, code);
-        Script.ensureNoEmptyLines(name, code);
+    }
+    public canRevert(): boolean {
+        return Boolean(this.revertCode);
     }
 }
 
-export { IScript } from './IScript';
+function validateCode(name: string, code: string): void {
+    if (!code || code.length === 0) {
+        throw new Error(`Code of ${name} is empty or null`);
+    }
+    ensureCodeHasUniqueLines(name, code);
+    ensureNoEmptyLines(name, code);
+}
+
+function ensureNoEmptyLines(name: string, code: string): void {
+    if (code.split('\n').some((line) => line.trim().length === 0)) {
+        throw Error(`Script has empty lines "${name}"`);
+    }
+}
+
+function mayBeUniqueLine(codeLine: string): boolean {
+    const trimmed = codeLine.trim();
+    if (trimmed === ')' || trimmed === '(') { // "(" and ")" are used often in batch code
+        return false;
+    }
+    return true;
+}
+
+function ensureCodeHasUniqueLines(name: string, code: string): void {
+    const lines = code.split('\n')
+        .filter((line) => mayBeUniqueLine(line));
+    if (lines.length === 0) {
+        return;
+    }
+    const duplicateLines = lines.filter((e, i, a) => a.indexOf(e) !== i);
+    if (duplicateLines.length !== 0) {
+        throw Error(`Duplicates detected in script "${name}":\n ${duplicateLines.join('\n')}`);
+    }
+}