feat(changelog): added changelog schematics

src/changelog/index.ts

@@ -1,10 +1,39 @@
-import { Rule, SchematicContext, Tree } from '@angular-devkit/schematics';
+import { Rule, SchematicContext, SchematicsException, Tree } from '@angular-devkit/schematics';
+import { NodePackageInstallTask } from '@angular-devkit/schematics/tasks';
 
-
-// You don't have to export the function as default. You can also have more than one rule factory
-// per file.
 export function changelog(_options: any): Rule {
   return (tree: Tree, _context: SchematicContext) => {
+
+    const packageJsonBuffer = tree.read("package.json");
+    if (!packageJsonBuffer) {
+      throw new SchematicsException("Not an npm project. Couldn't find package.json");
+    }
+
+    const packageJson = JSON.parse(packageJsonBuffer.toString());
+
+    const scripts = "scripts";
+    const changelogScript = "changelog";
+    const changelogScriptCmd = "./node_modules/.bin/conventional-changelog -p angular -i CHANGELOG.md -s -r 0";
+    if (!packageJson[scripts]) {
+      packageJson[scripts] = {};
+    }
+    packageJson[scripts][changelogScript] = changelogScriptCmd;
+
+    const devDeps = "devDependencies";
+    const changelog = "conventional-changelog-cli";
+    const version = "latest";
+    if (!packageJson[devDeps]) {
+      packageJson[devDeps] = {};
+    }
+    if (!packageJson[devDeps][changelog]) {
+      packageJson[devDeps][changelog] = version;
+    }
+
+    tree.overwrite('package.json', JSON.stringify(packageJson, null, 2));
+    _context.logger.log('info', `Added "${changelogScript}" to "${scripts}" in package.json`);
+    _context.logger.log('info', `Added "${changelog}@${version}" to ${devDeps}`);
+    _context.addTask(new NodePackageInstallTask());
+
     return tree;
   };
 }