Create new command to format the asyncapi document

src/commands/format.ts

@@ -0,0 +1,62 @@
+import { Args } from '@oclif/core';
+import { promises as fs } from 'fs';
+import * as yaml from 'js-yaml';
+import Command from '../core/base';
+import { load } from '../core/models/SpecificationFile';
+import { ValidationError } from '../core/errors/validation-error';
+import { formatFlags } from '../core/flags/format.flags';
+
+export default class Format extends Command {
+  static description = 'Format AsyncAPI specification file';
+
+  static examples = [
+    'asyncapi format ./asyncapi.yaml',
+    'asyncapi format ./asyncapi.yaml --output formatted-asyncapi.yaml',
+  ];
+
+  static flags = formatFlags();
+
+  static args = {
+    'spec-file': Args.string({description: 'spec path, url, or context-name', required: true}),
+  };
+
+  async run() {
+    const { args, flags } = await this.parse(Format);
+    const filePath = args['spec-file'];
+    const outputPath = flags.output; 
+
+    try {
+      this.specFile = await load(filePath);
+    } catch (err) {
+      this.error(
+        new ValidationError({
+          type: 'invalid-file',
+          filepath: filePath,
+        })
+      );
+    }
+
+    const content = this.specFile.text();
+    let formatted: string;
+
+    try {
+      const parsed = yaml.load(content);
+      formatted = yaml.dump(parsed, {
+        indent: 2,
+        lineWidth: -1,
+        noRefs: true,
+        sortKeys: true,
+      });
+    } catch (err) {
+      this.error(`Error formatting file: ${err}`);
+    }
+
+    if (outputPath) {
+      await fs.writeFile(outputPath, formatted, 'utf8');
+      this.log(`The Asyncapi document has been formatted, the new formatted document is present in ${outputPath}`);
+    } else {
+      await fs.writeFile(filePath, formatted, 'utf8');
+      this.log(`Asyncapi document ${filePath} has been formatted in-place.`);
+    }
+  }
+}

src/core/flags/format.flags.ts

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+import { Flags } from '@oclif/core';
+
+export const formatFlags = () => {
+  return {
+    output: Flags.string({
+      char: 'o',
+      description: 'Output file path',
+    }),
+  };
+};