feat: enable headers in pre-request scripting [INS-3379] (Kong#7121)

* chore: enable Headers in pre-request scripting

* Update packages/insomnia/src/sdk/objects/__tests__/headers.test.ts

---------

Co-authored-by: Jack Kavanagh <jackkav@gmail.com>

Author: ihexxa

packages/insomnia/src/sdk/objects/__tests__/headers.test.ts

@@ -0,0 +1,18 @@
+import { describe, expect, it } from '@jest/globals';
+
+import { Header } from '../headers';
+
+describe('test Header object', () => {
+    it('test basic operations', () => {
+        const headerStr = 'Content-Type: application/json\nUser-Agent: MyClientLibrary/2.0\n';
+        const headerObjs = [
+            { key: 'Content-Type', value: 'application/json' },
+            { key: 'User-Agent', value: 'MyClientLibrary/2.0' },
+        ];
+
+        expect(Header.parse(headerStr)).toEqual(headerObjs);
+        expect(
+            Header.parse(Header.unparse(headerObjs))
+        ).toEqual(headerObjs);
+    });
+});

packages/insomnia/src/sdk/objects/headers.ts

@@ -0,0 +1,128 @@
+import { unsupportedError } from './insomnia';
+import { Property, PropertyList } from './properties';
+
+export interface HeaderDefinition {
+    key: string;
+    value: string;
+    id?: string;
+    name?: string;
+    type?: string;
+    disabled?: boolean;
+}
+
+export class Header extends Property {
+    _kind: string = 'Header';
+    type: string = '';
+    key: string;
+    value: string;
+
+    constructor(
+        opts: HeaderDefinition | string,
+        name?: string, // if it is defined, it overrides 'key' (not 'name')
+    ) {
+        super();
+
+        if (typeof opts === 'string') {
+            const obj = Header.parseSingle(opts);
+            this.key = obj.key;
+            this.value = obj.value;
+        } else {
+            this.id = opts.id ? opts.id : '';
+            this.key = opts.key ? opts.key : '';
+            this.name = name ? name : (opts.name ? opts.name : '');
+            this.value = opts.value ? opts.value : '';
+            this.type = opts.type ? opts.type : '';
+            this.disabled = opts ? opts.disabled : false;
+        }
+    }
+
+    static create(input?: { key: string; value: string } | string, name?: string): Header {
+        return new Header(input || { key: '', value: '' }, name);
+    }
+
+    static isHeader(obj: object) {
+        return '_kind' in obj && obj._kind === 'Header';
+    }
+
+    // example: 'Content-Type: application/json\nUser-Agent: MyClientLibrary/2.0\n'
+    static parse(headerString: string): { key: string; value: string }[] {
+        return headerString
+            .split('\n')
+            .filter(kvPart => kvPart.trim() !== '')
+            .map(kvPart => Header.parseSingle(kvPart));
+    }
+
+    static parseSingle(headerStr: string): { key: string; value: string } {
+        // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers
+        // the first colon is the separator
+        const separatorPos = headerStr.indexOf(':');
+
+        if (separatorPos <= 0) {
+            throw Error('Header.parseSingle: the header string seems invalid');
+        }
+
+        const key = headerStr.slice(0, separatorPos);
+        const value = headerStr.slice(separatorPos + 1);
+
+        return { key: key.trim(), value: value.trim() };
+    }
+
+    static unparse(headers: { key: string; value: string }[] | PropertyList<Header>, separator?: string): string {
+        const headerArray: { key: string; value: string }[] = [
+            ...headers.map(
+                header => this.unparseSingle(header), {}
+            ),
+        ];
+
+        return headerArray.join(separator || '\n');
+    }
+
+    static unparseSingle(header: { key: string; value: string } | Header): string {
+        // both PropertyList and object contains 'key' and 'value'
+        return `${header.key}: ${header.value}`;
+    }
+
+    update(newHeader: { key: string; value: string }) {
+        this.key = newHeader.key;
+        this.value = newHeader.value;
+    }
+
+    valueOf() {
+        return this.value;
+    }
+}
+
+export class HeaderList<T extends Header> extends PropertyList<T> {
+    constructor(
+        parent: PropertyList<T> | undefined,
+        populate: T[]
+    ) {
+        super(
+            Header,
+            undefined,
+            populate
+        );
+        this.parent = parent;
+    }
+
+    static isHeaderList(obj: any) {
+        return '_kind' in obj && obj._kind === 'HeaderList';
+    }
+
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    eachParent(_iterator: any, _context?: object | undefined) {
+        throw unsupportedError('eachParent');
+    }
+
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    toObject(_excludeDisabled?: boolean, _caseSensitive?: boolean, _multiValue?: boolean, _sanitizeKeys?: boolean) {
+        throw unsupportedError('toObject');
+    }
+
+    contentSize(): number {
+        return this.list
+            .map(header => header.toString())
+            .map(headerStr => headerStr.length) // TODO: handle special characters
+            .reduce((totalSize, headerSize) => totalSize + headerSize, 0);
+    }
+}

packages/insomnia/src/sdk/objects/index.ts

@@ -1 +1,2 @@
 export { PropertyBase, Property, PropertyList } from './properties';
+export { Header, HeaderList } from './headers';

packages/insomnia/src/sdk/objects/properties.ts

@@ -184,8 +184,8 @@ export class PropertyList<T extends Property> {
     protected list: T[] = [];
 
     constructor(
-        protected readonly _typeClass: {}, // TODO: it is not used before collection is introduced
-        protected readonly parent: Property | PropertyList<any> | undefined,
+        protected _typeClass: {}, // TODO: it is not used before collection is introduced
+        protected parent: Property | PropertyList<any> | undefined,
         populate: T[],
     ) {
         this.parent = parent;