scroll/src/common/editor.ts

import { Ansi } from './ansi.ts';
import { importForRuntime } from './runtime.ts';
import { ctrl_key } from './strings.ts';

class Buffer {
	#b = '';

	constructor() {
	}

	append(s: string): void {
		this.#b += s;
	}

	appendLine(s: string): void {
		this.#b += s + '\r\n';
	}

	clear(): void {
		this.#b = '';
	}

	getBuffer(): string {
		return this.#b;
	}
}

export class Editor {
	#buffer: Buffer;
	constructor() {
		this.#buffer = new Buffer();
	}

	/**
	 * Determine what to do based on input
	 * @param input - the decoded chunk of stdin
	 */
	public processKeyPress(input: string): boolean {
		switch (input) {
			case ctrl_key('q'):
				this.clearScreen();
				return false;

			default:
				return true;
		}
	}

	/**
	 * Clear the screen and write out the buffer
	 */
	public async refreshScreen(): Promise<void> {
		const { write } = await importForRuntime('terminal_io');

		this.clearScreen();
		this.drawRows();

		await write(this.#buffer.getBuffer());
		this.#buffer.clear();
	}

	private drawRows(): void {
		for (let y = 0; y <= 24; y++) {
			this.#buffer.appendLine('~');
		}
	}

	private clearScreen(): void {
		this.#buffer.append(Ansi.ClearScreen);
		this.#buffer.append(Ansi.ResetCursor);
	}
}