sproutclaw/packages/coding-agent/examples/extensions/pi-dosbox/src/dosbox-component.ts

/**
 * DOSBox TUI Component
 *
 * Renders DOSBox framebuffer as an image in the terminal.
 * Connects to the persistent DosboxInstance.
 */

import type { Component } from "@mariozechner/pi-tui";
import {
	allocateImageId,
	deleteKittyImage,
	Image,
	type ImageTheme,
	isKeyRelease,
	Key,
	matchesKey,
	truncateToWidth,
} from "@mariozechner/pi-tui";
import { DosboxInstance } from "./dosbox-instance.js";

const MAX_WIDTH_CELLS = 120;

// js-dos key codes
const KBD: Record<string, number> = {
	enter: 257,
	backspace: 259,
	tab: 258,
	esc: 256,
	space: 32,
	leftshift: 340,
	rightshift: 344,
	leftctrl: 341,
	rightctrl: 345,
	leftalt: 342,
	rightalt: 346,
	up: 265,
	down: 264,
	left: 263,
	right: 262,
	home: 268,
	end: 269,
	pageup: 266,
	pagedown: 267,
	insert: 260,
	delete: 261,
	f1: 290,
	f2: 291,
	f3: 292,
	f4: 293,
	f5: 294,
	f6: 295,
	f7: 296,
	f8: 297,
	f9: 298,
	f10: 299,
	f11: 300,
	f12: 301,
};

export class DosboxComponent implements Component {
	private tui: { requestRender: () => void };
	private onClose: () => void;
	private instance: DosboxInstance | null = null;
	private image: Image | null = null;
	private imageTheme: ImageTheme;
	private loadingMessage = "Connecting to DOSBox...";
	private errorMessage: string | null = null;
	private cachedLines: string[] = [];
	private cachedWidth = 0;
	private cachedVersion = -1;
	private version = 0;
	private disposed = false;
	private imageId: number;
	private kittyPushed = false;
	private frameListener: ((rgba: Uint8Array, width: number, height: number) => void) | null = null;

	wantsKeyRelease = true;

	constructor(tui: { requestRender: () => void }, fallbackColor: (s: string) => string, onClose: () => void) {
		this.tui = tui;
		this.onClose = onClose;
		this.imageTheme = { fallbackColor };
		this.imageId = allocateImageId();
		void this.connect();
	}

	private async connect(): Promise<void> {
		try {
			this.instance = await DosboxInstance.getInstance();

			// Set up frame listener
			this.frameListener = (rgba: Uint8Array, width: number, height: number) => {
				this.updateFrame(rgba, width, height);
			};
			this.instance.addFrameListener(this.frameListener);

			// Get initial state
			const state = this.instance.getState();
			if (state.lastFrame && state.width && state.height) {
				this.updateFrame(state.lastFrame, state.width, state.height);
			}

			// Push Kitty enhanced mode for proper key press/release
			process.stdout.write("\x1b[>15u");
			this.kittyPushed = true;

			this.tui.requestRender();
		} catch (error) {
			this.errorMessage = error instanceof Error ? error.message : String(error);
			this.tui.requestRender();
		}
	}

	private updateFrame(rgba: Uint8Array, width: number, height: number): void {
		const png = this.encodePng(width, height, rgba);
		const base64 = png.toString("base64");
		this.image = new Image(
			base64,
			"image/png",
			this.imageTheme,
			{ maxWidthCells: MAX_WIDTH_CELLS, imageId: this.imageId },
			{ widthPx: width, heightPx: height },
		);
		this.version++;
		this.tui.requestRender();
	}

	private encodePng(width: number, height: number, rgba: Uint8Array): Buffer {
		const { deflateSync } = require("node:zlib");
		const stride = width * 4;
		const raw = Buffer.alloc((stride + 1) * height);
		for (let y = 0; y < height; y++) {
			const rowOffset = y * (stride + 1);
			raw[rowOffset] = 0;
			raw.set(rgba.subarray(y * stride, y * stride + stride), rowOffset + 1);
		}

		const compressed = deflateSync(raw);

		const header = Buffer.alloc(13);
		header.writeUInt32BE(width, 0);
		header.writeUInt32BE(height, 4);
		header[8] = 8;
		header[9] = 6;

		const signature = Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]);
		const ihdr = this.createChunk("IHDR", header);
		const idat = this.createChunk("IDAT", compressed);
		const iend = this.createChunk("IEND", Buffer.alloc(0));

		return Buffer.concat([signature, ihdr, idat, iend]);
	}

	private createChunk(type: string, data: Buffer): Buffer {
		const length = Buffer.alloc(4);
		length.writeUInt32BE(data.length, 0);
		const typeBuffer = Buffer.from(type, "ascii");
		const crcBuffer = Buffer.concat([typeBuffer, data]);
		const crc = this.crc32(crcBuffer);
		const crcOut = Buffer.alloc(4);
		crcOut.writeUInt32BE(crc, 0);
		return Buffer.concat([length, typeBuffer, data, crcOut]);
	}

	private crc32(buffer: Buffer): number {
		let crc = 0xffffffff;
		for (const byte of buffer) {
			crc = CRC_TABLE[(crc ^ byte) & 0xff] ^ (crc >>> 8);
		}
		return (crc ^ 0xffffffff) >>> 0;
	}

	handleInput(data: string): void {
		const released = isKeyRelease(data);

		if (!released && matchesKey(data, Key.ctrl("q"))) {
			this.dispose();
			this.onClose();
			return;
		}

		const ci = this.instance?.getCommandInterface();
		if (!ci) return;

		const parsed = parseKeyWithModifiers(data);
		if (!parsed) return;

		const { keyCode, shift, ctrl, alt } = parsed;

		if (shift) ci.sendKeyEvent(KBD.leftshift, !released);
		if (ctrl) ci.sendKeyEvent(KBD.leftctrl, !released);
		if (alt) ci.sendKeyEvent(KBD.leftalt, !released);

		ci.sendKeyEvent(keyCode, !released);
	}

	invalidate(): void {
		this.cachedWidth = 0;
	}

	render(width: number): string[] {
		if (this.errorMessage) {
			return [truncateToWidth(`DOSBox error: ${this.errorMessage}`, width)];
		}
		if (!this.instance?.isReady()) {
			return [truncateToWidth(this.loadingMessage, width)];
		}
		if (!this.image) {
			return [truncateToWidth("Waiting for DOSBox frame...", width)];
		}
		if (width === this.cachedWidth && this.cachedVersion === this.version) {
			return this.cachedLines;
		}

		const imageLines = this.image.render(width);
		const footer = truncateToWidth("\x1b[2mCtrl+Q to detach (DOSBox keeps running)\x1b[22m", width);
		const lines = [...imageLines, footer];

		this.cachedLines = lines;
		this.cachedWidth = width;
		this.cachedVersion = this.version;

		return lines;
	}

	dispose(): void {
		if (this.disposed) return;
		this.disposed = true;

		// Delete the terminal image
		process.stdout.write(deleteKittyImage(this.imageId));

		if (this.kittyPushed) {
			process.stdout.write("\x1b[<u");
			this.kittyPushed = false;
		}

		// Remove frame listener but DON'T dispose the instance
		if (this.instance && this.frameListener) {
			this.instance.removeFrameListener(this.frameListener);
		}
	}
}

const CRC_TABLE = createCrcTable();

function createCrcTable(): Uint32Array {
	const table = new Uint32Array(256);
	for (let i = 0; i < 256; i++) {
		let c = i;
		for (let j = 0; j < 8; j++) {
			if (c & 1) {
				c = 0xedb88320 ^ (c >>> 1);
			} else {
				c >>>= 1;
			}
		}
		table[i] = c >>> 0;
	}
	return table;
}

interface ParsedKey {
	keyCode: number;
	shift: boolean;
	ctrl: boolean;
	alt: boolean;
}

function decodeModifiers(modifierField: number): { shift: boolean; ctrl: boolean; alt: boolean } {
	const modifiers = modifierField - 1;
	return {
		shift: (modifiers & 1) !== 0,
		alt: (modifiers & 2) !== 0,
		ctrl: (modifiers & 4) !== 0,
	};
}

function parseKeyWithModifiers(data: string): ParsedKey | null {
	if (data.startsWith("\x1b[") && data.endsWith("u")) {
		const body = data.slice(2, -1);
		const [keyPart, modifierPart] = body.split(";");
		if (keyPart) {
			const codepoint = parseInt(keyPart.split(":")[0], 10);
			if (!Number.isNaN(codepoint)) {
				const modifierField = modifierPart ? parseInt(modifierPart.split(":")[0], 10) : 1;
				const { shift, alt, ctrl } = decodeModifiers(Number.isNaN(modifierField) ? 1 : modifierField);
				const keyCode = codepointToJsDosKey(codepoint);
				if (keyCode !== null) {
					return { keyCode, shift, ctrl, alt };
				}
			}
		}
	}

	const csiMatch = data.match(/^\x1b\[(\d+);(\d+)(?::\d+)?([~A-Za-z])$/);
	if (csiMatch) {
		const code = parseInt(csiMatch[1], 10);
		const modifierField = parseInt(csiMatch[2], 10);
		const suffix = csiMatch[3];
		const { shift, alt, ctrl } = decodeModifiers(modifierField);
		const keyCode = mapCsiKeyToJsDos(code, suffix);
		if (keyCode === null) return null;
		return { keyCode, shift, ctrl, alt };
	}

	const keyCode = mapKeyToJsDos(data);
	if (keyCode === null) return null;
	const shift = data.length === 1 && data >= "A" && data <= "Z";
	return { keyCode, shift, ctrl: false, alt: false };
}

function codepointToJsDosKey(codepoint: number): number | null {
	if (codepoint === 13) return KBD.enter;
	if (codepoint === 9) return KBD.tab;
	if (codepoint === 27) return KBD.esc;
	if (codepoint === 8 || codepoint === 127) return KBD.backspace;
	if (codepoint === 32) return KBD.space;
	if (codepoint >= 97 && codepoint <= 122) return codepoint - 32;
	if (codepoint >= 65 && codepoint <= 90) return codepoint;
	if (codepoint >= 48 && codepoint <= 57) return codepoint;
	return null;
}

function mapCsiKeyToJsDos(code: number, suffix: string): number | null {
	switch (suffix) {
		case "A":
			return KBD.up;
		case "B":
			return KBD.down;
		case "C":
			return KBD.right;
		case "D":
			return KBD.left;
		case "H":
			return KBD.home;
		case "F":
			return KBD.end;
		case "P":
			return KBD.f1;
		case "Q":
			return KBD.f2;
		case "R":
			return KBD.f3;
		case "S":
			return KBD.f4;
		case "Z":
			return KBD.tab;
		case "~":
			switch (code) {
				case 1:
				case 7:
					return KBD.home;
				case 2:
					return KBD.insert;
				case 3:
					return KBD.delete;
				case 4:
				case 8:
					return KBD.end;
				case 5:
					return KBD.pageup;
				case 6:
					return KBD.pagedown;
				case 15:
					return KBD.f5;
				case 17:
					return KBD.f6;
				case 18:
					return KBD.f7;
				case 19:
					return KBD.f8;
				case 20:
					return KBD.f9;
				case 21:
					return KBD.f10;
				case 23:
					return KBD.f11;
				case 24:
					return KBD.f12;
				default:
					return null;
			}
		default:
			return null;
	}
}

function mapKeyToJsDos(data: string): number | null {
	if (matchesKey(data, Key.enter)) return KBD.enter;
	if (matchesKey(data, Key.backspace)) return KBD.backspace;
	if (matchesKey(data, Key.tab)) return KBD.tab;
	if (matchesKey(data, Key.escape)) return KBD.esc;
	if (matchesKey(data, Key.space)) return KBD.space;
	if (matchesKey(data, Key.up)) return KBD.up;
	if (matchesKey(data, Key.down)) return KBD.down;
	if (matchesKey(data, Key.left)) return KBD.left;
	if (matchesKey(data, Key.right)) return KBD.right;
	if (matchesKey(data, Key.pageUp)) return KBD.pageup;
	if (matchesKey(data, Key.pageDown)) return KBD.pagedown;
	if (matchesKey(data, Key.home)) return KBD.home;
	if (matchesKey(data, Key.end)) return KBD.end;
	if (matchesKey(data, Key.insert)) return KBD.insert;
	if (matchesKey(data, Key.delete)) return KBD.delete;
	if (matchesKey(data, Key.f1)) return KBD.f1;
	if (matchesKey(data, Key.f2)) return KBD.f2;
	if (matchesKey(data, Key.f3)) return KBD.f3;
	if (matchesKey(data, Key.f4)) return KBD.f4;
	if (matchesKey(data, Key.f5)) return KBD.f5;
	if (matchesKey(data, Key.f6)) return KBD.f6;
	if (matchesKey(data, Key.f7)) return KBD.f7;
	if (matchesKey(data, Key.f8)) return KBD.f8;
	if (matchesKey(data, Key.f9)) return KBD.f9;
	if (matchesKey(data, Key.f10)) return KBD.f10;
	if (matchesKey(data, Key.f11)) return KBD.f11;
	if (matchesKey(data, Key.f12)) return KBD.f12;

	if (data.length === 1) {
		const code = data.charCodeAt(0);
		if (data >= "a" && data <= "z") return code - 32;
		if (data >= "A" && data <= "Z") return code;
		if (data >= "0" && data <= "9") return code;
	}
	return null;
}