/**
 * The starting point for running scroll
 */
import { Editor, getRuntime, getTermios } from './common/mod.ts';
import { KeyCommand } from './common/ansi.ts';

const decoder = new TextDecoder();

function readKey(raw: Uint8Array): string {
	const parsed = decoder.decode(raw);

	// Return the input if it's unambiguous
	if (parsed in KeyCommand) {
		return parsed;
	}

	// Some keycodes have multiple potential inputs
	switch (parsed) {
		case '\x1bOH':
		case '\x1b[7~':
		case '\x1b[1~':
		case '\x1b[H':
			return KeyCommand.Home;

		case '\x1bOF':
		case '\x1b[8~':
		case '\x1b[4~':
		case '\x1b[F':
			return KeyCommand.End;

		default:
			return parsed;
	}
}

export async function main() {
	const runTime = await getRuntime();
	const { term, onExit } = runTime;

	// Setup raw mode, and tear down on error or normal exit
	const t = await getTermios();
	t.enableRawMode();
	onExit(() => {
		t.disableRawMode();
	});

	const terminalSize = await term.getTerminalSize();

	// Create the editor itself
	const editor = new Editor(terminalSize);
	if (term.argv.length > 0) {
		const filename = term.argv[0];
		if (filename.trim() !== '') {
			await editor.open(filename);
		}
	}
	await editor.refreshScreen();

	// The main event loop
	for await (const chunk of term.inputLoop()) {
		// Process input
		const char = readKey(chunk);
		const shouldLoop = editor.processKeyPress(char);
		if (!shouldLoop) {
			return 0;
		}

		// Render output
		await editor.refreshScreen();
	}

	return -1;
}

/**
 * Start the event loop
 */
await main();