/** Compose the default text for a challenge post. */
export function composeChallengePost(
	opponentHandle: string,
	gameUrl: string,
): string {
	return `I'm challenging @${opponentHandle} to a game of chess on checkmate.blue!\n\n${gameUrl}`;
}

/** Compose the default text for a game result post. */
export function composeGameResultPost(
	myColor: 'white' | 'black',
	result: { result: '1-0' | '0-1' | '1/2-1/2'; reason: string },
	opponentHandle: string,
	moveCount: number,
	gameUrl: string,
): string {
	const opponent = `@${opponentHandle}`;
	const moveSuffix = moveCount > 10 ? ` in ${moveCount} moves` : '';

	const iWin =
		(result.result === '1-0' && myColor === 'white') ||
		(result.result === '0-1' && myColor === 'black');
	const isDraw = result.result === '1/2-1/2';

	let text: string;
	if (iWin && result.reason === 'checkmate') {
		text = `Checkmate! I won against ${opponent} on checkmate.blue${moveSuffix}`;
	} else if (iWin && result.reason === 'resignation') {
		text = `Victory! ${opponent} resigned our game on checkmate.blue${moveSuffix}`;
	} else if (iWin) {
		text = `I won against ${opponent} on checkmate.blue${moveSuffix}`;
	} else if (isDraw) {
		const drawReasons: Record<string, string> = {
			stalemate: 'Stalemate',
			agreement: 'Draw by agreement',
			repetition: 'Draw by repetition',
			fifty_moves: 'Draw by 50-move rule',
			insufficient: 'Draw by insufficient material',
		};
		const label = drawReasons[result.reason] ?? 'Draw';
		text = `${label} with ${opponent} on checkmate.blue${moveSuffix}`;
	} else {
		if (result.reason === 'checkmate') {
			text = `Got checkmated by ${opponent} on checkmate.blue -- good game!${moveSuffix}`;
		} else {
			text = `Good game against ${opponent} on checkmate.blue${moveSuffix}`;
		}
	}

	return `${text}\n\n${gameUrl}`;
}

/** Count graphemes accurately (handles emoji, combining characters). */
export function graphemeCount(text: string): number {
	const segmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' });
	let count = 0;
	for (const _ of segmenter.segment(text)) count++;
	return count;
}

/** Open the Bluesky compose page with pre-populated text. */
export function openBlueskyCompose(text: string): void {
	const url = `https://bsky.app/intent/compose?text=${encodeURIComponent(text)}`;
	window.open(url, '_blank');
}