import type { PausePeriod } from "./types.ts";

export function activeDurationMs(startedAt?: number, finishedAt?: number, pausePeriods: PausePeriod[] = [], now = Date.now()): number {
	if (startedAt === undefined) return 0;
	const endedAt = finishedAt ?? now;
	const pausedMs = pausePeriods.reduce((total, period) => {
		const overlapStartedAt = Math.max(startedAt, period.startedAt);
		const overlapFinishedAt = Math.min(endedAt, period.finishedAt ?? now);
		return total + Math.max(0, overlapFinishedAt - overlapStartedAt);
	}, 0);
	return Math.max(0, endedAt - startedAt - pausedMs);
}

export function formatDuration(startedAt?: number, finishedAt?: number, pausePeriods: PausePeriod[] = [], now = Date.now()): string {
	if (startedAt === undefined) return "未开始";
	const elapsedSeconds = Math.floor(activeDurationMs(startedAt, finishedAt, pausePeriods, now) / 1000);
	const seconds = elapsedSeconds % 60;
	const minutes = Math.floor(elapsedSeconds / 60) % 60;
	const hours = Math.floor(elapsedSeconds / 3_600) % 24;
	const days = Math.floor(elapsedSeconds / 86_400);
	const pad = (value: number) => String(value).padStart(2, "0");

	if (days > 0) return `${days}天${pad(hours)}小时${pad(minutes)}分${pad(seconds)}秒`;
	if (hours > 0) return `${hours}小时${pad(minutes)}分${pad(seconds)}秒`;
	if (minutes > 0) return `${minutes}分${pad(seconds)}秒`;
	return `${seconds}秒`;
}