export interface SprintLike {
  id: string;
  startDate: string;
  endDate: string;
  status: "planning" | "active" | "completed";
}

function parseSprintStart(value: string): Date {
  const match = value.match(/^(\d{4})-(\d{2})-(\d{2})/)
  if (match) {
    return new Date(Number(match[1]), Number(match[2]) - 1, Number(match[3]), 0, 0, 0, 0)
  }
  return new Date(value)
}

function parseSprintEnd(value: string): Date {
  const match = value.match(/^(\d{4})-(\d{2})-(\d{2})/)
  if (match) {
    return new Date(Number(match[1]), Number(match[2]) - 1, Number(match[3]), 23, 59, 59, 999)
  }
  const parsed = new Date(value)
  parsed.setHours(23, 59, 59, 999)
  return parsed
}

export function isSprintInProgress(startDate: string, endDate: string, now: Date = new Date()): boolean {
  const sprintStart = parseSprintStart(startDate)
  const sprintEnd = parseSprintEnd(endDate)
  return sprintStart <= now && sprintEnd >= now
}

export function findCurrentSprint<T extends SprintLike>(
  sprints: T[],
  options?: {
    now?: Date
    includeCompletedFallback?: boolean
  }
): T | null {
  const now = options?.now ?? new Date()
  const includeCompletedFallback = options?.includeCompletedFallback ?? false
  const inProgress = sprints.filter((s) => isSprintInProgress(s.startDate, s.endDate, now))

  return (
    inProgress.find((s) => s.status === "active") ??
    inProgress.find((s) => s.status !== "completed") ??
    (includeCompletedFallback ? inProgress[0] ?? null : null)
  )
}