Scrum4Me/lib/insights/velocity.ts

import { prisma } from '@/lib/prisma'
import { productAccessFilter } from '@/lib/product-access'

export interface VelocitySprint {
  sprintId: string
  sprintGoal: string
  productId: string
  productName: string
  doneCount: number
  completedAt: string
}

export interface VelocityData {
  sprints: VelocitySprint[]
  productNames: { id: string; name: string }[]
}

export async function getVelocity(userId: string, sprintsBack = 5): Promise<VelocityData> {
  const sprints = await prisma.sprint.findMany({
    where: {
      status: 'COMPLETED',
      product: productAccessFilter(userId),
    },
    orderBy: { completed_at: 'desc' },
    take: sprintsBack,
    select: {
      id: true,
      sprint_goal: true,
      completed_at: true,
      product: { select: { id: true, name: true } },
      tasks: { select: { status: true } },
    },
  })

  // Reverse to chronological order (oldest first, for x-axis)
  // Type-guard so the narrowed array carries `completed_at: Date` (not Date | null).
  // A `.filter(s => s.completed_at != null)` alone does NOT narrow the element type.
  type SprintWithCompletedAt = (typeof sprints)[number] & { completed_at: Date }
  const chronological = [...sprints]
    .filter((s): s is SprintWithCompletedAt => s.completed_at != null)
    .reverse()

  const result: VelocitySprint[] = chronological.map(sprint => ({
    sprintId: sprint.id,
    sprintGoal: sprint.sprint_goal,
    productId: sprint.product.id,
    productName: sprint.product.name,
    doneCount: sprint.tasks.filter(t => t.status === 'DONE').length,
    completedAt: sprint.completed_at.toISOString(),
  }))

  const seen = new Set<string>()
  const productNames: { id: string; name: string }[] = []
  for (const s of result) {
    if (!seen.has(s.productId)) {
      seen.add(s.productId)
      productNames.push({ id: s.productId, name: s.productName })
    }
  }

  return { sprints: result, productNames }
}