import { prisma } from '@/lib/prisma'

const STORY_AUTO_RE = /^ST-(\d+)$/
const PBI_AUTO_RE = /^PBI-(\d+)$/

const VALID_CODE_RE = /^[A-Za-z0-9._-]+$/

export const MAX_CODE_LENGTH = 30

export function isValidCode(code: string): boolean {
  return code.length > 0 && code.length <= MAX_CODE_LENGTH && VALID_CODE_RE.test(code)
}

export function normalizeCode(input: string | null | undefined): string | null {
  if (input == null) return null
  const trimmed = input.trim()
  return trimmed === '' ? null : trimmed
}

function nextSequential(existing: (string | null)[], pattern: RegExp): number {
  let max = 0
  for (const c of existing) {
    if (!c) continue
    const m = c.match(pattern)
    if (m) {
      const n = Number.parseInt(m[1], 10)
      if (!Number.isNaN(n) && n > max) max = n
    }
  }
  return max + 1
}

export async function generateNextStoryCode(productId: string): Promise<string> {
  const stories = await prisma.story.findMany({
    where: { product_id: productId },
    select: { code: true },
  })
  const next = nextSequential(stories.map((s) => s.code), STORY_AUTO_RE)
  return `ST-${String(next).padStart(3, '0')}`
}

export async function generateNextPbiCode(productId: string): Promise<string> {
  const pbis = await prisma.pbi.findMany({
    where: { product_id: productId },
    select: { code: true },
  })
  const next = nextSequential(pbis.map((p) => p.code), PBI_AUTO_RE)
  return `PBI-${next}`
}

export function deriveTaskCode(storyCode: string | null, indexOneBased: number): string | null {
  if (!storyCode) return null
  return `${storyCode}.${indexOneBased}`
}