import path from "node:path"

const FALLBACK_EXTENSION = "bin"
const DEFAULT_VARIANT = "original"

type BuildMediaStorageKeyParams = {
  tenantId: string
  assetId: string
  fileRole: string
  variant?: string
  fileName: string
}

function normalizeSegment(value: string): string {
  return value
    .toLowerCase()
    .replace(/[^a-z0-9._-]+/g, "-")
    .replace(/^-+|-+$/g, "")
}

function extensionFromFilename(fileName: string): string {
  const extension = path.extname(fileName).slice(1)

  if (!extension) {
    return FALLBACK_EXTENSION
  }

  const normalized = normalizeSegment(extension)

  return normalized.length > 0 ? normalized : FALLBACK_EXTENSION
}

export function buildMediaStorageKey(params: BuildMediaStorageKeyParams): string {
  const normalizedTenantId = normalizeSegment(params.tenantId) || "default"
  const normalizedAssetId = normalizeSegment(params.assetId)
  const normalizedFileRole = normalizeSegment(params.fileRole) || "original"
  const normalizedVariant = normalizeSegment(params.variant ?? DEFAULT_VARIANT) || DEFAULT_VARIANT
  const extension = extensionFromFilename(params.fileName)
  const fileName = `${normalizedAssetId}__${normalizedVariant}.${extension}`

  return [
    "tenant",
    normalizedTenantId,
    "asset",
    normalizedAssetId,
    normalizedFileRole,
    fileName,
  ].join("/")
}