project-nomad/admin/app/utils/zim_download_resolution.ts

65 lines
2.0 KiB
TypeScript

import type { CatalogResult } from '../services/kiwix_catalog_service.js'
import type { SpecResource } from '../../types/collections.js'
import { isGatedResource } from './hosted_content.js'
export type ResolvedZimDownload = {
url: string
version: string
sizeBytes: number | undefined
}
function compareZimVersions(left: string, right: string): number {
const parse = (value: string): [number, number] | null => {
const match = /^(\d{4})-(\d{1,2})$/.exec(value)
if (!match) return null
const month = Number.parseInt(match[2], 10)
if (month < 1 || month > 12) return null
return [Number.parseInt(match[1], 10), month]
}
const leftParts = parse(left)
const rightParts = parse(right)
if (!leftParts || !rightParts) return left.localeCompare(right)
return leftParts[0] - rightParts[0] || leftParts[1] - rightParts[1]
}
export function resolveZimDownload(
resource: SpecResource,
latest: CatalogResult | null
): ResolvedZimDownload {
const manifestSizeBytes = resource.size_mb > 0 ? resource.size_mb * 1024 * 1024 : undefined
// Content we host ourselves is pinned to the manifest URL, never the Kiwix
// catalog. It isn't in the openzim catalog at all, so this is normally a no-op
// — but a resource-id collision would otherwise silently redirect a gated
// download to a third-party mirror, losing both the auth header and any
// guarantee about what the bytes are.
//
// Consequence, stated rather than implied: gated content does NOT participate
// in catalog-driven auto-update. New versions ship by bumping the manifest.
if (isGatedResource(resource)) {
return {
url: resource.url,
version: resource.version,
sizeBytes: manifestSizeBytes,
}
}
if (!latest || compareZimVersions(latest.version, resource.version) < 0) {
return {
url: resource.url,
version: resource.version,
sizeBytes: manifestSizeBytes,
}
}
return {
url: latest.download_url,
version: latest.version,
sizeBytes: latest.size_bytes > 0 ? latest.size_bytes : manifestSizeBytes,
}
}