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import type { ContentManifest, ChunkPayload } from '@hollowdark/content-system/manifest/schema'
import { HollowdarkContentCache } from '@hollowdark/persistence/db'
import type { JsonValue } from '@hollowdark/utils/types/json'
let cacheInstance: HollowdarkContentCache | null = null
function cache(): HollowdarkContentCache {
if (cacheInstance === null) {
cacheInstance = new HollowdarkContentCache()
}
return cacheInstance
}
const MANIFEST_CACHE_KEY = 'latest'
/**
* Fetch the content manifest from static hosting. Falls back to the last
* cached manifest when the network request fails — the game works fully
* offline once the first download has succeeded.
*/
export async function fetchManifest(baseUrl: string): Promise<ContentManifest> {
const url = `${baseUrl}/content-manifest.json`
try {
const response = await fetch(url, { cache: 'no-cache' })
if (!response.ok) throw new Error(`manifest ${response.status}`)
const live = (await response.json()) as ContentManifest
await cache().manifest.put({
id: MANIFEST_CACHE_KEY,
contentVersion: live.content_version,
appVersion: live.app_version,
generatedAt: live.generated_at,
payload: live as unknown as JsonValue
})
return live
} catch {
const cached = await cache().manifest.get(MANIFEST_CACHE_KEY)
if (cached === undefined) {
throw new Error('Content manifest unavailable and no cached copy exists.')
}
return cached.payload as unknown as ContentManifest
}
}
/**
* Load a single chunk by id, using the manifest to resolve the hashed
* URL. Served from the IndexedDB cache whenever the cached hash matches
* the manifest's; refetched otherwise. Falls back to the cached payload
* on network failure so gameplay continues offline.
*/
export async function loadChunk(
chunkId: string,
manifest: ContentManifest,
baseUrl: string
): Promise<ChunkPayload> {
const entry = manifest.chunks[chunkId]
if (entry === undefined) {
throw new Error(`Content chunk not listed in manifest: ${chunkId}`)
}
const cached = await cache().content.get(chunkId)
if (cached !== undefined && cached.hash === entry.hash) {
return { chunkId, data: cached.data, version: cached.version, hash: cached.hash }
}
try {
const response = await fetch(`${baseUrl}${entry.url}`)
if (!response.ok) throw new Error(`chunk ${response.status}`)
const data = (await response.json()) as JsonValue
await cache().content.put({
chunkId,
version: entry.version,
hash: entry.hash,
data,
fetchedAt: new Date().toISOString()
})
return { chunkId, data, version: entry.version, hash: entry.hash }
} catch (err) {
if (cached !== undefined) {
return { chunkId, data: cached.data, version: cached.version, hash: cached.hash }
}
throw err
}
}
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