refactor: move set-content-type function (#162)

packages/verified-fetch/src/index.ts

@@ -628,6 +628,7 @@ import { type Libp2p, type ServiceMap } from '@libp2p/interface'
 import { dns } from '@multiformats/dns'
 import { createHelia, type HeliaInit } from 'helia'
 import { createLibp2p, type Libp2pOptions } from 'libp2p'
+import { type ContentTypeParser } from './types.js'
 import { getLibp2pConfig } from './utils/libp2p-defaults.js'
 import { VerifiedFetch as VerifiedFetchClass } from './verified-fetch.js'
 import type { GetBlockProgressEvents, Helia, Routing } from '@helia/interface'
@@ -751,19 +752,7 @@ export interface CreateVerifiedFetchOptions {
   sessionTTLms?: number
 }
 
-/**
- * A ContentTypeParser attempts to return the mime type of a given file. It
- * receives the first chunk of the file data and the file name, if it is
- * available.  The function can be sync or async and if it returns/resolves to
- * `undefined`, `application/octet-stream` will be used.
- */
-export interface ContentTypeParser {
-  /**
-   * Attempt to determine a mime type, either via of the passed bytes or the
-   * filename if it is available.
-   */
-  (bytes: Uint8Array, fileName?: string): Promise<string | undefined> | string | undefined
-}
+export type { ContentTypeParser } from './types.js'
 
 export type BubbledProgressEvents =
   // unixfs-exporter

packages/verified-fetch/src/types.ts

@@ -30,3 +30,17 @@ export interface FetchHandlerFunctionArg {
    */
   resource: string
 }
+
+/**
+ * A ContentTypeParser attempts to return the mime type of a given file. It
+ * receives the first chunk of the file data and the file name, if it is
+ * available.  The function can be sync or async and if it returns/resolves to
+ * `undefined`, `application/octet-stream` will be used.
+ */
+export interface ContentTypeParser {
+  /**
+   * Attempt to determine a mime type, either via of the passed bytes or the
+   * filename if it is available.
+   */
+  (bytes: Uint8Array, fileName?: string): Promise<string | undefined> | string | undefined
+}

packages/verified-fetch/src/utils/set-content-type.ts

@@ -0,0 +1,38 @@
+import { type Logger } from '@libp2p/interface'
+import { type ContentTypeParser } from '../types.js'
+import { isPromise } from './type-guards.js'
+
+export interface SetContentTypeOptions {
+  bytes: Uint8Array
+  path: string
+  response: Response
+  defaultContentType?: string
+  contentTypeParser: ContentTypeParser | undefined
+  log: Logger
+}
+
+export async function setContentType ({ bytes, path, response, contentTypeParser, log, defaultContentType = 'application/octet-stream' }: SetContentTypeOptions): Promise<void> {
+  let contentType: string | undefined
+
+  if (contentTypeParser != null) {
+    try {
+      let fileName = path.split('/').pop()?.trim()
+      fileName = fileName === '' ? undefined : fileName
+      const parsed = contentTypeParser(bytes, fileName)
+
+      if (isPromise(parsed)) {
+        const result = await parsed
+
+        if (result != null) {
+          contentType = result
+        }
+      } else if (parsed != null) {
+        contentType = parsed
+      }
+    } catch (err) {
+      log.error('error parsing content type', err)
+    }
+  }
+  log.trace('setting content type to "%s"', contentType ?? defaultContentType)
+  response.headers.set('content-type', contentType ?? defaultContentType)
+}

packages/verified-fetch/src/utils/type-guards.ts

@@ -0,0 +1,3 @@
+export function isPromise <T> (p?: any): p is Promise<T> {
+  return p?.then != null
+}

packages/verified-fetch/src/utils/walk-path.ts

@@ -19,7 +19,7 @@ export interface PathWalkerFn {
   (blockstore: ReadableStorage, path: string, options?: PathWalkerOptions): Promise<PathWalkerResponse>
 }
 
-export async function walkPath (blockstore: ReadableStorage, path: string, options?: PathWalkerOptions): Promise<PathWalkerResponse> {
+async function walkPath (blockstore: ReadableStorage, path: string, options?: PathWalkerOptions): Promise<PathWalkerResponse> {
   const ipfsRoots: CID[] = []
   let terminalElement: UnixFSEntry | undefined
 

packages/verified-fetch/src/verified-fetch.ts

@@ -6,7 +6,7 @@ import { code as dagPbCode } from '@ipld/dag-pb'
 import { type AbortOptions, type Logger, type PeerId } from '@libp2p/interface'
 import { Record as DHTRecord } from '@libp2p/kad-dht'
 import { Key } from 'interface-datastore'
-import { exporter } from 'ipfs-unixfs-exporter'
+import { exporter, type ObjectNode } from 'ipfs-unixfs-exporter'
 import toBrowserReadableStream from 'it-to-browser-readablestream'
 import { LRUCache } from 'lru-cache'
 import { type CID } from 'multiformats/cid'
@@ -32,12 +32,12 @@ import { resourceToSessionCacheKey } from './utils/resource-to-cache-key.js'
 import { setCacheControlHeader, setIpfsRoots } from './utils/response-headers.js'
 import { badRequestResponse, movedPermanentlyResponse, notAcceptableResponse, notSupportedResponse, okResponse, badRangeResponse, okRangeResponse, badGatewayResponse, notFoundResponse } from './utils/responses.js'
 import { selectOutputType } from './utils/select-output-type.js'
+import { setContentType } from './utils/set-content-type.js'
 import { handlePathWalking, isObjectNode } from './utils/walk-path.js'
 import type { CIDDetail, ContentTypeParser, CreateVerifiedFetchOptions, Resource, ResourceDetail, VerifiedFetchInit as VerifiedFetchOptions } from './index.js'
 import type { FetchHandlerFunctionArg, RequestFormatShorthand } from './types.js'
 import type { Helia, SessionBlockstore } from '@helia/interface'
 import type { Blockstore } from 'interface-blockstore'
-import type { ObjectNode } from 'ipfs-unixfs-exporter'
 
 const SESSION_CACHE_MAX_SIZE = 100
 const SESSION_CACHE_TTL_MS = 60 * 1000
@@ -398,7 +398,7 @@ export class VerifiedFetch {
         redirected
       })
 
-      await this.setContentType(firstChunk, path, response)
+      await setContentType({ bytes: firstChunk, path, response, contentTypeParser: this.contentTypeParser, log: this.log })
       setIpfsRoots(response, ipfsRoots)
 
       return response
@@ -434,37 +434,11 @@ export class VerifiedFetch {
     // if the user has specified an `Accept` header that corresponds to a raw
     // type, honour that header, so for example they don't request
     // `application/vnd.ipld.raw` but get `application/octet-stream`
-    await this.setContentType(result, path, response, getOverridenRawContentType({ headers: options?.headers, accept }))
+    await setContentType({ bytes: result, path, response, defaultContentType: getOverridenRawContentType({ headers: options?.headers, accept }), contentTypeParser: this.contentTypeParser, log: this.log })
 
     return response
   }
 
-  private async setContentType (bytes: Uint8Array, path: string, response: Response, defaultContentType = 'application/octet-stream'): Promise<void> {
-    let contentType: string | undefined
-
-    if (this.contentTypeParser != null) {
-      try {
-        let fileName = path.split('/').pop()?.trim()
-        fileName = fileName === '' ? undefined : fileName
-        const parsed = this.contentTypeParser(bytes, fileName)
-
-        if (isPromise(parsed)) {
-          const result = await parsed
-
-          if (result != null) {
-            contentType = result
-          }
-        } else if (parsed != null) {
-          contentType = parsed
-        }
-      } catch (err) {
-        this.log.error('error parsing content type', err)
-      }
-    }
-    this.log.trace('setting content type to "%s"', contentType ?? defaultContentType)
-    response.headers.set('content-type', contentType ?? defaultContentType)
-  }
-
   /**
    * If the user has not specified an Accept header or format query string arg,
    * use the CID codec to choose an appropriate handler for the block data.
@@ -614,7 +588,3 @@ export class VerifiedFetch {
     await this.helia.stop()
   }
 }
-
-function isPromise <T> (p?: any): p is Promise<T> {
-  return p?.then != null
-}