Resolve a link content type per url rather than per event

src/app/components/ContentLinkBlock.svelte

@@ -16,7 +16,7 @@
 
 <script lang="ts">
   import {call, ellipsize, displayUrl} from "@welshman/lib"
-  import {isRelayUrl, tagSpec, tagValue} from "@welshman/util"
+  import {isRelayUrl} from "@welshman/util"
   import {Capacitor} from "@capacitor/core"
   import {preventDefault, stopPropagation} from "@lib/html"
   import Link from "@lib/components/Link.svelte"
@@ -26,7 +26,12 @@
   import ContentLinkBlockImage from "@app/components/ContentLinkBlockImage.svelte"
   import {pushModal} from "@app/modal"
   import {PLATFORM_URL, THUMBNAIL_URL} from "@app/env"
-  import {AUDIO_CONTENT_TYPES, IMAGE_CONTENT_TYPES, VIDEO_CONTENT_TYPES} from "@app/content"
+  import {
+    getUrlContentType,
+    AUDIO_CONTENT_TYPES,
+    IMAGE_CONTENT_TYPES,
+    VIDEO_CONTENT_TYPES,
+  } from "@app/content"
   import {isRoomId} from "@app/rooms"
 
   const {value, event} = $props()
@@ -41,7 +46,7 @@
     return [url, true]
   })
 
-  const fileType = tagValue(tagSpec("file-type"), event.tags) || ""
+  const fileType = getUrlContentType(url, event)
 
   const isAudio =
     Boolean(url.match(/\.(mp3|m4a|wav|ogg|oga|opus|flac)$/)) ||

src/app/components/ContentLinkBlockImage.svelte

@@ -1,26 +1,16 @@
 <script lang="ts">
   import {onMount, onDestroy} from "svelte"
   import {displayUrl, once} from "@welshman/lib"
-  import {
-    getBlob,
-    decryptFile,
-    makeBlossomAuthEvent,
-    matchTags,
-    tagSpec,
-    tagValue,
-  } from "@welshman/util"
+  import {getBlob, decryptFile, makeBlossomAuthEvent, tagSpec, tagValue} from "@welshman/util"
   import LinkRound from "@assets/icons/link-round.svg?dataurl"
   import Icon from "@lib/components/Icon.svelte"
   import {user} from "@app/core"
+  import {getUrlTags} from "@app/content"
 
   const {value, event, ...props} = $props()
 
   const url = value.url.toString()
-  // An imeta tag packs its own tags into space-separated values, so unpack the one for this url.
-  const meta =
-    matchTags(tagSpec("imeta"), event.tags)
-      .map(([, ...values]: string[]) => values.map(value => value.split(" ")))
-      .find(meta => tagValue(tagSpec("url"), meta) === url) || event.tags
+  const meta = getUrlTags(url, event)
 
   // Fallback to filename if hash was omitted from the message for interoperability
   const hash = tagValue(tagSpec("x"), meta) || url.split(/[\/\.]/).slice(-2)[0]

src/app/components/ContentLinkInline.svelte

@@ -1,18 +1,17 @@
 <script lang="ts">
   import {displayUrl} from "@welshman/lib"
-  import {tagSpec, tagValue} from "@welshman/util"
   import {preventDefault, stopPropagation} from "@lib/html"
   import LinkRound from "@assets/icons/link-round.svg?dataurl"
   import Icon from "@lib/components/Icon.svelte"
   import ContentLinkDetail from "@app/components/ContentLinkDetail.svelte"
   import ContentLinkUrl from "@app/components/ContentLinkUrl.svelte"
   import {pushModal} from "@app/modal"
-  import {IMAGE_CONTENT_TYPES} from "@app/content"
+  import {getUrlContentType, IMAGE_CONTENT_TYPES} from "@app/content"
 
   const {value, event} = $props()
 
   const url = value.url.toString()
-  const fileType = tagValue(tagSpec("file-type"), event.tags) || ""
+  const fileType = getUrlContentType(url, event)
 
   const expand = () => pushModal(ContentLinkDetail, {value, event}, {fullscreen: true})
 </script>

src/app/content.ts

@@ -15,8 +15,11 @@ import {
   THREAD,
   ZAP_GOAL,
   ZAP_RECEIPT,
+  matchTags,
+  tagSpec,
+  tagValue,
 } from "@welshman/util"
-import type {Filter} from "@welshman/util"
+import type {Filter, TrustedEvent} from "@welshman/util"
 import {ENABLE_ZAPS} from "@app/env"
 export const IMAGE_CONTENT_TYPES = ["image/jpeg", "image/png", "image/gif", "image/webp"]
 
@@ -32,6 +35,28 @@ export const AUDIO_CONTENT_TYPES = [
   "audio/flac",
 ]
 
+export const getUrlTags = (url: string, event: TrustedEvent) => {
+  // An imeta tag packs its own tags into space-separated values, so unpack them.
+  const imetas = matchTags(tagSpec("imeta"), event.tags).map(([, ...values]: string[]) =>
+    values.map(value => value.split(" ")),
+  )
+  const imeta = imetas.find(meta => tagValue(tagSpec("url"), meta) === url)
+
+  if (imeta) {
+    return imeta
+  }
+
+  // A nip 17 file message describes its one file on the event itself, but an event carrying imeta
+  // has said all it has to say about each url, so any other link in it is described by nothing.
+  return imetas.length > 0 ? [] : event.tags
+}
+
+export const getUrlContentType = (url: string, event: TrustedEvent) => {
+  const tags = getUrlTags(url, event)
+
+  return tagValue(tagSpec("m"), tags) || tagValue(tagSpec("file-type"), tags) || ""
+}
+
 export const makeCommentFilter = (kinds: number[], extra: Filter = {}) => ({
   kinds: [COMMENT],
   "#K": kinds.map(String),