feat(nc-gui): add getBackgroundImage & fileNotFoundImgSrc and revise showFallback

packages/nc-gui/composables/useAttachment.ts

@@ -1,22 +1,51 @@
 const useAttachment = () => {
   const { appInfo } = useGlobal()
 
+  // TODO: not hardcode _nuxt
+  const fileNotFoundImgSrc = `/_nuxt/assets/img/file-not-found.png`
+
   const getAttachmentSrc = (item: Record<string, any>) => {
-    if (item.data) {
+    if (item?.data) {
       return item.data
-    } else if (item.path) {
+    } else if (item?.path) {
       return `${appInfo.value.ncSiteUrl}/${item.path}`
+    } else if (item?.url) {
+      return item.url
     }
-    return item.url
+    return fileNotFoundImgSrc
   }
 
-  const showFallback = (evt: any, item: Record<string, any>) => {
+  // try `${appInfo.value.ncSiteUrl}/${item.path}`
+  // if it fails -> try item.url
+  // if it fails -> try default image
+  const showFallback = async (evt: any, item: Record<string, any>) => {
     evt.onerror = null
-    evt.target.src = item.url
+    if (item?.url) {
+      await fetch(item.url)
+        .then((res) => {
+          if (!res.ok || res.headers.get('Content-Type') !== item.mimetype) {
+            throw new Error('Failed to load the file')
+          }
+        })
+        .then((_) => {
+          evt.target.src = item.url
+        })
+        .catch((_) => {
+          evt.target.src = fileNotFoundImgSrc
+        })
+    } else {
+      evt.target.src = fileNotFoundImgSrc
+    }
+  }
+
+  const getBackgroundImage = (item: Record<string, any>) => {
+    return `url('${getAttachmentSrc(item)}'), url(${item.url}), url(${fileNotFoundImgSrc})`
   }
 
   return {
     getAttachmentSrc,
+    getBackgroundImage,
+    fileNotFoundImgSrc,
     showFallback,
   }
 }