'Image stores' to enable better image caching

lib.js

@@ -46,7 +46,7 @@ export const getLinkExtname = link =>
   Path.extname(new URL(link).pathname)
 
 export const getImageBasePath = (source, postId) =>
-  `images/${source.name}-${postId}`
+  `${source.name}-${postId}`
 
 export const writeStylesheet = (path, { directory, batch }) =>
   batch.add(
@@ -66,12 +66,29 @@ export const testBlacklist = (array, blacklist) =>
   blacklist.find(tag => array.includes(tag)) !== undefined
 
 export const createView = (directory, pageSize, extra = {}) => {
-  return {
+  let view = {
     batch: new PromiseBatch(),
     directory,
     pageSize,
     ...extra
   }
+
+  return view
+}
+
+export const openImageStore = async view => {
+  let imageStorePath = Path.join(view.directory, view.imageStoreDirectory)
+  let dirents = await FS.readdir(imageStorePath, { withFileTypes: true })
+  view.imageStore = new Map()
+
+  for(let dirent of dirents) {
+    if(dirent.isFile()) {
+      let basename = dirent.name.slice(0, dirent.name.lastIndexOf('.'))
+      view.imageStore.set(basename, Path.join(view.imageStoreDirectory, dirent.name))
+    }
+  }
+
+  return view
 }
 
 export const isUnset = (value) => {
@@ -251,14 +268,22 @@ export const createPosts = async (channel, source, fromDate, reducerCallback) =>
 
     source.items.push(item)
 
-    let promise = reducerCallback(post)
-      .then(post => {
-        if(post) {
-          source.posts.push(post)
-        }
-      })
+    let postResolvable = reducerCallback(post)
+    
+    if(postResolvable instanceof Promise) {
+      postResolvable
+        .then(post => {
+          if(post) {
+            source.posts.push(post)
+          }
+        })
+    } else {
+      if(postResolvable) {
+        source.posts.push(postResolvable)
+      }
+    }
 
-    promises.push(promise)
+    promises.push(postResolvable)
   }
 
   await Promise.all(promises)
@@ -513,7 +538,7 @@ export const renderNavEntry = (list) => {
 // |   | | | | | | |   | | | | |
 // `-' `-' ' ' `-` `-' ' `-' ' '
 
-export const downloadImage = async (url, basename, { courtesyWait, retryAttempts }, { batch, directory }) => {
+export const downloadImage = async (url, basename, { courtesyWait, retryAttempts }, { batch, directory, imageStoreDirectory }) => {
   let response = await retryDelayedFetch(url, {}, courtesyWait, retryAttempts)
     .catch(err => console.error(`Failed download of ${url}:`, err, err.errors) )
 
@@ -532,7 +557,7 @@ export const downloadImage = async (url, basename, { courtesyWait, retryAttempts
     }
 
     let relativePath = basename + extension
-    let path = Path.join(directory, relativePath)
+    let path = Path.join(directory, imageStoreDirectory, relativePath)
 
     const download = () => write(path, response.body)
       .then(annotate( `Downloaded ${relativePath}`))
@@ -552,8 +577,13 @@ export const downloadImages = (images, source, postId, view) => {
 
   for(let i = 0; i < images.length; i++) {
     let basename = images.length > 1 ? basePath + '-' + i : basePath
+    let pathname = view.imageStore.get(basename)
 
-    pathnames.push(downloadImage(images[i], basename, source, view))
+    if(isUnset(pathname)) {
+      pathname = downloadImage(images[i], basename, source, view)
+    }
+
+    pathnames.push(pathname)
   }
   
   return Promise.all(pathnames)
@@ -827,4 +857,4 @@ export const mastodon = {
       return post
     }
   }
-}
+}