src/main/kotlin/net/pterodactylus/sone/core/DefaultElementLoader.kt

   1 package net.pterodactylus.sone.core
   2
   3 import com.google.common.cache.CacheBuilder
   4 import freenet.keys.FreenetURI
   5 import java.io.ByteArrayInputStream
   6 import javax.imageio.ImageIO
   7 import javax.inject.Inject
   8
   9 /**
  10  * [ElementLoader] implementation that uses a simple Guava [com.google.common.cache.Cache].
  11  */
  12 class DefaultElementLoader @Inject constructor(private val freenetInterface: FreenetInterface) : ElementLoader {
  13
  14         private val loadingLinks = CacheBuilder.newBuilder().build<String, Boolean>()
  15         private val imageCache = CacheBuilder.newBuilder().build<String, LinkedImage>()
  16         private val callback = object : FreenetInterface.BackgroundFetchCallback {
  17                 override fun loaded(uri: FreenetURI, mimeType: String, data: ByteArray) {
  18                         if (!mimeType.startsWith("image/")) {
  19                                 return
  20                         }
  21                         ByteArrayInputStream(data).use {
  22                                 ImageIO.read(it)
  23                         }?.let {
  24                                 imageCache.get(uri.toString()) { LinkedImage(uri.toString()) }
  25                         }
  26                         removeLoadingLink(uri)
  27                 }
  28
  29                 override fun failed(uri: FreenetURI) {
  30                         removeLoadingLink(uri)
  31                 }
  32
  33                 private fun removeLoadingLink(uri: FreenetURI) {
  34                         synchronized(loadingLinks) {
  35                                 loadingLinks.invalidate(uri.toString())
  36                         }
  37                 }
  38         }
  39
  40         override fun loadElement(link: String): LinkedElement {
  41                 synchronized(loadingLinks) {
  42                         imageCache.getIfPresent(link)?.run {
  43                                 return this
  44                         }
  45                         if (loadingLinks.getIfPresent(link) == null) {
  46                                 loadingLinks.put(link, true)
  47                                 freenetInterface.startFetch(FreenetURI(link), callback)
  48                         }
  49                 }
  50                 return object : LinkedElement {
  51                         override val link = link
  52                         override val loading = true
  53                 }
  54         }
  55
  56 }