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 cancelForMimeType(uri: FreenetURI, mimeType: String): Boolean {
  18                         return !mimeType.startsWith("image/")
  19                 }
  20
  21                 override fun loaded(uri: FreenetURI, mimeType: String, data: ByteArray) {
  22                         if (!mimeType.startsWith("image/")) {
  23                                 return
  24                         }
  25                         ByteArrayInputStream(data).use {
  26                                 ImageIO.read(it)
  27                         }?.let {
  28                                 imageCache.get(uri.toString()) { LinkedImage(uri.toString()) }
  29                         }
  30                         removeLoadingLink(uri)
  31                 }
  32
  33                 override fun failed(uri: FreenetURI) {
  34                         removeLoadingLink(uri)
  35                 }
  36
  37                 private fun removeLoadingLink(uri: FreenetURI) {
  38                         synchronized(loadingLinks) {
  39                                 loadingLinks.invalidate(uri.toString())
  40                         }
  41                 }
  42         }
  43
  44         override fun loadElement(link: String): LinkedElement {
  45                 synchronized(loadingLinks) {
  46                         imageCache.getIfPresent(link)?.run {
  47                                 return this
  48                         }
  49                         if (loadingLinks.getIfPresent(link) == null) {
  50                                 loadingLinks.put(link, true)
  51                                 freenetInterface.startFetch(FreenetURI(link), callback)
  52                         }
  53                 }
  54                 return object : LinkedElement {
  55                         override val link = link
  56                         override val loading = true
  57                 }
  58         }
  59
  60 }