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Implement HTTP Cache Checking #39

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13 changes: 12 additions & 1 deletion app/src/main/java/org/cssnr/remotewallpaper/db/RemoteDao.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ import androidx.room.Room
import androidx.room.RoomDatabase
import androidx.room.Transaction
import androidx.room.Upsert
import androidx.room.migration.Migration
import androidx.sqlite.db.SupportSQLiteDatabase
import java.util.concurrent.Executors

Expand Down Expand Up @@ -68,17 +69,26 @@ data class Remote(
//@PrimaryKey(autoGenerate = true) val id: Long = 0,
@PrimaryKey val url: String,
val active: Boolean = false,
val etag: String? = null,
val lastModified: String? = null,
)


@Database(entities = [Remote::class], version = 1, exportSchema = false)
@Database(entities = [Remote::class], version = 2, exportSchema = false)
abstract class RemoteDatabase : RoomDatabase() {
abstract fun remoteDao(): RemoteDao

companion object {
@Volatile
private var instance: RemoteDatabase? = null

private val MIGRATION_1_2 = object : Migration(1, 2) {
override fun migrate(db: SupportSQLiteDatabase) {
db.execSQL("ALTER TABLE Remote ADD COLUMN etag TEXT DEFAULT NULL")
db.execSQL("ALTER TABLE Remote ADD COLUMN lastModified TEXT DEFAULT NULL")
}
}

private val defaultData: List<Remote> = listOf(
Remote("https://picsum.photos/4800/2400", active = true),
Remote("https://picsum.photos/4800/2400?blur=10", active = false),
Expand All @@ -103,6 +113,7 @@ abstract class RemoteDatabase : RoomDatabase() {
}
}
})
.addMigrations(MIGRATION_1_2)
.build().also { instance = it }
}
}
Expand Down
52 changes: 41 additions & 11 deletions app/src/main/java/org/cssnr/remotewallpaper/ui/home/HomeFragment.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@ import org.cssnr.remotewallpaper.R
import org.cssnr.remotewallpaper.databinding.FragmentHomeBinding
import org.cssnr.remotewallpaper.db.HistoryDatabase
import org.cssnr.remotewallpaper.db.HistoryItem
import org.cssnr.remotewallpaper.db.Remote
import org.cssnr.remotewallpaper.db.RemoteDatabase
import java.io.File
import java.io.FileOutputStream
Expand Down Expand Up @@ -188,7 +189,7 @@ fun Context.showAddDialog() {
if (url.isNotEmpty()) {
CoroutineScope(Dispatchers.IO).launch {
try {
downloadImage(url)
downloadImage(Remote(url = url))
withContext(Dispatchers.Main) {
Toast.makeText(this@showAddDialog, "Done.", Toast.LENGTH_SHORT).show()
dialog.dismiss()
Expand All @@ -208,6 +209,11 @@ fun Context.showAddDialog() {
dialog.show()
}

sealed class DownloadResult {
data class Downloaded(val response: Response) : DownloadResult()
data object NotModified : DownloadResult()
}

// TODO: updateWallpaper is used globally to update the wallpaper and should be a package
// The rest of the functions are only used by updateWallpaper and are internal to updateWallpaper
suspend fun Context.updateWallpaper(): Boolean {
Expand All @@ -220,10 +226,19 @@ suspend fun Context.updateWallpaper(): Boolean {
Log.d("updateWallpaper", "remote: $remote")
if (remote != null) {
history.remote = remote.url
val response = withContext(Dispatchers.IO) { downloadImage(remote.url) }
history.status = response.code
history.url = response.request.url.toString()
Log.d("updateWallpaper", "response: $response")
val result = withContext(Dispatchers.IO) { downloadImage(remote) }
when (result) {
is DownloadResult.Downloaded -> {
history.status = result.response.code
history.url = result.response.request.url.toString()
Log.d("updateWallpaper", "response: ${result.response}")
}
is DownloadResult.NotModified -> {
history.status = 304
history.url = remote.url
Log.i("updateWallpaper", "Image not modified, skipping wallpaper update")
}
}
// TODO: Replace timestamp with history.timestamp
val timestamp: String =
ZonedDateTime.now().format(DateTimeFormatter.ISO_ZONED_DATE_TIME)
Expand All @@ -246,19 +261,34 @@ suspend fun Context.updateWallpaper(): Boolean {
}
}

fun Context.downloadImage(url: String): Response {
suspend fun Context.downloadImage(remote: Remote): DownloadResult {
val client = OkHttpClient.Builder()
.followRedirects(true)
.build()

val request = Request.Builder()
.url(url)
.build()
val requestBuilder = Request.Builder().url(remote.url)
remote.etag?.let { requestBuilder.header("If-None-Match", it) }
remote.lastModified?.let { requestBuilder.header("If-Modified-Since", it) }

val response = client.newCall(request).execute()
val response = client.newCall(requestBuilder.build()).execute()

response.use {
if (it.code == 304) {
Log.d("downloadImage", "304 Not Modified for ${remote.url}")
return DownloadResult.NotModified
}
if (!it.isSuccessful) throw Exception("Failed to download image: $it")

val newEtag = it.header("ETag")
val newLastModified = it.header("Last-Modified")
if (newEtag != null || newLastModified != null) {
val dao = RemoteDatabase.getInstance(this).remoteDao()
withContext(Dispatchers.IO) {
dao.addOrUpdate(remote.copy(etag = newEtag, lastModified = newLastModified))
}
Log.d("downloadImage", "Saved cache headers: etag=$newEtag, lastModified=$newLastModified")
}

val body = it.body
val imageFile = File(filesDir, "wallpaper.img")

Expand All @@ -270,7 +300,7 @@ fun Context.downloadImage(url: String): Response {

setAutoCroppedWallpaper(imageFile)
}
return response
return DownloadResult.Downloaded(response)
}

fun Context.setAutoCroppedWallpaper(imageFile: File) {
Expand Down
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