RealImageLoader.kt

package coil

import android.content.Context
import android.util.Log
import androidx.annotation.MainThread
import coil.decode.BitmapFactoryDecoder
import coil.disk.DiskCache
import coil.fetch.AssetUriFetcher
import coil.fetch.BitmapFetcher
import coil.fetch.ByteBufferFetcher
import coil.fetch.ContentUriFetcher
import coil.fetch.DrawableFetcher
import coil.fetch.FileFetcher
import coil.fetch.HttpUriFetcher
import coil.fetch.ResourceUriFetcher
import coil.intercept.EngineInterceptor
import coil.intercept.RealInterceptorChain
import coil.key.FileKeyer
import coil.key.UriKeyer
import coil.map.ByteArrayMapper
import coil.map.FileUriMapper
import coil.map.HttpUrlMapper
import coil.map.ResourceIntMapper
import coil.map.ResourceUriMapper
import coil.map.StringMapper
import coil.memory.MemoryCache
import coil.request.DefaultRequestOptions
import coil.request.Disposable
import coil.request.ErrorResult
import coil.request.ImageRequest
import coil.request.ImageResult
import coil.request.NullRequestData
import coil.request.NullRequestDataException
import coil.request.OneShotDisposable
import coil.request.RequestService
import coil.request.SuccessResult
import coil.target.Target
import coil.target.ViewTarget
import coil.transition.NoneTransition
import coil.transition.TransitionTarget
import coil.util.Emoji
import coil.util.ImageLoaderOptions
import coil.util.Logger
import coil.util.SystemCallbacks
import coil.util.awaitStarted
import coil.util.emoji
import coil.util.get
import coil.util.log
import coil.util.requestManager
import coil.util.toDrawable
import kotlinx.coroutines.CancellationException
import kotlinx.coroutines.CoroutineExceptionHandler
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.SupervisorJob
import kotlinx.coroutines.async
import kotlinx.coroutines.cancel
import kotlinx.coroutines.coroutineScope
import kotlinx.coroutines.job
import kotlinx.coroutines.withContext
import okhttp3.Call
import java.util.concurrent.atomic.AtomicBoolean
import kotlin.coroutines.coroutineContext

internal class RealImageLoader(
    val context: Context,
    override val defaults: DefaultRequestOptions,
    val memoryCacheLazy: Lazy<MemoryCache?>,
    val diskCacheLazy: Lazy<DiskCache?>,
    val callFactoryLazy: Lazy<Call.Factory>,
    val eventListenerFactory: EventListener.Factory,
    val componentRegistry: ComponentRegistry,
    val options: ImageLoaderOptions,
    val logger: Logger?,
) : ImageLoader {

    private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Main.immediate +
        CoroutineExceptionHandler { _, throwable -> logger?.log(TAG, throwable) })
    private val systemCallbacks = SystemCallbacks(this, context, options.networkObserverEnabled)
    private val requestService = RequestService(this, systemCallbacks, logger)
    override val memoryCache by memoryCacheLazy
    override val diskCache by diskCacheLazy
    override val components = componentRegistry.newBuilder()
        // Mappers
        .add(HttpUrlMapper())
        .add(StringMapper())
        .add(FileUriMapper())
        .add(ResourceUriMapper())
        .add(ResourceIntMapper())
        .add(ByteArrayMapper())
        // Keyers
        .add(UriKeyer())
        .add(FileKeyer(options.addLastModifiedToFileCacheKey))
        // Fetchers
        .add(HttpUriFetcher.Factory(callFactoryLazy, diskCacheLazy, options.respectCacheHeaders))
        .add(FileFetcher.Factory())
        .add(AssetUriFetcher.Factory())
        .add(ContentUriFetcher.Factory())
        .add(ResourceUriFetcher.Factory())
        .add(DrawableFetcher.Factory())
        .add(BitmapFetcher.Factory())
        .add(ByteBufferFetcher.Factory())
        // Decoders
        .add(BitmapFactoryDecoder.Factory(options.bitmapFactoryMaxParallelism))
        .build()
    private val interceptors = components.interceptors +
        EngineInterceptor(this, requestService, logger)
    private val isShutdown = AtomicBoolean(false)

    override fun enqueue(request: ImageRequest): Disposable {
        // Start executing the request on the main thread.
        val job = scope.async {
            executeMain(request, REQUEST_TYPE_ENQUEUE).also { result ->
                if (result is ErrorResult) logger?.log(TAG, result.throwable)
            }
        }

        // Update the current request attached to the view and return a new disposable.
        return if (request.target is ViewTarget<*>) {
            request.target.view.requestManager.getDisposable(job)
        } else {
            OneShotDisposable(job)
        }
    }

    override suspend fun execute(request: ImageRequest) = coroutineScope {
        // Start executing the request on the main thread.
        val job = async(Dispatchers.Main.immediate) {
            executeMain(request, REQUEST_TYPE_EXECUTE)
        }

        // Update the current request attached to the view and await the result.
        if (request.target is ViewTarget<*>) {
            request.target.view.requestManager.getDisposable(job)
        }
        return@coroutineScope job.await()
    }

    @MainThread
    private suspend fun executeMain(initialRequest: ImageRequest, type: Int): ImageResult {
        // Wrap the request to manage its lifecycle.
        val requestDelegate = requestService.requestDelegate(initialRequest, coroutineContext.job)
            .apply { assertActive() }

        // Apply this image loader's defaults to this request.
        val request = initialRequest.newBuilder().defaults(defaults).build()

        // Create a new event listener.
        val eventListener = eventListenerFactory.create(request)

        try {
            // Fail before starting if data is null.
            if (request.data == NullRequestData) throw NullRequestDataException()

            // Set up the request's lifecycle observers.
            requestDelegate.start()

            // Enqueued requests suspend until the lifecycle is started.
            if (type == REQUEST_TYPE_ENQUEUE) request.lifecycle.awaitStarted()

            // Set the placeholder on the target.
            val placeholderBitmap = memoryCache?.get(request.placeholderMemoryCacheKey)?.bitmap
            val placeholder = placeholderBitmap?.toDrawable(request.context) ?: request.placeholder
            request.target?.onStart(placeholder)
            eventListener.onStart(request)
            request.listener?.onStart(request)

            // Resolve the size.
            eventListener.resolveSizeStart(request)
            val size = request.sizeResolver.size()
            eventListener.resolveSizeEnd(request, size)

            // Execute the interceptor chain.
            val result = withContext(request.interceptorDispatcher) {
                RealInterceptorChain(
                    initialRequest = request,
                    interceptors = interceptors,
                    index = 0,
                    request = request,
                    size = size,
                    eventListener = eventListener,
                    isPlaceholderCached = placeholderBitmap != null
                ).proceed(request)
            }

            // Set the result on the target.
            when (result) {
                is SuccessResult -> onSuccess(result, request.target, eventListener)
                is ErrorResult -> onError(result, request.target, eventListener)
            }
            return result
        } catch (throwable: Throwable) {
            if (throwable is CancellationException) {
                onCancel(request, eventListener)
                throw throwable
            } else {
                // Create the default error result if there's an uncaught exception.
                val result = requestService.errorResult(request, throwable)
                onError(result, request.target, eventListener)
                return result
            }
        } finally {
            requestDelegate.complete()
        }
    }

    /** Called by [SystemCallbacks.onTrimMemory]. */
    @Suppress("SAFE_CALL_WILL_CHANGE_NULLABILITY", "UNNECESSARY_SAFE_CALL")
    internal fun onTrimMemory(level: Int) {
        // https://github.com/coil-kt/coil/issues/1211
        memoryCacheLazy?.value?.trimMemory(level)
    }

    override fun shutdown() {
        if (isShutdown.getAndSet(true)) return
        scope.cancel()
        systemCallbacks.shutdown()
        memoryCache?.clear()
    }

    override fun newBuilder() = ImageLoader.Builder(this)

    private fun onSuccess(
        result: SuccessResult,
        target: Target?,
        eventListener: EventListener
    ) {
        val request = result.request
        val dataSource = result.dataSource
        logger?.log(TAG, Log.INFO) {
            "${dataSource.emoji} Successful (${dataSource.name}) - ${request.data}"
        }
        transition(result, target, eventListener) { target?.onSuccess(result.drawable) }
        eventListener.onSuccess(request, result)
        request.listener?.onSuccess(request, result)
    }

    private fun onError(
        result: ErrorResult,
        target: Target?,
        eventListener: EventListener
    ) {
        val request = result.request
        logger?.log(TAG, Log.INFO) {
            "${Emoji.SIREN} Failed - ${request.data} - ${result.throwable}"
        }
        transition(result, target, eventListener) { target?.onError(result.drawable) }
        eventListener.onError(request, result)
        request.listener?.onError(request, result)
    }

    private fun onCancel(request: ImageRequest, eventListener: EventListener) {
        logger?.log(TAG, Log.INFO) {
            "${Emoji.CONSTRUCTION} Cancelled - ${request.data}"
        }
        eventListener.onCancel(request)
        request.listener?.onCancel(request)
    }

    private inline fun transition(
        result: ImageResult,
        target: Target?,
        eventListener: EventListener,
        setDrawable: () -> Unit
    ) {
        if (target !is TransitionTarget) {
            setDrawable()
            return
        }

        val transition = result.request.transitionFactory.create(target, result)
        if (transition is NoneTransition) {
            setDrawable()
            return
        }

        eventListener.transitionStart(result.request, transition)
        transition.transition()
        eventListener.transitionEnd(result.request, transition)
    }

    companion object {
        private const val TAG = "RealImageLoader"
        private const val REQUEST_TYPE_ENQUEUE = 0
        private const val REQUEST_TYPE_EXECUTE = 1
    }
}