fix: styles and scripts not injected into epub navigator

readium/navigator/src/main/java/org/readium/r2/navigator/epub/WebViewServer.kt

@@ -10,6 +10,7 @@ package org.readium.r2.navigator.epub
 
 import android.app.Application
 import android.os.PatternMatcher
+import android.webkit.MimeTypeMap
 import android.webkit.WebResourceRequest
 import android.webkit.WebResourceResponse
 import androidx.webkit.WebViewAssetLoader
@@ -28,9 +29,11 @@ import org.readium.r2.shared.util.data.ReadError
 import org.readium.r2.shared.util.data.asInputStream
 import org.readium.r2.shared.util.http.HttpHeaders
 import org.readium.r2.shared.util.http.HttpRange
+import org.readium.r2.shared.util.mediatype.MediaType
 import org.readium.r2.shared.util.resource.Resource
 import org.readium.r2.shared.util.resource.StringResource
 import org.readium.r2.shared.util.resource.fallback
+import org.readium.r2.shared.util.toUrl
 
 /**
  * Serves the publication resources and application assets in the EPUB navigator web views.
@@ -44,8 +47,11 @@ internal class WebViewServer(
     private val onResourceLoadFailed: (Url, ReadError) -> Unit,
 ) {
     companion object {
-        val publicationBaseHref = AbsoluteUrl("https://readium/publication/")!!
-        val assetsBaseHref = AbsoluteUrl("https://readium/assets/")!!
+        const val READIUM_PACKAGE_HOSTNAME = "readium_package"
+        const val ASSETS_HOSTNAME = "readium_assets"
+
+        val publicationBaseHref = AbsoluteUrl("https://$READIUM_PACKAGE_HOSTNAME/")!!
+        val assetsBaseHref = AbsoluteUrl("https://$ASSETS_HOSTNAME/")!!
 
         fun assetUrl(path: String): Url? =
             Url.fromDecodedPath(path)?.let { assetsBaseHref.resolve(it) }
@@ -54,28 +60,64 @@ internal class WebViewServer(
     /**
      * Serves the requests of the navigator web views.
      *
-     * https://readium/publication/ serves the publication resources through its fetcher.
-     * https://readium/assets/ serves the application assets.
+     * https://readium_package/ serves the publication resources through its fetcher.
+     * https://readium_assets/ serves the application assets.
      */
     fun shouldInterceptRequest(request: WebResourceRequest, css: ReadiumCss): WebResourceResponse? {
-        if (request.url.host != "readium") return null
         val path = request.url.path ?: return null
+        val hostname = request.url.host ?: return null
+        val requestUrl = request.url.toUrl() ?: return null
+        val range = HttpHeaders(request.requestHeaders).range
 
-        return when {
-            path.startsWith("/publication/") -> {
-                val href = Url.fromDecodedPath(path.removePrefix("/publication/"))
-                    ?: return null
+        return when (hostname) {
+            READIUM_PACKAGE_HOSTNAME -> {
+                // Request is for a packaged resource.
+                val href = Url.fromDecodedPath(path.removePrefix("/"))
+                    ?: return serveErrorResponse()
 
                 servePublicationResource(
                     href = href,
-                    range = HttpHeaders(request.requestHeaders).range,
+                    range = range,
                     css = css
                 )
             }
-            path.startsWith("/assets/") && isServedAsset(path.removePrefix("/assets/")) -> {
+
+            ASSETS_HOSTNAME if isServedAsset(path.removePrefix("/")) -> {
+                // Request is for a known asset.
                 assetsLoader.shouldInterceptRequest(request.url)
             }
-            else -> null
+
+            ASSETS_HOSTNAME -> {
+                val error = ReadError.Decoding(
+                    "Attempted to load an unknown asset from $requestUrl"
+                )
+                onResourceLoadFailed(requestUrl, error)
+                serveErrorResponse() // Request is for an unknown asset.
+            }
+
+            else -> {
+                // Request is for streaming a resource, if the baseUrl an AbsoluteUrl and hostname
+                // is not ASSETS_HOSTNAME or READIUM_PACKAGE_HOSTNAME
+                val baseUrl = publication.baseUrl as? AbsoluteUrl ?: run {
+                    val error = ReadError.Decoding(
+                        "baseUrl is not an AbsoluteUrl, cannot load remote resource from $requestUrl"
+                    )
+                    onResourceLoadFailed(requestUrl, error)
+                    return serveErrorResponse()
+                }
+
+                val href =
+                    // Look up the link in the publication to make sure we have the right resource.
+                    publicationLinkFromHref(baseUrl.resolve(requestUrl))?.href?.resolve()
+                        ?: publicationLinkFromHref(baseUrl.relativize(requestUrl))?.href?.resolve()
+                        ?: requestUrl
+
+                servePublicationResource(
+                    href = href,
+                    range = range,
+                    css = css
+                )
+            }
         }
     }
 
@@ -84,15 +126,17 @@ internal class WebViewServer(
      *
      * If the [Resource] is an HTML document, injects the required JavaScript and CSS files.
      */
-    private fun servePublicationResource(href: Url, range: HttpRange?, css: ReadiumCss): WebResourceResponse {
-        val link = publication.linkWithHref(href)
-            // Query parameters must be kept as they might be relevant for the fetcher.
-            ?.copy(href = Href(href))
-            ?: Link(href = href)
+    private fun servePublicationResource(
+        href: Url,
+        range: HttpRange?,
+        css: ReadiumCss
+    ): WebResourceResponse {
+        val link = publicationLinkFromHref(href)
+        // Link not found, create a Link from the href and guess the MediaType
+            ?: Link(href = href, mediaType = mediaTypeFromUrl(href))
 
         // Drop anchor because it is meant to be interpreted by the client.
         val urlWithoutAnchor = href.removeFragment()
-
         var resource = publication
             .get(urlWithoutAnchor)
             ?.fallback {
@@ -106,41 +150,52 @@ internal class WebViewServer(
             errorResource()
         }
 
-        link.mediaType
-            ?.takeIf { it.isHtml }
-            ?.let {
-                resource = resource.injectHtml(
-                    publication,
-                    mediaType = it,
-                    css,
-                    baseHref = assetsBaseHref,
-                    disableSelectionWhenProtected = disableSelectionWhenProtected
-                )
-            }
+        // Only inject html when the profile is EPUB
+        if (publication.conformsTo(Publication.Profile.EPUB)) {
+            link.mediaType
+                ?.takeIf { it.isHtml }
+                ?.let {
+                    resource = resource.injectHtml(
+                        publication,
+                        mediaType = it,
+                        css,
+                        baseHref = assetsBaseHref,
+                        disableSelectionWhenProtected = disableSelectionWhenProtected
+                    )
+                }
+        }
 
+        return serveResource(resource, range, link.mediaType)
+    }
+
+    private fun serveResource(
+        resource: Resource,
+        range: HttpRange?,
+        mediaType: MediaType?,
+    ): WebResourceResponse {
         val headers = mutableMapOf(
             "Accept-Ranges" to "bytes"
         )
 
+        val stream = resource.asInputStream()
         if (range == null) {
             return WebResourceResponse(
-                link.mediaType?.toString(),
+                mediaType?.toString(),
                 null,
                 200,
                 "OK",
                 headers,
-                resource.asInputStream()
+                stream
             )
         } else { // Byte range request
-            val stream = resource.asInputStream()
             val length = stream.available()
             val longRange = range.toLongRange(length.toLong())
             headers["Content-Range"] = "bytes ${longRange.first}-${longRange.last}/$length"
             // Content-Length will automatically be filled by the WebView using the Content-Range header.
             // headers["Content-Length"] = (longRange.last - longRange.first + 1).toString()
             // Weirdly, the WebView will call itself stream.skip to skip to the requested range.
             return WebResourceResponse(
-                link.mediaType?.toString(),
+                mediaType?.toString(),
                 null,
                 206,
                 "Partial Content",
@@ -149,6 +204,26 @@ internal class WebViewServer(
             )
         }
     }
+
+    /**
+     * Resolve the [MediaType] from an [Url].
+     */
+    private fun mediaTypeFromUrl(href: Url): MediaType? {
+        val ext = MimeTypeMap.getFileExtensionFromUrl(href.normalize().toString()) ?: return null
+        val mimetype = MimeTypeMap.getSingleton().getMimeTypeFromExtension(ext) ?: return null
+
+        return MediaType.invoke(mimetype)
+    }
+
+    /**
+     * Get link in publication from a [Url] and replace href to preserve request query parameters.
+     */
+    private fun publicationLinkFromHref(href: Url): Link? {
+        return publication.linkWithHref(href)
+            // Query parameters must be kept as they might be relevant for the fetcher.
+            ?.copy(href = Href(href))
+    }
+
     private fun errorResource(): Resource =
         StringResource {
             withContext(Dispatchers.IO) {
@@ -161,6 +236,10 @@ internal class WebViewServer(
             }
         }
 
+    private fun serveErrorResponse(): WebResourceResponse {
+        return serveResource(errorResource(), null, MediaType.XHTML)
+    }
+
     private fun isServedAsset(path: String): Boolean =
         servedAssetPatterns.any { it.match(path) }
 
@@ -169,7 +248,7 @@ internal class WebViewServer(
 
     private val assetsLoader =
         WebViewAssetLoader.Builder()
-            .setDomain("readium")
-            .addPathHandler("/assets/", WebViewAssetLoader.AssetsPathHandler(application))
+            .setDomain(ASSETS_HOSTNAME)
+            .addPathHandler("/", WebViewAssetLoader.AssetsPathHandler(application))
             .build()
 }

readium/shared/src/main/java/org/readium/r2/shared/util/Url.kt

@@ -310,6 +310,11 @@ public class AbsoluteUrl private constructor(override val uri: Uri) : Url() {
     public val isContent: Boolean get() =
         scheme.isContent
 
+    /**
+     * Hostname of the URL.
+     */
+    public val host: String? get() = uri.host
+
     /**
      * Converts the URL to a [File], if it's a file URL.
      */