Support for EPUB internal links (#28)

Author: mihai-wolfpack

CHANGELOG.md

@@ -22,7 +22,8 @@ All notable changes to this project will be documented in this file. Take a look
 #### Navigator
 
 * `EpubNavigatorFragment`'s `goForward()` and `goBackward()` are now jumping to the previous or next pages instead of resources.
-* [#20](https://github.com/readium/kotlin-toolkit/issues/20) EPUB navigator stuck between two pages with vertical swipes
+* [#20](https://github.com/readium/kotlin-toolkit/issues/20) EPUB navigator stuck between two pages with vertical swipes.
+* [#27](https://github.com/readium/kotlin-toolkit/issues/27) Internal links break the EPUB navigator (contributed by [@mihai-wolfpack](https://github.com/readium/kotlin-toolkit/pull/28)).
 
 
 ## [2.1.0]

readium/navigator/src/main/java/org/readium/r2/navigator/R2BasicWebView.kt

@@ -65,6 +65,11 @@ open class R2BasicWebView(context: Context, attrs: AttributeSet) : WebView(conte
          * Returns the custom [ActionMode.Callback] to be used with the text selection menu.
          */
         val selectionActionModeCallback: ActionMode.Callback? get() = null
+
+        /**
+         * Offers an opportunity to override a request loaded by the given web view.
+         */
+        fun shouldOverrideUrlLoading(webView: WebView, request: WebResourceRequest): Boolean = false
     }
 
     lateinit var listener: Listener
@@ -471,31 +476,10 @@ open class R2BasicWebView(context: Context, attrs: AttributeSet) : WebView(conte
         }
     }
 
-    /**
-     * Prevents opening external links in the web view.
-     * To be called from the WebViewClient implementation attached to the web view.
-     */
     internal fun shouldOverrideUrlLoading(request: WebResourceRequest): Boolean {
-        val resourceUrl = url ?: return false
-
-        // List of hosts that are allowed to be loaded in the web view.
-        // The host of the page already loaded in the web view is always allowed.
-        val passthroughHosts = listOfNotNull(
-            "localhost", "127.0.0.1",
-            tryOrNull { Uri.parse(resourceUrl) }?.host
-        )
-        if (!passthroughHosts.contains(request.url.host)) {
-            openExternalLink(request.url)
-            return true
-        }
-
-        return false
-    }
+        if (resourceUrl == request.url?.toString()) return false
 
-    private fun openExternalLink(url: Uri) {
-        CustomTabsIntent.Builder()
-            .build()
-            .launchUrl(context, url)
+        return listener.shouldOverrideUrlLoading(this, request)
     }
 
     // Text selection ActionMode overrides

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

@@ -10,11 +10,15 @@ import android.content.Context
 import android.content.SharedPreferences
 import android.graphics.PointF
 import android.graphics.RectF
+import android.net.Uri
 import android.os.Bundle
 import android.view.ActionMode
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import android.webkit.WebResourceRequest
+import android.webkit.WebView
+import androidx.browser.customtabs.CustomTabsIntent
 import androidx.collection.forEach
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentActivity
@@ -46,7 +50,6 @@ import org.readium.r2.shared.publication.*
 import org.readium.r2.shared.publication.epub.EpubLayout
 import org.readium.r2.shared.publication.presentation.presentation
 import org.readium.r2.shared.publication.services.isRestricted
-import org.readium.r2.shared.publication.services.positions
 import org.readium.r2.shared.publication.services.positionsByReadingOrder
 import kotlin.math.ceil
 import kotlin.reflect.KClass
@@ -262,7 +265,6 @@ class EpubNavigatorFragment private constructor(
     internal var pendingLocator: Locator? = null
 
     override fun go(locator: Locator, animated: Boolean, completion: () -> Unit): Boolean {
-
         val href = locator.href
             // Remove anchor
             .substringBefore("#")
@@ -470,6 +472,36 @@ class EpubNavigatorFragment private constructor(
 
         override val selectionActionModeCallback: ActionMode.Callback?
             get() = config.selectionActionModeCallback
+
+        /**
+         * Prevents opening external links in the web view and handles internal links.
+         */
+        override fun shouldOverrideUrlLoading(webView: WebView, request: WebResourceRequest): Boolean {
+            val url = request.url?.toString()
+                ?: return false
+
+            val baseUrl = baseUrl.takeIf { it.isNotBlank() }
+                ?: publication.linkWithRel("self")?.href
+                ?: return false
+
+            if (!url.startsWith(baseUrl)) {
+                openExternalLink(request.url)
+            } else {
+                // Navigate to an internal link
+                go(Link(href = url.removePrefix(baseUrl).addPrefix("/")))
+            }
+
+            return true
+        }
+
+        private fun openExternalLink(url: Uri) {
+            val context = context ?: return
+            tryOrLog {
+                CustomTabsIntent.Builder()
+                    .build()
+                    .launchUrl(context, url)
+            }
+        }
     }
 
     override fun goForward(animated: Boolean, completion: () -> Unit): Boolean {