1 files changed, 77 insertions, 0 deletions
diff --git a/plugins/all-modules-page/src/main/kotlin/templates/ExternalModuleLinkResolver.kt b/plugins/all-modules-page/src/main/kotlin/templates/ExternalModuleLinkResolver.kt
new file mode 100644
index 00000000..d0e787b6
--- /dev/null
+++ b/plugins/all-modules-page/src/main/kotlin/templates/ExternalModuleLinkResolver.kt
@@ -0,0 +1,77 @@
+package org.jetbrains.dokka.allModulesPage.templates
+
+import org.jetbrains.dokka.DokkaConfiguration
+import org.jetbrains.dokka.base.DokkaBase
+import org.jetbrains.dokka.base.resolvers.local.DokkaLocationProvider.Companion.identifierToFilename
+import org.jetbrains.dokka.base.resolvers.shared.ExternalDocumentation
+import org.jetbrains.dokka.base.resolvers.shared.PackageList
+import org.jetbrains.dokka.base.resolvers.shared.RecognizedLinkFormat
+import org.jetbrains.dokka.links.DRI
+import org.jetbrains.dokka.plugability.DokkaContext
+import org.jetbrains.dokka.plugability.plugin
+import org.jetbrains.dokka.plugability.query
+import java.io.File
+import java.net.URL
+
+interface ExternalModuleLinkResolver {
+    fun resolve(dri: DRI, fileContext: File): String?
+    fun resolveLinkToModuleIndex(moduleName: String): String?
+}
+
+class DefaultExternalModuleLinkResolver(val context: DokkaContext) : ExternalModuleLinkResolver {
+    private val elpFactory = context.plugin<DokkaBase>().query { externalLocationProviderFactory }
+    private val externalDocumentations by lazy(::setupExternalDocumentations)
+    private val elps by lazy {
+        elpFactory.flatMap { externalDocumentations.map { ed -> it.getExternalLocationProvider(ed) } }.filterNotNull()
+    }
+
+    private fun setupExternalDocumentations(): List<ExternalDocumentation> {
+        val packageLists =
+            context.configuration.modules.map(::loadPackageListForModule).toMap()
+        return packageLists.mapNotNull { (module, packageList) ->
+            packageList?.let {
+                ExternalDocumentation(
+                    URL("file:/${module.name}/${module.name}"),
+                    packageList
+                )
+            }
+        }
+    }
+
+    private fun loadPackageListForModule(module: DokkaConfiguration.DokkaModuleDescription) =
+        module.sourceOutputDirectory.resolve(File(identifierToFilename(module.name))).let {
+            it to PackageList.load(
+                URL("file:" + it.resolve("package-list").path),
+                8,
+                true
+            )
+        }
+
+    override fun resolve(dri: DRI, fileContext: File): String? {
+        val absoluteLink = elps.mapNotNull { it.resolve(dri) }.firstOrNull() ?: return null
+        val modulePath = context.configuration.outputDir.absolutePath.split(File.separator)
+        val contextPath = fileContext.absolutePath.split(File.separator)
+        val commonPathElements = modulePath.zip(contextPath)
+            .takeWhile { (a, b) -> a == b }.count()
+
+        return (List(contextPath.size - commonPathElements - 1) { ".." } + modulePath.drop(commonPathElements)).joinToString(
+            "/"
+        ) + absoluteLink.removePrefix("file:")
+    }
+
+    override fun resolveLinkToModuleIndex(moduleName: String): String? =
+        context.configuration.modules.firstOrNull { it.name == moduleName }
+            ?.let { module ->
+                val (_, packageList) = loadPackageListForModule(module)
+                val extension = when (packageList?.linkFormat) {
+                    RecognizedLinkFormat.KotlinWebsiteHtml,
+                    RecognizedLinkFormat.DokkaOldHtml,
+                    RecognizedLinkFormat.DokkaHtml -> ".html"
+                    RecognizedLinkFormat.DokkaGFM,
+                    RecognizedLinkFormat.DokkaJekyll -> ".md"
+                    else -> ""
+                }
+                "${module.relativePathToOutputDirectory}/${identifierToFilename(moduleName)}/index$extension"
+            }
+
+}