Implement hover request for packages

src/main/kotlin/texlab/LanguageServerImpl.kt

@@ -44,6 +44,7 @@ class LanguageServerImpl : LanguageServer {
             completionProvider = CompletionOptions(true, listOf("\\", "{", "}", "@"))
             foldingRangeProvider = Either.forLeft(true)
             definitionProvider = true
+            hoverProvider = true
         }
 
         return CompletableFuture.completedFuture(InitializeResult(capabilities))

src/main/kotlin/texlab/TextDocumentServiceImpl.kt

@@ -1,6 +1,5 @@
 package texlab
 
-import com.overzealous.remark.Remark
 import org.eclipse.lsp4j.*
 import org.eclipse.lsp4j.jsonrpc.messages.Either
 import org.eclipse.lsp4j.services.TextDocumentService
@@ -189,14 +188,8 @@ class TextDocumentServiceImpl(private val workspace: Workspace) : TextDocumentSe
             if (unresolved.kind == CompletionItemKind.Class) {
                 val metadata = metadataProvider.getMetadata(unresolved.label)
                 if (metadata != null) {
-                    val description = Remark().convert(metadata.descriptions.firstOrNull()?.text)
-                    val documentation = MarkupContent().apply {
-                        kind = MarkupKind.MARKDOWN
-                        value = description
-                    }
-
                     unresolved.detail = metadata.caption
-                    unresolved.setDocumentation(documentation)
+                    unresolved.setDocumentation(metadata.description)
                 }
             }
 
@@ -226,4 +219,29 @@ class TextDocumentServiceImpl(private val workspace: Workspace) : TextDocumentSe
             return CompletableFuture.completedFuture(location?.let { mutableListOf(it) })
         }
     }
+
+    override fun hover(params: TextDocumentPositionParams): CompletableFuture<Hover> {
+        val include = synchronized(workspace) {
+            val uri = URI.create(params.textDocument.uri)
+            val document = workspace.documents
+                    .filterIsInstance<LatexDocument>()
+                    .firstOrNull { it.uri == uri }
+                    ?: return CompletableFuture.completedFuture(null)
+
+            document.tree.includes
+                    .filter { it.command.name.text == "\\usepackage" || it.command.name.text == "\\documentclass" }
+                    .firstOrNull { it.command.range.contains(params.position) }
+                    ?: return CompletableFuture.completedFuture(null)
+        }
+
+        return CompletableFuture.supplyAsync {
+            val metadata = metadataProvider.getMetadata(include.path)
+            val description = metadata?.description
+            if (description != null) {
+                Hover(description)
+            } else {
+                null
+            }
+        }
+    }
 }

src/main/kotlin/texlab/metadata/CtanPackageMetadataProvider.kt

@@ -12,7 +12,7 @@ class CtanPackageMetadataProvider : PackageMetadataProvider {
             val json = URL("https://ctan.org/json/2.0/pkg/$name").readText()
             val mapper = jacksonObjectMapper()
                     .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
-            return mapper.readValue<PackageMetadata>(json)
+            mapper.readValue<PackageMetadata>(json)
         } catch (e: IOException) {
             null
         }

src/main/kotlin/texlab/metadata/HtmlToMarkdownConverter.kt

@@ -0,0 +1,15 @@
+package texlab.metadata
+
+import com.fasterxml.jackson.databind.util.StdConverter
+import com.overzealous.remark.Remark
+import org.eclipse.lsp4j.MarkupContent
+import org.eclipse.lsp4j.MarkupKind
+
+class HtmlToMarkdownConverter : StdConverter<String, MarkupContent>() {
+    override fun convert(value: String): MarkupContent {
+        return MarkupContent().apply {
+            kind = MarkupKind.MARKDOWN
+            this.value = Remark().convert(value)
+        }
+    }
+}

src/main/kotlin/texlab/metadata/PackageDescription.kt

@@ -1,4 +1,9 @@
 package texlab.metadata
 
+import com.fasterxml.jackson.annotation.JsonProperty
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize
+import org.eclipse.lsp4j.MarkupContent
+
 data class PackageDescription(val language: String?,
-                              val text: String)
+                              @JsonDeserialize(converter = HtmlToMarkdownConverter::class)
+                              @JsonProperty("text") val markup: MarkupContent)

src/main/kotlin/texlab/metadata/PackageMetadata.kt

@@ -1,5 +1,10 @@
 package texlab.metadata
 
+import org.eclipse.lsp4j.MarkupContent
+
 data class PackageMetadata(val name: String,
                            val caption: String,
-                           val descriptions: List<PackageDescription>)
+                           private val descriptions: List<PackageDescription>) {
+    val description: MarkupContent?
+        get() = descriptions.firstOrNull() { it.language == null }?.markup
+}