Better error handling

app/src/main/kotlin/SimpleNotes.kt

@@ -6,13 +6,11 @@ import be.simplenotes.app.controllers.SettingsController
 import be.simplenotes.app.controllers.UserController
 import be.simplenotes.app.filters.AuthFilter
 import be.simplenotes.app.filters.AuthType
+import be.simplenotes.app.filters.ErrorFilter
 import be.simplenotes.app.routes.Router
 import be.simplenotes.app.utils.StaticFileResolver
 import be.simplenotes.app.utils.StaticFileResolverImpl
-import be.simplenotes.app.views.BaseView
-import be.simplenotes.app.views.NoteView
-import be.simplenotes.app.views.SettingView
-import be.simplenotes.app.views.UserView
+import be.simplenotes.app.views.*
 import be.simplenotes.domain.domainModule
 import be.simplenotes.domain.usecases.NoteService
 import be.simplenotes.persistance.DbMigrations
@@ -20,8 +18,10 @@ import be.simplenotes.persistance.persistanceModule
 import be.simplenotes.search.searchModule
 import be.simplenotes.shared.config.DataSourceConfig
 import be.simplenotes.shared.config.JwtConfig
+import org.http4k.core.Filter
 import org.http4k.core.RequestContexts
 import org.koin.core.context.startKoin
+import org.koin.core.qualifier.named
 import org.koin.core.qualifier.qualifier
 import org.koin.dsl.module
 import org.slf4j.LoggerFactory
@@ -71,6 +71,7 @@ val serverModule = module {
             get(),
             requiredAuth = get(AuthType.Required.qualifier),
             optionalAuth = get(AuthType.Optional.qualifier),
+            errorFilter = get(named("ErrorFilter")),
             get()
         )()
     }
@@ -78,6 +79,8 @@ val serverModule = module {
     single { RequestContexts() }
     single(AuthType.Optional.qualifier) { AuthFilter(get(), AuthType.Optional, get())() }
     single(AuthType.Required.qualifier) { AuthFilter(get(), AuthType.Required, get())() }
+    single(named("ErrorFilter")) { ErrorFilter(get())() }
+    single { ErrorView(get()) }
 }
 
 val userModule = module {

app/src/main/kotlin/filters/ErrorFilter.kt

@@ -1,25 +1,32 @@
 package be.simplenotes.app.filters
 
-import org.http4k.core.Filter
-import org.http4k.core.Response
-import org.http4k.core.Status
+import be.simplenotes.app.extensions.html
+import be.simplenotes.app.views.ErrorView
+import org.http4k.core.*
 import org.slf4j.LoggerFactory
+import java.sql.SQLTransientException
+
+class ErrorFilter(private val errorView: ErrorView) {
 
-object ErrorFilter {
     private val logger = LoggerFactory.getLogger(javaClass)
 
     operator fun invoke(): Filter = Filter { next ->
         {
             try {
                 val response = next(it)
-                if (response.status == Status.NOT_FOUND) Response(Status.NOT_FOUND).body("TODO(NOT_FOUND)")
+                if (response.status == Status.NOT_FOUND) Response(Status.NOT_FOUND)
+                    .html(errorView.error(ErrorView.Type.NotFound))
                 else response
             } catch (e: Exception) {
                 logger.error(e.stackTraceToString())
-                Response(Status.INTERNAL_SERVER_ERROR).body("TODO(INTERNAL_SERVER_ERROR)")
+                if (e is SQLTransientException)
+                    Response(Status.SERVICE_UNAVAILABLE).html(errorView.error(ErrorView.Type.SqlTransientError))
+                        .noCache()
+                else
+                    Response(Status.INTERNAL_SERVER_ERROR).html(errorView.error(ErrorView.Type.Other)).noCache()
             } catch (e: NotImplementedError) {
                 logger.error(e.stackTraceToString())
-                Response(Status.INTERNAL_SERVER_ERROR).body("TODO(NotImplementedError)")
+                Response(Status.NOT_IMPLEMENTED).html(errorView.error(ErrorView.Type.Other)).noCache()
             }
         }
     }

app/src/main/kotlin/routes/Router.kt

@@ -23,6 +23,7 @@ class Router(
     private val settingsController: SettingsController,
     private val requiredAuth: Filter,
     private val optionalAuth: Filter,
+    private val errorFilter: Filter,
     private val contexts: RequestContexts,
 ) {
     operator fun invoke(): RoutingHttpHandler {
@@ -65,7 +66,7 @@ class Router(
             requiredAuth.then(protectedRoutes),
         )
 
-        val globalFilters = ErrorFilter()
+        val globalFilters = errorFilter
             .then(InitialiseRequestContext(contexts))
             .then(SecurityFilter())
             .then(ResponseFilters.GZip())

app/src/main/kotlin/views/ErrorView.kt

@@ -0,0 +1,34 @@
+package be.simplenotes.app.views
+
+import be.simplenotes.app.utils.StaticFileResolver
+import be.simplenotes.app.views.components.Alert
+import be.simplenotes.app.views.components.alert
+import kotlinx.html.FlowContent
+import kotlinx.html.a
+import kotlinx.html.div
+
+class ErrorView(staticFileResolver: StaticFileResolver) : View(staticFileResolver) {
+
+    enum class Type(val title: String) {
+        SqlTransientError("Database unavailable"),
+        NotFound("Not Found"),
+        Other("Error"),
+    }
+
+    fun error(errorType: Type) = renderPage(errorType.title, jwtPayload = null) {
+        div("container mx-auto p-4") {
+            when (errorType) {
+                Type.SqlTransientError -> alert(Alert.Warning,
+                    errorType.title,
+                    "Please try again later",
+                    multiline = true)
+                Type.NotFound -> alert(Alert.Warning, errorType.title, "Page not found", multiline = true)
+                Type.Other -> alert(Alert.Warning, errorType.title)
+            }
+            div {
+                a(href = "/", classes = "btn btn-green") { +"Go back to the homepage" }
+            }
+        }
+    }
+
+}

app/src/main/kotlin/views/components/Alerts.kt

@@ -2,7 +2,7 @@ package be.simplenotes.app.views.components
 
 import kotlinx.html.*
 
-fun FlowContent.alert(type: Alert, title: String, details: String? = null) {
+fun FlowContent.alert(type: Alert, title: String, details: String? = null, multiline: Boolean = false) {
     val colors = when (type) {
         Alert.Success -> "bg-green-500 border border-green-400 text-gray-800"
         Alert.Warning -> "bg-red-500 border border-red-400 text-red-200"
@@ -10,7 +10,10 @@ fun FlowContent.alert(type: Alert, title: String, details: String? = null) {
     div("$colors px-4 py-3 mb-4 rounded relative") {
         attributes["role"] = "alert"
         strong("font-bold") { +title }
-        details?.let { span("block sm:inline") { +details } }
+        details?.let {
+            if (multiline) p { +details }
+            else span("block sm:inline") { +details }
+        }
     }
 }
 

search/src/main/kotlin/NoteSearcherImpl.kt

@@ -1,6 +1,7 @@
 package be.simplenotes.search
 
 import be.simplenotes.domain.model.PersistedNote
+import be.simplenotes.domain.model.PersistedNoteMetadata
 import be.simplenotes.domain.usecases.search.NoteSearcher
 import be.simplenotes.domain.usecases.search.SearchTerms
 import be.simplenotes.search.utils.rmdir
@@ -80,13 +81,17 @@ class NoteSearcherImpl(basePath: Path = Path.of("/tmp", "lucene")) : NoteSearche
         indexNote(userId, note)
     }
 
-    override fun search(userId: Int, terms: SearchTerms) =
+    override fun search(userId: Int, terms: SearchTerms) = try {
         indexSearcher(userId).query {
             or { titleField eq terms.title }
             or { tagsField eq terms.tag }
             or { contentField eq terms.content }
             listOf(titleField, tagsField, contentField) anyMatch terms.all
         }.map(Document::toNoteMeta)
+    } catch (e: IndexNotFoundException) {
+        logger.warn("Index not found for user $userId")
+        emptyList()
+    }
 
     override fun dropIndex(userId: Int) = rmdir(File(baseFile, userId.toString()).toPath())