fix: /list-servers now pages the response (#111)

src/main/kotlin/de/darkatra/vrising/discord/commands/ListServersCommand.kt

@@ -1,6 +1,9 @@
 package de.darkatra.vrising.discord.commands
 
 import de.darkatra.vrising.discord.BotProperties
+import de.darkatra.vrising.discord.commands.parameters.PageParameter
+import de.darkatra.vrising.discord.commands.parameters.addPageParameter
+import de.darkatra.vrising.discord.commands.parameters.getPageParameter
 import de.darkatra.vrising.discord.serverstatus.ServerStatusMonitorRepository
 import de.darkatra.vrising.discord.serverstatus.model.ServerStatusMonitor
 import dev.kord.core.Kord
@@ -11,6 +14,8 @@ import dev.kord.core.entity.interaction.GuildChatInputCommandInteraction
 import org.springframework.boot.context.properties.EnableConfigurationProperties
 import org.springframework.stereotype.Component
 
+private const val PAGE_SIZE = 10
+
 @Component
 @EnableConfigurationProperties(BotProperties::class)
 class ListServersCommand(
@@ -30,22 +35,48 @@ class ListServersCommand(
         ) {
             dmPermission = true
             disableCommandInGuilds()
+
+            addPageParameter(required = false)
         }
     }
 
     override suspend fun handle(interaction: ChatInputCommandInteraction) {
 
+        val page = interaction.getPageParameter() ?: 0
+        PageParameter.validate(page)
+
+        val totalElements = when (interaction) {
+            is GuildChatInputCommandInteraction -> serverStatusMonitorRepository.count(interaction.guildId.toString())
+            is GlobalChatInputCommandInteraction -> serverStatusMonitorRepository.count()
+        }
+        val totalPages = totalElements / PAGE_SIZE + 1
+
+        if (page >= totalPages) {
+            interaction.deferEphemeralResponse().respond {
+                content = "This page does not exist."
+            }
+            return
+        }
+
         val serverStatusMonitors: List<ServerStatusMonitor> = when (interaction) {
-            is GuildChatInputCommandInteraction -> serverStatusMonitorRepository.getServerStatusMonitors(interaction.guildId.toString())
-            is GlobalChatInputCommandInteraction -> serverStatusMonitorRepository.getServerStatusMonitors()
+            is GuildChatInputCommandInteraction -> serverStatusMonitorRepository.getServerStatusMonitors(
+                discordServerId = interaction.guildId.toString(),
+                offset = page * PAGE_SIZE,
+                limit = PAGE_SIZE
+            )
+
+            is GlobalChatInputCommandInteraction -> serverStatusMonitorRepository.getServerStatusMonitors(
+                offset = page * PAGE_SIZE,
+                limit = PAGE_SIZE
+            )
         }
 
         interaction.deferEphemeralResponse().respond {
             content = when (serverStatusMonitors.isEmpty()) {
                 true -> "No servers found."
                 false -> serverStatusMonitors.joinToString(separator = "\n") { serverStatusMonitor ->
                     "${serverStatusMonitor.id} - ${serverStatusMonitor.hostname}:${serverStatusMonitor.queryPort} - ${serverStatusMonitor.status.name}"
-                }
+                } + "\n*Current Page: $page, Total Pages: $totalPages*"
             }
         }
     }

src/main/kotlin/de/darkatra/vrising/discord/commands/parameters/PageParameter.kt

@@ -0,0 +1,29 @@
+package de.darkatra.vrising.discord.commands.parameters
+
+import de.darkatra.vrising.discord.commands.exceptions.ValidationException
+import dev.kord.core.entity.interaction.ChatInputCommandInteraction
+import dev.kord.rest.builder.interaction.GlobalChatInputCreateBuilder
+import dev.kord.rest.builder.interaction.integer
+
+object PageParameter {
+    const val NAME = "page"
+
+    fun validate(page: Int) {
+        if (page < 0) {
+            throw ValidationException("'$NAME' must be greater than or equal to zero. Rejected: $page")
+        }
+    }
+}
+
+fun GlobalChatInputCreateBuilder.addPageParameter(required: Boolean = true) {
+    integer(
+        name = PageParameter.NAME,
+        description = "The page. Defaults to 0, the first page."
+    ) {
+        this.required = required
+    }
+}
+
+fun ChatInputCommandInteraction.getPageParameter(): Int? {
+    return command.integers[PageParameter.NAME]?.let { Math.toIntExact(it) }
+}

src/main/kotlin/de/darkatra/vrising/discord/serverstatus/ServerStatusMonitorRepository.kt

@@ -5,6 +5,7 @@ import de.darkatra.vrising.discord.serverstatus.exceptions.OutdatedServerStatusM
 import de.darkatra.vrising.discord.serverstatus.model.ServerStatusMonitor
 import de.darkatra.vrising.discord.serverstatus.model.ServerStatusMonitorStatus
 import org.dizitart.kno2.filters.and
+import org.dizitart.no2.FindOptions
 import org.dizitart.no2.Nitrite
 import org.dizitart.no2.objects.ObjectFilter
 import org.dizitart.no2.objects.filters.ObjectFilters
@@ -64,24 +65,51 @@ class ServerStatusMonitorRepository(
         return repository.find(objectFilter).firstOrNull()
     }
 
-    fun getServerStatusMonitors(discordServerId: String? = null, status: ServerStatusMonitorStatus? = null): List<ServerStatusMonitor> {
+    fun getServerStatusMonitors(
+        discordServerId: String? = null,
+        status: ServerStatusMonitorStatus? = null,
+        offset: Int? = null,
+        limit: Int? = null
+    ): List<ServerStatusMonitor> {
 
-        val filters = buildList<ObjectFilter> {
+        val objectFilter = buildList<ObjectFilter> {
             if (discordServerId != null) {
                 add(ObjectFilters.eq("discordServerId", discordServerId))
             }
             if (status != null) {
                 add(ObjectFilters.eq("status", status))
             }
+        }.reduceOrNull { acc: ObjectFilter, objectFilter: ObjectFilter -> acc.and(objectFilter) }
+
+        if (offset != null && limit != null) {
+
+            if (offset >= repository.size()) {
+                return emptyList()
+            }
+
+            val findOptions = FindOptions.limit(offset, limit)
+            return when {
+                objectFilter != null -> repository.find(objectFilter, findOptions).toList()
+                else -> repository.find(findOptions).toList()
+            }
         }
 
-        val objectFilter = filters.reduceOrNull { acc: ObjectFilter, objectFilter: ObjectFilter -> acc.and(objectFilter) }
         return when {
             objectFilter != null -> repository.find(objectFilter).toList()
             else -> repository.find().toList()
         }
     }
 
+    fun count(
+        discordServerId: String? = null,
+    ): Int {
+
+        return when {
+            discordServerId != null -> repository.find(ObjectFilters.eq("discordServerId", discordServerId)).size()
+            else -> repository.find().size()
+        }
+    }
+
     private fun updateVersion(serverStatusMonitor: ServerStatusMonitor): ServerStatusMonitor {
         return serverStatusMonitor.apply {
             @Suppress("DEPRECATION") // this is the internal usage the warning is referring to