add category and global meta (#438)

server/src/main/kotlin/suwayomi/tachidesk/global/impl/GlobalMeta.kt

@@ -0,0 +1,43 @@
+package suwayomi.tachidesk.global.impl
+
+import org.jetbrains.exposed.sql.insert
+import org.jetbrains.exposed.sql.select
+import org.jetbrains.exposed.sql.selectAll
+import org.jetbrains.exposed.sql.transactions.transaction
+import org.jetbrains.exposed.sql.update
+import suwayomi.tachidesk.global.model.table.GlobalMetaTable
+
+/*
+ * Copyright (C) Contributors to the Suwayomi project
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+object GlobalMeta {
+    fun modifyMeta(key: String, value: String) {
+        transaction {
+            val meta = transaction {
+                GlobalMetaTable.select { GlobalMetaTable.key eq key }
+            }.firstOrNull()
+
+            if (meta == null) {
+                GlobalMetaTable.insert {
+                    it[GlobalMetaTable.key] = key
+                    it[GlobalMetaTable.value] = value
+                }
+            } else {
+                GlobalMetaTable.update({ GlobalMetaTable.key eq key }) {
+                    it[GlobalMetaTable.value] = value
+                }
+            }
+        }
+    }
+
+    fun getMetaMap(): Map<String, String> {
+        return transaction {
+            GlobalMetaTable.selectAll()
+                .associate { it[GlobalMetaTable.key] to it[GlobalMetaTable.value] }
+        }
+    }
+}