Add base classes for encoding/decoding configs

Signed-off-by: Graham <gpe@openrs2.org>

cache/src/main/kotlin/org/openrs2/cache/config/ArchiveConfigTypeList.kt

@@ -0,0 +1,29 @@
+package org.openrs2.cache.config
+
+import org.openrs2.cache.Cache
+
+public abstract class ArchiveConfigTypeList<T : ConfigType>(
+    cache: Cache,
+    archive: Int,
+    private val fileBits: Int
+) : ConfigTypeList<T>(cache, archive) {
+    private val fileMask = (1 shl fileBits) - 1
+
+    override fun calculateCapacity(): Int {
+        val archiveCapacity = cache.capacity(archive)
+        if (archiveCapacity == 0) {
+            return 0
+        }
+
+        val groupCapacity = cache.capacity(archive, archiveCapacity - 1)
+        return ((archiveCapacity - 1) shl fileBits) or groupCapacity
+    }
+
+    override fun getGroupId(id: Int): Int {
+        return id ushr fileBits
+    }
+
+    override fun getFileId(id: Int): Int {
+        return id and fileMask
+    }
+}

cache/src/main/kotlin/org/openrs2/cache/config/ConfigType.kt

@@ -0,0 +1,21 @@
+package org.openrs2.cache.config
+
+import io.netty.buffer.ByteBuf
+
+public abstract class ConfigType(
+    public val id: Int
+) {
+    public abstract fun read(buf: ByteBuf, code: Int)
+    public abstract fun write(buf: ByteBuf)
+
+    public fun read(buf: ByteBuf) {
+        while (true) {
+            val code = buf.readUnsignedByte().toInt()
+            if (code == 0) {
+                break
+            }
+
+            read(buf, code)
+        }
+    }
+}

cache/src/main/kotlin/org/openrs2/cache/config/ConfigTypeList.kt

@@ -0,0 +1,42 @@
+package org.openrs2.cache.config
+
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap
+import org.openrs2.buffer.use
+import org.openrs2.cache.Cache
+
+public abstract class ConfigTypeList<T : ConfigType>(
+    protected val cache: Cache,
+    protected val archive: Int
+) {
+    private val types = Int2ObjectOpenHashMap<T>()
+
+    public val capacity: Int by lazy {
+        calculateCapacity()
+    }
+
+    public operator fun get(id: Int): T? {
+        var type = types[id]
+        if (type != null) {
+            return type
+        }
+
+        val group = getGroupId(id)
+        val file = getFileId(id)
+        if (!cache.exists(archive, group, file)) {
+            // TODO(gpe): the client returns an empty config - should we do that?
+            return null
+        }
+
+        cache.read(archive, group, file).use { buf ->
+            type = allocate(id)
+            type.read(buf)
+            types[id] = type
+            return type
+        }
+    }
+
+    protected abstract fun allocate(id: Int): T
+    protected abstract fun calculateCapacity(): Int
+    protected abstract fun getGroupId(id: Int): Int
+    protected abstract fun getFileId(id: Int): Int
+}

cache/src/main/kotlin/org/openrs2/cache/config/GroupConfigTypeList.kt

@@ -0,0 +1,21 @@
+package org.openrs2.cache.config
+
+import org.openrs2.cache.Cache
+
+public abstract class GroupConfigTypeList<T : ConfigType>(
+    cache: Cache,
+    archive: Int,
+    private val group: Int
+) : ConfigTypeList<T>(cache, archive) {
+    override fun calculateCapacity(): Int {
+        return cache.capacity(archive, group)
+    }
+
+    override fun getGroupId(id: Int): Int {
+        return group
+    }
+
+    override fun getFileId(id: Int): Int {
+        return id
+    }
+}