feat(database): build a custom serializer for SavedPost

database/build.gradle.kts

@@ -9,6 +9,7 @@ import dev.msfjarvis.claw.gradle.addTestDependencies
 plugins {
   id("dev.msfjarvis.claw.android-library")
   id("dev.msfjarvis.claw.kotlin-android")
+  alias(libs.plugins.kotlin.serialization)
   alias(libs.plugins.anvil)
   alias(libs.plugins.sqldelight)
   alias(libs.plugins.whetstone)
@@ -33,6 +34,7 @@ dependencies {
   implementation(libs.sqldelight.androidDriver)
   implementation(libs.sqldelight.primitiveAdapters)
   implementation(libs.sqlite.android)
+  implementation(libs.kotlinx.serialization.core)
 
   testImplementation(libs.sqldelight.jvmDriver)
   addTestDependencies(project)

database/src/main/kotlin/dev/msfjarvis/claw/database/SavedPostSerializer.kt

@@ -0,0 +1,99 @@
+/*
+ * Copyright © 2023 Harsh Shandilya.
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ */
+package dev.msfjarvis.claw.database
+
+import dev.msfjarvis.claw.database.local.SavedPost
+import kotlinx.serialization.ExperimentalSerializationApi
+import kotlinx.serialization.KSerializer
+import kotlinx.serialization.Serializer
+import kotlinx.serialization.builtins.ListSerializer
+import kotlinx.serialization.builtins.serializer
+import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.descriptors.buildClassSerialDescriptor
+import kotlinx.serialization.descriptors.element
+import kotlinx.serialization.encoding.CompositeDecoder
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
+import kotlinx.serialization.encoding.decodeStructure
+import kotlinx.serialization.encoding.encodeStructure
+
+@OptIn(ExperimentalSerializationApi::class)
+@Serializer(forClass = SavedPost::class)
+class SavedPostSerializer : KSerializer<SavedPost> {
+  private val delegateSerializer = ListSerializer(String.serializer())
+  override val descriptor: SerialDescriptor =
+    buildClassSerialDescriptor("SavedPost") {
+      element<String>("shortId")
+      element<String>("title")
+      element<String>("url")
+      element<String>("createdAt")
+      element<Int?>("commentCount", isOptional = true)
+      element<String>("commentsUrl")
+      element<String>("submitterName")
+      element<String>("submitterAvatarUrl")
+      element<List<String>>("tags")
+      element<String>("description")
+    }
+
+  override fun deserialize(decoder: Decoder): SavedPost {
+    return decoder.decodeStructure(descriptor) {
+      var shortId = ""
+      var title = ""
+      var url = ""
+      var createdAt = ""
+      var commentCount: Int? = null
+      var commentsUrl = ""
+      var submitterName = ""
+      var submitterAvatarUrl = ""
+      var tags = emptyList<String>()
+      var description = ""
+      while (true) {
+        when (val index = decodeElementIndex(descriptor)) {
+          0 -> shortId = decodeStringElement(descriptor, 0)
+          1 -> title = decodeStringElement(descriptor, 1)
+          2 -> url = decodeStringElement(descriptor, 2)
+          3 -> createdAt = decodeStringElement(descriptor, 3)
+          4 -> commentCount = decodeNullableSerializableElement(descriptor, 4, Int.serializer())
+          5 -> commentsUrl = decodeStringElement(descriptor, 5)
+          6 -> submitterName = decodeStringElement(descriptor, 6)
+          7 -> submitterAvatarUrl = decodeStringElement(descriptor, 7)
+          8 -> tags = decodeSerializableElement(descriptor, 8, delegateSerializer)
+          9 -> description = decodeStringElement(descriptor, 9)
+          CompositeDecoder.DECODE_DONE -> break
+          else -> error("Unexpected index: $index")
+        }
+      }
+      SavedPost(
+        shortId = shortId,
+        title = title,
+        url = url,
+        createdAt = createdAt,
+        commentCount = commentCount,
+        commentsUrl = commentsUrl,
+        submitterName = submitterName,
+        submitterAvatarUrl = submitterAvatarUrl,
+        tags = tags,
+        description = description,
+      )
+    }
+  }
+
+  override fun serialize(encoder: Encoder, value: SavedPost) {
+    encoder.encodeStructure(descriptor) {
+      encodeStringElement(descriptor, 0, value.shortId)
+      encodeStringElement(descriptor, 1, value.title)
+      encodeStringElement(descriptor, 2, value.url)
+      encodeStringElement(descriptor, 3, value.createdAt)
+      encodeNullableSerializableElement(descriptor, 4, Int.serializer(), value.commentCount)
+      encodeStringElement(descriptor, 5, value.commentsUrl)
+      encodeStringElement(descriptor, 6, value.submitterName)
+      encodeStringElement(descriptor, 7, value.submitterAvatarUrl)
+      encodeSerializableElement(descriptor, 8, delegateSerializer, value.tags)
+      encodeStringElement(descriptor, 9, value.description)
+    }
+  }
+}