android: add paging setup

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

android/build.gradle.kts

@@ -4,16 +4,12 @@ plugins {
   kotlin("android")
 }
 
-group = "dev.msfjarvis.claw"
-
-version = "1.0"
-
-repositories { google() }
-
 dependencies {
+  implementation(projects.api)
   implementation(projects.common)
-  implementation("androidx.appcompat:appcompat:1.4.0-alpha02")
   implementation("androidx.activity:activity-compose:1.3.0-beta01")
+  implementation("androidx.appcompat:appcompat:1.4.0-alpha02")
+  implementation("androidx.paging:paging-compose:1.0.0-alpha10")
 }
 
 android {

android/src/main/java/dev/msfjarvis/claw/android/paging/LobstersPagingSource.kt

@@ -0,0 +1,29 @@
+package dev.msfjarvis.claw.android.paging
+
+import androidx.paging.PagingSource
+import androidx.paging.PagingState
+import dev.msfjarvis.claw.api.model.LobstersPost
+
+class LobstersPagingSource(
+  private val getMorePosts: suspend (Int) -> List<LobstersPost>,
+) : PagingSource<Int, LobstersPost>() {
+
+  override suspend fun load(params: LoadParams<Int>): LoadResult<Int, LobstersPost> {
+    return try {
+      val page = params.key ?: 1
+      val posts = getMorePosts(page)
+
+      LoadResult.Page(
+        data = posts,
+        prevKey = if (page == 1) null else page - 1,
+        nextKey = page.plus(1)
+      )
+    } catch (e: Exception) {
+      LoadResult.Error(e)
+    }
+  }
+
+  override fun getRefreshKey(state: PagingState<Int, LobstersPost>): Int {
+    return state.pages.size + 1
+  }
+}