Reimplement in Kotlin

1 files changed, 62 insertions, 0 deletions

diff --git a/src/main/kotlin/io/jamesbarnett/redditlite/service/SubredditService.kt b/src/main/kotlin/io/jamesbarnett/redditlite/service/SubredditService.kt
new file mode 100644
index 0000000..8c01c93
--- /dev/null
+++ b/src/main/kotlin/io/jamesbarnett/redditlite/service/SubredditService.kt
@@ -0,0 +1,62 @@
+package io.jamesbarnett.redditlite.service
+
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule
+import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
+import com.fasterxml.jackson.module.kotlin.treeToValue
+import io.jamesbarnett.redditlite.model.Comment
+import io.jamesbarnett.redditlite.model.Post
+import io.jamesbarnett.redditlite.model.PostDetail
+import org.springframework.boot.web.client.RestTemplateBuilder
+import org.springframework.stereotype.Service
+import org.springframework.web.client.RestTemplate
+import java.time.Duration
+
+const val REDDIT_API_ROOT_URL = "https://reddit.com/r/"
+
+@Service
+class SubredditService (restTemplateBuilder: RestTemplateBuilder) {
+
+  val objectMapper: ObjectMapper = jacksonObjectMapper()
+      .registerModule(JavaTimeModule())
+
+  val restTemplate: RestTemplate = restTemplateBuilder
+      .setConnectTimeout(Duration.ofSeconds(5))
+      .setReadTimeout(Duration.ofSeconds(10))
+      // Custom UA required to prevent rate limiting: https://github.com/reddit-archive/reddit/wiki/API#rules
+      .defaultHeader("User-Agent", "reddit-lite")
+      .build()
+
+  fun getPosts(subreddit: String, postsAfterId: String?): List<Post> {
+    val jsonResponse = restTemplate.getForObject("${REDDIT_API_ROOT_URL}${subreddit}/.json${if (postsAfterId != null) "?after=${postsAfterId}" else ""}", String::class.java)
+    return objectMapper.readTree(jsonResponse)
+      .path("data")
+      .path("children")
+      .findValues("data")
+      .map { objectMapper.treeToValue(it, Post::class.java) }
+  }
+
+  fun getPostDetail(subreddit: String, postId: String): PostDetail {
+    val jsonResponse = restTemplate.getForObject("${REDDIT_API_ROOT_URL}${subreddit}/comments/${postId}/.json", String::class.java)
+    val rootNode = objectMapper.readTree(jsonResponse)
+
+    val post = objectMapper.treeToValue(
+      rootNode
+        .path(0)
+        .path("data")
+        .path("children")
+        .path(0)
+        .path("data"),
+      Post::class.java)
+
+    val comments = rootNode
+      .path(1)
+      .path("data")
+      .path("children")
+      .findValues("data")
+      .map { Comment(it, objectMapper) }
+
+    return PostDetail(post, comments)
+  }
+
+}
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