feat: actively fetch a PR on first paste

src/main/kotlin/com/wire/github/EventsHandler.kt

@@ -1,8 +1,11 @@
 package com.wire.github
 
+import com.wire.github.github.GitHubAppClient
 import com.wire.github.github.GitHubPullRequestLinkParser
+import com.wire.github.github.GitHubPullRequestReference
 import com.wire.github.github.GitHubRepository
 import com.wire.github.github.GitHubWebhookManager
+import com.wire.github.util.TemplateHandler
 import com.wire.sdk.WireEventsHandlerSuspending
 import com.wire.sdk.model.Conversation
 import com.wire.sdk.model.ConversationMember
@@ -14,6 +17,8 @@ import org.slf4j.LoggerFactory
 class EventsHandler : WireEventsHandlerSuspending() {
     private val logger = LoggerFactory.getLogger(this::class.java)
     private val gitHubWebhookManager by lazy { GlobalContext.get().get<GitHubWebhookManager>() }
+    private val gitHubAppClient by lazy { GlobalContext.get().get<GitHubAppClient>() }
+    private val templateHandler by lazy { GlobalContext.get().get<TemplateHandler>() }
 
     override suspend fun onTextMessageReceived(wireMessage: WireMessage.Text) {
         if (wireMessage.text.equals(HELP_COMMAND, ignoreCase = true)) {
@@ -32,20 +37,26 @@ class EventsHandler : WireEventsHandlerSuspending() {
             )
             return
         }
-        val repositories = GitHubPullRequestLinkParser.parse(wireMessage.text)
-        if (repositories.isEmpty()) {
+        val pullRequests = GitHubPullRequestLinkParser.parse(wireMessage.text)
+        if (pullRequests.isEmpty()) {
             return
         }
 
+        val conversationId = wireMessage.conversationId
         registerRepositories(
-            repositories = repositories,
-            conversationId = wireMessage.conversationId
-        )?.let { message ->
+            repositories = pullRequests.map { it.repository }.toSet(),
+            conversationId = conversationId
+        )?.let { statusMessage ->
             sendMessage(
-                conversationId = wireMessage.conversationId,
-                text = message
+                conversationId = conversationId,
+                text = statusMessage
             )
         }
+
+        announcePullRequests(
+            pullRequests = pullRequests,
+            conversationId = conversationId
+        )
     }
 
     override suspend fun onAppAddedToConversation(
@@ -104,6 +115,33 @@ class EventsHandler : WireEventsHandlerSuspending() {
         return results.takeIf { it.isNotEmpty() }?.joinToString("\n")
     }
 
+    private fun announcePullRequests(
+        pullRequests: Set<GitHubPullRequestReference>,
+        conversationId: QualifiedId
+    ) {
+        pullRequests.forEach { reference ->
+            val pullRequest = runCatching {
+                gitHubAppClient.fetchPullRequest(
+                    repository = reference.repository,
+                    number = reference.number
+                )
+            }.onFailure { exception ->
+                logger.warn(
+                    "Failed to fetch pull request " +
+                        "${reference.repository.fullName}#${reference.number}",
+                    exception
+                )
+            }.getOrNull() ?: return@forEach
+
+            templateHandler.renderPullRequest(pullRequest)?.let { message ->
+                sendMessage(
+                    conversationId = conversationId,
+                    text = message
+                )
+            }
+        }
+    }
+
     private fun sendMessage(
         conversationId: QualifiedId,
         text: String

src/main/kotlin/com/wire/github/github/GitHubAppClient.kt

@@ -1,5 +1,6 @@
 package com.wire.github.github
 
+import com.wire.github.response.model.PullRequest
 import com.wire.github.util.ENV_VAR_GITHUB_CLIENT_ID
 import com.wire.github.util.ENV_VAR_GITHUB_PRIVATE_KEY
 import com.wire.github.util.KtxSerializer
@@ -60,6 +61,30 @@ class GitHubAppClient(
         )
     }
 
+    fun fetchPullRequest(
+        repository: GitHubRepository,
+        number: Int
+    ): PullRequest {
+        val token = createInstallationAccessToken(repository)
+        val response = send(
+            request = requestBuilder(
+                "/repos/${repository.owner}/${repository.name}/pulls/$number"
+            ).GET()
+                .withBearer(token)
+                .build()
+        )
+
+        require(response.statusCode() in SUCCESS_STATUS_CODES) {
+            "GitHub failed to fetch pull request ${repository.fullName}#$number: " +
+                "${response.statusCode()} ${response.body()}"
+        }
+
+        return KtxSerializer.json.decodeFromString(
+            PullRequest.serializer(),
+            response.body()
+        )
+    }
+
     fun deleteRepositoryWebhook(
         repository: GitHubRepository,
         webhookId: Long

src/main/kotlin/com/wire/github/github/GitHubPullRequestLinkParser.kt

@@ -1,23 +1,30 @@
 package com.wire.github.github
 
 object GitHubPullRequestLinkParser {
-    fun parse(text: String): Set<GitHubRepository> =
+    fun parse(text: String): Set<GitHubPullRequestReference> =
         pullRequestUrlRegex
             .findAll(text)
-            .map { match ->
-                GitHubRepository(
-                    owner = match.groups[OWNER_GROUP]?.value.orEmpty(),
-                    name = match.groups[REPOSITORY_GROUP]?.value.orEmpty()
+            .mapNotNull { match ->
+                val number = match.groups[NUMBER_GROUP]?.value?.toIntOrNull()
+                    ?: return@mapNotNull null
+
+                GitHubPullRequestReference(
+                    repository = GitHubRepository(
+                        owner = match.groups[OWNER_GROUP]?.value.orEmpty(),
+                        name = match.groups[REPOSITORY_GROUP]?.value.orEmpty()
+                    ),
+                    number = number
                 )
             }.toSet()
 
     private val pullRequestUrlRegex =
         Regex(
             """https://github\.com/""" +
                 """(?<owner>[A-Za-z0-9_.-]+)/""" +
-                """(?<repository>[A-Za-z0-9_.-]+)/pull/\d+\b"""
+                """(?<repository>[A-Za-z0-9_.-]+)/pull/(?<number>\d+)\b"""
         )
 
     private const val OWNER_GROUP = "owner"
     private const val REPOSITORY_GROUP = "repository"
+    private const val NUMBER_GROUP = "number"
 }

src/main/kotlin/com/wire/github/github/GitHubPullRequestReference.kt

@@ -0,0 +1,6 @@
+package com.wire.github.github
+
+data class GitHubPullRequestReference(
+    val repository: GitHubRepository,
+    val number: Int
+)

src/main/kotlin/com/wire/github/util/TemplateHandler.kt

@@ -4,6 +4,7 @@ import com.github.mustachejava.DefaultMustacheFactory
 import com.github.mustachejava.Mustache
 import com.github.mustachejava.MustacheNotFoundException
 import com.wire.github.response.model.GitHubResponse
+import com.wire.github.response.model.PullRequest
 import java.io.PrintWriter
 import java.io.StringWriter
 import java.util.Locale
@@ -22,20 +23,38 @@ class TemplateHandler {
             response = response
         ) ?: return null
 
-        return try {
-            val template = compileTemplate(
-                path = path
-            )
+        return render(
+            path = path,
+            model = response
+        )
+    }
+
+    /**
+     * Renders the message for a pull request fetched directly (e.g. when its link is
+     * pasted into the chat) rather than received via a webhook event.
+     */
+    fun renderPullRequest(pullRequest: PullRequest): String? =
+        render(
+            path = actionTemplatePath(
+                event = PULL_REQUEST_EVENT,
+                action = LINKED_ACTION
+            ),
+            model = mapOf(PULL_REQUEST_MODEL_KEY to pullRequest)
+        )
 
+    private fun render(
+        path: String,
+        model: Any
+    ): String? =
+        try {
             populateTemplate(
-                mustache = template,
-                model = response
+                mustache = compileTemplate(path = path),
+                model = model
             )?.trim()?.takeIf { it.isNotBlank() }
         } catch (exception: MustacheNotFoundException) {
             logger.error("MustacheNotFoundException: $exception")
             null
         }
-    }
 
     private fun templatePath(
         event: String,
@@ -78,7 +97,7 @@ class TemplateHandler {
 
     private fun populateTemplate(
         mustache: Mustache,
-        model: GitHubResponse
+        model: Any
     ): String? =
         StringWriter()
             .apply {
@@ -88,6 +107,9 @@ class TemplateHandler {
     private companion object {
         const val LANGUAGE_ENGLISH = "en"
         const val TEMPLATE_DIRECTORY = "templates"
+        const val PULL_REQUEST_EVENT = "pull_request"
+        const val LINKED_ACTION = "linked"
+        const val PULL_REQUEST_MODEL_KEY = "pullRequest"
         const val EVENT_WORKFLOW_RUN = "workflow_run"
     }
 }

src/main/resources/templates/en/pull_request.linked.template

@@ -0,0 +1,7 @@
+{{! Rendered when a PR link is pasted into the chat — an active fetch of the PR's current state, not a GitHub webhook event. }}
+{{! Always announces the PR. The body is shown only when the PR is not a draft; a draft shows the header alone, and its body arrives later via pull_request.ready_for_review once it is marked ready. }}
+[**{{pullRequest.title}}**]({{pullRequest.htmlUrl}}) (+{{pullRequest.additions}}/-{{pullRequest.deletions}}) by **@{{pullRequest.user.login}}** {{#pullRequest.draft}}(**DRAFT**){{/pullRequest.draft}}
+{{^pullRequest.draft}}
+
+{{{pullRequest.body}}}
+{{/pullRequest.draft}}