fix: reduce github context read from env to mitigate "argument list t…

…oo long" bug (#43)

src/commonMain/kotlin/com/monta/slack/notifier/command/PublishSlackCommand.kt

@@ -3,16 +3,38 @@ package com.monta.slack.notifier.command
 import com.github.ajalt.clikt.core.CliktCommand
 import com.github.ajalt.clikt.parameters.options.option
 import com.github.ajalt.clikt.parameters.options.required
+import com.monta.slack.notifier.model.GithubPushContext
 import com.monta.slack.notifier.model.JobStatus
 import com.monta.slack.notifier.model.JobType
 import com.monta.slack.notifier.service.PublishSlackService
+import com.monta.slack.notifier.util.JsonUtil
+import com.monta.slack.notifier.util.readStringFromFile
 import kotlinx.coroutines.runBlocking
 
 class PublishSlackCommand : CliktCommand() {
+    val githubEventPath: String by option(
+        help = "Github Context event json file path",
+        envvar = "GITHUB_EVENT_PATH"
+    ).required()
+
+    val githubRepository: String by option(
+        help = "Github Context repository",
+        envvar = "GITHUB_REPOSITORY"
+    ).required()
+
+    val githubRunId: String by option(
+        help = "Github Context run id",
+        envvar = "GITHUB_RUN_ID"
+    ).required()
 
-    private val githubContext: String by option(
-        help = "Github Context",
-        envvar = "PUBLISH_SLACK_GITHUB_CONTEXT"
+    val githubWorkflow: String by option(
+        help = "Github Context workflow",
+        envvar = "GITHUB_WORKFLOW"
+    ).required()
+
+    val githubRefName: String by option(
+        help = "Github Context ref name",
+        envvar = "GITHUB_REF_NAME"
     ).required()
 
     private val serviceName: String? by option(
@@ -52,20 +74,33 @@ class PublishSlackCommand : CliktCommand() {
 
     override fun run() {
         runBlocking {
+            val githubPushContext = getGithubPushContext()
             PublishSlackService(
                 serviceName = serviceName.valueOrNull(),
                 serviceEmoji = serviceEmoji.valueOrNull(),
                 slackToken = slackToken,
                 slackChannelId = slackChannelId
             ).publish(
-                githubContext = githubContext,
+                githubPushContext = githubPushContext,
                 jobType = JobType.fromString(jobType),
                 jobStatus = JobStatus.fromString(jobStatus),
                 slackMessageId = slackMessageId.valueOrNull()
             )
         }
     }
 
+    private fun getGithubPushContext(): GithubPushContext {
+        val eventJson = readStringFromFile(githubEventPath)
+        val event = JsonUtil.instance.decodeFromString<GithubPushContext.Event>(eventJson)
+        return GithubPushContext(
+            repository = githubRepository,
+            runId = githubRunId,
+            workflow = githubWorkflow,
+            event = event,
+            refName = githubRefName
+        )
+    }
+
     /**
      * Needed for optional parameters as the return the empty string instead of null
      * if set via ENV variables (as we do from our GitHub Actions)

src/commonMain/kotlin/com/monta/slack/notifier/service/PublishSlackService.kt

@@ -4,7 +4,6 @@ import com.monta.slack.notifier.SlackClient
 import com.monta.slack.notifier.model.GithubPushContext
 import com.monta.slack.notifier.model.JobStatus
 import com.monta.slack.notifier.model.JobType
-import com.monta.slack.notifier.util.JsonUtil
 import com.monta.slack.notifier.util.writeToOutput
 
 class PublishSlackService(
@@ -22,13 +21,11 @@ class PublishSlackService(
     )
 
     suspend fun publish(
-        githubContext: String,
+        githubPushContext: GithubPushContext,
         jobType: JobType,
         jobStatus: JobStatus,
         slackMessageId: String?
     ): String {
-        val githubPushContext = JsonUtil.instance.decodeFromString<GithubPushContext>(githubContext)
-
         val messageId = if (slackMessageId.isNullOrBlank()) {
             slackClient.create(
                 githubPushContext = githubPushContext,

src/commonMain/kotlin/com/monta/slack/notifier/util/FileUtils.kt

@@ -0,0 +1,29 @@
+package com.monta.slack.notifier.util
+
+import kotlinx.cinterop.ByteVar
+import kotlinx.cinterop.allocArray
+import kotlinx.cinterop.memScoped
+import kotlinx.cinterop.toKString
+import platform.posix.fclose
+import platform.posix.fgets
+import platform.posix.fopen
+
+fun readStringFromFile(filePath: String): String {
+    val returnBuffer = StringBuilder()
+    val file = fopen(filePath, "r")
+        ?: throw IllegalArgumentException("Cannot open file $filePath for reading")
+    try {
+        memScoped {
+            val readBufferLength = 64 * 1024
+            val buffer = allocArray<ByteVar>(readBufferLength)
+            var line = fgets(buffer, readBufferLength, file)?.toKString()
+            while (line != null) {
+                returnBuffer.append(line)
+                line = fgets(buffer, readBufferLength, file)?.toKString()
+            }
+        }
+    } finally {
+        fclose(file)
+    }
+    return returnBuffer.toString()
+}