[ECO-4962] feat: add ChatApi implementation

Created basic ChatApi implementation to perform REST request to the Chat Backend

chat-android/build.gradle.kts

@@ -34,7 +34,8 @@ android {
 }
 
 dependencies {
-    implementation(libs.ably.android)
+    api(libs.ably.android)
+    implementation(libs.gson)
 
     testImplementation(libs.junit)
     androidTestImplementation(libs.androidx.test.core)

chat-android/src/main/java/com/ably/chat/ChatApi.kt

@@ -0,0 +1,149 @@
+package com.ably.chat
+
+import com.google.gson.JsonElement
+import com.google.gson.JsonObject
+import io.ably.lib.http.HttpCore
+import io.ably.lib.http.HttpUtils
+import io.ably.lib.types.AblyException
+import io.ably.lib.types.AsyncHttpPaginatedResponse
+import io.ably.lib.types.ErrorInfo
+import io.ably.lib.types.Param
+import kotlin.coroutines.resume
+import kotlin.coroutines.resumeWithException
+import kotlin.coroutines.suspendCoroutine
+
+private const val API_PROTOCOL_VERSION = 3
+private const val PROTOCOL_VERSION_PARAM_NAME = "v"
+private val apiProtocolParam = Param(PROTOCOL_VERSION_PARAM_NAME, API_PROTOCOL_VERSION.toString())
+
+// TODO make this class internal
+class ChatApi(private val realtimeClient: RealtimeClient) {
+
+    suspend fun getMessages(roomId: String, params: QueryOptions): PaginatedResult<Message> {
+        return makeAuthorizedPaginatedRequest(
+            url = "/chat/v1/rooms/$roomId/messages",
+            method = "GET",
+            params = params.toParams(),
+        ) {
+            Message(
+                timeserial = it.asJsonObject.get("timeserial").asString,
+                clientId = it.asJsonObject.get("clientId").asString,
+                roomId = it.asJsonObject.get("roomId").asString,
+                text = it.asJsonObject.get("text").asString,
+                createdAt = it.asJsonObject.get("createdAt").asLong,
+                metadata = it.asJsonObject.get("metadata")?.asJsonObject?.toMap() ?: mapOf(),
+                headers = it.asJsonObject.get("headers")?.asJsonObject?.toMap() ?: mapOf(),
+            )
+        }
+    }
+
+    suspend fun sendMessage(roomId: String, params: SendMessageParams): CreateMessageResponse {
+        val body = JsonObject().apply {
+            addProperty("text", params.text)
+            params.headers?.let {
+                add("headers", it.toJson())
+            }
+            params.metadata?.let {
+                add("metadata", it.toJson())
+            }
+        }
+
+        return makeAuthorizedRequest(
+            "/chat/v1/rooms/$roomId/messages",
+            "POST",
+            body,
+        )?.let {
+            CreateMessageResponse(
+                timeserial = it.asJsonObject.get("timeserial").asString,
+                createdAt = it.asJsonObject.get("createdAt").asLong,
+            )
+        } ?: throw AblyException.fromErrorInfo(ErrorInfo("Send message endpoint returned empty value", HttpStatusCodes.InternalServerError))
+    }
+
+    suspend fun getOccupancy(roomId: String): OccupancyEvent {
+        return this.makeAuthorizedRequest("/chat/v1/rooms/$roomId/occupancy", "GET")?.let {
+            OccupancyEvent(
+                connections = it.asJsonObject.get("connections").asInt,
+                presenceMembers = it.asJsonObject.get("presenceMembers").asInt,
+            )
+        } ?: throw AblyException.fromErrorInfo(ErrorInfo("Occupancy endpoint returned empty value", HttpStatusCodes.InternalServerError))
+    }
+
+    private suspend fun makeAuthorizedRequest(
+        url: String,
+        method: String,
+        body: JsonElement? = null,
+    ): JsonElement? = suspendCoroutine { continuation ->
+        val requestBody = body.toRequestBody()
+        realtimeClient.requestAsync(
+            method,
+            url,
+            arrayOf(apiProtocolParam),
+            requestBody,
+            arrayOf(),
+            object :
+                AsyncHttpPaginatedResponse.Callback {
+                override fun onResponse(response: AsyncHttpPaginatedResponse?) {
+                    continuation.resume(response?.items()?.firstOrNull())
+                }
+
+                override fun onError(reason: ErrorInfo?) {
+                    continuation.resumeWithException(AblyException.fromErrorInfo(reason))
+                }
+            },
+        )
+    }
+
+    private suspend fun <T> makeAuthorizedPaginatedRequest(
+        url: String,
+        method: String,
+        params: List<Param> = listOf(),
+        transform: (JsonElement) -> T,
+    ): PaginatedResult<T> = suspendCoroutine { continuation ->
+        realtimeClient.requestAsync(
+            method,
+            url,
+            (params + apiProtocolParam).toTypedArray(),
+            null,
+            arrayOf(),
+            object :
+                AsyncHttpPaginatedResponse.Callback {
+                override fun onResponse(response: AsyncHttpPaginatedResponse?) {
+                    continuation.resume(response.toPaginatedResult(transform))
+                }
+
+                override fun onError(reason: ErrorInfo?) {
+                    continuation.resumeWithException(AblyException.fromErrorInfo(reason))
+                }
+            },
+        )
+    }
+}
+
+data class CreateMessageResponse(val timeserial: String, val createdAt: Long)
+
+private fun JsonElement?.toRequestBody(useBinaryProtocol: Boolean = false): HttpCore.RequestBody =
+    HttpUtils.requestBodyFromGson(this, useBinaryProtocol)
+
+private fun Map<String, String>.toJson() = JsonObject().apply {
+    forEach { (key, value) -> addProperty(key, value) }
+}
+
+private fun JsonObject.toMap() = buildMap<String, String> {
+    entrySet().filter { (_, value) -> value.isJsonPrimitive }.forEach { (key, value) -> put(key, value.asString) }
+}
+
+private fun QueryOptions.toParams() = buildList {
+    start?.let { add(Param("start", it)) }
+    end?.let { add(Param("end", it)) }
+    add(Param("limit", limit))
+    add(
+        Param(
+            "direction",
+            when (orderBy) {
+                QueryOptions.MessageOrder.NewestFirst -> "backwards"
+                QueryOptions.MessageOrder.OldestFirst -> "forwards"
+            },
+        ),
+    )
+}

chat-android/src/main/java/com/ably/chat/ErrorCodes.kt

@@ -87,4 +87,29 @@ object ErrorCodes {
      * An unknown error has happened in the room lifecycle.
      */
     const val RoomLifecycleError = 102_105
+
+    /**
+     * The request cannot be understood
+     */
+    const val BadRequest = 40_000
+}
+
+/**
+ * Http Status Codes
+ */
+object HttpStatusCodes {
+
+    const val BadRequest = 400
+
+    const val Unauthorized = 401
+
+    const val InternalServerError = 500
+
+    const val NotImplemented = 501
+
+    const val ServiceUnavailable = 502
+
+    const val GatewayTimeout = 503
+
+    const val Timeout = 504
 }

chat-android/src/main/java/com/ably/chat/Message.kt

@@ -32,7 +32,7 @@ data class Message(
     /**
      * The text of the message.
      */
-    val textval: String,
+    val text: String,
 
     /**
      * The timestamp at which the message was created.
@@ -66,5 +66,5 @@ data class Message(
      * Do not use the headers for authoritative information. There is no server-side
      * validation. When reading the headers treat them like user input.
      */
-    val headersval: MessageHeaders,
+    val headers: MessageHeaders,
 )

chat-android/src/main/java/com/ably/chat/PaginatedResult.kt

@@ -0,0 +1,66 @@
+package com.ably.chat
+
+import com.google.gson.JsonElement
+import io.ably.lib.types.AblyException
+import io.ably.lib.types.AsyncHttpPaginatedResponse
+import io.ably.lib.types.ErrorInfo
+import kotlin.coroutines.resume
+import kotlin.coroutines.resumeWithException
+import kotlin.coroutines.suspendCoroutine
+
+/**
+ * Represents the result of a paginated query.
+ */
+interface PaginatedResult<T> {
+
+    /**
+     * The items returned by the query.
+     */
+    val items: List<T>
+
+    /**
+     * Fetches the next page of items.
+     */
+    suspend fun next(): PaginatedResult<T>
+
+    /**
+     * Whether there are more items to query.
+     *
+     * @returns `true` if there are more items to query, `false` otherwise.
+     */
+    fun hasNext(): Boolean
+}
+
+fun <T> AsyncHttpPaginatedResponse?.toPaginatedResult(transform: (JsonElement) -> T): PaginatedResult<T> =
+    this?.let { AsyncPaginatedResultWrapper(it, transform) } ?: EmptyPaginatedResult()
+
+private class EmptyPaginatedResult<T> : PaginatedResult<T> {
+    override val items: List<T>
+        get() = emptyList()
+
+    override suspend fun next(): PaginatedResult<T> = this
+
+    override fun hasNext(): Boolean = false
+}
+
+private class AsyncPaginatedResultWrapper<T>(
+    val asyncPaginatedResult: AsyncHttpPaginatedResponse,
+    val transform: (JsonElement) -> T,
+) : PaginatedResult<T> {
+    override val items: List<T>
+        get() = asyncPaginatedResult.items()?.map(transform) ?: emptyList()
+
+    override suspend fun next(): PaginatedResult<T> = suspendCoroutine { continuation ->
+        asyncPaginatedResult.next(object : AsyncHttpPaginatedResponse.Callback {
+            override fun onResponse(response: AsyncHttpPaginatedResponse?) {
+                continuation.resume(response.toPaginatedResult(transform))
+            }
+
+            override fun onError(reason: ErrorInfo?) {
+                continuation.resumeWithException(AblyException.fromErrorInfo(reason))
+            }
+        })
+    }
+
+    override fun hasNext(): Boolean = asyncPaginatedResult.hasNext()
+}

gradle/libs.versions.toml

@@ -14,6 +14,7 @@ espresso-core = "3.6.1"
 lifecycle-runtime-ktx = "2.8.4"
 activity-compose = "1.9.1"
 compose-bom = "2024.06.00"
+gson = "2.11.0"
 
 [libraries]
 junit = { group = "junit", name = "junit", version.ref = "junit" }
@@ -36,6 +37,8 @@ androidx-ui-test-manifest = { group = "androidx.compose.ui", name = "ui-test-man
 androidx-ui-test-junit4 = { group = "androidx.compose.ui", name = "ui-test-junit4" }
 androidx-material3 = { group = "androidx.compose.material3", name = "material3" }
 
+gson = { group = "com.google.code.gson", name = "gson", version.ref = "gson" }
+
 [plugins]
 detekt = { id = "io.gitlab.arturbosch.detekt", version.ref = "detekt"}
 android-kotlin = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }