Add new error cases and fix properties access & history (#49)

* fix visibility of Usage and Metrics fields

* add Input is Too Long error based on ValidationError

* better manage conversation history

Author: sebsto

Sources/BedrockService.swift

@@ -223,6 +223,14 @@ public struct BedrockService: Sendable {
                     )
                 }
             }
+        } else if let validationError = error as? AWSBedrockRuntime.ValidationException {
+            logger.trace("ValidationException while \(context)", metadata: ["error": "\(error)"])
+            let message = validationError.properties.message ?? "Validation error occurred"
+            if message.contains("Input is too long") {
+                throw BedrockLibraryError.inputTooLong(message)
+            } else {
+                throw BedrockLibraryError.invalid(message)
+            }
         } else {
             logger.trace("Error while \(context)", metadata: ["error": "\(error)"])
             throw error

Sources/BedrockServiceError.swift

@@ -41,6 +41,7 @@ public enum BedrockLibraryError: Error {
     case notSupported(String)
     case notFound(String)
     case authenticationFailed(String)
+    case inputTooLong(String)
     case unknownError(String)
 
     public var message: String {
@@ -86,6 +87,8 @@ public enum BedrockLibraryError: Error {
             return "Not found: \(message)"
         case .authenticationFailed(let message):
             return "Authentication failed: \(message)"
+        case .inputTooLong(let message):
+            return "Input too long: \(message)"
         case .unknownError(let message):
             return "Unknown error: \(message)"
         }

Sources/Converse/ConverseRequestBuilder.swift

@@ -97,14 +97,21 @@ public struct ConverseRequestBuilder: Sendable {
         try withHistory(History(history))
     }
     public func withHistory(_ history: History) throws -> ConverseRequestBuilder {
-        if let lastMessage = history.last {
+
+        if history.count > 0,
+            let lastMessage = history.last
+        {
             guard lastMessage.role == .assistant else {
                 throw BedrockLibraryError.ConverseRequestBuilder("Last message in history must be from assistant.")
             }
         }
-        if toolResult != nil {
+        if history.count > 0,
+            toolResult != nil
+        {
             guard case .toolUse(_) = history.last?.content.last else {
-                throw BedrockLibraryError.invalidPrompt("Tool result is defined but last message is not tool use.")
+                throw BedrockLibraryError.ConverseRequestBuilder(
+                    "Tool result is defined but last message is not tool use."
+                )
             }
         }
         var copy = self

Sources/Converse/History.swift

@@ -30,6 +30,10 @@ public struct History: Codable, Sendable {
         self.messages = messages
     }
 
+    public init(_ slide: Slice<History>) {
+        self.messages = Array(slide)
+    }
+
     public mutating func append(_ message: Message) {
         messages.append(message)
     }

Sources/Converse/Streaming/ResponseMetaData.swift

@@ -54,15 +54,15 @@ public struct ResponseMetadata: Codable, Sendable {
             self.totalTokens = sdkUsage.totalTokens ?? 0
         }
 
-        let inputTokens: Int
-        let outputTokens: Int
-        let totalTokens: Int
+        public let inputTokens: Int
+        public let outputTokens: Int
+        public let totalTokens: Int
     }
 
     public struct Metrics: Codable, Sendable {
         package init(from sdkMetrics: BedrockRuntimeClientTypes.ConverseStreamMetrics) throws {
             self.latencyMs = Int(sdkMetrics.latencyMs ?? 0)
         }
-        let latencyMs: Int
+        public let latencyMs: Int
     }
 }