package cogito

// StreamEventType identifies the kind of streaming event.
type StreamEventType string

const (
	StreamEventReasoning  StreamEventType = "reasoning"   // LLM thinking delta
	StreamEventContent    StreamEventType = "content"     // answer text delta
	StreamEventToolCall   StreamEventType = "tool_call"   // tool selected + args
	StreamEventToolResult StreamEventType = "tool_result" // tool execution result
	StreamEventStatus     StreamEventType = "status"      // status message
	StreamEventDone       StreamEventType = "done"        // stream complete
	StreamEventError      StreamEventType = "error"       // error
	StreamEventSubAgent   StreamEventType = "sub_agent"   // sub-agent event
)

// StreamEvent represents a single streaming event from the LLM or tool pipeline.
type StreamEvent struct {
	Type          StreamEventType
	Content       string   // text delta (reasoning/content)
	ToolName      string   // for tool_call/tool_result — name (first chunk only)
	ToolArgs      string   // for tool_call: argument delta string
	ToolCallID    string   // OpenAI tool_call ID (first chunk only)
	ToolCallIndex int      // which tool call (for parallel tool calls)
	ToolResult    string   // tool result text
	FinishReason  string   // "stop", "tool_calls", etc. (populated on done)
	Error         error    // populated on error
	Usage         LLMUsage // populated on done
	AgentID       string   // populated for sub-agent events
}

// StreamCallback is a function that receives streaming events.
type StreamCallback func(StreamEvent)