import type { Message } from '@/stores/hermes/chat'

// Group only within an uninterrupted turn. Tool rows remain available after
// the combined answer; user, command and system messages are hard boundaries.
export function groupRunMessages(messages: Message[], runActive: boolean): Message[] {
  const result: Message[] = []
  let assistants: Message[] = []
  let tools: Message[] = []
  let marker: string | null = null

  function flush(completed: boolean) {
    if (assistants.length) {
      const first = assistants[0]
      result.push({
        ...first,
        toolMessages: tools.length ? tools : undefined,
        contentSegments: assistants.map(m => m.content).filter(text => text.trim()),
        id: assistants[assistants.length - 1].id,
        content: assistants.map(m => m.content).filter(text => text.trim()).join('\n\n'),
        reasoning: assistants.map(m => m.reasoning).filter(Boolean).join('\n\n') || undefined,
        attachments: assistants.flatMap(m => m.attachments || []),
        isStreaming: assistants.some(m => m.isStreaming),
      })
    }
    if (tools.length && !assistants.length) {
      result.push({ id: `tool-group-${tools[0].id}`, role: 'system', content: '', timestamp: tools[0].timestamp, systemType: 'tool-group', toolMessages: tools })
    }
    if (completed && assistants.length) {
      result.push({ id: `run-end-${assistants[0].id}`, role: 'system', content: '', timestamp: assistants[assistants.length - 1].timestamp, systemType: 'run-end' })
    }
    assistants = []
    tools = []
    marker = null
  }

  for (const message of messages) {
    if (message.role !== 'assistant' && message.role !== 'tool') {
      flush(true)
      result.push(message)
      continue
    }
    if (marker && message.runMarker && marker !== message.runMarker) flush(true)
    marker ||= message.runMarker || null
    if (message.role === 'assistant') assistants.push(message)
    else tools.push(message)
  }
  flush(!runActive)
  return result
}