// TokenScope analyzer — classifies message parts into category breakdown.
// Ported from opencode-tokenscope (MIT).

export interface TokenBreakdown {
  system: number;
  user: number;
  assistant: number;
  tools: number;
  reasoning: number;
  total: number;
}

const CHARS_PER_TOKEN = 4;

function estimateTokens(text: string): number {
  return Math.ceil(text.length / CHARS_PER_TOKEN);
}

export function analyzeMessages(parts: any[]): TokenBreakdown {
  const breakdown: TokenBreakdown = { system: 0, user: 0, assistant: 0, tools: 0, reasoning: 0, total: 0 };

  for (const part of parts) {
    const role = part.role ?? '';
    const content = part.content ?? '';
    const tokens = estimateTokens(content);

    switch (role) {
      case 'system':
        breakdown.system += tokens;
        break;
      case 'user':
        breakdown.user += tokens;
        break;
      case 'assistant':
        breakdown.assistant += tokens;
        if (part.tool_calls) {
          for (const tc of part.tool_calls) {
            breakdown.tools += estimateTokens(JSON.stringify(tc));
          }
        }
        break;
      case 'tool':
        breakdown.tools += tokens;
        break;
      default:
        breakdown.assistant += tokens;
    }

    if (part.reasoning_parts) {
      for (const rp of part.reasoning_parts) {
        const rTokens = estimateTokens(rp.text ?? '');
        breakdown.reasoning += rTokens;
        breakdown.assistant -= rTokens;
      }
    }
  }

  breakdown.total = breakdown.system + breakdown.user + breakdown.assistant + breakdown.tools + breakdown.reasoning;
  return breakdown;
}