'use strict';

// 轻量 trace 明细：LLM/工具步骤写入 agent_trace_steps（瀑布图数据源）。
// TRACE_ENABLED=false 时不写，零开销。
function createTraceWriter(pool, enabled = false) {
  let ready = null;
  function ensureTable() {
    if (!pool) return Promise.resolve();
    if (!ready) {
      ready = pool.query(`
        CREATE TABLE IF NOT EXISTS agent_trace_steps (
          id BIGSERIAL PRIMARY KEY,
          trace_id TEXT,
          conv_id TEXT,
          step_type TEXT,
          phase TEXT,
          turn INTEGER,
          model TEXT,
          tool_name TEXT,
          prompt_tokens INTEGER,
          completion_tokens INTEGER,
          duration_ms INTEGER,
          finish_reason TEXT,
          created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
        )
      `).catch((e) => console.error('[trace_writer] table init error:', e.message.slice(0, 120)));
    }
    return ready;
  }

  async function writeSteps(steps, traceId, convId) {
    if (!enabled || !pool || !steps || !steps.length) return;
    await ensureTable();
    const values = [];
    const params = [];
    let i = 1;
    for (const s of steps) {
      values.push(`($${i++},$${i++},$${i++},$${i++},$${i++},$${i++},$${i++},$${i++},$${i++},$${i++},$${i++})`);
      params.push(traceId || null, convId || null, s.step_type || null, s.phase || null, s.turn ?? null, s.model || null, s.tool_name || null, s.prompt_tokens ?? null, s.completion_tokens ?? null, s.duration_ms ?? null, s.finish_reason || null);
    }
    try {
      await pool.query(`INSERT INTO agent_trace_steps (trace_id,conv_id,step_type,phase,turn,model,tool_name,prompt_tokens,completion_tokens,duration_ms,finish_reason) VALUES ${values.join(',')}`, params);
    } catch (err) {
      console.error('[trace_writer] insert error:', err.message.slice(0, 120));
    }
  }

  return { writeSteps, enabled };
}

module.exports = { createTraceWriter };