export type AnalysisType = 'lab-report' | 'trends' | 'checkup-plan' | 'report-summary';

interface AnalyzeBody {
  report_id?: string;
  patient_id?: string;
  metrics?: string[];
}

const ENDPOINT_MAP: Record<AnalysisType, string> = {
  'lab-report': '/ai/analyze/lab-report',
  'trends': '/ai/analyze/trends',
  'checkup-plan': '/ai/analyze/checkup-plan',
  'report-summary': '/ai/analyze/report-summary',
};

export interface SseCallbacks {
  onChunk: (content: string, index: number) => void;
  onError: (message: string) => void;
  onDone: (analysisId: string) => void;
}

export async function startAnalysis(
  type: AnalysisType,
  body: AnalyzeBody,
  callbacks: SseCallbacks,
): Promise<AbortController> {
  const controller = new AbortController();
  const endpoint = ENDPOINT_MAP[type];

  const token = localStorage.getItem('hms-token');
  const resp = await fetch(`/api/v1${endpoint}`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      Authorization: `Bearer ${token}`,
    },
    body: JSON.stringify(body),
    signal: controller.signal,
  });

  if (!resp.ok) {
    const err = await resp.json().catch(() => ({ message: '分析请求失败' }));
    callbacks.onError(err?.message || `HTTP ${resp.status}`);
    return controller;
  }

  const reader = resp.body?.getReader();
  if (!reader) {
    callbacks.onError('无法读取响应流');
    return controller;
  }

  const decoder = new TextDecoder();
  let chunkIndex = 0;
  let buffer = '';

  (async () => {
    try {
      while (true) {
        const { done, value } = await reader.read();
        if (done) break;

        buffer += decoder.decode(value, { stream: true });
        const lines = buffer.split('\n');
        buffer = lines.pop() || '';

        for (const line of lines) {
          if (line.startsWith('data: ')) {
            const data = line.slice(6);
            if (data === '[DONE]') {
              continue;
            }
            try {
              const event = JSON.parse(data);
              if (event.type === 'chunk' && event.content) {
                callbacks.onChunk(event.content, chunkIndex++);
              } else if (event.type === 'done' && event.analysis_id) {
                callbacks.onDone(event.analysis_id);
              } else if (event.type === 'error') {
                callbacks.onError(event.message || '分析出错');
              }
            } catch {
              // 非 JSON 行，跳过
            }
          }
        }
      }
    } catch (err) {
      if (!controller.signal.aborted) {
        callbacks.onError(err instanceof Error ? err.message : '连接中断');
      }
    }
  })();

  return controller;
}