import type { SseEventType } from './types';

export interface ParsedSseEvent {
  type: SseEventType;
  data: Record<string, unknown>;
}

export function parseSseChunk(previous: string, chunk: string): { events: ParsedSseEvent[]; remainder: string } {
  const buffer = previous + chunk;
  const rawEvents = buffer.split('\n\n');
  const remainder = rawEvents.pop() ?? '';
  const events: ParsedSseEvent[] = [];

  for (const raw of rawEvents) {
    const eventMatch = raw.match(/^event:\s*(.+)$/m);
    const dataMatch = raw.match(/^data:\s*(.+)$/m);
    if (!eventMatch || !dataMatch) continue;

    const type = eventMatch[1].trim() as SseEventType;
    try {
      events.push({ type, data: JSON.parse(dataMatch[1]) });
    } catch {
      events.push({ type: 'error', data: { message: 'SSE 数据解析失败' } });
    }
  }

  return { events, remainder };
}