/** 合并聊天窗口的收发事件；每次同步只接受后端读取的云端消息，不上报客户端正文。 */
export function createImChatArchiveTrigger(
    syncPage: (params: { diagnosis_id: number; scope: 'current'; sync_token?: string }) => Promise<{
        sync_token?: string; completed: boolean; errors?: string[]
    }>,
    onError: (error: unknown) => void = () => {}
) {
    const jobs = new Map<number, { again: boolean; promise: Promise<void> }>()
    return (diagnosisId: number): Promise<void> => {
        if (!Number.isInteger(diagnosisId) || diagnosisId <= 0) return Promise.resolve()
        const pending = jobs.get(diagnosisId)
        if (pending) {
            pending.again = true
            return pending.promise
        }
        const job = { again: false, promise: Promise.resolve() }
        jobs.set(diagnosisId, job)
        job.promise = (async () => {
            try {
                do {
                    job.again = false
                    let token: string | undefined
                    for (;;) {
                        const result = await syncPage({ diagnosis_id: diagnosisId, scope: 'current', sync_token: token })
                        if (result.completed) {
                            if (result.errors?.length) throw new Error(result.errors.join('；'))
                            break
                        }
                        if (!result.sync_token) throw new Error('聊天记录同步未返回进度')
                        token = result.sync_token
                    }
                    // 同步期间收到新消息时再追一次，覆盖新消息晚于本轮首页的情况。
                } while (job.again)
            } catch (error) {
                onError(error)
            } finally {
                jobs.delete(diagnosisId)
            }
        })()
        return job.promise
    }
}