import { BadRequestException } from '@nestjs/common';
import { PrismaService } from '../prisma/prisma.service';
import type { GatewayUplinkEventDto, UplinkMatchCandidateInput } from './send-chain.contracts';

export type UplinkMatch = {
  tenantId?: string;
  applicationId?: string;
  messageRecordId?: string;
  messageId?: string;
  matchStatus: string;
  matchReason: string;
  candidates: UplinkMatchCandidateInput[];
};

/** Attribution is application-level; a reply need not identify one original SMS. */
export async function resolveUplinkMatch(
  db: PrismaService,
  data: GatewayUplinkEventDto,
  channel: { id: string; srcId?: string | null },
): Promise<UplinkMatch> {
  const receivedAt = data.receivedAt ? new Date(data.receivedAt) : new Date();
  if (!Number.isFinite(receivedAt.getTime())) throw new BadRequestException('上行接收时间无效');
  const configuredHours = Number(process.env.UPLINK_MATCH_WINDOW_HOURS ?? 72);
  const hours =
    Number.isFinite(configuredHours) && configuredHours >= 1 && configuredHours <= 8760 ? configuredHours : 72;
  const since = new Date(receivedAt.getTime() - hours * 3_600_000);
  const channelEvidence = {
    channelId: channel.id,
    submitStatus: 'accepted',
    submittedAt: { gte: since, lte: receivedAt },
  };
  if (data.messageId) {
    const message = await db.smsMessageRecord.findFirst({
      where: {
        messageId: data.messageId,
        phoneNumber: data.phoneNumber,
        tenantId: { not: null },
        applicationId: { not: null },
        submitRecords: { some: channelEvidence },
      },
      select: { id: true, messageId: true, tenantId: true, applicationId: true },
    });
    if (message?.tenantId && message.applicationId)
      return {
        tenantId: message.tenantId,
        applicationId: message.applicationId,
        messageRecordId: message.id,
        messageId: message.messageId,
        matchStatus: 'matched',
        matchReason: 'messageId 与手机号、通道发送事实一致',
        candidates: [],
      };
  }
  const accessNumber = data.destId || channel.srcId || '';
  // Do not truncate routes before deduplicating applications: it can manufacture uniqueness.
  const routes = accessNumber
    ? await db.channelRouteRule.findMany({
        where: {
          applicationId: { not: null },
          status: 'active',
          group: { items: { some: { channelId: channel.id, channel: { srcId: accessNumber } } } },
        },
        select: { applicationId: true },
        distinct: ['applicationId'],
      })
    : [];
  const ids = routes.flatMap((r) => (r.applicationId ? [r.applicationId] : []));
  const applications = ids.length
    ? await db.smsApplication.findMany({
        where: { id: { in: ids }, status: 'active' },
        select: { id: true, tenantId: true, name: true },
      })
    : [];
  // Read only attribution columns, but inspect the complete window, not its last two SMS.
  const messages = await db.smsMessageRecord.findMany({
    where: {
      phoneNumber: data.phoneNumber,
      tenantId: { not: null },
      applicationId: { not: null },
      submitRecords: { some: channelEvidence },
    },
    select: { id: true, messageId: true, tenantId: true, applicationId: true },
    orderBy: { id: 'asc' },
  });
  const groups = new Map<string, typeof messages>();
  for (const message of messages) {
    if (!message.tenantId || !message.applicationId) continue;
    const key = JSON.stringify([message.tenantId, message.applicationId]);
    const group = groups.get(key) ?? [];
    group.push(message);
    groups.set(key, group);
  }
  const accessCandidates: UplinkMatchCandidateInput[] = applications.map((a) => ({
    tenantId: a.tenantId,
    applicationId: a.id,
    matchSource: 'access_number',
    confidence: 70,
    reason: '共享接入号应用候选，尚无唯一发送证据',
  }));
  if (groups.size === 1) {
    const records = [...groups.values()][0];
    const message = records[0];
    // A conflicting configured access number is evidence against automatic assignment.
    if (!applications.length || applications.some((a) => a.id === message.applicationId))
      return {
        tenantId: message.tenantId!,
        applicationId: message.applicationId!,
        messageRecordId: records.length === 1 ? message.id : undefined,
        messageId: records.length === 1 ? message.messageId : undefined,
        matchStatus: 'matched',
        matchReason:
          records.length === 1
            ? `手机号、通道及接收前 ${hours} 小时唯一匹配`
            : `手机号、通道及接收前 ${hours} 小时应用唯一；原短信不唯一`,
        candidates: [],
      };
  }
  // No sending evidence: retain the existing unique-access application attribution.
  if (!groups.size && applications.length === 1)
    return {
      tenantId: applications[0].tenantId,
      applicationId: applications[0].id,
      matchStatus: 'matched',
      matchReason: '接入号唯一匹配应用，无唯一原短信',
      candidates: [],
    };
  const candidates = new Map(accessCandidates.map((c) => [c.applicationId, c]));
  for (const records of groups.values()) {
    const m = records[0];
    candidates.set(m.applicationId!, {
      tenantId: m.tenantId!,
      applicationId: m.applicationId!,
      messageRecordId: records.length === 1 ? m.id : undefined,
      matchSource: 'phone_window',
      confidence: 70,
      reason: `同通道接收前 ${hours} 小时有 ${records.length} 条下发；须确认应用归属`,
    });
  }
  return candidates.size
    ? {
        matchStatus: 'ambiguous',
        matchReason: '应用归属仍有多候选或接入号与发送事实冲突',
        candidates: [...candidates.values()],
      }
    : { matchStatus: 'unmatched', matchReason: '未匹配到接入号应用或时间窗内同通道发送事实', candidates: [] };
}