/**
 * message 用例 —— 编排 domain,依赖 port.ts(编码规范 §5.3)。
 */
import type { StaffId } from '@contracts';
import type { MessageService, SendElicitation, SendNotice } from '../../contract.ts';
import { MessageNotAnswerableError } from '../../contract.ts';
import type { Clock, IdGenerator, MessageRepository, PositionResolver } from '../../port.ts';
import type { MessageKind, SystemMessage } from '../domain/message-kind.ts';
import { canAnswer } from '../domain/message-kind.ts';

export type MessageServiceDeps = {
  readonly repo: MessageRepository;
  readonly org: PositionResolver;
  readonly clock: Clock;
  readonly ids: IdGenerator;
};

export function createMessageService(deps: MessageServiceDeps): MessageService {
  function build(
    kind: MessageKind,
    staffId: StaffId,
    title: string,
    body: string,
    extra: Partial<SystemMessage> = {},
  ): SystemMessage {
    return {
      id: deps.ids.next(),
      kind,
      staffId,
      title,
      body,
      at: deps.clock.now().toISOString(),
      ...extra,
    };
  }

  async function fanOut(kind: MessageKind, staff: ReadonlyArray<{ id: StaffId }>, title: string, body: string, eventRef?: string) {
    for (const person of staff) {
      await deps.repo.insert(build(kind, person.id, title, body, eventRef === undefined ? {} : { eventRef }));
    }
  }

  return {
    async inbox(staffId, options) {
      return deps.repo.list(staffId, options?.unreadOnly ?? false, options?.limit ?? 100);
    },

    async markRead(messageId) {
      await deps.repo.markRead(messageId, deps.clock.now());
    },

    async notify(input: SendNotice) {
      return deps.repo.insert(
        build('notice', input.staffId, input.title, input.body, input.eventRef === undefined ? {} : { eventRef: input.eventRef }),
      );
    },

    async sendElicitation(input: SendElicitation) {
      return deps.repo.insert(
        build('elicitation', input.staffId, input.title, input.body, {
          card: { cardId: input.cardId, sourceTaskId: input.sourceTaskId, payload: input.payload },
        }),
      );
    },

    async answer(messageId, staffId, answer) {
      const message = await deps.repo.get(messageId);
      if (message === undefined || !canAnswer(message, staffId)) {
        throw new MessageNotAnswerableError(messageId);
      }
      await deps.repo.markAnswered(messageId, deps.clock.now(), answer);
      const updated = await deps.repo.get(messageId);
      if (updated === undefined) throw new MessageNotAnswerableError(messageId);
      return updated;
    },

    /** 驳回重答:新卡实例(附驳回理由与原答引用),原卡闭合 —— 每次请求与回答都是独立消息 */
    async rejectAndReask(messageId, reason) {
      const original = await deps.repo.get(messageId);
      if (original === undefined || original.card === undefined) {
        throw new MessageNotAnswerableError(messageId);
      }
      const reask = build('elicitation', original.staffId as StaffId, original.title, original.body, {
        card: {
          cardId: deps.ids.next(),
          sourceTaskId: original.card.sourceTaskId,
          payload: original.card.payload,
          rejectedReason: reason,
        },
      });
      const created = await deps.repo.insert(reask);
      await deps.repo.supersede(messageId, created.id, reason);
      return created;
    },

    /** 死信:送相关人的消息要素**与**治理台 · 任务管理(OS 6.3) */
    async deadLetter(envelope, error) {
      const governance = await deps.org.governanceStaff();
      await fanOut(
        'dead-letter',
        governance,
        `事件投递失败入死信:${envelope.type}`,
        `事件 ${envelope.id} 重试超限。原因:${error}`,
        envelope.trace.storeRef,
      );
    },

    /** 无主兜底:相关人 = 通道实例配置的默认认领岗位;未配置则落治理台 */
    async unowned(envelope, fallbackPosition) {
      const recipients =
        fallbackPosition === undefined
          ? await deps.org.governanceStaff()
          : await deps.org.staffOfPosition(fallbackPosition);
      const targets = recipients.length > 0 ? recipients : await deps.org.governanceStaff();
      const subject = typeof envelope.payload.data['subject'] === 'string' ? envelope.payload.data['subject'] : '(无主题)';
      await fanOut(
        'unowned',
        targets,
        `无主入站待认领:${subject}`,
        `事件 ${envelope.id} 未命中任何任务监听与触发器。原件:${envelope.payload.originRef ?? '无'}`,
        envelope.trace.storeRef,
      );
    },
  };
}