/**
 * mail 与 channel / toolbox 的接线(app 层;设计稿 §8;ADR-013):
 *   ① channel 订阅方:入站 → channel.ingestMail(账号绑的通道)—— 活动经现有事件链收到信
 *   ② channel 的 MailTransport:出站 → mail.send(按 from 找账号,对不上不回落默认)
 *   ③ `mail.send` 工具处理器:活动侧出站,放行时经 ToolInvoker 执行;dryRun 只校验不发(注册试运行会真调处理器)
 * 三段都是纯映射 + 一次调用,单测直接对函数。
 */
import type { InboundMail, MailSendInput } from '@contracts';
import type { MailTransport } from '@modules/channel';
import type { InboundHandler, MailInboundDetail, MailService } from '@modules/mail';
import {
  bodyTextOf,
  MailAccountDisabledError,
  MailAccountNotFoundError,
  MailNoDefaultAccountError,
  MailSecretMissingError,
  MailSendInvalidError,
  threadIdOf,
} from '@modules/mail';
import type { ToolHandler } from '@modules/toolbox';

/**
 * mail 的入站详情 → channel 的 InboundMail:只带存下来的附件。
 *
 * **线程口径只有一处**:`threadIdOf`(mail 模块的 domain,取这一串的根;缘由与反例见那里)。
 * 这里曾经内联过一份同义实现,而模块里那一份当时取的是最近一跳 —— 同一个模块两套相反的语义,
 * 下一个人照导出的那个接线就会接反。现在调它。
 */
export function toInboundMail(mail: MailInboundDetail): InboundMail {
  const threadId = threadIdOf(mail);
  return {
    messageId: mail.messageId,
    ...(threadId === undefined ? {} : { threadId }),
    from: mail.from.address,
    to: mail.to.map((a) => a.address),
    cc: mail.cc.map((a) => a.address),
    subject: mail.subject,
    body: bodyTextOf({ ...(mail.text === null ? {} : { text: mail.text }), ...(mail.html === null ? {} : { html: mail.html }) }),
    receivedAt: mail.receivedAt,
    attachments: mail.attachments.flatMap((a) =>
      a.ref === null ? [] : [{ name: a.name, contentType: a.contentType, size: a.size, ref: a.ref }],
    ),
  };
}

/** 只要 `ingestMail` 这一个口,出参不看(InboundOutcome 由 channel 自己留痕) */
export function channelSubscriber(channel: { ingestMail(channelId: string, mail: InboundMail): Promise<unknown> }): InboundHandler {
  return async (mail, ctx) => {
    if (ctx.channelId === undefined) return { skipped: '账号未绑定通道' };
    await channel.ingestMail(ctx.channelId, toInboundMail(mail));
    // 显式回 undefined —— 投递成功就是「没话说」;`noImplicitReturns` 不许一条路返值一条路掉出去
    return undefined;
  };
}

/** channel 的出站面:厂商失败抛出 —— channel.sendMail 的调用方(放行落地)要看到失败 */
export function channelTransport(mail: Pick<MailService, 'send'>): MailTransport {
  return {
    async send(input) {
      const result = await mail.send({
        from: input.from,
        to: [...input.to],
        cc: [...input.cc],
        bcc: [],
        subject: input.subject,
        text: input.body,
        ...(input.threadId === undefined ? {} : { inReplyTo: input.threadId }),
        references: input.threadId === undefined ? [] : [input.threadId],
        attachments: input.attachments.map((a) => ({ name: a.name, contentType: 'application/octet-stream', uploadRef: a.ref })),
        requestedBy: { kind: 'channel' },
      });
      if (result.state === 'failed') throw new Error(`发信失败:${result.error ?? '未知'}`);
      return { messageId: result.messageId, threadId: input.threadId ?? result.messageId };
    },
  };
}

function recipientsOf(value: unknown): string[] {
  if (Array.isArray(value)) return value.filter((v): v is string => typeof v === 'string').map((v) => v.trim()).filter((v) => v !== '');
  if (typeof value === 'string') return value.split(/[,;]/).map((s) => s.trim()).filter((s) => s !== '');
  return [];
}

function attachmentsOf(value: unknown): MailSendInput['attachments'] {
  if (!Array.isArray(value)) return [];
  return value.flatMap((v) => {
    if (typeof v !== 'object' || v === null) return [];
    const a = v as Record<string, unknown>;
    const uploadRef = typeof a['uploadRef'] === 'string' && a['uploadRef'] !== '' ? a['uploadRef'] : undefined;
    // 没给 uploadRef 的附件**不静默丢掉**:活动说「带上 q.pdf」,信发了附件没了还回 queued:true,是界面撒谎
    if (uploadRef === undefined) throw new MailSendInvalidError([`附件 ${String(a['name'] ?? '(无名)')} 没给 uploadRef`]);
    const name = typeof a['name'] === 'string' && a['name'] !== '' ? a['name'] : uploadRef;
    return [{ name, contentType: 'application/octet-stream', uploadRef }];
  });
}

export function mailSendTool(mail: Pick<MailService, 'send'>): ToolHandler {
  return async ({ input, connection, idempotencyKey }) => {
    const to = recipientsOf(input['to']);
    const cc = recipientsOf(input['cc']);
    const bcc = recipientsOf(input['bcc']);
    const subject = typeof input['subject'] === 'string' ? input['subject'] : '';
    const body = typeof input['body'] === 'string' && input['body'] !== '' ? input['body'] : undefined;
    const html = typeof input['html'] === 'string' && input['html'] !== '' ? input['html'] : undefined;
    const inReplyTo = typeof input['inReplyTo'] === 'string' && input['inReplyTo'] !== '' ? input['inReplyTo'] : undefined;
    // 账号:入参指定 > 连接配置('default' = 默认账号)
    const configured = connection['account'];
    const accountId =
      typeof input['accountId'] === 'string' && input['accountId'] !== ''
        ? input['accountId']
        : configured !== undefined && configured !== '' && configured !== 'default'
          ? configured
          : undefined;

    if (input['dryRun'] === true) {
      const problems = [
        ...(to.length === 0 ? ['收件人至少一个'] : []),
        ...(subject === '' ? ['主题不能为空'] : []),
        ...(body === undefined && html === undefined ? ['正文 body / html 至少一个'] : []),
      ];
      return problems.length === 0
        ? { ok: true, output: { queued: false, dryRun: true } }
        : { ok: false, error: { code: 'invalid', retryable: false, message: problems.join('; ') } };
    }

    try {
      const result = await mail.send({
        ...(accountId === undefined ? {} : { accountId }),
        to,
        cc,
        bcc,
        subject,
        ...(body === undefined ? {} : { text: body }),
        ...(html === undefined ? {} : { html }),
        ...(inReplyTo === undefined ? {} : { inReplyTo }),
        references: inReplyTo === undefined ? [] : [inReplyTo],
        attachments: attachmentsOf(input['attachments']),
        ...(idempotencyKey === undefined ? {} : { idempotencyKey }),
        requestedBy: { kind: 'tool', tool: 'mail.send' },
      });
      if (result.state === 'failed') {
        return { ok: false, error: { code: 'send-failed', retryable: true, message: result.error ?? '发信失败' } };
      }
      return { ok: true, output: { queued: true, outboundId: result.outboundId, messageId: result.messageId, state: result.state } };
    } catch (error) {
      if (error instanceof MailSendInvalidError) return { ok: false, error: { code: 'invalid', retryable: false, message: error.message } };
      if (
        error instanceof MailNoDefaultAccountError ||
        error instanceof MailAccountNotFoundError ||
        error instanceof MailAccountDisabledError ||
        error instanceof MailSecretMissingError
      ) {
        return { ok: false, error: { code: 'no-account', retryable: false, message: error.message } };
      }
      throw error;
    }
  };
}