/**
 * llm 用例 —— LLM 实例的四元绑定管理(编码规范 §5.3;语义出处 OS 02 系统管理)。
 */
import type { LlmInstanceView } from '@contracts';
import type { LlmService, UpsertLlmInstance } from '../../contract.ts';
import type { Clock, IdGenerator, LlmInstanceRepository, ProviderInvoker, SecretBox } from '../../port.ts';
import { pickSystemUse, toPublicView, validateBinding } from '../domain/model-binding.ts';
import { resolveBaseUrl } from '../domain/provider-profile.ts';
import type { ModelBinding } from '../domain/model-binding.ts';

export type LlmServiceDeps = {
  readonly instances: LlmInstanceRepository;
  readonly provider: ProviderInvoker;
  readonly secrets: SecretBox;
  readonly clock: Clock;
  readonly ids: IdGenerator;
};

export function createLlmService(deps: LlmServiceDeps): LlmService {
  return {
    async list(): Promise<LlmInstanceView[]> {
      const all = await deps.instances.list();
      return all.map(toPublicView);
    },

    async upsert(input: UpsertLlmInstance): Promise<LlmInstanceView> {
      const existing = input.id === undefined ? undefined : await deps.instances.findById(input.id);
      // 只写不读:apiKey 留空即保持原密文(ADR-009 #4)
      const apiKeyCipher =
        input.apiKey !== undefined && input.apiKey !== ''
          ? deps.secrets.seal(input.apiKey)
          : existing?.apiKeyCipher;

      const binding: ModelBinding = {
        id: existing?.id ?? input.id ?? deps.ids.next(),
        name: input.name,
        provider: input.provider,
        // URL 留空即取该 provider 的默认端点:选了 deepseek 就不必再背一遍它的地址
        // URL 留空即取该 provider 的默认端点:选了 deepseek 就不必再背一遍它的地址
        baseUrl: resolveBaseUrl(input.provider, input.baseUrl),
        model: input.model,
        apiKeyCipher,
        systemUse: input.systemUse,
        enabled: input.enabled,
      };
      const saved = await deps.instances.upsert(binding);
      return toPublicView(saved);
    },

    async remove(id) {
      await deps.instances.remove(id);
    },

    async probe(id) {
      const binding = await deps.instances.findById(id);
      if (binding === undefined) return { ok: false, error: '实例不存在' };
      const violations = validateBinding(binding);
      if (violations.length > 0) {
        return { ok: false, error: violations.map((v) => `${v.field}:${v.message}`).join('; ') };
      }
      const started = deps.clock.now().getTime();
      try {
        await deps.provider.invoke({
          binding,
          apiKey: deps.secrets.open(binding.apiKeyCipher!),
          call: { model: binding.name, prompt: 'ping', maxOutputTokens: 8, label: 'probe' },
        });
        return { ok: true, latencyMs: deps.clock.now().getTime() - started };
      } catch (error) {
        return { ok: false, error: error instanceof Error ? error.message : String(error) };
      }
    },

    /**
     * 测试连接(草稿)—— **只测不存**。
     *
     * 「测试」按下去就把表单写进库,是个会咬人的副作用:人只想知道这把钥匙对不对,
     * 结果端点被改了、实例被建了,取消也收不回来。所以这里拿**临时绑定**去试:
     * 密钥现填就用现填的,没填就取这条实例已存的密文(改端点、换型号不必重打钥匙)。
     */
    async probeDraft(draft) {
      const stored = draft.id === undefined ? undefined : await deps.instances.findById(draft.id);
      const cipher = draft.apiKey === undefined || draft.apiKey === '' ? stored?.apiKeyCipher : deps.secrets.seal(draft.apiKey);
      const binding: ModelBinding = {
        id: stored?.id ?? 'draft',
        name: draft.name ?? stored?.name ?? draft.model,
        provider: draft.provider,
        baseUrl: resolveBaseUrl(draft.provider, draft.baseUrl),
        model: draft.model,
        apiKeyCipher: cipher,
        systemUse: false,
        enabled: true,
      };
      const violations = validateBinding(binding);
      if (violations.length > 0) {
        return { ok: false, error: violations.map((v) => `${v.field}:${v.message}`).join('; ') };
      }
      const started = deps.clock.now().getTime();
      try {
        await deps.provider.invoke({
          binding,
          apiKey: deps.secrets.open(binding.apiKeyCipher!),
          call: { model: binding.name, prompt: 'ping', maxOutputTokens: 8, label: 'probe' },
        });
        return { ok: true, latencyMs: deps.clock.now().getTime() - started };
      } catch (error) {
        return { ok: false, error: error instanceof Error ? error.message : String(error) };
      }
    },

    async assertNamesBound(names) {
      const all = await deps.instances.list();
      const bound = new Set(all.filter((b) => validateBinding(b).length === 0 && b.enabled).map((b) => b.name));
      const missing = [...new Set(names)].filter((n) => !bound.has(n));
      return { ok: missing.length === 0, missing };
    },

    async systemUseBinding() {
      return pickSystemUse(await deps.instances.list());
    },
  };
}