/**
 * 假 Provider（任务 A2.3）：给契约测试与 Core 单测当靶子，不接任何真实系统。
 *
 * 能力刻意覆盖几条分支：读、写、慢调用（测超时）、声明错误分类（测映射）、裸异常（测未知结果）。
 * 它带调用计数，便于断言「幂等重试只执行一次」。
 */
import type { ExecutionReceipt } from '@aps/contracts';

import { ProviderError } from './errors.js';
import type { Capability, CapabilityCall, ExecutionContext, HealthStatus, ImpactPreview, Provider, ProviderManifest } from './index.js';

export interface FakeProvider extends Provider {
  stats: {
    calls: Record<string, number>;
    /** 每次调用拿到的身份与凭据句柄形态：给 A4 的凭据用例断言「凭据只走句柄、不进参数」 */
    contexts: Array<{ executionId: string; accountId?: string; hasCredentials: boolean; params: unknown }>;
  };
}

export function createFakeProvider(id = 'fake'): FakeProvider {
  const calls: Record<string, number> = {};
  const contexts: FakeProvider['stats']['contexts'] = [];

  const capabilities: Capability[] = [
    {
      id: `${id}.echo`,
      title: '回显输入',
      description: '把输入原样返回，用于联调链路',
      effect: 'read',
      mode: 'sync',
      whenNotToUse: '需要真实业务数据时不要用',
      synonyms: ['回显', '测试'],
      inputSchema: { type: 'object', properties: { text: { type: 'string' } }, required: ['text'] },
      outputSchema: { type: 'object', properties: { echo: { type: 'string' } } },
      idempotency: 'none',
      errors: ['invalid_argument'],
    },
    {
      id: `${id}.write`,
      title: '假写入',
      description: '模拟一次写操作，用于验证幂等与确认链路',
      effect: 'write',
      mode: 'sync',
      inputSchema: { type: 'object', properties: { value: { type: 'number' } } },
      outputSchema: { type: 'object', properties: { applied: { type: 'boolean' } } },
      idempotency: 'key',
      errors: ['invalid_argument', 'conflict'],
    },
    {
      id: `${id}.slow`,
      title: '慢调用',
      description: '按参数等待若干毫秒，用于验证超时与结果未知',
      effect: 'read',
      mode: 'sync',
      inputSchema: { type: 'object', properties: { ms: { type: 'number' } } },
      outputSchema: { type: 'object' },
      idempotency: 'none',
      errors: ['unknown_result'],
    },
    {
      id: `${id}.declare-error`,
      title: '声明错误',
      description: '按参数抛出指定分类的错误，用于验证错误归一化',
      effect: 'read',
      mode: 'sync',
      inputSchema: { type: 'object', properties: { kind: { type: 'string' } } },
      outputSchema: { type: 'object' },
      idempotency: 'none',
      errors: ['invalid_argument', 'forbidden', 'conflict', 'rate_limited', 'unavailable', 'unknown_result'],
    },
    {
      id: `${id}.crash`,
      title: '裸异常',
      description: '抛裸异常，验证归一为 unknown_result',
      effect: 'read',
      mode: 'sync',
      inputSchema: { type: 'object' },
      outputSchema: { type: 'object' },
      idempotency: 'none',
      errors: ['unknown_result'],
    },
  ];

  return {
    stats: { calls, contexts },
    async describe(): Promise<ProviderManifest> {
      // 假 Provider 没有账号概念：不需要身份绑定（真实系统默认需要，见 ProviderManifest.requiresIdentity）
      return { id, displayName: '假 Provider', version: '0.0.0', platformVersion: 1, requiresIdentity: false, capabilities };
    },
    async invoke(context: ExecutionContext, call: CapabilityCall): Promise<ExecutionReceipt> {
      const known = capabilities.find((capability) => capability.id === call.capabilityId);
      if (!known) throw new ProviderError('invalid_argument', `假 Provider 没有能力 ${call.capabilityId}`);
      calls[call.capabilityId] = (calls[call.capabilityId] ?? 0) + 1;
      contexts.push({
        executionId: context.executionId,
        ...(context.identity === undefined ? {} : { accountId: context.identity.accountId }),
        hasCredentials: context.credentials !== undefined,
        params: call.params,
      });

      const params = (call.params ?? {}) as Record<string, unknown>;
      switch (known.id) {
        case `${id}.echo`:
          if (typeof params.text !== 'string' || params.text === '') {
            throw new ProviderError('invalid_argument', 'text 不能为空');
          }
          return { executionId: context.executionId, status: 'succeeded', result: { echo: params.text } };
        case `${id}.write`:
          return { executionId: context.executionId, status: 'succeeded', result: { applied: true, idempotencyKey: context.idempotencyKey ?? null } };
        case `${id}.slow`: {
          const ms = typeof params.ms === 'number' ? params.ms : 100;
          await new Promise((resolve) => setTimeout(resolve, ms));
          return { executionId: context.executionId, status: 'succeeded', result: { waitedMs: ms } };
        }
        case `${id}.declare-error`: {
          const kind = typeof params.kind === 'string' ? params.kind : 'unavailable';
          throw new ProviderError(kind as ProviderError['kind'], `按要求抛出 ${kind}`);
        }
        default:
          throw new Error('假 Provider 内部异常：没有兜底分支');
      }
    },
    async health(): Promise<HealthStatus> {
      return { status: 'ok', checkedAt: Date.now() };
    },
    async preview(_context: ExecutionContext, call: CapabilityCall): Promise<ImpactPreview> {
      const params = (call.params ?? {}) as Record<string, unknown>;
      if (call.capabilityId !== `${id}.write`) {
        throw new ProviderError('invalid_argument', `假 Provider 没有 ${call.capabilityId} 的影响预览`);
      }
      return {
        impactSummary: `会把值写成 ${String(params.value ?? '')}（假 Provider，不碰真实数据）`,
        revision: 7,
        paramsPreview: { value: params.value ?? null },
      };
    },
  };
}