/**
 * 平台配置（ADR-0011）。
 *
 * 读取顺序：环境变量 > 配置文件 > 默认值。
 * 配置文件默认在 ~/.aps/config.json（桌面端与本地开发的惯例位置），可用 APS_CONFIG_FILE 指向别处。
 * 密钥只在这里出现一次，其余模块拿到的都是配置对象；日志一律用 redactConfig()。
 */
import { existsSync, readFileSync } from 'node:fs';
import { homedir } from 'node:os';
import { join } from 'node:path';

export type LlmProvider = 'deepseek' | 'openai' | 'compatible';

export interface LlmConfig {
  provider: LlmProvider;
  baseUrl: string;
  model: string;
  /** 未配置时为空字符串：引擎不可用，但平台照常启动 */
  apiKey: string;
}

export interface CapabilityConfig {
  /** 开发期默认 true；接入真实身份后应为 false，由授权表逐条给出 */
  defaultAllow: boolean;
  /** 只读模式：屏蔽写能力 */
  denyWrite: boolean;
  /** 授权表：谁能看到哪些能力（按 id 前缀） */
  grants: Array<{ userId?: string; tenantId?: string; allow: string[] }>;
}

export interface EngineConfig {
  /** fake = 假引擎（默认）；pi = Pi 子进程（A3.3） */
  kind: 'fake' | 'pi';
}

export interface PlatformConfig {
  llm: LlmConfig;
  engine: EngineConfig;
  capabilities: CapabilityConfig;
  database: { path: string };
  /** 凭据主密钥文件（A4.3）：只存密钥，凭据密文在平台库里 */
  security: { credentialKeyPath: string };
  server: { host: string; port: number };
  /** 客户端构建产物目录，可覆盖（默认仓库内 client/app/dist） */
  clientDist?: string;
}

export interface LoadConfigInput {
  env?: NodeJS.ProcessEnv;
  /** 便于测试：覆盖用户主目录 */
  homeDir?: string;
}

const DEFAULT_BASE_URLS: Record<string, string> = {
  deepseek: 'https://api.deepseek.com/v1',
  openai: 'https://api.openai.com/v1',
};

export function configFilePath(input: LoadConfigInput = {}): string {
  const env = input.env ?? process.env;
  const explicit = env.APS_CONFIG_FILE;
  if (explicit && explicit.trim() !== '') return explicit;
  return join(input.homeDir ?? homedir(), '.aps', 'config.json');
}

interface FileConfig {
  llm?: Partial<LlmConfig>;
  engine?: Partial<EngineConfig>;
  capabilities?: Partial<CapabilityConfig>;
  database?: { path?: string };
  security?: { credentialKeyPath?: string };
  server?: { host?: string; port?: number };
  clientDist?: string;
}

function readFileConfig(path: string): FileConfig {
  if (!existsSync(path)) return {};
  try {
    return JSON.parse(readFileSync(path, 'utf8')) as FileConfig;
  } catch (error) {
    // 配置文件坏了要吵：静默忽略会让密钥问题变得难以排查
    throw new Error(`配置文件解析失败：${path}（${error instanceof Error ? error.message : '未知错误'}）`, { cause: error });
  }
}

export function loadConfig(input: LoadConfigInput = {}): PlatformConfig {
  const env = input.env ?? process.env;
  const file = readFileConfig(configFilePath(input));

  const provider = (env.APS_LLM_PROVIDER ?? file.llm?.provider ?? 'deepseek') as LlmProvider;
  const baseUrl = env.APS_LLM_BASE_URL ?? file.llm?.baseUrl ?? DEFAULT_BASE_URLS[provider] ?? '';
  const model = env.APS_LLM_MODEL ?? file.llm?.model ?? 'deepseek-chat';
  const apiKey = env.APS_LLM_API_KEY ?? file.llm?.apiKey ?? '';

  const defaultDbPath = join(input.homeDir ?? homedir(), '.aps', 'aps.sqlite');
  const dbPath = env.APS_DB_PATH ?? file.database?.path ?? defaultDbPath;

  const keyPath = env.APS_CREDENTIAL_KEY_FILE ?? file.security?.credentialKeyPath ?? join(input.homeDir ?? homedir(), '.aps', 'secret.key');
  const port = Number.parseInt(env.APS_PORT ?? '', 10);

  // 引擎选择：显式配置优先；没配就按「有没有密钥」自动决定——没密钥只能用假引擎（ADR-0011）
  const requestedEngine = (env.APS_ENGINE ?? file.engine?.kind ?? '').toLowerCase();
  const engine: EngineConfig = {
    kind: requestedEngine === 'pi' || requestedEngine === 'fake' ? (requestedEngine as EngineConfig['kind']) : apiKey.trim() !== '' ? 'pi' : 'fake',
  };

  return {
    llm: { provider, baseUrl, model, apiKey },
    engine,
    capabilities: {
      // 环境变量优先；1/true 为真，0/false 为假
      defaultAllow: !['0', 'false'].includes(String(env.APS_CAPABILITY_DEFAULT_ALLOW ?? file.capabilities?.defaultAllow ?? true).toLowerCase()),
      denyWrite: ['1', 'true'].includes(String(env.APS_CAPABILITY_DENY_WRITE ?? file.capabilities?.denyWrite ?? false).toLowerCase()),
      grants: file.capabilities?.grants ?? [],
    },
    database: { path: dbPath },
    security: { credentialKeyPath: keyPath },
    server: {
      host: env.APS_HOST ?? file.server?.host ?? '127.0.0.1',
      port: Number.isFinite(port) ? port : (file.server?.port ?? 5199),
    },
    ...(env.APS_CLIENT_DIST ?? file.clientDist ?? '' ? { clientDist: env.APS_CLIENT_DIST ?? file.clientDist ?? '' } : {}),
  };
}

/** 引擎是否可用：只有配了密钥才算可用 */
export function isEngineConfigured(config: PlatformConfig): boolean {
  return config.llm.apiKey.trim() !== '';
}

/** 脱敏视图：日志与启动横幅只能用它 */
export function redactConfig(config: PlatformConfig): Record<string, unknown> {
  return {
    engine: { kind: config.engine.kind },
    capabilities: { defaultAllow: config.capabilities.defaultAllow, denyWrite: config.capabilities.denyWrite, grants: config.capabilities.grants.length },
    llm: {
      provider: config.llm.provider,
      baseUrl: config.llm.baseUrl,
      model: config.llm.model,
      apiKey: config.llm.apiKey === '' ? '(未配置)' : `(已配置，长度 ${config.llm.apiKey.length})`,
    },
    database: { path: config.database.path },
    security: { credentialKeyPath: config.security.credentialKeyPath },
    server: { host: config.server.host, port: config.server.port },
  };
}