import { mkdir, readFile, writeFile } from 'node:fs/promises';
import { join } from 'node:path';
import { getCodexDataDir } from './codexHome';
import { DEFAULT_API_KEY_ENV, type CodexProviderSpec, type CodexRuntime, type JsonValue } from './codexRuntime';
import type { AppliedProviderInfo, ApplyProviderInput } from './types';

/**
 * 把后端「模型管理」里的一条记录翻译成 Codex 的 model provider。
 * 全程不做任何 Codex/OpenAI 账号登录：靠 wire_api="responses" + requires_openai_auth=false + env_key。
 * apiKey 只存在于内存与子进程环境变量，落盘的 AppliedProvider 不含任何密钥。
 */

export const PROVIDER_ID = 'zsjz';

export type AppliedProvider = AppliedProviderInfo;

export interface ProviderCompatibility {
  compatible: boolean;
  /** null 表示网络不可达，无法判定 */
  status: number | null;
  detail: string;
}

const EXTRA_ALLOWLIST: readonly string[] = [
  'request_max_retries',
  'stream_max_retries',
  'stream_idle_timeout_ms',
  'query_params',
];

function providerFile(): string {
  return join(getCodexDataDir(), 'provider.json');
}

/** Codex 要求 base_url 是 API 根（形如 https://api.openai.com/v1），它自己再拼 /responses */
export function normalizeBaseUrl(raw: string | null | undefined): string | null {
  const value = (raw ?? '').trim().replace(/\/+$/u, '');
  return value || null;
}

/** 给页面的非阻断提示；返回 null 表示没问题 */
export function baseUrlHint(baseUrl: string | null): string | null {
  if (!baseUrl) return '未配置 base_url';
  if (!/^https?:\/\//u.test(baseUrl)) return 'base_url 必须以 http:// 或 https:// 开头';
  if (!/\/v\d+$/u.test(baseUrl)) {
    return 'base_url 通常应写到版本段（如 .../v1），否则 Codex 拼出的 /responses 可能 404';
  }
  return null;
}

function parseJsonRecord(raw: unknown): Record<string, unknown> | null {
  if (!raw) return null;
  if (typeof raw === 'object' && !Array.isArray(raw)) return raw as Record<string, unknown>;
  if (typeof raw !== 'string') return null;
  try {
    const parsed = JSON.parse(raw) as unknown;
    return parsed && typeof parsed === 'object' && !Array.isArray(parsed)
      ? (parsed as Record<string, unknown>)
      : null;
  } catch {
    return null;
  }
}

function readStringMap(raw: unknown): Record<string, string> | null {
  const record = parseJsonRecord(raw);
  if (!record) return null;
  const result: Record<string, string> = {};
  for (const [key, value] of Object.entries(record)) {
    if (typeof value === 'string' && value) result[key] = value;
  }
  return Object.keys(result).length ? result : null;
}

/** Codex 内置 ollama/lmstudio 走 OpenAI 兼容根（.../v1），而库里常只存到 host:port */
function normalizeOssBaseUrl(raw: string | null | undefined): string | null {
  const base = normalizeBaseUrl(raw);
  if (!base) return null;
  return /\/v\d+$/u.test(base) ? base : `${base}/v1`;
}

/** OLLAMA 用 Codex 内置 provider（Responses API，默认端口 11434），不需要 api key */
function resolveBuiltinProvider(input: ApplyProviderInput): string | null {
  if (input.builtinProvider) return input.builtinProvider;
  const type = `${input.providerType ?? ''}`.trim().toUpperCase();
  if (type === 'OLLAMA') return 'ollama';
  if (type === 'LMSTUDIO') return 'lmstudio';
  return null;
}

export function toProviderSpec(input: ApplyProviderInput): CodexProviderSpec {
  const model = `${input.modelId ?? ''}`.trim();
  if (!model) throw new Error('缺少 modelId');

  const builtinProvider = resolveBuiltinProvider(input);
  if (builtinProvider) {
    return {
      id: null,
      builtinProvider,
      model,
      name: input.name ?? `${builtinProvider} 本地模型`,
      // 内置 provider 的默认地址是 localhost，必须把库里的真实地址带上，否则连不到远端 Ollama
      baseUrl: normalizeOssBaseUrl(input.baseUrl),
    };
  }

  const baseUrl = normalizeBaseUrl(input.baseUrl);
  if (!baseUrl) throw new Error('缺少 baseUrl');

  const config = parseJsonRecord(input.config);
  const extra: Record<string, JsonValue> = {};
  for (const [key, value] of Object.entries(config ?? {})) {
    if (EXTRA_ALLOWLIST.includes(key)) extra[key] = value as JsonValue;
  }

  return {
    id: PROVIDER_ID,
    name: input.name ?? model,
    baseUrl,
    model,
    apiKey: input.apiKey ?? null,
    envKey: DEFAULT_API_KEY_ENV,
    httpHeaders: readStringMap(input.headersJson),
    extra: Object.keys(extra).length ? extra : null,
  };
}

/** config 里被丢弃的非白名单键，用于页面提示 */
export function describeDroppedKeys(input: ApplyProviderInput): string[] {
  const config = parseJsonRecord(input.config);
  return Object.keys(config ?? {}).filter((key) => !EXTRA_ALLOWLIST.includes(key));
}

/**
 * 探测端点是否实现了 Responses API。
 * 404/405 = 未实现（Codex 0.155 起已下线 wire_api="chat"，chat-only 端点用不了）；
 * 401/403/400/422/2xx = 路由存在，判为兼容。
 */
export async function probeResponsesEndpoint(
  baseUrl: string,
  apiKey?: string | null,
): Promise<ProviderCompatibility> {
  const url = `${baseUrl.replace(/\/+$/u, '')}/responses`;
  let status: number;
  try {
    const response = await fetch(url, {
      method: 'POST',
      headers: {
        'content-type': 'application/json',
        ...(apiKey ? { authorization: `Bearer ${apiKey}` } : {}),
      },
      body: JSON.stringify({ model: 'probe', input: 'probe' }),
      signal: AbortSignal.timeout(8_000),
    });
    status = response.status;
  } catch (error) {
    return {
      compatible: false,
      status: null,
      detail: `端点不可达：${error instanceof Error ? error.message : String(error)}`,
    };
  }
  if (status === 404 || status === 405) {
    return {
      compatible: false,
      status,
      detail: `该端点未实现 Responses API（HTTP ${status}）。Codex 0.155 起已下线 wire_api="chat"，只提供 /chat/completions 的服务需要额外网关转换。`,
    };
  }
  return { compatible: true, status, detail: `端点已实现 Responses API（HTTP ${status}）` };
}

export async function readAppliedProvider(): Promise<AppliedProvider | null> {
  try {
    const raw = JSON.parse(await readFile(providerFile(), 'utf8')) as Partial<AppliedProvider>;
    return raw.model ? (raw as AppliedProvider) : null;
  } catch {
    return null;
  }
}

async function writeAppliedProvider(value: AppliedProvider | null): Promise<void> {
  await mkdir(getCodexDataDir(), { recursive: true });
  await writeFile(providerFile(), JSON.stringify(value ?? {}, null, 2), 'utf8');
}

/** 应用一条模型配置：先探端点，再重启子进程（api_key 走 env，换 key 必须重启） */
export async function applyProvider(
  runtime: CodexRuntime,
  input: ApplyProviderInput & { modelRecordId?: string | number | null },
): Promise<AppliedProvider> {
  const spec = toProviderSpec(input);
  // 只要显式配了地址就探（含远端 Ollama）：应用成功后才发现连不上，比这里直接报错更难排查。
  // 内置 provider 没配地址时不探（默认 localhost，可能压根没起本地服务）。
  if (spec.baseUrl) {
    const probe = await probeResponsesEndpoint(spec.baseUrl, spec.apiKey);
    if (!probe.compatible) throw new Error(probe.detail);
  }
  await runtime.applyProvider(spec);
  const applied: AppliedProvider = {
    model: spec.model,
    modelRecordId: input.modelRecordId === undefined || input.modelRecordId === null
      ? null
      : String(input.modelRecordId),
    baseUrl: spec.baseUrl ?? null,
    providerId: spec.id,
    builtinProvider: spec.builtinProvider ?? null,
    name: spec.name ?? null,
    appliedAt: new Date().toISOString(),
  };
  await writeAppliedProvider(applied);
  return applied;
}

export async function clearProvider(runtime: CodexRuntime): Promise<void> {
  await runtime.applyProvider(null);
  await writeAppliedProvider(null);
}