/**
 * Cloudflare OAuth 路由(docs/02):
 *   GET  /api/oauth/cloudflare/start?node_id=  生成 state,返回授权跳转 URL
 *   GET  /api/oauth/cloudflare/callback        授权回调:state 校验、token 兑换、自动安装
 *   POST /api/oauth/cloudflare/sim/approve     sim 模式模拟用户授权(仅本地)
 *   GET  /api/oauth/connections                已建立的 OAuth 连接
 *
 * 安全:state 一次性(用后即删)、5 分钟过期、绑定 node_id;token AES-GCM 加密入库,
 * 不进前端与日志;Account ownership 以 token 实际可访问的 accounts 为准。
 */

import { Hono } from "hono";
import type { Env, AppVars } from "../env.ts";
import { requireSession } from "../middleware.ts";
import { aesEncrypt, deriveAesKey, ids } from "../../../shared/src/index.ts";
import { CF_OAUTH_AUTHORIZE_URL, CF_OAUTH_SCOPES, getCFApi } from "../services/cfapi.ts";
import { provisionNode } from "../services/provision.ts";
import { getSetting } from "../db.ts";
import { nowIso, readJson } from "../util.ts";

type App = Hono<{ Bindings: Env; Variables: AppVars }>;

/** # 成员变量: OAuth state 有效期(秒) **/
const STATE_TTL_SECONDS = 300;

/** # 函数
 * 是否使用真实 Cloudflare OAuth
 */
export function isRealOAuth(env: Env): boolean {
  return Boolean(env.CF_OAUTH_CLIENT_ID && env.CF_OAUTH_CLIENT_SECRET && !env.WMAILHUB_SIM_CF);
}

/** # 函数
 * 装配 OAuth 路由
 */
export function oauthRoutes(): App {
  const app = new Hono<{ Bindings: Env; Variables: AppVars }>();
  app.use("*", requireSession);

  /** 授权模式与入口信息(前端 Add Node 向导用) */
  app.get("/mode", (c) => {
    return c.json({
      mode: isRealOAuth(c.env) ? "cloudflare" : "sim",
      authorize_url_base: isRealOAuth(c.env) ? CF_OAUTH_AUTHORIZE_URL : null,
    });
  });

  /** 开始授权:创建 state 并返回跳转 URL */
  app.get("/cloudflare/start", async (c) => {
    const nodeId = new URL(c.req.url).searchParams.get("node_id") ?? "";
    const node = await c.env.DB.prepare("SELECT id FROM nodes WHERE id = ? AND status = 'pending_oauth' OR id = ?")
      .bind(nodeId, nodeId)
      .first<{ id: string }>();
    if (!node) return c.json({ error: "node not found" }, 404);

    const state = "cfstate_" + ids.oauthState();
    await c.env.DB.prepare(
      "INSERT INTO oauth_states (state, node_id, created_at, expires_at) VALUES (?, ?, ?, ?)",
    )
      .bind(state, nodeId, nowIso(), new Date(Date.now() + STATE_TTL_SECONDS * 1000).toISOString())
      .run();

    if (isRealOAuth(c.env)) {
      const base = c.env.PUBLIC_BASE_URL ?? new URL(c.req.url).origin;
      const redirectUri = c.env.CF_OAUTH_REDIRECT_URI ?? `${base}/api/oauth/cloudflare/callback`;
      const url =
        `${CF_OAUTH_AUTHORIZE_URL}?response_type=code` +
        `&client_id=${encodeURIComponent(c.env.CF_OAUTH_CLIENT_ID!)}` +
        `&redirect_uri=${encodeURIComponent(redirectUri)}` +
        `&scope=${encodeURIComponent(CF_OAUTH_SCOPES)}` +
        `&state=${encodeURIComponent(state)}`;
      return c.json({ url, state });
    }
    // sim 模式:前端内置模拟授权页
    return c.json({ url: `/oauth/sim/authorize?state=${encodeURIComponent(state)}`, state });
  });

  /** 授权回调(浏览器重垒):校验 state -> 兑换 token -> 自动安装 -> 跳回控制台 */
  app.get("/cloudflare/callback", async (c) => {
    const url = new URL(c.req.url);
    const code = url.searchParams.get("code") ?? "";
    const state = url.searchParams.get("state") ?? "";
    const verdict = await consumeState(c.env, state);
    if (!verdict) {
      return c.text("OAuth state invalid or expired (possible CSRF)", 400);
    }
    const cf = getCFApi(c.env, c.env.DB);
    try {
      const base = c.env.PUBLIC_BASE_URL ?? url.origin;
      const redirectUri = c.env.CF_OAUTH_REDIRECT_URI ?? `${base}/api/oauth/cloudflare/callback`;
      const token = await cf.exchangeToken(code, redirectUri);
      // 加密入库(不进前端/日志)
      await saveConnection(c.env, token.accessToken, token.expiresIn);
      const result = await provisionNode(c.env, { nodeId: verdict.nodeId, accessToken: token.accessToken });
      const target = `/nodes?provision=${encodeURIComponent(verdict.nodeId)}&ok=${result.ok ? 1 : 0}`;
      return c.redirect(target, 302);
    } catch (err) {
      return c.text(`OAuth provisioning failed: ${err instanceof Error ? err.message : String(err)}`, 500);
    }
  });

  /** sim 模式:模拟授权页的确认动作(本地开发用,需会话) */
  app.post("/cloudflare/sim/approve", async (c) => {
    const body = await readJson<{ state?: string }>(c.req.raw);
    const verdict = await consumeState(c.env, body.state ?? "");
    if (!verdict) return c.json({ error: "state invalid or expired" }, 400);
    const cf = getCFApi(c.env, c.env.DB);
    const token = await cf.exchangeToken("sim-code", "urn:unused");
    await saveConnection(c.env, token.accessToken, token.expiresIn);
    const result = await provisionNode(c.env, { nodeId: verdict.nodeId, accessToken: token.accessToken });
    return c.json({ ok: result.ok, error: result.error, node_id: verdict.nodeId });
  });

  /** 已有连接列表(不含 token) */
  app.get("/connections", async (c) => {
    const rows = await c.env.DB.prepare(
      "SELECT id, provider, account_id, expires_at, created_at FROM oauth_connections ORDER BY created_at DESC",
    ).all();
    return c.json({ items: rows.results });
  });

  return app;
}

/** # 函数
 * 消费一次性 state:存在且未过期则删除并返回 node_id,否则 null(CSRF 防护核心)
 */
async function consumeState(
  env: Env,
  state: string,
): Promise<{ nodeId: string } | null> {
  if (!state) return null;
  const row = await env.DB.prepare("SELECT node_id, expires_at FROM oauth_states WHERE state = ?")
    .bind(state)
    .first<{ node_id: string; expires_at: string }>();
  if (!row) return null;
  await env.DB.prepare("DELETE FROM oauth_states WHERE state = ?").bind(state).run();
  if (row.expires_at < nowIso()) return null;
  return { nodeId: row.node_id };
}

/** # 函数
 * OAuth access token 加密入库
 */
async function saveConnection(env: Env, accessToken: string, expiresIn: number): Promise<void> {
  const key = await deriveAesKey(await getSetting(env, "app_secret") ?? "wmailhub");
  const encrypted = await aesEncrypt(key, accessToken);
  await env.DB.prepare(
    `INSERT INTO oauth_connections (id, provider, account_id, encrypted_access_token, refresh_token, expires_at, created_at, updated_at)
     VALUES (?, 'cloudflare', NULL, ?, NULL, ?, ?, ?)`,
  )
    .bind(ids.oauth(), encrypted, new Date(Date.now() + expiresIn * 1000).toISOString(), nowIso(), nowIso())
    .run();
}