/**
 * Redis 客户端
 * 支持单节点和集群模式
 * 前缀：admin:*
 */
import Redis, { default as Cluster } from "ioredis";
import type { ClusterNode } from "ioredis";
import { REDIS_URL, REDIS_CLUSTER_URLS } from "./env";

// Admin 专用的 Redis 前缀
const ADMIN_PREFIX = "admin:session:";
// 平台用户 Session 前缀（与 Rust 主应用一致）
const PLATFORM_SESSION_PREFIX = "session:user_uid:";

let redis: Redis | null = null;

function createSingleClient(): Redis {
  return new Redis(REDIS_URL, {
    lazyConnect: true,
    retryStrategy(times) {
      return Math.min(times * 100, 3000);
    },
    maxRetriesPerRequest: 3,
  });
}

function createClusterClient(): Redis {
  if (REDIS_CLUSTER_URLS.length === 0) {
    return createSingleClient();
  }

  const nodes: ClusterNode[] = REDIS_CLUSTER_URLS.map((url) => {
    const u = new URL(url);
    return { host: u.hostname, port: parseInt(u.port || "6379", 10) };
  });

  const firstUrl = new URL(REDIS_CLUSTER_URLS[0]);

  // ioredis 5.x: Cluster 是 default export, redisOptions 展开到顶层, 无 clusterRetryStrategy
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  const cluster = new (Cluster as any)(nodes, {
    lazyConnect: true,
    maxRetriesPerRequest: 3,
    retryStrategy: (times: number) => Math.min(times * 100, 3000),
    // 从第一个 URL 提取认证信息（所有节点共用相同密码）
    username: firstUrl.username || undefined,
    password: firstUrl.password || undefined,
  });

  return cluster as Redis;
}

export function getRedis(): Redis {
  if (!redis) {
    redis =
      REDIS_CLUSTER_URLS.length > 1 ? createClusterClient() : createSingleClient();
  }
  return redis;
}

export function closeRedis(): Promise<unknown> {
  if (redis) {
    return redis.quit();
  }
  return Promise.resolve();
}

/**
 * 获取 Admin session 的 Redis key
 */
function adminSessionKey(sessionId: string): string {
  return `${ADMIN_PREFIX}${sessionId}`;
}

/**
 * 序列化 session 状态
 * 兼容 Rust session 格式: { v: 1, state: {...} }
 */
function serializeSessionState(state: Record<string, unknown>): string {
  return JSON.stringify({ v: 1, state });
}

/**
 * 反序列化 session 状态
 */
function deserializeSessionState(raw: string): Record<string, unknown> {
  try {
    const parsed = JSON.parse(raw);
    if (parsed && typeof parsed === "object" && "state" in parsed && parsed.state) {
      return parsed.state as Record<string, unknown>;
    }
    return parsed as Record<string, unknown>;
  } catch {
    return {};
  }
}

// ============ Session 操作 ============

export async function saveSession(
  sessionId: string,
  state: Record<string, unknown>,
  ttlSeconds: number
): Promise<void> {
  const r = getRedis();
  const key = adminSessionKey(sessionId);
  const value = serializeSessionState(state);
  await r.setex(key, ttlSeconds, value);
}

export async function loadSession(
  sessionId: string
): Promise<Record<string, unknown> | null> {
  const r = getRedis();
  const key = adminSessionKey(sessionId);
  const raw = await r.get(key);
  if (!raw) return null;
  return deserializeSessionState(raw);
}

export async function updateSession(
  sessionId: string,
  state: Record<string, unknown>,
  ttlSeconds: number
): Promise<void> {
  const r = getRedis();
  const key = adminSessionKey(sessionId);
  const value = serializeSessionState(state);
  await r.setex(key, ttlSeconds, value);
}

export async function deleteSession(sessionId: string): Promise<void> {
  const r = getRedis();
  const key = adminSessionKey(sessionId);
  await r.del(key);
}

export async function refreshSessionTtl(
  sessionId: string,
  ttlSeconds: number
): Promise<void> {
  const r = getRedis();
  const key = adminSessionKey(sessionId);
  await r.expire(key, ttlSeconds);
}

// ============ 在线用户管理（SCAN，不使用 KEYS）============

export interface SessionInfo {
  sessionId: string;
  userId: string | null;
  username: string | null;
  ipAddress: string | null;
  userAgent: string | null;
  createdAt: string | null;
}

export async function getOnlineSessions(): Promise<SessionInfo[]> {
  const r = getRedis();
  const sessions: SessionInfo[] = [];
  let cursor = "0";

  do {
    const [nextCursor, keys] = await r.scan(
      cursor,
      "MATCH",
      `${ADMIN_PREFIX}*`,
      "COUNT",
      100
    );
    cursor = nextCursor;

    if (keys.length > 0) {
      const pipeline = r.pipeline();
      for (const key of keys) {
        pipeline.get(key);
      }
      const results = await pipeline.exec();

      for (let i = 0; i < keys.length; i++) {
        const raw = results?.[i]?.[1] as string | null;
        if (raw) {
          const state = deserializeSessionState(raw);
          sessions.push({
            sessionId: keys[i].replace(ADMIN_PREFIX, ""),
            userId: String(state["session:user_uid"] ?? ""),
            username: (state["session:username"] as string) || null,
            ipAddress: (state["session:ip_address"] as string) || null,
            userAgent: (state["session:user_agent"] as string) || null,
            createdAt: (state["session:created_at"] as string) || null,
          });
        }
      }
    }
  } while (cursor !== "0");

  return sessions;
}

export async function getUserSessions(
  userId: string
): Promise<SessionInfo[]> {
  const allSessions = await getOnlineSessions();
  return allSessions.filter((s) => s.userId === userId);
}

export async function kickUser(userId: string): Promise<number> {
  const sessions = await getUserSessions(userId);
  if (sessions.length === 0) return 0;

  const r = getRedis();
  const pipeline = r.pipeline();
  for (const s of sessions) {
    pipeline.del(`${ADMIN_PREFIX}${s.sessionId}`);
  }
  const results = await pipeline.exec();
  return results?.filter((r) => r[0] === null && r[1] === 1).length ?? 0;
}

export async function kickSession(sessionId: string): Promise<boolean> {
  const r = getRedis();
  const result = await r.del(`${ADMIN_PREFIX}${sessionId}`);
  return result === 1;
}

// ============ 平台用户会话管理（SCAN session:user_uid:*）============

export interface PlatformSessionInfo {
  sessionId: string;
  userId: string;
  username: string | null;
  workspaceId: string | null;
  ipAddress: string | null;
  userAgent: string | null;
  createdAt: string | null;
}

export async function getOnlinePlatformSessions(): Promise<PlatformSessionInfo[]> {
  const r = getRedis();
  const sessions: PlatformSessionInfo[] = [];
  let cursor = "0";

  do {
    const [nextCursor, keys] = await r.scan(
      cursor,
      "MATCH",
      `${PLATFORM_SESSION_PREFIX}*`,
      "COUNT",
      100
    );
    cursor = nextCursor;

    if (keys.length > 0) {
      const pipeline = r.pipeline();
      for (const key of keys) {
        pipeline.get(key);
      }
      const results = await pipeline.exec();

      for (let i = 0; i < keys.length; i++) {
        const raw = results?.[i]?.[1] as string | null;
        if (raw) {
          const state = deserializeSessionState(raw);
          sessions.push({
            sessionId: keys[i].replace(PLATFORM_SESSION_PREFIX, ""),
            userId: String(state["session:user_uid"] ?? ""),
            username: (state["session:username"] as string) || null,
            workspaceId: (state["session:workspace_id"] as string) || null,
            ipAddress: (state["session:ip_address"] as string) || null,
            userAgent: (state["session:user_agent"] as string) || null,
            createdAt: (state["session:created_at"] as string) || null,
          });
        }
      }
    }
  } while (cursor !== "0");

  return sessions;
}

export async function kickPlatformSession(sessionId: string): Promise<boolean> {
  const r = getRedis();
  const result = await r.del(`${PLATFORM_SESSION_PREFIX}${sessionId}`);
  return result === 1;
}