const SERVER_STORAGE_KEY = "llm_monitor_servers";
const ACTIVE_SERVER_KEY = "llm_monitor_active_server";
const DATA_REFRESH_INTERVAL_MS = 30000;
const SERVER_CACHE_SUFFIXES = ["health", "models", "running"];

function normalizeHost(host) {
  if (!host) {
    return "";
  }

  const trimmed = host.trim();
  if (!trimmed) {
    return "";
  }

  return trimmed.replace(/\/+$/, "");
}

function loadServers() {
  const raw = localStorage.getItem(SERVER_STORAGE_KEY);
  if (!raw) {
    return [];
  }

  try {
    const parsed = JSON.parse(raw);
    if (!Array.isArray(parsed)) {
      return [];
    }

    return parsed
      .map((item) => ({
        id: String(item.id || ""),
        name: String(item.name || "").trim(),
        host: normalizeHost(item.host || "")
      }))
      .filter((item) => item.id && item.name && item.host);
  } catch {
    return [];
  }
}

function saveServers(servers) {
  localStorage.setItem(SERVER_STORAGE_KEY, JSON.stringify(servers));
  cleanupOrphanedServerCaches(servers);
}

function generateServerId() {
  return `srv_${Date.now()}_${Math.random().toString(16).slice(2, 8)}`;
}

function getActiveServerId() {
  return localStorage.getItem(ACTIVE_SERVER_KEY);
}

function setActiveServerId(serverId) {
  localStorage.setItem(ACTIVE_SERVER_KEY, serverId);
}

function getServerById(serverId) {
  return loadServers().find((server) => server.id === serverId) || null;
}

function getServerIdFromQuery() {
  const params = new URLSearchParams(window.location.search);
  return params.get("server") || "";
}

function getActiveServer() {
  const queryServerId = getServerIdFromQuery();
  if (queryServerId) {
    const fromQuery = getServerById(queryServerId);
    if (fromQuery) {
      setActiveServerId(fromQuery.id);
      return fromQuery;
    }
  }

  const activeServerId = getActiveServerId();
  if (activeServerId) {
    const activeServer = getServerById(activeServerId);
    if (activeServer) {
      return activeServer;
    }
  }

  const servers = loadServers();
  if (servers.length > 0) {
    setActiveServerId(servers[0].id);
    return servers[0];
  }

  return null;
}

function buildServerUrl(path, serverId) {
  const url = new URL(path, window.location.origin);
  if (serverId) {
    url.searchParams.set("server", serverId);
  }
  return `${url.pathname}${url.search}`;
}

function getServerStorageKey(serverId, suffix) {
  return `llm_monitor_${suffix}_${serverId}`;
}

function readServerCache(serverId, suffix) {
  if (!serverId) {
    return null;
  }

  const raw = localStorage.getItem(getServerStorageKey(serverId, suffix));
  if (!raw) {
    return null;
  }

  try {
    return JSON.parse(raw);
  } catch {
    return null;
  }
}

function writeServerCache(serverId, suffix, value) {
  if (!serverId) {
    return value;
  }

  const storageKey = getServerStorageKey(serverId, suffix);
  const candidates = [value];

  cleanupOrphanedServerCaches();

  if (suffix === "models") {
    candidates.push(createSlimModelsCache(value));
  }

  for (const candidate of candidates) {
    try {
      localStorage.setItem(storageKey, JSON.stringify(candidate));
      return candidate;
    } catch (error) {
      if (!isQuotaExceededError(error)) {
        throw error;
      }
    }
  }

  // Last resort: free stale server caches and retry with the smallest payload.
  cleanupOrphanedServerCaches(loadServers());

  if (suffix === "models") {
    const slimValue = createSlimModelsCache(value);
    try {
      localStorage.setItem(storageKey, JSON.stringify(slimValue));
      return slimValue;
    } catch (error) {
      if (!isQuotaExceededError(error)) {
        throw error;
      }
      console.warn(`Cache quota exceeded for ${storageKey}; using in-memory models data only.`);
      return null;
    }
  }

  console.warn(`Cache quota exceeded for ${storageKey}; skipping persistence for this payload.`);
  return null;
}

function createSlimModelsCache(value) {
  if (!value || typeof value !== "object") {
    return value;
  }

  const slimValue = { ...value };
  if (slimValue.showByModel) {
    delete slimValue.showByModel;
    slimValue.showDetailsDeferred = true;
  }

  return slimValue;
}

function isQuotaExceededError(error) {
  return error instanceof DOMException && (
    error.code === 22 ||
    error.code === 1014 ||
    error.name === "QuotaExceededError" ||
    error.name === "NS_ERROR_DOM_QUOTA_REACHED"
  );
}

function cleanupOrphanedServerCaches(servers = loadServers()) {
  const validServerIds = new Set(servers.map((server) => server.id));
  const keysToRemove = [];

  for (let index = 0; index < localStorage.length; index += 1) {
    const key = localStorage.key(index);
    if (!key) {
      continue;
    }

    for (const suffix of SERVER_CACHE_SUFFIXES) {
      const prefix = `llm_monitor_${suffix}_`;
      if (!key.startsWith(prefix)) {
        continue;
      }

      const serverId = key.slice(prefix.length);
      if (!validServerIds.has(serverId)) {
        keysToRemove.push(key);
      }
    }
  }

  keysToRemove.forEach((key) => localStorage.removeItem(key));
}

function clearServerCaches(serverId) {
  if (!serverId) {
    return;
  }

  SERVER_CACHE_SUFFIXES.forEach((suffix) => {
    localStorage.removeItem(getServerStorageKey(serverId, suffix));
  });
}

function getCacheTimestamp(cacheValue) {
  if (!cacheValue || !cacheValue.timestamp) {
    return 0;
  }

  const parsed = Date.parse(cacheValue.timestamp);
  return Number.isNaN(parsed) ? 0 : parsed;
}

function getLatestServerCacheTimestamp(serverId, suffixes) {
  return suffixes.reduce((latest, suffix) => {
    const value = readServerCache(serverId, suffix);
    return Math.max(latest, getCacheTimestamp(value));
  }, 0);
}

function isCacheStale(timestamp, maxAgeMs = DATA_REFRESH_INTERVAL_MS) {
  if (!timestamp) {
    return true;
  }

  return (Date.now() - timestamp) >= maxAgeMs;
}

function hasDeferredShowDetails(cacheValue) {
  return Boolean(cacheValue && cacheValue.showDetailsDeferred);
}