/**
 * Grafana Dashboard API Client
 *
 * Fetches dashboard data and panel snapshots from Grafana.
 * Requires service account token with Viewer role.
 *
 * Setup:
 *   1. Grafana UI > Administration > Service Accounts > Add
 *   2. Create token, set GRAFANA_API_TOKEN env var
 *   3. Or use Grafana API directly: POST /api/serviceaccounts
 */

const GRAFANA_URL = process.env.GRAFANA_URL || 'https://grafana.riotpiao.com';
const GRAFANA_API_TOKEN = process.env.GRAFANA_API_TOKEN || '';

interface GrafanaHeaders {
  'Content-Type': string;
  Authorization?: string;
}

function headers(): GrafanaHeaders {
  const h: GrafanaHeaders = { 'Content-Type': 'application/json' };
  if (GRAFANA_API_TOKEN) {
    h.Authorization = `Bearer ${GRAFANA_API_TOKEN}`;
  }
  return h;
}

export interface Dashboard {
  uid: string;
  title: string;
  panels: Panel[];
}

export interface Panel {
  id: number;
  title: string;
  type: string;
  gridPos: { h: number; w: number; x: number; y: number };
}

export interface DashboardMeta {
  uid: string;
  title: string;
  url: string;
  slug: string;
}

/**
 * Get dashboard by UID
 */
export async function getDashboard(uid: string): Promise<Dashboard> {
  const response = await fetch(`${GRAFANA_URL}/api/dashboards/uid/${uid}`, {
    headers: headers(),
  });

  if (!response.ok) {
    throw new Error(`Grafana API error: ${response.status} ${await response.text()}`);
  }

  const data = await response.json();
  return data.dashboard;
}

/**
 * List all dashboards
 */
export async function listDashboards(): Promise<DashboardMeta[]> {
  const response = await fetch(`${GRAFANA_URL}/api/search?type=dash-db`, {
    headers: headers(),
  });

  if (!response.ok) {
    throw new Error(`Grafana API error: ${response.status}`);
  }

  return response.json();
}

/**
 * Query Prometheus datasource directly via Grafana proxy
 * Bypasses need for direct Prometheus access
 */
export async function queryPrometheus(
  query: string,
  start?: number,
  end?: number,
  step?: number
): Promise<PrometheusResult> {
  const params = new URLSearchParams({
    query,
    start: String(start || Math.floor(Date.now() / 1000) - 3600),
    end: String(end || Math.floor(Date.now() / 1000)),
    step: String(step || 60),
  });

  const response = await fetch(
    `${GRAFANA_URL}/api/datasources/proxy/uid/prometheus/api/v1/query_range?${params}`,
    { headers: headers() }
  );

  if (!response.ok) {
    throw new Error(`Prometheus query error: ${response.status}`);
  }

  return response.json();
}

export interface PrometheusResult {
  status: string;
  data: {
    resultType: string;
    result: {
      metric: Record<string, string>;
      values: [number, string][];
    }[];
  };
}

/**
 * Get LLM-specific metrics
 */
export async function getLLMMetrics(): Promise<LLMMetrics> {
  const [podsReady, cpuUsage, memoryUsage] = await Promise.all([
    queryPrometheus('sum(kube_pod_status_ready{namespace="llm-serving",condition="true"})'),
    queryPrometheus('sum(rate(container_cpu_usage_seconds_total{namespace="llm-serving"}[5m])) by (pod)'),
    queryPrometheus('sum(container_memory_working_set_bytes{namespace="llm-serving"}) by (pod)'),
  ]);

  return {
    podsReady: extractLatestValue(podsReady),
    cpuByPod: extractSeriesLatest(cpuUsage),
    memoryByPod: extractSeriesLatest(memoryUsage),
  };
}

export interface LLMMetrics {
  podsReady: number;
  cpuByPod: Record<string, number>;
  memoryByPod: Record<string, number>;
}

function extractLatestValue(result: PrometheusResult): number {
  const values = result.data?.result?.[0]?.values;
  if (!values || values.length === 0) return 0;
  return parseFloat(values[values.length - 1][1]);
}

function extractSeriesLatest(result: PrometheusResult): Record<string, number> {
  const out: Record<string, number> = {};
  for (const series of result.data?.result || []) {
    const pod = series.metric.pod || 'unknown';
    const values = series.values;
    if (values && values.length > 0) {
      out[pod] = parseFloat(values[values.length - 1][1]);
    }
  }
  return out;
}

/**
 * Generate iframe embed URL for a panel
 * Requires Grafana security.allow_embedding=true
 */
export function getPanelEmbedUrl(
  dashboardUid: string,
  panelId: number,
  from = 'now-6h',
  to = 'now',
  refresh = '30s'
): string {
  return `${GRAFANA_URL}/d-solo/${dashboardUid}?panelId=${panelId}&from=${from}&to=${to}&refresh=${refresh}`;
}

/**
 * Generate full dashboard URL
 */
export function getDashboardUrl(dashboardUid: string): string {
  return `${GRAFANA_URL}/d/${dashboardUid}`;
}