import type { IMetrics, IThroughputData, IThroughputHistoryPoint } from './models/metrics-types.js';
import type { RustProxyBridge } from './rust-proxy-bridge.js';

/**
 * Adapts Rust JSON metrics to the IMetrics interface.
 *
 * Polls the Rust binary periodically via the bridge and caches the result.
 * All IMetrics getters read from the cache synchronously.
 *
 * Rust Metrics JSON fields (camelCase via serde):
 *   activeConnections, totalConnections, bytesIn, bytesOut,
 *   throughputInBytesPerSec, throughputOutBytesPerSec,
 *   routes: { [routeName]: { activeConnections, totalConnections, bytesIn, bytesOut, ... } }
 */
export class RustMetricsAdapter implements IMetrics {
  private bridge: RustProxyBridge;
  private cache: any = null;
  private pollTimer: ReturnType<typeof setInterval> | null = null;
  private pollIntervalMs: number;

  constructor(bridge: RustProxyBridge, pollIntervalMs = 1000) {
    this.bridge = bridge;
    this.pollIntervalMs = pollIntervalMs;
  }

  /**
   * Poll Rust for metrics once. Can be awaited to ensure cache is fresh.
   */
  public async poll(): Promise<void> {
    try {
      this.cache = await this.bridge.getMetrics();
    } catch {
      // Ignore poll errors (bridge may be shutting down)
    }
  }

  public startPolling(): void {
    if (this.pollTimer) return;
    // Immediate first poll so cache is populated ASAP
    this.poll();
    this.pollTimer = setInterval(() => {
      this.poll();
    }, this.pollIntervalMs);
    if (this.pollTimer.unref) {
      this.pollTimer.unref();
    }
  }

  public stopPolling(): void {
    if (this.pollTimer) {
      clearInterval(this.pollTimer);
      this.pollTimer = null;
    }
  }

  // --- IMetrics implementation ---

  public connections = {
    active: (): number => {
      return this.cache?.activeConnections ?? 0;
    },
    total: (): number => {
      return this.cache?.totalConnections ?? 0;
    },
    byRoute: (): Map<string, number> => {
      const result = new Map<string, number>();
      if (this.cache?.routes) {
        for (const [name, rm] of Object.entries(this.cache.routes)) {
          result.set(name, (rm as any).activeConnections ?? 0);
        }
      }
      return result;
    },
    byIP: (): Map<string, number> => {
      // Per-IP tracking not yet available from Rust
      return new Map();
    },
    topIPs: (_limit?: number): Array<{ ip: string; count: number }> => {
      // Per-IP tracking not yet available from Rust
      return [];
    },
  };

  public throughput = {
    instant: (): IThroughputData => {
      return {
        in: this.cache?.throughputInBytesPerSec ?? 0,
        out: this.cache?.throughputOutBytesPerSec ?? 0,
      };
    },
    recent: (): IThroughputData => {
      return {
        in: this.cache?.throughputRecentInBytesPerSec ?? 0,
        out: this.cache?.throughputRecentOutBytesPerSec ?? 0,
      };
    },
    average: (): IThroughputData => {
      return this.throughput.instant();
    },
    custom: (_seconds: number): IThroughputData => {
      return this.throughput.instant();
    },
    history: (_seconds: number): Array<IThroughputHistoryPoint> => {
      // Throughput history not yet available from Rust
      return [];
    },
    byRoute: (_windowSeconds?: number): Map<string, IThroughputData> => {
      const result = new Map<string, IThroughputData>();
      if (this.cache?.routes) {
        for (const [name, rm] of Object.entries(this.cache.routes)) {
          result.set(name, {
            in: (rm as any).throughputInBytesPerSec ?? 0,
            out: (rm as any).throughputOutBytesPerSec ?? 0,
          });
        }
      }
      return result;
    },
    byIP: (_windowSeconds?: number): Map<string, IThroughputData> => {
      return new Map();
    },
  };

  public requests = {
    perSecond: (): number => {
      // Rust tracks connections, not HTTP requests (TCP-level proxy)
      return 0;
    },
    perMinute: (): number => {
      return 0;
    },
    total: (): number => {
      // Use total connections as a proxy for total requests
      return this.cache?.totalConnections ?? 0;
    },
  };

  public totals = {
    bytesIn: (): number => {
      return this.cache?.bytesIn ?? 0;
    },
    bytesOut: (): number => {
      return this.cache?.bytesOut ?? 0;
    },
    connections: (): number => {
      return this.cache?.totalConnections ?? 0;
    },
  };

  public percentiles = {
    connectionDuration: (): { p50: number; p95: number; p99: number } => {
      return { p50: 0, p95: 0, p99: 0 };
    },
    bytesTransferred: (): {
      in: { p50: number; p95: number; p99: number };
      out: { p50: number; p95: number; p99: number };
    } => {
      return {
        in: { p50: 0, p95: 0, p99: 0 },
        out: { p50: 0, p95: 0, p99: 0 },
      };
    },
  };
}