/**
 * Viking Server Manager - Local OpenViking Server Management
 *
 * Manages a local OpenViking server instance for privacy-first deployment.
 * All data is stored locally in ~/.openviking/ - nothing is uploaded to remote servers.
 *
 * Usage:
 *   const manager = getVikingServerManager();
 *
 *   // Check server status
 *   const status = await manager.getStatus();
 *
 *   // Start server if not running
 *   if (!status.running) {
 *     await manager.start();
 *   }
 *
 *   // Server is now available at http://127.0.0.1:1933
 */

import { invoke } from '@tauri-apps/api/core';

// === Types ===

export interface VikingServerStatus {
  running: boolean;
  port: number;
  pid?: number;
  dataDir?: string;
  version?: string;
  error?: string;
}

export interface VikingServerConfig {
  port?: number;
  dataDir?: string;
  configFile?: string;
}

// === Default Configuration ===

const DEFAULT_CONFIG: Required<VikingServerConfig> = {
  port: 1933,
  dataDir: '',  // Will use default ~/.openviking/workspace
  configFile: '',  // Will use default ~/.openviking/ov.conf
};

// === Server Manager Class ===

export class VikingServerManager {
  private status: VikingServerStatus | null = null;
  private startPromise: Promise<VikingServerStatus> | null = null;

  /**
   * Get current server status
   */
  async getStatus(): Promise<VikingServerStatus> {
    try {
      this.status = await invoke<VikingServerStatus>('viking_server_status');
      return this.status;
    } catch (err) {
      console.error('[VikingServerManager] Failed to get status:', err);
      return {
        running: false,
        port: DEFAULT_CONFIG.port,
        error: err instanceof Error ? err.message : String(err),
      };
    }
  }

  /**
   * Start local OpenViking server
   * If server is already running, returns current status
   */
  async start(config?: VikingServerConfig): Promise<VikingServerStatus> {
    // Prevent concurrent start attempts
    if (this.startPromise) {
      return this.startPromise;
    }

    // Check if already running
    const currentStatus = await this.getStatus();
    if (currentStatus.running) {
      console.log('[VikingServerManager] Server already running on port', currentStatus.port);
      return currentStatus;
    }

    this.startPromise = this.doStart(config);

    try {
      const result = await this.startPromise;
      return result;
    } finally {
      this.startPromise = null;
    }
  }

  private async doStart(config?: VikingServerConfig): Promise<VikingServerStatus> {
    const fullConfig = { ...DEFAULT_CONFIG, ...config };

    console.log('[VikingServerManager] Starting local server on port', fullConfig.port);

    try {
      const status = await invoke<VikingServerStatus>('viking_server_start', {
        config: {
          port: fullConfig.port,
          dataDir: fullConfig.dataDir || undefined,
          configFile: fullConfig.configFile || undefined,
        },
      });

      this.status = status;
      console.log('[VikingServerManager] Server started:', status);
      return status;
    } catch (err) {
      const errorMsg = err instanceof Error ? err.message : String(err);
      console.error('[VikingServerManager] Failed to start server:', errorMsg);

      this.status = {
        running: false,
        port: fullConfig.port,
        error: errorMsg,
      };

      return this.status;
    }
  }

  /**
   * Stop local OpenViking server
   */
  async stop(): Promise<void> {
    console.log('[VikingServerManager] Stopping server');

    try {
      await invoke('viking_server_stop');
      this.status = {
        running: false,
        port: DEFAULT_CONFIG.port,
      };
      console.log('[VikingServerManager] Server stopped');
    } catch (err) {
      console.error('[VikingServerManager] Failed to stop server:', err);
      throw err;
    }
  }

  /**
   * Restart local OpenViking server
   */
  async restart(config?: VikingServerConfig): Promise<VikingServerStatus> {
    console.log('[VikingServerManager] Restarting server');

    try {
      const status = await invoke<VikingServerStatus>('viking_server_restart', {
        config: config ? {
          port: config.port,
          dataDir: config.dataDir,
          configFile: config.configFile,
        } : undefined,
      });

      this.status = status;
      console.log('[VikingServerManager] Server restarted:', status);
      return status;
    } catch (err) {
      const errorMsg = err instanceof Error ? err.message : String(err);
      console.error('[VikingServerManager] Failed to restart server:', errorMsg);

      this.status = {
        running: false,
        port: config?.port || DEFAULT_CONFIG.port,
        error: errorMsg,
      };

      return this.status;
    }
  }

  /**
   * Ensure server is running, starting if necessary
   * This is the main entry point for ensuring availability
   */
  async ensureRunning(config?: VikingServerConfig): Promise<boolean> {
    const status = await this.getStatus();

    if (status.running) {
      return true;
    }

    const startResult = await this.start(config);
    return startResult.running;
  }

  /**
   * Get the server URL for HTTP client connections
   */
  getServerUrl(port?: number): string {
    const actualPort = port || this.status?.port || DEFAULT_CONFIG.port;
    return `http://127.0.0.1:${actualPort}`;
  }

  /**
   * Check if server is available (cached status)
   */
  isRunning(): boolean {
    return this.status?.running ?? false;
  }

  /**
   * Clear cached status (force refresh on next call)
   */
  clearCache(): void {
    this.status = null;
  }
}

// === Singleton ===

let _instance: VikingServerManager | null = null;

export function getVikingServerManager(): VikingServerManager {
  if (!_instance) {
    _instance = new VikingServerManager();
  }
  return _instance;
}

export function resetVikingServerManager(): void {
  _instance = null;
}