import Docker from 'dockerode';
import WebSocket from 'ws';
import { exec } from 'child_process';
import { promisify } from 'util';
import path from 'path';
import fs from 'fs/promises';
import * as yaml from 'yaml';

const execAsync = promisify(exec);
const COMPOSE_DIR = process.env.COMPOSE_DIR || '/app/compose';

class DockerController {
  private static instance: DockerController;
  private docker: Docker;

  private constructor() {
    this.docker = new Docker({ socketPath: '/var/run/docker.sock' });
  }

  public static getInstance(): DockerController {
    if (!DockerController.instance) {
      DockerController.instance = new DockerController();
    }
    return DockerController.instance;
  }

  public async getDiskUsage() {
    const df = await this.docker.df();

    const calculateReclaimableContainers = (items: any[]) => {
      if (!items || !Array.isArray(items)) return 0;
      return items.filter(i => i.State !== 'running').reduce((acc, item) => {
        let size = item.SizeRw || item.SizeRootFs || 0;
        if (item.UsageData && typeof item.UsageData.Size === 'number') {
          size = item.UsageData.Size;
        }
        return acc + size;
      }, 0);
    };

    const calculateReclaimableImages = (items: any[]) => {
      if (!items || !Array.isArray(items)) return 0;
      return items.filter(i => i.Containers === 0).reduce((acc, item) => {
        let size = item.VirtualSize || item.Size || item.SharedSize || 0;
        if (item.UsageData && typeof item.UsageData.Size === 'number') {
          size = item.UsageData.Size;
        }
        return acc + size;
      }, 0);
    };

    const calculateReclaimableVolumes = (items: any[]) => {
      if (!items || !Array.isArray(items)) return 0;
      return items.filter(i => i.UsageData?.RefCount === 0).reduce((acc, item) => {
        let size = item.UsageData?.Size || 0;
        return acc + size;
      }, 0);
    };

    return {
      reclaimableImages: df.Images ? calculateReclaimableImages(df.Images) : 0,
      reclaimableContainers: df.Containers ? calculateReclaimableContainers(df.Containers) : 0,
      reclaimableVolumes: df.Volumes ? calculateReclaimableVolumes(df.Volumes) : 0,
    };
  }

  public async pruneSystem(target: 'containers' | 'images' | 'networks' | 'volumes') {
    let result: any = {};
    if (target === 'containers') {
      result = await this.docker.pruneContainers();
    } else if (target === 'images') {
      // Remove all unused images, not just dangling ones
      result = await this.docker.pruneImages({ filters: { dangling: { 'false': true } } });
    } else if (target === 'networks') {
      result = await this.docker.pruneNetworks();
    } else if (target === 'volumes') {
      result = await this.docker.pruneVolumes({ filters: { all: ['true'] } });
    }

    return {
      success: true,
      reclaimedBytes: result?.SpaceReclaimed || 0
    };
  }

  public async getRunningContainers() {
    const containers = await this.docker.listContainers({ all: false });
    return containers;
  }

  public async getAllContainers() {
    const containers = await this.docker.listContainers({ all: true });
    return containers;
  }

  public async getContainersByStack(stackName: string) {
    const stackDir = path.join(COMPOSE_DIR, stackName);

    try {
      const { stdout, stderr } = await execAsync('docker compose ps --format json -a', {
        cwd: stackDir,
        env: {
          ...process.env,
          PATH: process.env.PATH || '/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'
        }
      });

      // Robust JSON parsing - handle both JSON array and newline-separated JSON objects
      // Docker Compose v2 may return either format depending on version
      interface ComposeContainer {
        ID?: string;
        Name?: string;
        State?: string;
        Status?: string;
        Publishers?: { URL?: string, TargetPort?: number, PublishedPort?: number }[];
      }

      let containers: ComposeContainer[] = [];

      // Only parse if stdout has content
      if (stdout && stdout.trim() !== '') {
        try {
          // Try parsing as a standard JSON array
          const parsed = JSON.parse(stdout);
          containers = Array.isArray(parsed) ? parsed : [parsed];
        } catch (parseError) {
          // Fallback: parse newline-separated JSON objects, filtering out empty lines
          try {
            const lines = stdout.trim().split('\n').filter(line => line.trim() !== '');
            containers = lines.map(line => JSON.parse(line) as ComposeContainer);
          } catch (innerError) {
            // Log parsing failure with stderr for debugging
            console.error(`Docker Compose JSON Parse Error for ${stackName}:`, stderr || (parseError as Error).message);
            // Don't return empty - trigger smart fallback below
          }
        }
      }

      // If containers found via docker compose ps, return them
      if (containers.length > 0) {
        // Map to frontend's expected interface
        // Note: docker compose ps returns Name (singular), but frontend expects Names (array)
        // Dockerode returns Names with leading slash, so we add it for compatibility
        return containers.map((c) => {
          let Ports: { PrivatePort: number, PublicPort: number }[] = [];
          if (c.Publishers && Array.isArray(c.Publishers)) {
            Ports = c.Publishers
              .filter(p => typeof p.PublishedPort === 'number' && p.PublishedPort > 0)
              .map(p => ({ PrivatePort: (p.TargetPort || 0) as number, PublicPort: p.PublishedPort as number }));
          }
          return {
            Id: c.ID || '',
            Names: ['/' + (c.Name || '')],  // Add leading slash to match Dockerode format
            State: c.State || 'unknown',
            Status: c.Status || '',
            Ports
          };
        });
      }

      // SMART FALLBACK: Trigger when docker compose ps returns empty
      // This handles legacy containers with incorrect project labels
      return await this.smartFallback(stackName, stackDir);

    } catch (error) {
      // If command fails (e.g., stack not deployed, invalid YAML, missing env_file)
      const execError = error as { stderr?: string; message?: string };
      console.error(`Docker Compose Error for ${stackName}:`, execError.stderr || execError.message);

      // Try smart fallback even on error
      return await this.smartFallback(stackName, stackDir);
    }
  }

  /**
   * Smart Fallback: Find legacy containers by parsing compose YAML definitions.
   * This handles containers that were deployed with incorrect project labels
   * that cause `docker compose ps` to ignore them.
   */
  private async smartFallback(stackName: string, stackDir: string): Promise<any[]> {
    try {
      // 1. Flexible Compose File Discovery
      // Try multiple valid compose file names
      const composeFileNames = ['compose.yaml', 'docker-compose.yml', 'compose.yml', 'docker-compose.yaml'];
      let yamlContent: string | null = null;

      for (const fileName of composeFileNames) {
        try {
          yamlContent = await fs.readFile(path.join(stackDir, fileName), 'utf-8');
          break; // Successfully read a file, stop trying
        } catch {
          // File doesn't exist, try next
          continue;
        }
      }

      if (!yamlContent) {
        // No compose file found
        return [];
      }

      const parsedYaml = yaml.parse(yamlContent);

      if (!parsedYaml || !parsedYaml.services) return [];

      // 2. Extract expected container names with legacy prefix support
      const expectedNames: string[] = [];
      for (const [serviceName, serviceConfig] of Object.entries(parsedYaml.services)) {
        const config = serviceConfig as any;
        if (config.container_name) {
          expectedNames.push(config.container_name);
        } else {
          // Standard v2 naming
          expectedNames.push(serviceName);
          expectedNames.push(`${stackName}-${serviceName}-1`);
          // Legacy project prefix catch - accounts for orphan containers
          expectedNames.push(`compose-${serviceName}-1`);
          expectedNames.push(`compose_${serviceName}_1`);
        }
      }

      // 3. Query the raw Docker daemon
      const allContainers = await this.docker.listContainers({ all: true });

      // 4. Match containers by name
      const fallbackContainers = allContainers.filter(container => {
        // container.Names usually looks like ['/plex']
        return container.Names.some(name => {
          const strippedName = name.replace(/^\//, '');
          return expectedNames.includes(strippedName);
        });
      });

      // 5. Map to the frontend interface
      return fallbackContainers.map(c => {
        let Ports: { PrivatePort: number, PublicPort: number }[] = [];
        if (c.Ports && Array.isArray(c.Ports)) {
          Ports = c.Ports
            .filter((p: any) => typeof p.PublicPort === 'number' && p.PublicPort > 0)
            .map((p: any) => ({ PrivatePort: (p.PrivatePort || 0) as number, PublicPort: p.PublicPort as number }));
        }
        return {
          Id: c.Id,
          Names: c.Names,
          State: c.State,
          Status: c.Status,
          Ports
        };
      });
    } catch (fallbackError) {
      console.error(`Smart Fallback failed for ${stackName}:`, fallbackError);
      return [];
    }
  }

  // State-safe: silently ignores 304 "already started" errors
  public async startContainer(containerId: string) {
    try {
      const container = this.docker.getContainer(containerId);
      await container.start();
    } catch (error: any) {
      if (error?.statusCode === 304) {
        // Container already running — not an error
        return;
      }
      throw error;
    }
  }

  // State-safe: silently ignores 304 "already stopped" errors
  public async stopContainer(containerId: string) {
    try {
      const container = this.docker.getContainer(containerId);
      await container.stop();
    } catch (error: any) {
      if (error?.statusCode === 304) {
        // Container already stopped — not an error
        return;
      }
      throw error;
    }
  }

  public async restartContainer(containerId: string) {
    const container = this.docker.getContainer(containerId);
    await container.restart();
  }

  public async getOrphanContainers(knownStackNames: string[]) {
    // 1. Fetch all containers (running and stopped)
    const allContainers = await this.docker.listContainers({ all: true });

    // 2. Filter and categorize orphans
    const orphans: Record<string, any[]> = {};

    allContainers.forEach((container) => {
      // Look for the docker compose project label
      const projectName = container.Labels?.['com.docker.compose.project'];

      // If it has a project label, but the project is NOT in our known list...
      if (projectName && !knownStackNames.includes(projectName)) {
        if (!orphans[projectName]) {
          orphans[projectName] = [];
        }
        orphans[projectName].push({
          Id: container.Id,
          Names: container.Names,
          State: container.State,
          Status: container.Status,
          Image: container.Image
        });
      }
    });

    return orphans;
  }

  public async removeContainers(containerIds: string[]) {
    const results = [];
    for (const id of containerIds) {
      try {
        const container = this.docker.getContainer(id);
        await container.remove({ force: true });
        results.push({ id, success: true });
      } catch (error: any) {
        console.error(`Failed to remove container ${id}:`, error.message);
        results.push({ id, success: false, error: error.message });
      }
    }
    return results;
  }

  public async streamStats(containerId: string, ws: WebSocket) {
    const container = this.docker.getContainer(containerId);
    const stats = await container.stats({ stream: true });

    stats.on('data', (chunk: Buffer) => {
      ws.send(chunk.toString());
    });

    stats.on('error', (err: Error) => {
      ws.send(JSON.stringify({ error: err.message }));
    });

    stats.on('end', () => {
      ws.send(JSON.stringify({ end: true }));
    });
  }

  public async getContainerStatsStream(containerId: string): Promise<string> {
    const container = this.docker.getContainer(containerId);
    const stats = await container.stats({ stream: false });
    return typeof stats === 'string' ? stats : JSON.stringify(stats);
  }

  /**
   * Exec into a container with full session isolation.
   * All state (exec instance, stream) lives in this closure — no singleton traps.
   * The WebSocket message handler is registered here to handle input, resize, and cleanup.
   */
  public async execContainer(containerId: string, ws: WebSocket) {
    try {
      const container = this.docker.getContainer(containerId);

      // Try bash first, fall back to sh
      let exec: Docker.Exec;
      try {
        exec = await container.exec({
          AttachStdin: true,
          AttachStdout: true,
          AttachStderr: true,
          Tty: true,
          Cmd: ['/bin/bash'],
        });
      } catch {
        exec = await container.exec({
          AttachStdin: true,
          AttachStdout: true,
          AttachStderr: true,
          Tty: true,
          Cmd: ['/bin/sh'],
        });
      }

      const stream = await exec.start({ hijack: true, stdin: true });

      // --- Downstream: container output → client ---
      stream.on('data', (chunk: Buffer) => {
        if (ws.readyState === WebSocket.OPEN) {
          ws.send(chunk.toString());
        }
      });

      stream.on('error', (err: Error) => {
        console.error('Exec stream error:', err.message);
      });

      stream.on('end', () => {
        if (ws.readyState === WebSocket.OPEN) {
          ws.close();
        }
      });

      // --- Upstream: client messages → container ---
      ws.on('message', (raw: WebSocket.Data) => {
        try {
          const msg = JSON.parse(raw.toString());

          switch (msg.type) {
            case 'input':
              if (msg.data) {
                stream.write(msg.data);
              }
              break;

            case 'resize':
              if (msg.rows && msg.cols) {
                exec.resize({ h: msg.rows, w: msg.cols }).catch(() => {
                  // Ignore resize errors (exec may have ended)
                });
              }
              break;

            case 'ping':
              // Keep-alive, no-op
              break;
          }
        } catch {
          // Non-JSON or malformed message — ignore
        }
      });

      // --- Cleanup: prevent zombie processes ---
      ws.on('close', () => {
        try {
          stream.destroy();
        } catch {
          // Ignore destroy errors
        }
      });

    } catch (error) {
      const err = error as Error;
      console.error('Failed to exec container:', err.message);
      if (ws.readyState === WebSocket.OPEN) {
        ws.send(`\r\n\x1b[31mFailed to start shell: ${err.message}\x1b[0m\r\n`);
      }
    }
  }
}

export default DockerController;