/**
 * ISO Cache Manager
 * Manages cached Ubuntu ISOs with multi-version support
 */

import { log } from '../logging.ts';
import { path } from '../plugins.ts';
import { getCacheDir, ensureDir } from '../paths.ts';
import { IsoDownloader } from './iso-downloader.ts';

export interface ICacheEntry {
  version: string;
  architecture: 'amd64' | 'arm64';
  filename: string;
  path: string;
  size: number;
  downloadedAt: Date;
}

export class IsoCache {
  private cacheDir: string;
  private metadataPath: string;

  constructor() {
    this.cacheDir = getCacheDir();
    this.metadataPath = path.join(this.cacheDir, 'metadata.json');
  }

  /**
   * Initialize the cache directory
   */
  async init(): Promise<void> {
    await ensureDir(this.cacheDir);
  }

  /**
   * Get all cache entries
   */
  async list(): Promise<ICacheEntry[]> {
    try {
      const metadata = await Deno.readTextFile(this.metadataPath);
      return JSON.parse(metadata);
    } catch (err) {
      if (err instanceof Deno.errors.NotFound) {
        return [];
      }
      throw err;
    }
  }

  /**
   * Get a specific cache entry
   */
  async get(version: string, architecture: 'amd64' | 'arm64'): Promise<ICacheEntry | null> {
    const entries = await this.list();
    return entries.find((e) => e.version === version && e.architecture === architecture) || null;
  }

  /**
   * Check if an ISO is cached
   */
  async has(version: string, architecture: 'amd64' | 'arm64'): Promise<boolean> {
    const entry = await this.get(version, architecture);
    if (!entry) return false;

    // Verify the file still exists
    try {
      const stat = await Deno.stat(entry.path);
      return stat.isFile;
    } catch {
      // File doesn't exist, remove from metadata
      await this.remove(version, architecture);
      return false;
    }
  }

  /**
   * Add an ISO to the cache
   */
  async add(
    version: string,
    architecture: 'amd64' | 'arm64',
    sourcePath: string,
  ): Promise<ICacheEntry> {
    await this.init();

    const filename = IsoDownloader.getIsoFilename(version, architecture);
    const destPath = path.join(this.cacheDir, filename);

    // Copy file to cache
    await Deno.copyFile(sourcePath, destPath);

    // Get file size
    const stat = await Deno.stat(destPath);

    const entry: ICacheEntry = {
      version,
      architecture,
      filename,
      path: destPath,
      size: stat.size,
      downloadedAt: new Date(),
    };

    // Update metadata
    const entries = await this.list();
    const existingIndex = entries.findIndex(
      (e) => e.version === version && e.architecture === architecture,
    );

    if (existingIndex >= 0) {
      entries[existingIndex] = entry;
    } else {
      entries.push(entry);
    }

    await this.saveMetadata(entries);
    log.success(`ISO cached: ${version} ${architecture}`);

    return entry;
  }

  /**
   * Remove an ISO from the cache
   */
  async remove(version: string, architecture: 'amd64' | 'arm64'): Promise<void> {
    const entry = await this.get(version, architecture);
    if (!entry) {
      log.warn(`ISO not found in cache: ${version} ${architecture}`);
      return;
    }

    // Remove file
    try {
      await Deno.remove(entry.path);
    } catch (err) {
      if (!(err instanceof Deno.errors.NotFound)) {
        throw err;
      }
    }

    // Update metadata
    const entries = await this.list();
    const filtered = entries.filter(
      (e) => !(e.version === version && e.architecture === architecture),
    );
    await this.saveMetadata(filtered);

    log.success(`ISO removed from cache: ${version} ${architecture}`);
  }

  /**
   * Clean old cached ISOs
   */
  async clean(olderThanDays?: number): Promise<void> {
    const entries = await this.list();
    const now = new Date();

    for (const entry of entries) {
      const age = now.getTime() - new Date(entry.downloadedAt).getTime();
      const ageDays = age / (1000 * 60 * 60 * 24);

      if (!olderThanDays || ageDays > olderThanDays) {
        await this.remove(entry.version, entry.architecture);
      }
    }
  }

  /**
   * Get the path to a cached ISO
   */
  async getPath(version: string, architecture: 'amd64' | 'arm64'): Promise<string | null> {
    const entry = await this.get(version, architecture);
    return entry?.path || null;
  }

  /**
   * Download and cache an ISO
   */
  async downloadAndCache(
    version: string,
    architecture: 'amd64' | 'arm64',
    onProgress?: (downloaded: number, total: number) => void,
  ): Promise<string> {
    await this.init();

    const filename = IsoDownloader.getIsoFilename(version, architecture);
    const destPath = path.join(this.cacheDir, filename);

    const downloader = new IsoDownloader();

    await downloader.downloadWithVerification({
      ubuntuVersion: version,
      architecture,
      outputPath: destPath,
      onProgress,
    });

    // Add to cache metadata
    await this.add(version, architecture, destPath);

    return destPath;
  }

  /**
   * Save metadata to disk
   */
  private async saveMetadata(entries: ICacheEntry[]): Promise<void> {
    await ensureDir(this.cacheDir);
    await Deno.writeTextFile(this.metadataPath, JSON.stringify(entries, null, 2));
  }
}