/**
 * Updater
 *
 * Handles checking for updates, downloading new versions, and performing upgrades
 */

import { VERSION } from '../version.ts';
import { runCommand } from '../utils/command.ts';

export interface Release {
  version: string;
  tagName: string;
  publishedAt: Date;
  downloadUrl: string;
  isCurrent: boolean;
  isNewer: boolean;
  ageHours: number;
}

export interface AutoUpgradeStatus {
  enabled: boolean;
  targetVersion: string | null;
  scheduledIn: string | null;
  waitingForStability: boolean;
}

export interface UpdateInfo {
  currentVersion: string;
  releases: Release[];
  autoUpgrade: AutoUpgradeStatus;
  lastCheck: string | null;
}

interface GiteaRelease {
  id: number;
  tag_name: string;
  name: string;
  body: string;
  published_at: string;
  assets: GiteaAsset[];
}

interface GiteaAsset {
  id: number;
  name: string;
  browser_download_url: string;
  size: number;
}

export class Updater {
  private repoApiUrl = 'https://code.foss.global/api/v1/repos/ecobridge.xyz/eco_os/releases';
  private binaryPath = '/opt/eco/bin/eco-daemon';
  private releases: Release[] = [];
  private lastCheck: Date | null = null;
  private logFn: (msg: string) => void;

  constructor(logFn: (msg: string) => void) {
    this.logFn = logFn;
  }

  private log(message: string): void {
    this.logFn(`[Updater] ${message}`);
  }

  /**
   * Compare semantic versions
   * Returns: -1 if a < b, 0 if a == b, 1 if a > b
   */
  private compareVersions(a: string, b: string): number {
    const partsA = a.replace(/^v/, '').split('.').map(Number);
    const partsB = b.replace(/^v/, '').split('.').map(Number);

    for (let i = 0; i < Math.max(partsA.length, partsB.length); i++) {
      const numA = partsA[i] || 0;
      const numB = partsB[i] || 0;
      if (numA < numB) return -1;
      if (numA > numB) return 1;
    }
    return 0;
  }

  /**
   * Fetch available releases from Gitea
   */
  async checkForUpdates(): Promise<Release[]> {
    this.log('Checking for updates...');

    try {
      const response = await fetch(this.repoApiUrl);
      if (!response.ok) {
        throw new Error(`HTTP ${response.status}: ${response.statusText}`);
      }

      const giteaReleases: GiteaRelease[] = await response.json();
      const currentVersion = VERSION;
      const now = new Date();

      this.releases = giteaReleases
        .filter((r) => r.tag_name.startsWith('v'))
        .map((r) => {
          const version = r.tag_name.replace(/^v/, '');
          const publishedAt = new Date(r.published_at);
          const ageMs = now.getTime() - publishedAt.getTime();
          const ageHours = ageMs / (1000 * 60 * 60);

          // Find the daemon binary asset
          const daemonAsset = r.assets.find((a) =>
            a.name.includes('eco-daemon')
          );

          return {
            version,
            tagName: r.tag_name,
            publishedAt,
            downloadUrl: daemonAsset?.browser_download_url || '',
            isCurrent: version === currentVersion,
            isNewer: this.compareVersions(version, currentVersion) > 0,
            ageHours: Math.round(ageHours * 10) / 10,
          };
        })
        .filter((r) => r.downloadUrl) // Only include releases with daemon binary
        .sort((a, b) => this.compareVersions(b.version, a.version)); // Newest first

      this.lastCheck = now;
      this.log(`Found ${this.releases.length} releases, ${this.releases.filter((r) => r.isNewer).length} newer than current`);

      return this.releases;
    } catch (error) {
      this.log(`Failed to check for updates: ${error}`);
      return this.releases;
    }
  }

  /**
   * Get cached releases (call checkForUpdates first)
   */
  getReleases(): Release[] {
    return this.releases;
  }

  /**
   * Determine if auto-upgrade should happen and to which version
   */
  getAutoUpgradeStatus(): AutoUpgradeStatus {
    const newerReleases = this.releases.filter((r) => r.isNewer);

    if (newerReleases.length === 0) {
      return {
        enabled: true,
        targetVersion: null,
        scheduledIn: null,
        waitingForStability: false,
      };
    }

    // Find the latest newer release
    const latest = newerReleases[0];
    const hoursUntilUpgrade = 24 - latest.ageHours;

    if (hoursUntilUpgrade <= 0) {
      // Ready to upgrade now
      return {
        enabled: true,
        targetVersion: latest.version,
        scheduledIn: 'now',
        waitingForStability: false,
      };
    }

    // Still waiting for stability period
    const hours = Math.floor(hoursUntilUpgrade);
    const minutes = Math.round((hoursUntilUpgrade - hours) * 60);
    const scheduledIn = hours > 0 ? `${hours}h ${minutes}m` : `${minutes}m`;

    return {
      enabled: true,
      targetVersion: latest.version,
      scheduledIn,
      waitingForStability: true,
    };
  }

  /**
   * Get full update info for API response
   */
  getUpdateInfo(): UpdateInfo {
    return {
      currentVersion: VERSION,
      releases: this.releases,
      autoUpgrade: this.getAutoUpgradeStatus(),
      lastCheck: this.lastCheck?.toISOString() || null,
    };
  }

  /**
   * Download and install a specific version
   */
  async upgradeToVersion(version: string): Promise<{ success: boolean; message: string }> {
    const release = this.releases.find((r) => r.version === version);

    if (!release) {
      return { success: false, message: `Version ${version} not found` };
    }

    if (release.isCurrent) {
      return { success: false, message: `Already running version ${version}` };
    }

    this.log(`Starting upgrade to version ${version}...`);

    try {
      // Download new binary
      const tempPath = '/tmp/eco-daemon-new';
      this.log(`Downloading from ${release.downloadUrl}...`);

      const response = await fetch(release.downloadUrl);
      if (!response.ok) {
        throw new Error(`Download failed: HTTP ${response.status}`);
      }

      const data = await response.arrayBuffer();
      await Deno.writeFile(tempPath, new Uint8Array(data));

      // Verify download
      const stat = await Deno.stat(tempPath);
      if (stat.size < 1000000) {
        // Daemon should be at least 1MB
        throw new Error(`Downloaded file too small: ${stat.size} bytes`);
      }
      this.log(`Downloaded ${stat.size} bytes`);

      // Make executable
      await Deno.chmod(tempPath, 0o755);

      // Replace binary
      this.log('Replacing binary...');
      await runCommand('mv', [tempPath, this.binaryPath]);
      await Deno.chmod(this.binaryPath, 0o755);

      // Restart daemon via systemd
      this.log('Restarting daemon...');
      // Use spawn to avoid waiting for the restart
      const restartCmd = new Deno.Command('systemctl', {
        args: ['restart', 'eco-daemon'],
        stdout: 'null',
        stderr: 'null',
      });
      restartCmd.spawn();

      return { success: true, message: `Upgrading to v${version}...` };
    } catch (error) {
      this.log(`Upgrade failed: ${error}`);
      return { success: false, message: String(error) };
    }
  }

  /**
   * Check and perform auto-upgrade if conditions are met
   */
  async checkAutoUpgrade(): Promise<void> {
    await this.checkForUpdates();

    const status = this.getAutoUpgradeStatus();

    if (status.targetVersion && status.scheduledIn === 'now') {
      this.log(`Auto-upgrading to version ${status.targetVersion}...`);
      await this.upgradeToVersion(status.targetVersion);
    }
  }
}