import type {
  LicenseOptions,
  License,
  LicenseResult,
  LicenseStatus,
  CheckoutResult,
  ProductTier,
  Feature,
  LicenseChangeCallback,
} from './types';
import { Transport } from './transport';
import { LicenseCache, getDefaultStorage } from './storage';

/**
 * Default configuration options.
 */
const DEFAULT_OPTIONS: Partial<LicenseOptions> = {
  apiBaseUrl: 'https://api.ironlicensing.com',
  debug: false,
  enableOfflineCache: true,
  cacheValidationMinutes: 60,
  offlineGraceDays: 7,
  storageKeyPrefix: 'ironlicensing',
};

/**
 * IronLicensing client for license validation and activation.
 */
export class LicenseClient {
  private options: Required<LicenseOptions>;
  private transport: Transport;
  private cache: LicenseCache;
  private currentLicense: License | null = null;
  private onLicenseChangeCallbacks: LicenseChangeCallback[] = [];

  constructor(options: LicenseOptions) {
    this.options = { ...DEFAULT_OPTIONS, ...options } as Required<LicenseOptions>;

    if (!this.options.publicKey) {
      throw new Error('Public key is required');
    }
    if (!this.options.productSlug) {
      throw new Error('Product slug is required');
    }

    this.transport = new Transport(
      this.options.apiBaseUrl,
      this.options.publicKey,
      this.options.productSlug,
      this.options.debug,
    );

    this.cache = new LicenseCache(getDefaultStorage(), this.options.storageKeyPrefix);

    // Load cached license
    this.currentLicense = this.cache.getLicense();

    if (this.options.debug) {
      console.log('[IronLicensing] Client initialized');
    }
  }

  /**
   * Validates the current or provided license key.
   */
  async validate(licenseKey?: string): Promise<LicenseResult> {
    const key = licenseKey || this.cache.getLicenseKey();

    if (!key) {
      return { valid: false, error: 'No license key provided' };
    }

    // Check cache first
    if (this.options.enableOfflineCache) {
      const cached = this.getCachedValidation();
      if (cached) {
        return { ...cached, cached: true };
      }
    }

    // Validate online
    const result = await this.transport.validate(key);

    if (result.valid && result.license) {
      this.setLicense(result.license, key);
      this.cache.setValidationResult(result, new Date());
    }

    return result;
  }

  /**
   * Activates a license.
   */
  async activate(licenseKey: string, machineName?: string): Promise<LicenseResult> {
    const result = await this.transport.activate(licenseKey, machineName);

    if (result.valid && result.license) {
      this.setLicense(result.license, licenseKey);
      this.cache.setValidationResult(result, new Date());
    }

    return result;
  }

  /**
   * Deactivates the current license.
   */
  async deactivate(): Promise<boolean> {
    const key = this.cache.getLicenseKey();
    if (!key) return false;

    const success = await this.transport.deactivate(key);

    if (success) {
      this.setLicense(null, null);
      this.cache.clear();
    }

    return success;
  }

  /**
   * Starts a trial.
   */
  async startTrial(email: string): Promise<LicenseResult> {
    const result = await this.transport.startTrial(email);

    if (result.valid && result.license) {
      this.setLicense(result.license, result.license.key);
      this.cache.setValidationResult(result, new Date());
    }

    return result;
  }

  /**
   * Checks if a feature is enabled.
   */
  hasFeature(featureKey: string): boolean {
    if (!this.currentLicense) return false;
    const feature = this.currentLicense.features.find(f => f.key === featureKey);
    return feature?.enabled ?? false;
  }

  /**
   * Requires a feature, throwing if not available.
   */
  requireFeature(featureKey: string): void {
    if (!this.hasFeature(featureKey)) {
      throw new LicenseRequiredError(`Feature '${featureKey}' requires a valid license`);
    }
  }

  /**
   * Gets a feature by key.
   */
  getFeature(featureKey: string): Feature | undefined {
    return this.currentLicense?.features.find(f => f.key === featureKey);
  }

  /**
   * Gets all features.
   */
  getFeatures(): Feature[] {
    return this.currentLicense?.features || [];
  }

  /**
   * Gets the current license.
   */
  get license(): License | null {
    return this.currentLicense;
  }

  /**
   * Gets the current license status.
   */
  get status(): LicenseStatus {
    return this.currentLicense?.status ?? 'not_activated';
  }

  /**
   * Checks if the license is valid.
   */
  get isLicensed(): boolean {
    return this.currentLicense?.status === 'valid' || this.currentLicense?.status === 'trial';
  }

  /**
   * Checks if the license is a trial.
   */
  get isTrial(): boolean {
    return this.currentLicense?.status === 'trial' || this.currentLicense?.type === 'trial';
  }

  /**
   * Gets the license expiration date.
   */
  get expiresAt(): Date | undefined {
    return this.currentLicense?.expiresAt;
  }

  /**
   * Gets product tiers for purchase.
   */
  async getTiers(): Promise<ProductTier[]> {
    return this.transport.getTiers();
  }

  /**
   * Starts a purchase checkout.
   */
  async startPurchase(tierId: string, email: string): Promise<CheckoutResult> {
    return this.transport.startCheckout(tierId, email);
  }

  /**
   * Registers a callback for license changes.
   */
  onLicenseChange(callback: LicenseChangeCallback): () => void {
    this.onLicenseChangeCallbacks.push(callback);
    return () => {
      const index = this.onLicenseChangeCallbacks.indexOf(callback);
      if (index > -1) {
        this.onLicenseChangeCallbacks.splice(index, 1);
      }
    };
  }

  private setLicense(license: License | null, key: string | null): void {
    this.currentLicense = license;

    if (license) {
      this.cache.setLicense(license);
    }
    if (key) {
      this.cache.setLicenseKey(key);
    }

    // Notify listeners
    for (const callback of this.onLicenseChangeCallbacks) {
      try {
        callback(license);
      } catch (e) {
        console.error('[IronLicensing] Error in license change callback:', e);
      }
    }
  }

  private getCachedValidation(): LicenseResult | null {
    const cached = this.cache.getValidationResult();
    const time = this.cache.getValidationTime();

    if (!cached || !time) return null;

    // Check if cache is still valid
    const cacheAge = Date.now() - time.getTime();
    const maxAge = this.options.cacheValidationMinutes * 60 * 1000;

    if (cacheAge <= maxAge) {
      return cached;
    }

    // Check offline grace period
    const graceAge = this.options.offlineGraceDays * 24 * 60 * 60 * 1000;
    if (cacheAge <= graceAge && cached.valid) {
      if (this.options.debug) {
        console.log('[IronLicensing] Using offline grace period');
      }
      return cached;
    }

    return null;
  }
}

/**
 * Error thrown when a license or feature is required but not available.
 */
export class LicenseRequiredError extends Error {
  constructor(message: string) {
    super(message);
    this.name = 'LicenseRequiredError';
  }
}