/**
 * Feature Flags Configuration
 *
 * Controls which features are enabled/disabled for MVP.
 * Features marked as false are not yet implemented in the backend.
 *
 * All flags can be overridden via VITE_FEATURE_* env vars (see .env.example).
 * Feature status is documented in docs/FEATURE_STATUS.md
 */

function parseFeatureEnv(value: string | undefined, defaultValue: boolean): boolean {
  if (value === undefined || value === '') return defaultValue;
  const v = value.toLowerCase().trim();
  return v === 'true' || v === '1' || v === 'yes';
}

export const FEATURES = {
  /**
   * Two-Factor Authentication
   * Backend endpoints: /auth/2fa/setup, /auth/2fa/verify, /auth/2fa/disable, /auth/2fa/status
   */
  TWO_FACTOR_AUTH: parseFeatureEnv(
    import.meta.env.VITE_FEATURE_TWO_FACTOR_AUTH,
    true,
  ),

  /**
   * Playlist Collaboration Features
   * Backend endpoints: /playlists/:id/collaborators (GET, POST, PUT, DELETE)
   */
  PLAYLIST_COLLABORATION: parseFeatureEnv(
    import.meta.env.VITE_FEATURE_PLAYLIST_COLLABORATION,
    true,
  ),
  PLAYLIST_SEARCH: parseFeatureEnv(
    import.meta.env.VITE_FEATURE_PLAYLIST_SEARCH,
    true,
  ),
  PLAYLIST_SHARE: parseFeatureEnv(
    import.meta.env.VITE_FEATURE_PLAYLIST_SHARE,
    true,
  ),
  PLAYLIST_RECOMMENDATIONS: parseFeatureEnv(
    import.meta.env.VITE_FEATURE_PLAYLIST_RECOMMENDATIONS,
    true,
  ),

  /**
   * HLS Streaming
   * Backend endpoints: /api/v1/tracks/:id/hls/info, /api/v1/tracks/:id/hls/status
   *
   * Default flipped to `true` in v1.0.10 polish to match backend
   * `HLS_STREAMING=true` (Day 17 of the v1.0.9 sprint). Adaptive
   * bitrate via HLS is the canonical playback path; MP3 range
   * requests via `/api/v1/tracks/:id/stream` remain a fallback when
   * the browser can't play HLS or the transcoder hasn't produced
   * segments yet.
   *
   * Set VITE_FEATURE_HLS_STREAMING=false to opt out (unit-test envs
   * without a transcoder, or to bisect playback regressions).
   */
  HLS_STREAMING: parseFeatureEnv(
    import.meta.env.VITE_FEATURE_HLS_STREAMING,
    true,
  ),

  /**
   * Role Management
   * Backend endpoints: /api/v1/users/:userId/roles, /api/v1/roles/* (NOT IMPLEMENTED)
   */
  ROLE_MANAGEMENT: parseFeatureEnv(
    import.meta.env.VITE_FEATURE_ROLE_MANAGEMENT,
    true,
  ),

  /**
   * Notifications API
   * Backend endpoints: /api/v1/notifications/*
   */
  NOTIFICATIONS: parseFeatureEnv(
    import.meta.env.VITE_FEATURE_NOTIFICATIONS,
    true,
  ),

} as const;

/**
 * Type for feature flags
 */
export type FeatureFlag = keyof typeof FEATURES;

/**
 * Check if a feature is enabled
 */
export function isFeatureEnabled(feature: FeatureFlag): boolean {
  return Boolean(FEATURES[feature]);
}

/**
 * Assert that a feature is enabled, throw error if not
 */
export function requireFeature(feature: FeatureFlag): void {
  if (!isFeatureEnabled(feature)) {
    throw new Error(
      `Feature "${feature}" is not enabled. This feature is not available in the MVP.`,
    );
  }
}