// Image cache service — cache statistics, limits and eviction.
//
// This module used to also export `getCachedImageUrl`, which built
// `${serverUrl}/Items/${itemId}/Images/${imageType}` in the frontend. That was a
// Jellyfin route in the presentation layer — domain logic by this project's own
// litmus test (would it change if Jellyfin changed its API?) — and it was
// **dead**: nothing outside this file and its test ever called it. The live path
// is CachedImage.svelte -> commands.imageGetUrl -> Rust, which was already
// correct. It was deleted rather than migrated (DR-285).
//
// Note for whoever touches the CSP next: that function was the last
// `convertFileSrc` caller, so the asset-protocol grant narrowed to
// `$APPDATA/thumbnails/**` under DR-198 now has no caller at all and is a
// candidate for removal. Left in place here deliberately — dropping a capability
// grant is a security change that deserves its own commit and its own testing on
// Android, not a side effect of deleting dead code.
//
// TRACES: UR-007, UR-085 | DR-016, DR-285

import { commands } from "$lib/api/bindings";

/**
 * Statistics about the thumbnail cache
 */
export interface ImageCacheStats {
  totalSizeBytes: number;
  itemCount: number;
  limitBytes: number;
}

/**
 * Get thumbnail cache statistics
 */
export async function getCacheStats(): Promise<ImageCacheStats> {
  return commands.thumbnailGetStats();
}

/**
 * Set cache storage limit in bytes
 *
 * @param limitBytes - The maximum cache size in bytes (0 = unlimited)
 */
export async function setCacheLimit(limitBytes: number): Promise<void> {
  await commands.thumbnailSetLimit(limitBytes);
}

/**
 * Clear all cached thumbnails
 */
export async function clearCache(): Promise<void> {
  await commands.thumbnailClearCache();
}

/**
 * Delete cached thumbnails for a specific item
 *
 * @param itemId - The Jellyfin item ID
 */
export async function deleteItemCache(itemId: string): Promise<void> {
  await commands.thumbnailDeleteItem(itemId);
}

/**
 * Format bytes to human-readable string
 *
 * @param bytes - Number of bytes
 * @returns Human-readable string (e.g., "1.5 GB")
 */
export function formatBytes(bytes: number): string {
  if (bytes < 1024) return `${bytes} B`;
  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
  if (bytes < 1024 * 1024 * 1024) return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
  return `${(bytes / (1024 * 1024 * 1024)).toFixed(2)} GB`;
}

/**
 * Convert gigabytes to bytes
 */
export function gbToBytes(gb: number): number {
  return gb * 1024 * 1024 * 1024;
}

/**
 * Convert bytes to gigabytes
 */
export function bytesToGb(bytes: number): number {
  return bytes / (1024 * 1024 * 1024);
}