import type { ProxyFontsParams } from '$entities/Font/api';
import type { FilterManager } from '../filterManager/filterManager.svelte';

/**
 * Maps filter manager to proxy API parameters.
 *
 * Transforms UI filter state into proxy API query parameters.
 * Handles conversion from filter groups to API-specific parameters.
 *
 * @param manager - Filter manager instance with reactive state
 * @returns - Partial proxy API parameters ready for API call
 *
 * @example
 * ```ts
 * // Example filter manager state:
 * // {
 * //   queryValue: 'roboto',
 * //   providers: ['google'],
 * //   categories: ['sans-serif'],
 * //   subsets: ['latin']
 * // }
 *
 * const params = mapManagerToParams(manager);
 * // Returns: { provider: 'google', category: 'sans-serif', subset: 'latin', q: 'roboto' }
 * ```
 */
export function mapManagerToParams(manager: FilterManager): Partial<ProxyFontsParams> {
    const providers = manager.getGroup('providers')?.instance.selectedProperties.map(p => p.value);
    const categories = manager.getGroup('categories')?.instance.selectedProperties.map(p => p.value);
    const subsets = manager.getGroup('subsets')?.instance.selectedProperties.map(p => p.value);

    return {
        // Search query (debounced)
        q: manager.debouncedQueryValue || undefined,

        // Provider filter (single value - proxy API doesn't support array)
        // Use first provider if multiple selected, or undefined if none/all selected
        provider: providers && providers.length === 1
            ? (providers[0] as 'google' | 'fontshare')
            : undefined,

        // Category filter (single value - proxy API doesn't support array)
        // Use first category if multiple selected, or undefined if none/all selected
        category: categories && categories.length === 1
            ? (categories[0] as ProxyFontsParams['category'])
            : undefined,

        // Subset filter (single value - proxy API doesn't support array)
        // Use first subset if multiple selected, or undefined if none/all selected
        subset: subsets && subsets.length === 1
            ? (subsets[0] as ProxyFontsParams['subset'])
            : undefined,
    };
}