import type {
    FontWeight,
    UnifiedFont,
} from '../../model';

const SIZES = [100, 200, 300, 400, 500, 600, 700, 800, 900];

/**
 * Constructs a URL for a font based on the provided font and weight.
 * @param font - The font object.
 * @param weight - The weight of the font.
 * @returns The URL for the font.
 */
export function getFontUrl(font: UnifiedFont, weight: number): string | undefined {
    if (!SIZES.includes(weight)) {
        throw new Error(`Invalid weight: ${weight}`);
    }

    const weightKey = weight.toString() as FontWeight;

    // 1. Try exact match (Backend now maps "100".."900" to VF URL if variable)
    if (font.styles.variants?.[weightKey]) {
        return font.styles.variants[weightKey];
    }

    // 2. Fallbacks for Static Fonts (if exact weight missing)
    // Try 'regular' or '400' as safe defaults
    return font.styles.regular || font.styles.variants?.['400'] || font.styles.variants?.['regular'];
}