tethys.backend/app/Controllers/Http/Api/AvatarController.ts

import type { HttpContext } from '@adonisjs/core/http';
import { StatusCodes } from 'http-status-codes';

const prefixes = ['von', 'van'];

export default class AvatarController {
    public async generateAvatar({ request, response }: HttpContext) {
        try {
            const { name, size } = request.only(['name', 'size']);

            const initials = this.getInitials(name);

            const originalColor = this.getColorFromName(name);
            const backgroundColor = this.lightenColor(originalColor, 60);
            const textColor = this.darkenColor(originalColor);

            const svgContent = `
            <svg width="${size || 50}" height="${size || 50}" xmlns="http://www.w3.org/2000/svg">
              <rect width="100%" height="100%" fill="#${backgroundColor}"/>
              <text x="50%" y="50%" dominant-baseline="middle" text-anchor="middle" font-weight="bold" font-family="Arial, sans-serif" font-size="${
                  (size / 100) * 40 || 25
              }" fill="#${textColor}">${initials}</text>
            </svg>
          `;

            response.header('Content-type', 'image/svg+xml');
            response.header('Cache-Control', 'no-cache');
            response.header('Pragma', 'no-cache');
            response.header('Expires', '0');

            return response.send(svgContent);
        } catch (error) {
            return response.status(StatusCodes.OK).json({ error: error.message });
        }
    }

    private getInitials(name: string) {
        const parts = name.split(' ');
        let initials = '';

        if (parts.length >= 2) {
            const firstName = parts[0];
            const lastName = parts[parts.length - 1];

            const firstInitial = firstName.charAt(0).toUpperCase();
            const lastInitial = lastName.charAt(0).toUpperCase();

            if (prefixes.includes(lastName.toLowerCase()) && lastName === lastName.toUpperCase()) {
                initials = firstInitial + lastName.charAt(1).toUpperCase();
            } else {
                initials = firstInitial + lastInitial;
            }
        } else if (parts.length === 1) {
            initials = parts[0].substring(0, 2).toUpperCase();
        }

        return initials;
    }

    private getColorFromName(name: string) {
        let hash = 0;
        for (let i = 0; i < name.length; i++) {
            hash = name.charCodeAt(i) + ((hash << 5) - hash);
        }
        let color = '#';
        for (let i = 0; i < 3; i++) {
            const value = (hash >> (i * 8)) & 0xff;
            color += ('00' + value.toString(16)).substr(-2);
        }
        return color.replace('#', '');
    }

    private lightenColor(hexColor: string, percent: number) {
        let r = parseInt(hexColor.substring(0, 2), 16);
        let g = parseInt(hexColor.substring(2, 4), 16);
        let b = parseInt(hexColor.substring(4, 6), 16);

        r = Math.floor((r * (100 + percent)) / 100);
        g = Math.floor((g * (100 + percent)) / 100);
        b = Math.floor((b * (100 + percent)) / 100);

        r = r < 255 ? r : 255;
        g = g < 255 ? g : 255;
        b = b < 255 ? b : 255;

        const lighterHex = ((r << 16) | (g << 8) | b).toString(16);

        return lighterHex.padStart(6, '0');
    }

    private darkenColor(hexColor: string) {
        const r = parseInt(hexColor.slice(0, 2), 16);
        const g = parseInt(hexColor.slice(2, 4), 16);
        const b = parseInt(hexColor.slice(4, 6), 16);

        const darkerR = Math.round(r * 0.6);
        const darkerG = Math.round(g * 0.6);
        const darkerB = Math.round(b * 0.6);

        const darkerColor = ((darkerR << 16) + (darkerG << 8) + darkerB).toString(16);

        return darkerColor.padStart(6, '0');
    }
}