import { z } from 'zod';

import { UnauthorizedError } from './unauthorized-error.ts';
import { ApplicationError } from './application-error.ts';

/** Stable error payload shared by HTTP, SSE, and WebSocket. */
export type PublicError = {

    /** Protocol-independent status carried by every transport. */
    statusCode: number;

    /** Client-safe summary which never exposes an unexpected exception. */
    error: string;

    /** Structured field failures supplied only for validation errors. */
    details?: Array<{ path: string; message: string }>;
};

/**
 * Convert application failures into the common public transport contract.
 *
 * @param error - Any thrown value from a route or transport boundary.
 * @returns A sanitized error payload safe to encode on the wire.
 */
export const normalizePublicError = (error: unknown): PublicError => {
    if (error instanceof z.ZodError) {
        return {
            statusCode: 400,
            error: 'Validation Error',
            details: error.issues.map((issue) => ({
                path: issue.path.join('.'),
                message: issue.message,
            })),
        };
    }

    if (error instanceof UnauthorizedError) {
        return { statusCode: 401, error: error.message };
    }

    if (error instanceof ApplicationError) {
        return { statusCode: error.statusCode, error: error.message };
    }

    // Unknown exceptions are logged by adapters, but their messages stay private.
    return { statusCode: 500, error: 'Internal Server Error' };
};