import * as m from '$lib/paraglide/messages.js';

/**
 * Mirror of the backend ErrorCode enum.
 * Keep in sync with backend/src/main/java/org/raddatz/familienarchiv/exception/ErrorCode.java
 */
export type ErrorCode =
	| 'DOCUMENT_NOT_FOUND'
	| 'DOCUMENT_NO_FILE'
	| 'FILE_NOT_FOUND'
	| 'FILE_UPLOAD_FAILED'
	| 'UNSUPPORTED_FILE_TYPE'
	| 'USER_NOT_FOUND'
	| 'EMAIL_ALREADY_IN_USE'
	| 'WRONG_CURRENT_PASSWORD'
	| 'IMPORT_ALREADY_RUNNING'
	| 'INVALID_RESET_TOKEN'
	| 'ANNOTATION_NOT_FOUND'
	| 'ANNOTATION_OVERLAP'
	| 'COMMENT_NOT_FOUND'
	| 'UNAUTHORIZED'
	| 'FORBIDDEN'
	| 'VALIDATION_ERROR'
	| 'INTERNAL_ERROR';

export interface BackendError {
	code: ErrorCode;
	message: string; // English developer message — not shown to users
}

/**
 * Attempts to parse a backend ErrorResponse from a failed fetch response.
 * Returns null if the body is not valid JSON or does not contain a code field.
 */
export async function parseBackendError(res: Response): Promise<BackendError | null> {
	try {
		const body = await res.json();
		if (body && typeof body.code === 'string') {
			return body as BackendError;
		}
	} catch {
		// Body was not JSON
	}
	return null;
}

/** Returns a localised message for the given error code via Paraglide. Falls back to INTERNAL_ERROR. */
export function getErrorMessage(code: ErrorCode | string | undefined): string {
	switch (code) {
		case 'DOCUMENT_NOT_FOUND':
			return m.error_document_not_found();
		case 'DOCUMENT_NO_FILE':
			return m.error_document_no_file();
		case 'FILE_NOT_FOUND':
			return m.error_file_not_found();
		case 'FILE_UPLOAD_FAILED':
			return m.error_file_upload_failed();
		case 'UNSUPPORTED_FILE_TYPE':
			return m.error_unsupported_file_type();
		case 'USER_NOT_FOUND':
			return m.error_user_not_found();
		case 'EMAIL_ALREADY_IN_USE':
			return m.error_email_already_in_use();
		case 'WRONG_CURRENT_PASSWORD':
			return m.error_wrong_current_password();
		case 'IMPORT_ALREADY_RUNNING':
			return m.error_import_already_running();
		case 'INVALID_RESET_TOKEN':
			return m.error_invalid_reset_token();
		case 'ANNOTATION_NOT_FOUND':
			return m.error_annotation_not_found();
		case 'ANNOTATION_OVERLAP':
			return m.error_annotation_overlap();
		case 'COMMENT_NOT_FOUND':
			return m.error_comment_not_found();
		case 'UNAUTHORIZED':
			return m.error_unauthorized();
		case 'FORBIDDEN':
			return m.error_forbidden();
		case 'VALIDATION_ERROR':
			return m.error_validation_error();
		default:
			return m.error_internal_error();
	}
}