export default class APIContract {
    static validateResponse(response, schema, logger = null) {
        const errors = [];

        for (const [field, expectedType] of Object.entries(schema)) {
            if (!(field in response)) {
                errors.push(`Missing required field: ${field}`);
            } else {
                const actualType = typeof response[field];
                if (actualType !== expectedType) {
                    errors.push(
                        `Field '${field}' type mismatch: expected ${expectedType}, got ${actualType}`
                    );
                }
            }
        }

        if (errors.length > 0) {
            const message = `API Contract Violation:\n${errors.join('\n')}`;
            logger?.error(message);
            throw new Error(message);
        }

        return response;
    }

    static validateArray(array, itemSchema, logger = null) {
        if (!Array.isArray(array)) {
            logger?.error('Expected array but got non-array');
            throw new Error('Expected array response');
        }

        return array.map((item, index) => {
            try {
                return this.validateResponse(item, itemSchema, logger);
            } catch (error) {
                logger?.error(`Array item ${index} validation failed`, error);
                throw error;
            }
        });
    }
}