// SPDX-License-Identifier: MIT
/**
 * Validation utilities for safe proto value handling.
 *
 * These functions provide bounds checking and validation to prevent
 * DoS attacks via overflow, resource exhaustion, and silent data loss.
 */
import { InvalidArgumentError } from './errors.js';

/** Maximum allowed string length (1MB). */
export const MAX_STRING_LENGTH = 1024 * 1024;

/** Maximum allowed bytes length (16MB). */
export const MAX_BYTES_LENGTH = 16 * 1024 * 1024;

/**
 * Validate an integer value from proto.
 * Throws if the value is NaN, Infinity, or outside JavaScript's safe integer range.
 *
 * @param n - The number to validate.
 * @param context - Optional context for error messages.
 * @returns The validated number.
 * @throws InvalidArgumentError if validation fails.
 */
export function validateIntValue(n: number, context?: string): number {
  if (!Number.isFinite(n)) {
    const ctx = context ? ` (${context})` : '';
    throw new InvalidArgumentError(`Invalid integer value: not finite${ctx}`);
  }
  if (!Number.isSafeInteger(n)) {
    const ctx = context ? ` (${context})` : '';
    throw new InvalidArgumentError(
      `Integer value ${n} is outside safe range [-2^53+1, 2^53-1]${ctx}`
    );
  }
  return n;
}

/**
 * Validate a float value from proto.
 * Throws if the value is NaN or Infinity.
 *
 * @param n - The number to validate.
 * @param context - Optional context for error messages.
 * @returns The validated number.
 * @throws InvalidArgumentError if validation fails.
 */
export function validateFloatValue(n: number, context?: string): number {
  if (!Number.isFinite(n)) {
    const ctx = context ? ` (${context})` : '';
    throw new InvalidArgumentError(`Invalid float value: not finite${ctx}`);
  }
  return n;
}

/**
 * Validate a string value from proto.
 * Throws if the string exceeds the maximum allowed length.
 *
 * @param s - The string to validate.
 * @param context - Optional context for error messages.
 * @returns The validated string.
 * @throws InvalidArgumentError if validation fails.
 */
export function validateStringValue(s: string, context?: string): string {
  if (s.length > MAX_STRING_LENGTH) {
    const ctx = context ? ` (${context})` : '';
    throw new InvalidArgumentError(
      `String value exceeds maximum length of ${MAX_STRING_LENGTH} bytes${ctx}`
    );
  }
  return s;
}

/**
 * Validate a bytes value from proto.
 * Throws if the bytes exceed the maximum allowed length.
 *
 * @param b - The bytes to validate.
 * @param context - Optional context for error messages.
 * @returns The validated bytes.
 * @throws InvalidArgumentError if validation fails.
 */
export function validateBytesValue(b: Uint8Array, context?: string): Uint8Array {
  if (b.length > MAX_BYTES_LENGTH) {
    const ctx = context ? ` (${context})` : '';
    throw new InvalidArgumentError(
      `Bytes value exceeds maximum length of ${MAX_BYTES_LENGTH} bytes${ctx}`
    );
  }
  return b;
}

/**
 * Safely convert a numeric ID to a string.
 * Throws if the ID is outside JavaScript's safe integer range.
 *
 * @param id - The numeric ID to convert.
 * @param context - Optional context for error messages.
 * @returns The ID as a string.
 * @throws InvalidArgumentError if the ID is outside safe range.
 */
export function safeIdToString(id: number, context?: string): string {
  if (!Number.isSafeInteger(id)) {
    const ctx = context ? ` for ${context}` : '';
    throw new InvalidArgumentError(
      `ID value ${id} is outside safe integer range${ctx}`
    );
  }
  return String(id);
}

/**
 * Safely convert an array of numeric IDs to strings.
 * Throws if any ID is outside JavaScript's safe integer range.
 *
 * @param ids - The numeric IDs to convert.
 * @param context - Optional context for error messages.
 * @returns The IDs as strings.
 * @throws InvalidArgumentError if any ID is outside safe range.
 */
export function safeIdsToStrings(ids: number[], context?: string): string[] {
  return ids.map((id, index) => {
    const ctx = context ? `${context}[${index}]` : `index ${index}`;
    return safeIdToString(id, ctx);
  });
}