/**
 * Cloud Server API - Constants
 *
 * Centralized constants for the cloud server API.
 * All magic numbers and repeated constants should be defined here.
 */

// ============================================================
// Provider Configuration
// ============================================================

/**
 * Supported cloud providers
 */
export const SUPPORTED_PROVIDERS = ['linode', 'vultr', 'aws'] as const;
export type SupportedProvider = typeof SUPPORTED_PROVIDERS[number];

// ============================================================
// Cache Configuration
// ============================================================

/**
 * Cache TTL values in seconds
 */
export const CACHE_TTL = {
  /** Cache TTL for instance queries (5 minutes) */
  INSTANCES: 300,
  /** Cache TTL for health checks (30 seconds) */
  HEALTH: 30,
  /** Cache TTL for pricing data (1 hour) */
  PRICING: 3600,
  /** Default cache TTL (5 minutes) */
  DEFAULT: 300,
} as const;

/**
 * Cache TTL values in milliseconds
 */
export const CACHE_TTL_MS = {
  /** Cache TTL for instance queries (5 minutes) */
  INSTANCES: 5 * 60 * 1000,
  /** Cache TTL for health checks (30 seconds) */
  HEALTH: 30 * 1000,
  /** Cache TTL for pricing data (1 hour) */
  PRICING: 60 * 60 * 1000,
} as const;

// ============================================================
// Rate Limiting Configuration
// ============================================================

/**
 * Rate limiting defaults
 */
export const RATE_LIMIT_DEFAULTS = {
  /** Time window in milliseconds (1 minute) */
  WINDOW_MS: 60 * 1000,
  /** Maximum requests per window for /instances endpoint */
  MAX_REQUESTS_INSTANCES: 100,
  /** Maximum requests per window for /sync endpoint */
  MAX_REQUESTS_SYNC: 10,
} as const;

// ============================================================
// Pagination Configuration
// ============================================================

/**
 * Pagination defaults
 */
export const PAGINATION = {
  /** Default page number (1-indexed) */
  DEFAULT_PAGE: 1,
  /** Default number of results per page */
  DEFAULT_LIMIT: 50,
  /** Maximum number of results per page */
  MAX_LIMIT: 100,
  /** Default offset for pagination */
  DEFAULT_OFFSET: 0,
} as const;

// ============================================================
// HTTP Status Codes
// ============================================================

/**
 * HTTP status codes used throughout the API
 */
export const HTTP_STATUS = {
  /** 200 - OK */
  OK: 200,
  /** 201 - Created */
  CREATED: 201,
  /** 204 - No Content */
  NO_CONTENT: 204,
  /** 400 - Bad Request */
  BAD_REQUEST: 400,
  /** 401 - Unauthorized */
  UNAUTHORIZED: 401,
  /** 404 - Not Found */
  NOT_FOUND: 404,
  /** 413 - Payload Too Large */
  PAYLOAD_TOO_LARGE: 413,
  /** 429 - Too Many Requests */
  TOO_MANY_REQUESTS: 429,
  /** 500 - Internal Server Error */
  INTERNAL_ERROR: 500,
  /** 503 - Service Unavailable */
  SERVICE_UNAVAILABLE: 503,
} as const;

// ============================================================
// Database Configuration
// ============================================================

/**
 * Database table names
 */
export const TABLES = {
  PROVIDERS: 'providers',
  REGIONS: 'regions',
  INSTANCE_TYPES: 'instance_types',
  PRICING: 'pricing',
  PRICE_HISTORY: 'price_history',
} as const;

// ============================================================
// Query Configuration
// ============================================================

/**
 * Mapping of user-facing sort field names to database column names
 *
 * This is the single source of truth for sort field validation and mapping.
 * Query aliases: it=instance_types, pr=pricing, p=providers, r=regions
 */
export const SORT_FIELD_MAP: Record<string, string> = {
  price: 'pr.hourly_price',
  hourly_price: 'pr.hourly_price',
  monthly_price: 'pr.monthly_price',
  vcpu: 'it.vcpu',
  memory: 'it.memory_mb',
  memory_mb: 'it.memory_mb',
  memory_gb: 'it.memory_mb', // Note: memory_gb is converted to memory_mb at query level
  storage_gb: 'it.storage_gb',
  name: 'it.instance_name',
  instance_name: 'it.instance_name',
  provider: 'p.name',
  region: 'r.region_code',
} as const;

/**
 * Valid sort fields for instance queries (derived from SORT_FIELD_MAP)
 */
export const VALID_SORT_FIELDS = Object.keys(SORT_FIELD_MAP) as ReadonlyArray<string>;

export type ValidSortField = keyof typeof SORT_FIELD_MAP;

/**
 * Valid sort orders
 */
export const SORT_ORDERS = ['asc', 'desc'] as const;
export type SortOrder = typeof SORT_ORDERS[number];

/**
 * Valid instance families
 */
export const INSTANCE_FAMILIES = ['general', 'compute', 'memory', 'storage', 'gpu'] as const;
export type InstanceFamily = typeof INSTANCE_FAMILIES[number];

// ============================================================
// CORS Configuration
// ============================================================

/**
 * CORS configuration
 *
 * Security: Explicit allowed origins only. No wildcard fallback.
 * Development origins are separated and only used in development environment.
 */
export const CORS = {
  /** Default CORS origin - explicit production origin */
  DEFAULT_ORIGIN: 'https://anvil.it.com',
  /** Allowed production origins for CORS */
  ALLOWED_ORIGINS: [
    'https://anvil.it.com',
    'https://cloud.anvil.it.com',
    'https://hosting.anvil.it.com',
  ] as string[],
  /** Development origins - only used when ENVIRONMENT === 'development' */
  DEVELOPMENT_ORIGINS: [
    'http://localhost:3000',
    'http://127.0.0.1:3000',
  ] as string[],
  /** Max age for CORS preflight cache (24 hours) */
  MAX_AGE: '86400',
} as const;

// ============================================================
// Timeout Configuration
// ============================================================

/**
 * Timeout values in milliseconds
 */
export const TIMEOUTS = {
  /** Request timeout for AWS API calls (15 seconds) */
  AWS_REQUEST: 15000,
  /** Default API request timeout (30 seconds) */
  DEFAULT_REQUEST: 30000,
} as const;

// ============================================================
// Validation Constants
// ============================================================

/**
 * Validation rules
 */
export const VALIDATION = {
  /** Minimum memory in MB */
  MIN_MEMORY_MB: 1,
  /** Minimum vCPU count */
  MIN_VCPU: 1,
  /** Minimum price in USD */
  MIN_PRICE: 0,
} as const;

// ============================================================
// Request Security Configuration
// ============================================================

/**
 * Request security limits
 */
export const REQUEST_LIMITS = {
  /** Maximum request body size in bytes (10KB) */
  MAX_BODY_SIZE: 10 * 1024,
} as const;

// ============================================================
// USD Retail Pricing Configuration
// ============================================================

/**
 * Default USD retail pricing configuration
 *
 * These defaults are used to calculate retail prices from wholesale prices.
 * Calculation formula:
 * Retail = Wholesale × Margin (1.1) × VAT (1.1)
 * Retail = Wholesale × 1.21
 */
export const USD_RETAIL_DEFAULTS = {
  /** Margin multiplier (10% margin) */
  MARGIN_MULTIPLIER: 1.1,
  /** VAT multiplier (10% VAT) */
  VAT_MULTIPLIER: 1.1,
  /** Total multiplier (margin × VAT) */
  TOTAL_MULTIPLIER: 1.21,
} as const;

/**
 * Calculate USD retail hourly price from wholesale price
 * Applies margin and VAT
 *
 * @param wholesale - Wholesale hourly price in USD
 * @returns Retail price in USD, rounded to 4 decimal places
 *
 * @example
 * calculateRetailHourly(0.0075) // Returns 0.0091 (with defaults)
 * calculateRetailHourly(0.144)  // Returns 0.1742 (with defaults)
 */
export function calculateRetailHourly(wholesale: number): number {
  return Math.round(wholesale * USD_RETAIL_DEFAULTS.TOTAL_MULTIPLIER * 10000) / 10000;
}

/**
 * Calculate USD retail monthly price from wholesale price
 * Applies margin and VAT
 *
 * @param wholesale - Wholesale monthly price in USD
 * @returns Retail price in USD, rounded to nearest $1
 *
 * @example
 * calculateRetailMonthly(5)  // Returns 6 (with defaults)
 * calculateRetailMonthly(96) // Returns 116 (with defaults)
 */
export function calculateRetailMonthly(wholesale: number): number {
  return Math.round(wholesale * USD_RETAIL_DEFAULTS.TOTAL_MULTIPLIER);
}