frontend/src/utils/format.ts

/**
 * Safe formatting utilities for handling nullable/undefined values
 * Prevents crashes from null/undefined data in metadata
 */

const PLACEHOLDER = '—';

/**
 * Safely format a number with decimal places
 * Returns "—" for null/undefined/NaN values
 */
export function formatNumber(
  value: unknown,
  opts?: { decimals?: number; suffix?: string; prefix?: string }
): string {
  const { decimals = 2, suffix = '', prefix = '' } = opts || {};

  // Handle null/undefined
  if (value === null || value === undefined) {
    return PLACEHOLDER;
  }

  // Handle empty string
  if (value === '') {
    return PLACEHOLDER;
  }

  // Try to convert to number
  let num: number;
  if (typeof value === 'number') {
    num = value;
  } else if (typeof value === 'string') {
    num = parseFloat(value);
  } else {
    return PLACEHOLDER;
  }

  // Check if valid number
  if (!isFinite(num) || isNaN(num)) {
    return PLACEHOLDER;
  }

  // Format with decimals
  const formatted = num.toFixed(decimals);
  return `${prefix}${formatted}${suffix}`;
}

/**
 * Safely format an array of numbers or a single number
 * Handles RCSB fields like resolution_combined which can be number or array
 * Returns first numeric value if array, or formats single number
 */
export function formatArrayNumber(
  value: unknown,
  opts?: { decimals?: number; suffix?: string; prefix?: string; selectMin?: boolean }
): string {
  const { selectMin = false } = opts || {};

  // Handle null/undefined
  if (value === null || value === undefined) {
    return PLACEHOLDER;
  }

  // Handle array
  if (Array.isArray(value)) {
    if (value.length === 0) {
      return PLACEHOLDER;
    }

    // Filter to valid numbers
    const numbers = value
      .map(v => (typeof v === 'number' ? v : parseFloat(v)))
      .filter(n => isFinite(n) && !isNaN(n));

    if (numbers.length === 0) {
      return PLACEHOLDER;
    }

    // Select first or minimum
    const selected = selectMin ? Math.min(...numbers) : numbers[0];
    return formatNumber(selected, opts);
  }

  // Single value
  return formatNumber(value, opts);
}

/**
 * Safely format text, handling null/undefined/empty
 */
export function formatText(value: unknown, placeholder: string = PLACEHOLDER): string {
  if (value === null || value === undefined) {
    return placeholder;
  }

  if (typeof value === 'string') {
    const trimmed = value.trim();
    return trimmed === '' ? placeholder : trimmed;
  }

  if (typeof value === 'number') {
    return String(value);
  }

  if (typeof value === 'boolean') {
    return value ? 'Yes' : 'No';
  }

  // Fallback for objects
  return placeholder;
}

/**
 * Format temperature with Kelvin suffix
 */
export function formatTemperature(value: unknown): string {
  return formatNumber(value, { decimals: 1, suffix: ' K' });
}

/**
 * Format pH value
 */
export function formatPH(value: unknown): string {
  return formatNumber(value, { decimals: 1 });
}

/**
 * Format resolution (handles array or single value)
 */
export function formatResolution(value: unknown): string {
  return formatArrayNumber(value, { decimals: 2, suffix: ' Å', selectMin: true });
}

/**
 * Truncate long text with ellipsis
 */
export function truncateText(text: string, maxLength: number = 120): string {
  if (!text || text.length <= maxLength) {
    return text;
  }
  return text.substring(0, maxLength) + '...';
}